Battery Mixing integrating Lithium Lifepo4 AGM or Gel

[Screen Saver]

Dlochner: Hi Dave you didn't comment on the oil filter I mentioned before Did you agree or see my point. Many don't so Im used to that.
Yep your 100% correct not mainstream not tested, and a risk. Anything new is like that
I'm not setting off, well I did some 10 years ago, so untested is not exactly new to me. I'm on a number of manufactures Beta programs, so Im a little used to covering my arse in the event that the new product I'm testing doesn't work. This will be done with a fall back strategy and monitored. Life Insurance.. perhaps I need to add that to my risk analses....
Guys I'm keen to know what you see is worst case, as long as you also tell me technicaly how that might eventuate.
While Im not rich I cant see anything threating my life, or the boat for that matter, only my pocket burn.
I like to think those major risks I have catered for.

 

[dlochner]

Dlochner: Hi Dave you didn't comment on the oil filter I mentioned before Did you agree or see my point. Many don't so Im used to that.

I wanted to check out the specs myself before responding and simply haven't had the time to do so. I've had a busy work week and I'm out of town on an outfitting/refitting shopping trip. It is on my To-Do list for tomorrow when I'm home.

As for your plan, I'm simple is better kind of guy. The more complicated it is, the points of failure there are. What you plan to do seems unnecessarily complex. If it fails and you are near land supports, it may not be a big deal. Somewhere in the middle of the Pacific and it fails, it is a whole different problem. But if the system fails, then the effects of that failure affect many people, from you friends and family to the people who will be looking for you and paying for it. As the saying goes, its your boat, your life. If things go well, all is fine, if not the aftermath reaches beyond you and your boat.

 

[SG]

Yanmar 4JHTE - Oil Filters

Hi Dave, Yea, been there done that as they say. This is exactly my point. Im sorry to say the one they show as compatible for my 4JHTE (and your 3JH2E) is no where near it. Yes it fits, but that all you can say about it. Its NOT compatible.
Short story version; I go to buy new oil filter, tell the guy I want one of these (non original after market) , he says yep here ya go and whats it for. For Yanmar, he takes the filter back, says which model. 4HJTE, he says that's not compatible, and more over he says none you buy here will be (same in Ozy by the way). He says I can sell you anything anyone one can, but it wont be right and they wont know or tell you. He explains 99% of oil filters have a filter by pass built into it, so if the filter blocks, the engine at least still gets oil. Weeeee news to me but makes sense. He says modern day diesels run a much higher oil pressure than they did years ago. After I provided him a number of alternatives I had used in the past, he said all of those were a waste of time you need not have bothered, they all have a relief valve that is under 40psi and hence it will be in bypass mode as soon as the motor starts. Stunned I checked up my self, he was right all had the pressure relief valves well under 40psi ( about 11psi in the case of Wix where you pointed me) and all would have been doing nothing. I then check the Yanmar one and yep it was up around 55 as I recall. Many do not believe my story and live on the fact they have always used x y z. Check it yourself, Oh and its not just the 4JHTE by the way, I checked yours too, bypass is 11-14 your engine should be running at greater than 25 PSI, possibly as high as 65, so if your using there filter I suggest its doing nothing for you.

Where where and how were you measuring the oil pressure?

As I recall the pressure bypass (or relief) valve is in the center of the filter. The filter's relief has a bypass spring in the filter is designed to open based on the differential in pressure between the outside of the element and the center of the filter. I think that is called PSID. That's not the general sucking pressure.

The absolute pressure isn't, in and of itself the issue for the valving. You need the filter media and the valve to each do their own thing -- the valve is to little, except when it's called-up on (hopefully relatively rarely). The media is to take the vast bulk of the flow.

Diesels operate at significantly higher oil pressures than similar gasoline engines for a variety of reasons. The pressure itself is, within reason a good thing -- to a point. (See bernoulli's principal, for your amusement and/or information below.)

Moreover, if the filter isn't doing much, then you'd never need to change it -- and it wouldn't get dirty because the pressure relief valve (a/k/a bypass) wouldn't drag the dirty oil through the filter. That obviously doesn't happen on properly designed filters.

Benouilli's Principle (or Law) might be at play.

• 
  3:37
  
  Bernoullis Principle and Fluid Flow, Explained
  YouTube

There is a little video on this (you can search the web for many more) that explains some conceptual differences in oil filter design:

 

[walt]

As for imbalance between the AGM and Lithium, or to stop significant draining of one to the other, 40amp Shotkey diodes have been used, or DC to DC chargers.

A few possibly unimportant observations.. Those diodes you mentioned will have some voltage drop when forward biased.. like .3 to .4 volts when higher current is flowing (and its temperature dependent). Currents higher than 40 amp were mentioned and Mainesail's article also mentions FET switch current limitations in the LI internal circuits.

Batteries have a voltage temperature dependence and I did not check myself but the two different technologies may not track each other. Lots of voltages were mentioned and at least for lead acid, those voltage change with temperature. How good is the tracking between technologies. And do those Shotkey diode voltage drops need to be considered?

edit to add that generally higher current charging will monitor the battery voltage partly because the act of charging can change the battery temperature. You likely only have one temperature sensor per a charging source. Which technology should this go on?

Also, good for you to post an experiment. We all might learn something. I was wondering what is the benefit you see from mixing the technologies? What do you see as the problem you are solving?

 

[Screen Saver]

Hi Dave, Yes in principle I agree simple is more often better, but Lifpo4 and its management and charging is already fairly complicated. So all I’m really doing is leveraging off necessary management requirements. And building some redundancies in to cover things like house battery disconnects etc. If I just headed a post redundancies for LifePo4 for example many wouldn’t have thought twice, but because I dare to include AGM as apart of delivering that, there instant concern. Lithium is not for those who need simple in my, not yet anyway.

SG I’m not getting you point on the oil filter post it has lost me, sorry, the video clip first one demonstrates principle related to fluid dynamics and hydraulics. The second one is part of my point. Your oil pressure gauge if you have one show the oil pressure in the system, Are you trying to tell me that pressure is not sitting on the relief valve.. If so please explain for dummies. (or perhaps we should open another post ? Also in fact older diesels did not operate at higher oil pressures, ala tractors buldozers etc. My understanding is oil pressure should roughly relate to RPM, diesels typically slower so pressure can and was less often below 30 psi. Modern day diesels aka Yanmar are typically higher. Anyway happy to agree to differ or be corrected.

Walt: Yes the diodes will have some drop and this should be taken into account, as do shunts that most people forget about. I agree 100%. This of course applies to other charging systems such as solar, wind etc as well, you just may not know it. Yes agreed again those FETS are at the top end and there are limitations. Again these probably exist in your solar or wind controller already. Yes temperature sensing is a bit of an issue, even within a non-bespoke design as many BMS (Battery Management Systems) have only 1 sensor, So you could have 4 cells in bank, and perhaps 3 banks with one sensor. For the most part temperature sensing is not for the cell its for the bank and if you have 3 banks you have a problem. It would seem only the far more expensive BMS systems and after some effort can you find systems with multiple sensor capability. Environment temperature unless your pushing min max limits or going to charge in temperatures down around 2 or 3 c are not a problem. Its really cell temperatures Im interested in.
Yes I have no problem with posting experiments, even if they go wrong, we all learn.
So why am I going down this road what am I looking to solve. Really this was started by someone else around the bar, then I lost one of my 260AGMs which are only approaching 4 years old, but work hard. By the way there was 1 battery temperature sensor on my system, and of course it was on the middle battery, and it was an outside one that swelled up. So why would I replace the dead AGM with another new one, when I can in fact replace it with 200amp of LifePo4 for a very similar amount, and really I did not want to front up and replace all my AGMs. So how does one get there feet wet as they say. I was taught don’t try to prove your own theories, but try prove the inverse or the other guys theory who is knocking your own…. Ie you cant mix the technologies…So it was born 200 amp LifePo4, and 520amp of AGM’s now at about 70% efficiencies. Since inception at the bar the ground swell has now grown, so in all the order is for some 70 odd 200 amp cells. Contrary to many readers here, one of the important factors is to consider what will happen and what will you do and what will be destroyed “IF” the BMS takes your Lithium off line. Picture your house bank was switched off completely, you would possibly blow your alternator up, you may lose all your instruments, possibly depth sounder GPS, chart plotter, computer nav lights etc may all go off. The simplest way to combat that is… retain an AGM !! (an accept principle) that can not go off line just as your coming into the port at night in shallow water between reefs that you swore you never do again. Or build multiple banks and multiple BMS systems….. ie redundancies redundancies and more redundancies.. Ultimately I am doing both.

 

[SG]

SG I’m not getting you point on the oil filter post it has lost me, sorry, the video clip first one demonstrates principle related to fluid dynamics and hydraulics. The second one is part of my point. Your oil pressure gauge if you have one show the oil pressure in the system, Are you trying to tell me that pressure is not sitting on the relief valve.. If so please explain for dummies. (or perhaps we should open another post ? Also in fact older diesels did not operate at higher oil pressures, ala tractors buldozers etc. My understanding is oil pressure should roughly relate to RPM, diesels typically slower so pressure can and was less often below 30 psi. Modern day diesels aka Yanmar are typically higher. Anyway happy to agree to differ or be corrected.

The pressure relief valve, as I understand it, isn't a function of the absolute pressure; rather it's the differential in pressure that it's functioning on.

The actual pressure across the filter -- is different because of bernouli's principal. The bypass has a different flow within the filter, anyway (greater the flow, lower the pressure -- lower the flow- greater the pressure.). IF the system is STOPPED-up (or essentially so), then the pressure is (more) even -- one of the laws of hydraulics. When thinks are flowing, different things are happening. The closer to STOPPED, them more it's even in the system.

 

[Hayden Watson]

...SG I’m not getting you point on the oil filter post it has lost me, sorry, the video clip first one demonstrates principle related to fluid dynamics and hydraulics. The second one is part of my point. Your oil pressure gauge if you have one show the oil pressure in the system, Are you trying to tell me that pressure is not sitting on the relief valve.. If so please explain for dummies. (or perhaps we should open another post ? Also in fact older diesels did not operate at higher oil pressures, ala tractors buldozers etc. My understanding is oil pressure should roughly relate to RPM, diesels typically slower so pressure can and was less often below 30 psi. Modern day diesels aka Yanmar are typically higher. Anyway happy to agree to differ or be corrected.

The bypass in the filter is regulated by the difference in pressure of the oil on the pump (before filter) and the engine (after filter) The bypass is a small plate that has oil pressure on both sides and the difference in this pressure is due to the thickness of the oil and the degree that the filter media is plugged. There is a small spring that controls at what difference, the bypass opens. When the filter is clean and the oil is warm you will have very little difference (60psi/59psi i.e. 1psi difference) so almost any spring will work. The primary purpose of the bypass is to prevent oil starvation on cold startup. In very cold weather with a high bypass valve pressure(55psi), the oil is like molasses and will not go through the filter media so you get a large difference (60psi/10psi i.e. 50psi difference) so a 55psi bypass will not open and the bearings get nothing until the oil warms up enough to go through the filter.

 

[dlochner]

Hi Dave, Yea, been there done that as they say. This is exactly my point. Im sorry to say the one they show as compatible for my 4JHTE (and your 3JH2E) is no where near it. Yes it fits, but that all you can say about it. Its NOT compatible.
Short story version; I go to buy new oil filter, tell the guy I want one of these (non original after market) , he says yep here ya go and whats it for. For Yanmar, he takes the filter back, says which model. 4HJTE, he says that's not compatible, and more over he says none you buy here will be (same in Ozy by the way). He says I can sell you anything anyone one can, but it wont be right and they wont know or tell you. He explains 99% of oil filters have a filter by pass built into it, so if the filter blocks, the engine at least still gets oil. Weeeee news to me but makes sense. He says modern day diesels run a much higher oil pressure than they did years ago. After I provided him a number of alternatives I had used in the past, he said all of those were a waste of time you need not have bothered, they all have a relief valve that is under 40psi and hence it will be in bypass mode as soon as the motor starts. Stunned I checked up my self, he was right all had the pressure relief valves well under 40psi ( about 11psi in the case of Wix where you pointed me) and all would have been doing nothing. I then check the Yanmar one and yep it was up around 55 as I recall. Many do not believe my story and live on the fact they have always used x y z. Check it yourself, Oh and its not just the 4JHTE by the way, I checked yours too, bypass is 11-14 your engine should be running at greater than 25 PSI, possibly as high as 65, so if your using there filter I suggest its doing nothing for you.

Dlochner: Hi Dave you didn't comment on the oil filter I mentioned before Did you agree or see my point.

Had time to look up the specs.

According to the Yanmar Service Manual for the 3JH2 series, the oil bypass valve setting should be between 11.38 to 17.06 psi.

According to the WIX website, the 5138 filter has a bypass valve setting of 11-14 psi.

The WIX 5138 certainly seems to meet the Yanmar specs. It will potentially release unfiltered oil before the max pressure that Yanmar specifies, however, dirty oil is better than no oil.

Edit: Added the original quote from @screensaver about oil filters.

 

[Screen Saver]

Update 11/3/2020:
So I finally received my LifePo4 Batteries and BMS, Battery Management systems. As of this moment they are installed and running for the past 2 or 3 days. Although physical lock down is yet to occur.
Attached you will see what I received. 8 x LifePo4 batteries (total 400amphrs ), 2 BMS units, 1 Bluetooth module (should have been two) 1 USB interface ( should have been 2)
Some slight damage to the connector pins on the board, but no damage to the external packaging.
Each BMS is capable of delivering approx. 150amp continuously.( so 300amps in my case)

So the instillation is effective 2 x ( 4 lifePo4 cells @ 200amps, 1 BMS unit, 1 Bluetooth module, 1 USB Module)
The Bluetooth or USB modules are used for monitoring a pack of batteries at a cell or pack level.
On arrival all batteries were within 0.01 volts of each other.

In order to pass 150amps through a circuit board it needs fairly substantial
cabling and or connection points. So in my case I used 3 x 6mm cables for each high powered connection on the module and ran those into 1 x 000guage lug that was used on the original AGM batteries. You can see this in DSCF7431 along with the small leads that go to the individual cells for monitoring each cell. So quite simple really once you have the cable and lugs etc. In my case each was crimped and soldered.

All 8 cells (400amphrs) fitted in less space than the single original AGM (220amphr) battery was, and of cause I could actual lift the 400amps of LifePo4's easily, where as I could just with much effort lift the 400amps of AGM

Having got them in place with the small monitoring cables connected, the instruction suggest to make sure the output at B- & C- are the same. In my case they were not. So effectively no output from the BMS module. After installing the BMS monitoring software on my Android Tablet it became apparent that the BMS thought the temperature was -30c and hence disconnected the BMS, so no output. This turned out to be because the temperature sensor on one BMS module has been left off in the factory. So that is on its way to me as I write. However the other module worked fine. I later discovered that within the BMS software you can control many things, one being temperature shut off etc. So on the BMS unit without temperature sensing I simply change the parameter for cut off to -50c and it fired up no problem.

As you will may know part of my intention was to try a highbred system of LifePo4 and AGM. In order to have a stable and supported installation at this point the old AGM's are disconnected. This will come latter.

So at this point they are in connected and running the boat.

Coming up configuring:

 

[Screen Saver]

11/3/2020. Configuring my installation of LifePo4's

The BMS software, in my case xiaoxiang V3.1 is essential because if for what ever reason the BMS shuts down, either discharge or charge sides then at least at this moment it doesn't restart again until you switch it off and on via the BMS software. So as you may have read before elsewhere its is possible that the batteries become disconnected and hence you lose power. Just one reason for retaining some other battery, perhaps AGM/Gell for the start battery bank. So far mine has disconnected twice, once on intial install due to the temperature sensor missing, and once when I disconnected the negative lead of the batteries to re-route the cable. When I reconnected the negative lead it did not automatically come back. I suspect this is a setting in the BMS unit.

So effectively you can change all most every parameter, which is both good and dangerous, so one must be careful.

So in my case I have left the majority of BMS parameters as they came with its defaults for LifePo4.
However I have made the following changes;

I have changed temperature sensing due to a missing sensor.

I have also configured AMP hrs of the pack to 200amp
Overvoltage to 3.65, (14.6v) they should be able to sustain undamaged at least 14.8 for a relatively small period
Under voltage to 2.7 (10.8v) Both of under and overvoltage changes are I have done at cell and pack level
In essence the above changes are less stressful than the defaults it came with.

The software tracks and plots by graph all of the above, so once I have run for a weak or so, I will make more favorable changes, ie reduce overvoltage and increase under voltage. So these were my starting points.

Next was charging off of mains. I have a Link 1000 capable of around 150amp sustained charging. However at that rate even my AWG000 gets warm, so I typically contain charging to under 120 and ideally around 100amps. My link has no idea about Lithium batteries, it only knows conventional, Gell, AGM. So I have chosen Gell as its parameters are quite close to LifePo4, although not the same. With the Gell settings I can change the charge voltage so I have set this to 13.8v and again this is within LifePo4 specs.
When I turned on the mains charger my LifePo4's tried to suck up 180amps (90 each bank) even though they were far from flat, so I had to throttle back the charger, as I was not keen on pushing that out and also if I try that in a marina where power is not that great I will trip breakers, or possibly cook things. So it now puts out 100 amps and quickly drops back to 90 until almost full. In the case of my mains charger it considers full when it reaches the charge voltage and the current/amps input is less than 2 amps going into the battery. All of which is programable.

Next was the solar charger. I have approximately 1KW of solar. At the best I have noted I can produce about 80amps on top of what the boat draws at anchor. Regulation is done via 2 xantrex solar regulators. Again all 3 stage chargers but know nothing of LifePo4. On close examination and during setting these up for LifePo4 I discovered that one of the xantrex was trying to take the batteries up to well above where it should in 15volts. I now suspect this has happened probably when I was not on the boat, and it was on mains charger, and the solar took the Gell's to high causing it to fail. At least in the new system the BMS should shut this off before hand so even if the solar xantrex does this again it should not damage the LifePo4's

I discovered the above when I charged up LifePo4's on the mains charger and switch on the solar charger. Normaly both live together fine, but as I watched one charger did not stop at what should have been the top of the bulk charge. A bit of electronic cleaner sprayed on the adjustment trim pot and all was fine again. So both of these have been set to a bulk (ie top voltage) of 14.1v which should be ok AGM Gell and LifePo4.
Because these chargers do not know about LifePo4, they have float levels. In my case these are set to 13.4v, a little low perhaps for AGM or Gell depending where you read, but a good middle ground. Leaving LifePo4's on float has much debate, so in my case because we live aboard typically any float would be for a short period. If we leave the boat for some time I may need to reconsider/research float levels in regards to LifePo4.

So right now I'm on solar and monitoring all systems over the next week, both on the Bluetooth Battery Management System (BMS) and on the xantrix.
I consume 90-100amps from the time Solar stops till it starts again in the morning. So Im figuring on my 400amps of LifePo4 I probably have at least 3 days of no sun, maybe 4.

Once this is stable and been running for a bit I will then look at the Gell's.
I have chosen my settings to best suit my old batteries without compromising or risking the new LifePo4's
I also have the ability to monitor my Gells

I will let you know how that goes when I get there.

At the moment I am somewhat occupied trying to figure out if I must abandon my current trip to Taiwan and Japan because of all this paranoia... ops I guess that will get some comments.

Take care fair sailing to you.

 

[Will Gilmore]

Thanks screen saver. An awesome couple of posts and a great thread. I can't wait to see how your mixing experiment comes out.
I, with no knowledge or experience with battery science, believe it's doable.

-Will (Dragonfly)

 

[Screen Saver]

Preliminary results of combining LifePo4 & Gell (AGM should be very similar)

Firstly from an input parameter view most of the figures will vary depending on manufacture and supplier, and a number of you will Im sure disagree with the below figures, so ultimately you should use your manufactures figures.

In my case I have used the figures below as rough guide..
Charge min-max- damage Float Fully @ rest Dead Flat
AGM 14.4 -14.6 14.8 13.5 13.8 12.9 10.5
Gell 14.1-14.4 14.52 13.4 13.8 12.8 10.5
Lithium 14.3–14.4(cut off) – 16.8 13.4-13.6 13.2 10v Cut off

If you add a lifePo4 battery configuration with a battery management system (BMS) even if your charger does not perfectly line up with your battery specification you can use the BMS to protect/stop charging. But if you have any control at all over your charging systems then you should be able to fine tune them. If you don’t and you have a Gell setting, I would use the Gell setting. Remember to do this for ALL of your charging systems. Solar, Wind, Engine, Mains power etc.

For example if you had an AGM setup and wanted to integrate LifePo4, then the charging voltage for your AGM batteries is probably higher than you would ideally like to use on your LifePo4 ( although they should sustain it). So if you cant turn it down a little then via the BMS you can set it to disconnect charging of the LifePo4 at any voltage you desire and hence insure the LifePo4’s are not over charged. Roughly the minimum charge for AGM is around the maximum charge for LifePo4 without causeing damage to either.

This cut off concept in the BMS applies to over and or under parameters (ie going flat) charging or discharging states or levels.

In my case I have run on LifePo4’s with my Gells completely disconnected as a starting point. I then connected 1 Gell in parallel via a Digital Amp meter capable of sustain 20amp-25amp load.. This was essentially so I could see what was coming or going from the Gell’s. So I have 4 amp meters in use. One reads the total boat house current, 2 others read the BMS current supplied/consumed by each bank of LifePo4 and lastly another for the old Gells.

When the Gell was first added back in some 30 amps passed from LifePo4 to Gells dwindling down to next to nothing, and now the 3 banks Lifepo4 x 2 and the single Gell are all sitting at 13.4v, 13.5v


Charging:
So essentially from a charging view I can see no problem (to date) with integrating LifePo4.
In my case I have set cut offs to ensure if for any reason the desired LifePo4 specifications are about to be exceeded, then charging is cut off . In theory this should prevent any damage. At this stage I have had one LifePo4 cell get a little out of balance and currently looking at the in’s and outs of top and bottom balancing.

Discharging;
The behavior of LifePo4 under discharge is vastly different to any of the other battery types noted above. In my case I typically consume in excess of 100amp/hrs between sunset and sunrise. LifePo4 maintains roughly 90 % of its voltage, for 90% of its capacity. So with 400amp/hrs of LifePo4 which will maintain a voltage in excess 13v, very little of my 100amp consumption is supplied by my Gell.. Of the 100amps consumed over night less than 20amps came from my Gell. I assume as LifePo4 starts to run down towards 12v more and more will be supplied by the Gell.

I have yet see the behavior over different conditions or levels of consumption, but at this early stage it would seem to be a workable configuration.

Benefits:
At this stage it would seem the main benefit’s might be;

1. Most definitely the LifePo4’s are lighter, smaller and seem to be able to deal with higher currents for longer periods. I initially ran the boat on 1 x 200amp LifePo4 pack. I could not have done this on 1 x 200 amp AGM or Gell as it would have been running the AGM,s/Gell,s down to just over 50%, which is not good for there longevity. However LifePo4 deals just fine with this.
2. There is some information in regards to LifePo4’s shutting down or disconnecting if you do some research. If my LifePo4’s disconnected for any reason my old batteries will be sufficient to keep Nav gear and all that running which is obviously very important and in fact from my personal view very dangerous to not have some conventional battery support..
3. Again if LifePo4’s disconnect my 150amp Balmar alternator will not destroy the diodes because it has no where to send its current to, it will got to my Gell.
4. The monitoring software provides a very clear picture of your batteries and provides independent control of every parameter you will want. On either AGM or Gell you have no in site into the battery. The only thing I have found mildly helpful is the temperature sensing guns. You can point it at the different cells and get an idea of cell temperature difference and hence failures.

Negatives:

1. In my case mounting and trying to secure 8 batteries properly takes a bit of effort, plus mounting the BMS where its not going to get damaged or wet.
2. Connection is more complex for sure, but not beyond anyone if they take there time or in the worst case outsource the manufacturing of a few heavy duty cables
3. A conventional battery almost never goes off line or disconnects. These most definitely can disconnect just as if you’re main positive cable fell off. You can imagine the impact of that at the wrong time. So one way or another this must be addressed.
4. To manage the batteries via the software you need either a PC (USB) or Phone(Bluetooth). The phone (android) in my case is connecting via Bluetooth to the BMS. That works well. However I use that same phone to provide a mobile hotspot for internet and for Anchor watch. When Bluetooth is on my Wi-Fi Hotspot suffers performance wise and my anchor watch sometimes loses GPS, so it says Im dragging. I have now installed the software on my backup mobile which sits permanently at the chart table now.
5. While the BMS software is very good to look at and manage parameters, it seriously lacks any proactive alarms. All good while your looking at, and it will protect the battery if you have happy hour, but it wont beep buzz bitch if anything actually gets out of control.

Summary:
As I suspected and in spite of all those saying you can’t do it, or looking for the glow where I was, its done.
Moreover looking at the behavior and parameters I cant see any potential issues either.
It maybe the lower requirements of Lifepo4 levels are insufficient for AGM/Gell . So as a result you maybe shortening your life of the AGM’s or Gell’s. However one only goes down this road typically if there existing batteries are suffering, or they are looking to add amphrs. I doubt these lower settings will cause any damage to the existing Gells, but only time will tell.

In fact I now see NOT having some form of alternative /integration (ie Gell/AGM) to cater for disconnection as being somewhat reckless and should be a mandatory requirement.

Other than responding to questions etc I will not be updating this now for a month or so unless something significant creeps out of the woodwork.

I’m happy to answer any questions, take any criticism you may want to point my way.

 

[Hayden Watson]

Any updates on how your system is working?

 

[Screen Saver]

Hi Hayden,
Not a lot really at this point. I have had now both Gells fully & permanently included at least a week and have been watching the LifePo4's very closely to ensure I don't damage them. Because the manufactures peak working voltage specs on the LifePo4's are a little less than those of Gell' and I have enforced conservative & rigged cutoff protections and cant at this point see any behavior of concern. It perhaps maybe true my Gells are not seeing the full charge voltage they should have at this stage, given my conservative values. The LifePo4 supplier/manufacture has been very conservative in his charging discharging and cut off figures, which I'm using. However other manufactures and throughout the internet have higher and wider figures being quoted. In the end I don't need to take it up much to meet Gell or AGM requirements, so I may wind it up a bit at a latter. But for me slowly slowly, or the above readers might be right and say I told you so

As for the benefit, Im not sure that its actually that much. At the moment The LifePo4's are doing probably 90% or more of the work. Part of this will be the age of my Gells but much of it is the Characteristics of LifePo4. If you have some monitoring equipment on your current batteries and just look at the voltage you have, in very broad and rough terms anytime your existing (non Lithium) battery voltage is below about 13.1 13.2v the LifePo4's if they were there would be doing that work ! I dont think anyone would argue that a fully charged "AT REST" Gell or AGM Led Acid would be much less than that, in which case LifePo4's are doing the work.

Its hard for me to be accurate but from what Im seeing no more than 10% possibly 5% of my consumption is comming out of my old batteries.

However the big advantage and I think sufficient in its own right is that if the LifePo4's go off line, the boat does not suffer a blackout just at that crucial time entering a reef, or one of those night entries we shouldn't be doing, and I don't risk blowing up my Balmar alternator.

So far;
Would I go down the combination road again ?..... yes definitely, something is essential to cover Offline risks

Am I getting the added benefit I expected of the added amps/hrs from my old batteries by the combination ? .... No minimal in terms of amphrs at this point. It may change at under bottom end testing.

What would I do differently; ......... I would probably look to reconfigure my setup such that instead of covering Lifepo4's off line risks wiht house Gells/AGM, I would try to cover it via the start battery bank also Gell/AGM. Im not sure how I would do this at this point.

What else am I looking to quantify..... I have done measurements as to the value of retaining integration (ie LifePo4's and Gells) when the capacity of LifePo4's is above 50%. I have yet to do tests when the system gets below this, which should be fine for LifePo4's and should give the Gells some more work to do and add some value. But this is unproven at this point, just my theory.

Hope that helps

 

[Hayden Watson]

Hi Hayden,
...Its hard for me to be accurate but from what Im seeing no more than 10% possibly 5% of my consumption is comming out of my old batteries.

However the big advantage and I think sufficient in its own right is that if the LifePo4's go off line, the boat does not suffer a blackout just at that crucial time entering a reef, or one of those night entries we shouldn't be doing, and I don't risk blowing up my Balmar alternator...

Hope that helps

The "uninterruptible service" has always been what i see as the biggest advantage of your scheme. Both the stay alive for systems and diode protection for the alternator are critical functions.

 

[Screen Saver]

I also believe we have been conditioned to the requirement of a BMS, which is effectively what takes the batteries off line. The actual real need for this is in my mind questionable at best, although it does have phycological benefit when you look at it on the screen

For example much of the paranoia among boaties ( and others) with Lithium is the perceived risks with this technology, and 90% of that is coming from Lithium batteries, but NOT lifePo4 a completely different chemestry. While I personally can not say I have tested there destructive or self destructive characteristics, if what the so called experts and manufactures say is true, LifePo4 can not explode, catch fire etc any more than the other batteries. Yes a short circuit can see extreme currents, also true of my Gells and other technology.

Thermal runaway I have experienced on Gell's from overcharging, it wasn't that far from burring a whole in my friends yacht. There is much tado about balancing, if you have ever run across your batteries with a heat measuring gun on your Gells/AGMs you would notice a difference in temperature, that is an out of balance cell, or the specific gravity on a led acid. So why are we panicking about this on LifePo4's

As far as Im aware I have not seen or herd of anyone having a BMS system for there Gells or AGM's other than the ability to control there 3 stage charger. So we are conditioned to think we must have this device for LifePo4's to protect them, why do we not also need it to protect our AGMs or Gells.

Im sure there will be many who will also shoot that down, but I see no bases for it, as yet, assuming LifePo4's are as safe as what is suggested. So if the safety aspect is correct why is it we need BMS and don't for the others.
Without BMS;
No need to worry or protection against the system going offline Batteries cant go off line.... as with a coventional setup.
No risk of blowing up charging devices.
No need to have an APP configured and running on some device in case the batteries do go off line.
In my case instead of 2 banks of 4 individual cells, i would build 1 bank of 8 cells by connecting 4 banks of 2 batteries in parralel, this would help with balancing.

I may consider more seriously this concept in a few months and try and find some reputable or scientific evidence to support there safety aspects or better define the risks differences and better understand what the implications are. To date I haven't really dug around for this.

Over the years I have tended to find that many protection systems are set unnecessarily high, even in very basic area's. This boat was delivered with 500amp main fuse on the 12v side. This is crazy. I replaced with 250amp, it has never blown, and probably would be fine with 150amp, but I bought two 250amps ones. My genset shutdowns both thermal and electrical were also unnecessarily high and by setting these down defiantly saved me having to have heads machined gaskets replaced, and very expensive diodes in my Xantrex charger etc.
My LifePo4's I would fuse at around 150amps. I might have to condition the wife not to hit toaster and Microwave at the same time though.

So if I was to seriously consider the non BMS road I would among other things monitor and track my actual loads and fuse accordingly as I did years ago. Given I have 2 x BMS units, I would take an interim step and leave the BMS units there to monitor but bypass them. For sure if one of these BMS units dies I will do exactly the above and by-pass BMS and have considered adding a 250amp switch just in case that happens.

I would make sure I at least had visibility of the house bank voltage and current (which I do by default without BMS), and add thermocouple so I new the temperatures was not running away, although even as I type that, I ask my self why I didn't do that with AGM/Gell. All of cause assuming I find no firm reason why I should treat LifePo4 as something that needs kit gloves or it will go bang any more than 800amps of Gell or AGM for example. If such proof exists BMS is a must I think.

 

[Hayden Watson]

I am not too convinced that eliminating the BMS is a great idea. My thinking is that the primary purpose is not safety as much as it is to protect the cells from over/under voltage. I have been lead to believe that the LiFePo4 cells do not handle that as well as some other technologies and the unit cost makes me want to protect my investment.

 

[Maine Sail]

Your alternator only works when the engine is running. The simple solution is to install a Sterling Alternator Protection Device, and then, for cheap insurance, a $20.00 solenoid/contactor can be wired between the GEL bank and the LFP bank that is only energized by the engine run position of the engine panel. This only places the GEL in parallel with the LFP when the engine runs, not 100% of the time. Engine/Alternator on, LFP in parallel with GEL. Engine/Alternator off GEL bank isolated.

 

[Hayden Watson]

Your alternator only works when the engine is running. The simple solution is to install a Sterling Alternator Protection Device, and then, for cheap insurance, a $20.00 solenoid/contactor can be wired between the GEL bank and the LFP bank that is only energized by the engine run position of the engine panel. This only places the GEL in parallel with the LFP when the engine runs, not 100% of the time. Engine/Alternator on, LFP in parallel with GEL. Engine/Alternator off GEL bank isolated.

Wouldn't that defeat the idea of keeping the electronics working in the event of the BMS shutting down the LFP?

 

[Maine Sail]

Wouldn't that defeat the idea of keeping the electronics working in the event of the BMS shutting down the LFP?

This is only to protect the alternator when the engine is running. If your LFP bank feeds the house loads/electronics and it shuts down, it shuts down because something is wrong. This is why we always design with a reserve bank that can be brought on-line in-case of a BMS or LFP failure.

The problem with permanently paralleled LFP and LA is one of a shorted cell in the LA bank. We've seen this happen, with LA batteries, as has the OP, and even with LA batteries in parallel it can lead to thermal runaway. If we now connect them to a Li-Ion battery with an even higher voltage, and one that does not plummet even under high load, the current flow between the Li-Ion batteries and lead acid failed battery is increased.

This was after the shorted battery had been electrically isolated and cooled down a bit:

With LFP having a higher working voltage than LA, the risk of an LFP battery dumping it's energy into a failed/shorted LA battery can be dangerous. The ABYC may even disallow paralleling of LA and Li-Ion but the committee work is not yet done so nothing is set in stone.