Lithium battery question

[Bob S]

Been reading a lot on the subject as I am planning on upgrading soon. I’ve read Charging Marine Lithium Battery Banks | Nordkyn Design many times along with Rod’s How To, facebook and cruising forums. There is a lot to absorb. To those who have been running lithium for a while, I’m curious how often if ever have you experienced a battery disconnect event?

 

[JBP-PA]

Never. A reasonable design will avoid it.

 

[dlochner]

I've been running LFP full time for about 6 months. I'm still trying to figure out the BMS, unfortunately the company that made the batteries (KiloVault) is no longer.

When motoring, the BMS will disconnect when the battery is fully charged or near fully charged. It seems to taper the charge acceptance before disconnecting. When motoring there is always a load on the system, instruments, AIS, VHF, AP, etc. So I don't think the regulator notices the disconnect. To the best of my knowledge I have never had a disconnect at a high charging rate. Nonetheless I do have a Balmar alternator protection device installed.

Thanks for the link, I'll have to spend some reading it.

 

[Ralph Johnstone]

Nonetheless I do have a Balmar alternator protection device installed.

I don't get out much but I'm wondering why you couldn't just have a small load of, say 1.0A resistive load permanently attached to your alt. output to avoid having the alt. run with 0.0A should you experience a disconnect while charging.

 

[dlochner]

I don't get out much but I'm wondering why you couldn't just have a small load of, say 1.0A resistive load permanently attached to your alt. output to avoid having the alt. run with 0.0A should you experience a disconnect while charging.

The issue isn't the alternator running with no load, if there is no load the there is no circuit, can't make electricity if those electrons can get back to where they came from.

The answer is in Ohm's Law, E = IR. Voltage is equal to the amperage times resistance. When the resistance (load) goes from some number to infinity, the voltage spikes, because anything times infinity is infinity. Alternator innards can't handle infinite voltage. The Alternator protection module simply sits there minding its own business until there is a voltage spike at which it provides a load and dumps the voltage to ground thereby protecting the innards and saving the alternator. How the module does this is mostly a mystery to me.

 

[Bob S]

I'm still trying to figure out the BMS, unfortunately the company that made the batteries (KiloVault) is no longer.

I bought a 325w solar panel from Alte. I could drive there. I was planning on buying their Kilovault batteries but they stopped selling them. They were bought by another company, I spoke with them hoping they would continue selling batteries. I ended up buying 2 300ah Vatrers from Maine's link on black Friday less than what I paid for 6 GC batteries 8 years ago.
I'm curious what app you use for the BMS. I set mine up with Overkill Solar. I'm assuming most batteries being sold now are using JBD BMS's. The Overkill Solar app can configure a lot of features in the BMS. Have you tried that?

 

[dlochner]

The batteries I have a built in BMS, I really don't have access to the settings. In light use it seems like it's trying to keep the SOC at about 70%. The OverKill looks like it is for batteries without a BMS and homebuilt batteries.

 

[colemj]

Our lithium bank is almost 9yrs old and we have never had a disconnect event. Like mentioned, a properly designed system will never disconnect outside of preventing a catastrophic failure like an internal cell going bad or a charging source going rouge. The whole bank disconnect should be considered a last effort to save the system, and not a routine event when the batteries are full.

Instead, either the charging sources should be set to shut themselves down appropriately, or the BMS should control a charging bus or the charging source itself and shut only that down. If you have an internally regulated alternator without any control of its charging and its regulator is set higher than necessary, then either the BMS should be able to cut its field, or the alternator should be connected to the start battery and a programmable DC-DC charger used.

Same for the opposite direction with loads, where inverters, reefer/freezers, and similar things that can be programmed to shut themselves off before the BMS needs to, and installing low voltage disconnects to other equipment (or DC panel).

This is where one needs to be careful with lithium drop-ins. Few if any have the above abilities, so more care must be made with design in other parts of the system to compensate. If you have these batteries in parallel, once one shuts down, the problem escalates on the others and a quick chain reaction leaves you with a dark boat. There are many reports of just this experience with them, and I would consider that a safety issue.

Mark

 

[Johann]

We have had our main house 12V LFP install for just over 4 years and no BMS disconnects, except for intentional LVC during capacity testing.

I recently installed a 48V system as a generator replacement and that battery is an Epoch. Unlike most BMSs which disconnect on high voltage, the Epoch will also disconnect on full charge. So when it is above a certain voltage (3.425Vpc) and charging below about 3A, it will turn off the charge FETs. This is an issue if you can’t program the charger to stop absorption based on battery tail current. The Multiplus doesn’t support that and has a minimum absorption of 1h so we initially had BMS full charge disconnects (charge FETs only, discharge remain on) and the voltage spike.

My solution for the Multi is an absorption of 54.8V (3.425Vpc) which prevents the disconnects, but takes 2h of absorption to get reasonable near 100% SOC. Fortunately for alternator charging the Arco Zeus can exit on tail current, but I just got that up and running so no experience with full charges yet.

 

[MFD]

The batteries I have a built in BMS, I really don't have access to the settings. In light use it seems like it's trying to keep the SOC at about 70%. The OverKill looks like it is for batteries without a BMS and homebuilt batteries.

I have a pair of Epoch 460AH batteries. I installed the OverKill app on my phone and it works fine. It provides more information than the Epoch app does. Can't hurt to install it and try it out? You definitely want to be able to see the individual cel voltages and such if you can.

 

[Bob S]

Searching for info on Balmar’s 614 regulator to get an idea how people have been programming them I came across Dave’s post about the temp sensor. Quite interesting and I’m continually learning. I’m designing a system trying to avoid any chance of a disconnect. My equipment is older but programmable. Attached is a preliminary diagram Using the Beneteau switches recommended by Rod.
Observation
I finished charging both batteries with a bench top power supply. I started at 13.8 v and 25 amps and if I remember it brought me to about 80+% from 51%. I increased to 14.4 and dropped the amperage to 6 amp. The app said I was 100% but the amp hours were just short of 300 See attached. I increased it to 14.6v until I got an HOC disconnect but it got them to 300ah. Not something I want to happen on the boat. I am thinking it would be best to program my charging sources to bulk and absorb @ 13.8 and float at 13.2. I think this would keep them between 20-80% state of charge. I’m more concerned with the alternator. I try not to motor if I can but last season I had a few outings were I motored 8-10 hour runs. I read that it is possible to add a switch on the brown wire of the 614 to shut the alternator down. I think I’ll start out using alternator and Solar as the only charging sources and see how it does. I’ll occasionally plug in to shore power if needed to balance and recalibrate the shunt. Any of you using older technology I’d love to know how you programmed them. Any suggestions?

 

[dlochner]

I finished charging both batteries with a bench top power supply. I started at 13.8 v and 25 amps and if I remember it brought me to about 80+% from 51%. I increased to 14.4 and dropped the amperage to 6 amp. The app said I was 100% but the amp hours were just short of 300 See attached. I increased it to 14.6v until I got an HOC disconnect but it got them to 300ah.

The BMS is probably trying to balance each cell in the battery. Over time the individual cells become unbalanced, meaning the voltages vary too much. This can be a time consuming process. My batteries which haven't seen an AC charging in months has been working at for about 18 hours now. Best to use a charger that is designed for LFP batteries. Unlike LA batteries, it is not good to raise the voltage above the manufacturer's recommendation or you get the high voltage cutoff. Patience is the key. I purchased a separate Victron charger to do the balancing and maintenance charging during the off season. This is done individually for each battery and not as one bank. On the boat, the ProNautic charger does the work.

If the regulator is programmed correctly, there should be no need to take the alternator offline. If you want that capability, then add a service disconnect to the alternator output. this is useful for disconnecting the battery from the alternator while working on the engine or alternator. Connect the power supply for the regulator to the alternator side of the disconnect. Doing this shuts down the regulator any time the alternator is disconnected from the battery. There is an article on MarineHowTo.com that describes this arrangement.

There are limits to adapting old technology to new devices. Using an old 614 to with LFP batteries may not be good choice if it doesn't have an LFP setting. LFP batteries do not need equalizing or float stages. The alternator temp control is essential. Programming a Balmar regulator with the magnetic screwdriver while sitting in some awkward position is torture and not one of anyone's good ideas. Ditch it and get a 618 or a more modern regulator or pull the 614 take it home, power it with a 12v supply and then program it from the comfort of your easy chair. Rod has an article and video on MarineHowTo.com

On the system drawing, the 100a fuse on the starter is too low, you'll get a lot of nuisance blows. Go to 250 or 300. Make sure the Max Discharge rate for the LFP batteries is high enough to start the engine. Many LFP batteries have fairly low max discharge rates.

 

[colemj]

There are limits to adapting old technology to new devices. Using an old 614 to with LFP batteries may not be good choice if it doesn't have an LFP setting. LFP batteries do not need equalizing or float stages. The alternator temp control is essential. Programming a Balmar regulator with the magnetic screwdriver while sitting in some awkward position is torture and not one of anyone's good ideas. Ditch it and get a 618 or a more modern regulator or pull the 614 take it home, power it with a 12v supply and then program it from the comfort of your easy chair. Rod has an article and video on MarineHowTo.com

We have been using two 614's for 9yrs with LFP batteries. The 614's do have a LFP setting, but they also have complete control over all the parameters. Standard LFP settings are rarely the correct settings for any individual's need. Frankly, I don't know why they include them. The 614 has the same functionality as the 618, with the exception of the possibility of bluetooth if you have a SG200 monitor, and the "Sen" function, that isn't required.

I agree that the magnet thing is a PITA, but I programmed ours once and haven't touched them since, other than to bump a few parameters on one when we replaced an alternator with a higher output one.

Mark

 

[dlochner]

I've never had a 614. Back in the day when I had 4 GC batteries I used an ARS-5 which was more than adequate. When I went to Fireflys and eventually LFPs with a higher output alternator I went with a 618, which at the time was the latest and greatest regulator. Wakespeed wasn't on the market or it if was it was in its early infancy and way too expensive for a novel regulator.

 

[colemj]

Searching for info on Balmar’s 614 regulator to get an idea how people have been programming them I came across Dave’s post about the temp sensor. Quite interesting and I’m continually learning. I’m designing a system trying to avoid any chance of a disconnect. My equipment is older but programmable. Attached is a preliminary diagram Using the Beneteau switches recommended by Rod.
Observation
I finished charging both batteries with a bench top power supply. I started at 13.8 v and 25 amps and if I remember it brought me to about 80+% from 51%. I increased to 14.4 and dropped the amperage to 6 amp. The app said I was 100% but the amp hours were just short of 300 See attached. I increased it to 14.6v until I got an HOC disconnect but it got them to 300ah. Not something I want to happen on the boat. I am thinking it would be best to program my charging sources to bulk and absorb @ 13.8 and float at 13.2. I think this would keep them between 20-80% state of charge. I’m more concerned with the alternator. I try not to motor if I can but last season I had a few outings were I motored 8-10 hour runs. I read that it is possible to add a switch on the brown wire of the 614 to shut the alternator down. I think I’ll start out using alternator and Solar as the only charging sources and see how it does. I’ll occasionally plug in to shore power if needed to balance and recalibrate the shunt. Any of you using older technology I’d love to know how you programmed them. Any suggestions?

From your drawing, you have 600Ah of LFP? When you charged them to 13.8V @25A, that should have brought them very close to full. More than 80%, so perhaps the SOC meter needs calibrating, or needs time to learn.

Here is how voltage/current works in charging LFP. At higher C rates of charge, the voltage rises faster and hits the setpoint at a lower SOC than charging at low C rates. For example, we have a 1000Ah LFP bank. If it is charging at 0.25C (250A), and hits 13.8V (my charging setpoint), then I take it to 14.4V, it takes another 50Ah or so to reach 14.4V. That means it was ~95% SOC at 13.8V.

However, if I charge it at 0.04C (40A) to the same 13.8V, then take it to 14.4V, it only accepts another 5Ah or so, which means it was at 99%+ SOC at 13.8V.

Your 25A was ~0.06C, so when it reached 13.8V, it should have been ~98% SOC.

As for using "older technology" regulators, ours are set to charge to 13.7V, hold for 10min, then got to 13.2V float (basically shut down). Doing this shuts the alternators down when the battery is ~90% SOC, and I purposely did it this way because we have a lot of solar that can take up the last bit in a few minutes, and the alternators aren't our main charging source.

The regulators shut themselves down, so you don't need a disconnect for them. You can motor for days and they won't overcharge. One use for a disconnect (power interuption) is that it can be used to reset them to start charging again if you want.

Mark

 

[Bob S]

Make sure the Max Discharge rate for the LFP batteries is high enough to start the engine. Many LFP batteries have fairly low max discharge rates.

Dave,
● 200A Max Continuous Discharge (500A 3s Peak Discharge). according to Vatrer. I assume this would be x2. I don't plan on starting with the house but I believe they should not have a problem if I did. My windlass has an 80a breaker on it. It's factory set that it can only be used if the engine is running. I would assume this should not be a problem either but I plan on making sure it's wired to the start battery.
Mark,

From your drawing, you have 600Ah of LFP? When you charged them to 13.8V @25A, that should have brought them very close to full. More than 80%, so perhaps the SOC meter needs calibrating, or needs time to learn.

I wish I took a screenshot of the app at each point so I was going off memory. You are right that the battery was near full. I did these individually and did a capacity test after letting them sit 24 hours. I pulled 303 and 305ah respectively.

ours are set to charge to 13.7V, hold for 10min, then got to 13.2V float

This is what I was looking for! Sounds like a good starting point. I have the voltage reg under the aft cabin bed that has a 3" latex pad weighing a ton so I will not be adjusting with any frequency.

 

[dlochner]

My windlass has an 80a breaker on it. It's factory set that it can only be used if the engine is running. I would assume this should not be a problem either but I plan on making sure it's wired to the start battery.

The factory wired it this way to make it idiot proof and to not burn out the windlass motor. Our general practice is to always have the engine running when using the windlass, but there have been occasions when running the engine was not an option. Wire the windlass to the House Bank, you have more than enough power to run the windlass without the motor running unless the SOC is really low and a lot of anchor chain is out.

 

[colemj]

This is what I was looking for! Sounds like a good starting point.

Charging LFP highly depends on accurate voltage sensing. Make sure you run the sense wire directly to the batteries, and remember that the negative wire on the Balmar is part of the sense circuit, so that needs to go directly to the batteries also.

Mark

 

[jssailem]

Looking at your Vatrer battery specs:

300Ahr Vatrer Batteries
Charge Voltage	14.2V-14.6V
Max Continuous Charging Current	300A
Max Continuous Discharging Current	300A
Recommend Charge Current	60A (0.2C)

You might think of upping the charge voltage and current to optimize the life of the batteries.

 

[Bob S]

Make sure you run the sense wire directly to the batteries, and remember that the negative wire on the Balmar is part of the sense circuit, so that needs to go directly to the batteries also.

I'll soon be checking on how it was wired originally but I have read Rod's voltage sense article a few times. The Balmar manual shows the negative wired to the alternator which is wrong. It's probably the way I wired it 8 years ago.

You might think of upping the charge voltage and current to optimize the life of the batteries.

Battery Model	LiFePO4 Battery 12.8V 300Ah
Nominal Voltage	12.8V
Charge Voltage	14.2V - 14.6V
Charging Methods	4-String Charger (14.6V), Photovoltaic Solar Panels with MPPT, Inverter (Built-in AC to DC)
Weight	26.5KG / 58.42LBs
Energy	3840Wh
Max Continuous Charging Current	200A
Max Continuous Discharging Current	200A
Recommend Charge Current	60A (0.2C)
Max Load / Inverter Power	2560W
Operating Temperature Range	Charge: -20°C to 50°C (-4°F to 122°F) Discharge: -20°C to 60°C (-4°F to 140°F) Storage: -10°C to 50°C (14°F to 122°F) Low temp cut off protection (Discharge): -20°C ± 4°C (-4°F ± 7.2°F)
Waterproof Class	IP65
Terminal Type	M8
Dimension	520×269×220mm 20.47x10.59x8.66inch

Actually it's 200A and I was thinking of bulk charging at 14.2 but after reading until i have a migraine I think it best to keep the bank between 20-80% which is more than enough ah for my needs. I also have 525w of solar. I know you're setting up a system at the same time. I'm still concerned for an over current or under current disconnect with three different charging sources and the new batteries. We have to start somewhere.