Two-battery LiFePo4 system?

[jviss]

I am thinking of going for a Victron 100Ah LiFePo4 battery for my house, and a Victron 20Ah LiFePo4 battery for the engine start battery, and wiring them per @Maine Sail 's recommendation for use of the 1-2-Both-Off switch. The question is, is there an ACR that has programmable cut-in/cut-out voltages, so I can set them to appropriate values for LFP?

 

[Garbonzo]

Why the 20 AH start, and what is the max amp draw of that tiny thing. The Victron Orion is the gizmo you need and a traditional AGM start battery.

 

[AlanSD]

The 20A Superpack has nowhere near the capacity to start a typical marine engine, the 100A High Current would be more appropriate. However, there is another good reason to use an AGM for a start battery: if your lithium battery becomes over-full and the internal BMS trips, the alternator can suffer a failure.

For charging the lithium house bank, an Orion Smart will do that, but make sure you get the "Smart" one, which has multi-stage charging. Non-isolated will save you a few dollars and is fine for most applications. Or, if your alternator output is not too high, you can use a Victron Cyrix Li-ct relay. The "Li" designation is for lithium battery voltages.

 

[jviss]

O.K., but won't the Orion be a constant load on the LFP house

The 20A Superpack has nowhere near the capacity to start a typical marine engine, the 100A High Current would be more appropriate. However, there is another good reason to use an AGM for a start battery: if your lithium battery becomes over-full and the internal BMS trips, the alternator can suffer a failure.

For charging the lithium house bank, an Orion Smart will do that, but make sure you get the "Smart" one, which has multi-stage charging. Non-isolated will save you a few dollars and is fine for most applications. Or, if your alternator output is not too high, you can use a Victron Cyrix Li-ct relay. The "Li" designation is for lithium battery voltages.

Thanks. The Victron 20Ah LFP has a max discharge current of 80A for 10 seconds; the 20A refers to the capacity, not the max. output current. That said, I don't know what will happen with te high inrush current of the starter. I doubt the BMS would act fast enough to shut down the output, but I don't know.[1]

With your suggested scheme you'd be limited to the charging output of the Orion, which is 18A, and you'd lose the fast charging advantage of LFP. I think you can parallel them, but you'd need three of them to get to the 50A charge capacity of a single 100Ah Superpack.

By the way, does the SuperPack battery have an output to shut down an alternator or charger when it approaches full?



[1] the documentation on Victron's products is frustrating. It's hard to find things, and even when you get to the "manuals" section, it's tough to even use the web interface, as the scrolling is so weird.

 

[jviss]

Why the 20 AH start, and what is the max amp draw of that tiny thing.

Updated:
80A. The 100Ah battery's max output is 100A. The 100Ah High Current" battery's max output is 150A.

I didn't know about the high current one until now, but I can't find one for sale anywhere.

 

[AlanSD]

I don't know what will happen with te high inrush current of the starter. I doubt the BMS would act fast enough to shut down the output, but I don't know.

Yes, the inrush will shut it down. Depending on your engine, you'll need +/- 180A to run it, plus 3x to 5x that for a split-second, and potentially more for a small fraction of a second.

The SuperPack is self-contained, not a component system that has an accessible BMS to hook to the alternator (and would you want the alternator to stop charging both batteries should one go over-voltage?)

You could get the 30A Orion Smart, that would be a better choice than 2 of the 18A ones.

The info is all there on the Victron site, both data sheets and manuals for all of the items. You can also download the Wiring Unlimited book and a number of schematics. That said, working with a technician or dealer who is familiar with these will likely save you a lot of money in the end.

 

[jviss]

The info is all there on the Victron site, both data sheets and manuals for all of the items. You can also download the Wiring Unlimited book and a number of schematics.

Yes, just takes some time to plow through it, I'm getting there now!

 

[jviss]

Yes, the inrush will shut it down. Depending on your engine, you'll need +/- 180A to run it, plus 3x to 5x that for a split-second, and potentially more for a small fraction of a second.

The SuperPack is self-contained, not a component system that has an accessible BMS to hook to the alternator (and would you want the alternator to stop charging both batteries should one go over-voltage?)

You could get the 30A Orion Smart, that would be a better choice than 2 of the 18A ones.

The info is all there on the Victron site, both data sheets and manuals for all of the items. You can also download the Wiring Unlimited book and a number of schematics. That said, working with a technician or dealer who is familiar with these will likely save you a lot of money in the end.

Thanks. So, I guess a small AGM starting battery coupled with an LFP, BMS, etc., would be the best approach.

 

[Garbonzo]

Thanks. So, I guess a small AGM starting battery coupled with an LFP, BMS, etc., would be the best approach.

Yep, thats the ticket, and the Orion will do virtually anything... turn on shut off etc. I have the 30 amp with battleborn house and AGM starter and it is flawless. Since the Li's don't need to be kept full I just shut charging off till they run down a ways to reduce the number of cycles.

 

[jviss]

I guess I'm unhappy about this solution. What I really want, I guess, is a drop-in LFP with an output to shut off the alternator field current if over charging or over voltage; and an echo charger for my AGM starting batt with an adjustable LVD set to 14.2V or so, or just another LFP batt for engine starting and an adjustable ACR set at 14.1 or 14.2 or so, with a shut-down (disconnect) input that the start battery could trigger.

 

[Maine Sail]

I guess I'm unhappy about this solution. What I really want, I guess, is a drop-in LFP with an output to shut off the alternator field current if over charging or over voltage; and an echo charger for my AGM starting batt with an adjustable LVD set to 14.2V or so, or just another LFP batt for engine starting and an adjustable ACR set at 14.1 or 14.2 or so, with a shut-down (disconnect) input that the start battery could trigger.

Lithionicshas this and it can be done with Victron & Mastervolt as well..

 

[jviss]

Lithionicshas this and it can be done with Victron & Mastervolt as well..

Oh, thanks, I should look more closely. Can you say what Victronics components I'd need to do this?

 

[AlanSD]

Oh, thanks, I should look more closely. Can you say what Victronics components I'd need to do this?

It sounds like you're looking at "drop-in" systems, with the management system integrated into the battery case. If you want to control your alternator, that would need a component-type setup, with a separate battery management system, a few relays, and more wiring for each battery. That requires a bit of expertise to make sure everything plays well together. It would be quite a leap in complexity in comparison to just using an AGM start battery.

That said,there is quite a bit of information at victronenergy.com under their battery section.

 

[Johann]

Yeah, for 2-3 times more Lithionics will sell you snake oil. good luck.

What exactly about a robust battery, designed to UL1973, with external communication, alternator field cutoff, a high amp BMS, and enclosed in a case that can withstand the temperature of an LFP fire is “snake oil”?

 

[Maine Sail]

Yeah, for 2-3 times more Lithionics will sell you snake oil. good luck.

Lithionics is absolutely not selling snake oil....

 

[jviss]

I direct you to the Facebook forum

What's the name of the forum?

 

[Johann]

OK, Since you mentioned Fit RV and the EKKO, I direct you to the Facebook forum, where a legion of problems from bad batteries, bad BMS, poor balancing and more, (also lots of Balmar issues also). Dual battey installations have had balance problems, charging problems and more. AND this is in a $7000 dollarinstall of a 300 AH battery. That's snake oil to me, and everyone is buying in, maybe with a couple years more of testing and troubleshooting they will be there but not at $4500 buck and 3 K installation.

Sorry, but those are the facts, and are relevant to boats or RV's, that 300AH box is simply not ready for distribution.

Yes, I would like to know the Facebook group name. I installed my 3 315ah Lithionics (internal BMS model) in 2020 and would like to see what issues others may be having. I will say performance wise mine are flawless. They was a BMS firmware update that made my internal SOC meter inaccurate on the high side, but with the latest FW it seems to be solved. Without having read others issues, I will say that people new to LFP, when given loads of information from the BMS, seem to over analyze everything. Maybe that’s why battleborn doesn’t give access to its BMS data… you never know if a battery is not balanced within itself or the pack. Regarding balancing between paralleled batteries, I don’t think you will ever find an install where they share the load (or charge) equally. Even with perfect wiring, there are differences in each batteries’ internal resistance, the crimps, the fuses, the breakers, the torque on each connection… you can’t be perfect. But it doesn’t matter if you have a robust battery in a well designed system since approaching the knees the batteries will balance themselves out as their resistance changes. Anyway, I look forward to reading about the issues on FB

 

[Garbonzo]

Winnebago EKKO Owners

 

[jviss]

Winnebago EKKO Owners

Funny, that was not my first guess.

 

[Johann]

Well I just read about 50 posts after searching “Lithionics” in the FB group. I am shocked at the low level of effort Winnebago put into integrating LFP batteries in the Ekko and training their employees. They retained a battery meter set for Lead batteries that would indicate 100% until the Lithionics went into Reserve Voltage Cutoff. Many posts about this…. Just losing power in the night with 100% on the Ekko battery meter. Then being told by the dealer that the battery is bad and needed to be replaced!!!! What??!!

Then several improperly programmed or failed Balmars, Zamp controllers, Xantrex inverters… what’s going on over there? One guy says his Lithionics battery had an internal short that was corrected by a firmware update… Really?? Probably just at RVC like the others and the dealer called it a short (He did smell something electrical, but that could be anything), but hey, it’s got new firmware now so all is good. There are several reports of unbalanced charge/discharge in parallel, but is that the batteries or the installation?

There is one guy whose batteries went to sleep after a long period of non-use. At around 50% SOC. That is strange and not in the manual…

Anyway thanks for the link to the group, but it looks to me like Winnebago issues, not Lithionics.
EDIT: Found one post with a legit faulty BMS, AND one with Bluetooth failure.