Help Please! - New LiTime Battery Installation

[MSL]

Installation seemed to go smoothly, then checked batteries 18 hours post installation; one at 68% other at 99%.

Details below:

Bought two LiTime Grp 24 100 Ah Bluetooth with self-heating batteries in Nov 2024. Sat in house until a few days ago when I started prep to install them. Charged batteries individually to 100% SOC, then connected them in parallel and let them sit about 18 hours to balance. After balancing both batteries were still at 100%. Batteries were installed in parallel yesterday afternoon.

I had all chargers (Phoenix Smart 12/50, Smart Solar 75/15, and Orion XS 12/50) disabled (off). Overnight the power draw from lights, etc., was about 2 amps. This morning, about 18 hours after installation, one battery is at 99% and the other at 68%. I disconnected the cables connecting both batteries and measured the voltage of each; they each measure between 13.27 and 13.28 volts.

I re-checked my connections prior to disconnecting the batteries; all seemed tight and correct. Both batteries are connected negative to negative and positive to positive, and the positive of the load goes to one battery (the one at 99%) and the negative goes to the other battery (the one at 68%). See attached photo.

I need to get this sorted out quickly as we’re scheduled to leave in 5 days, Mar 21st, for a 2-month trip.

What am I missing? Is there a defective battery?

Thanks in advance, Mark

[os1r1s]

It looks like those batteries have bluetooth. Can you check the cell volatges and see if any alarms have tripped?

[MSL]

Originally Posted by os1r1s

It looks like those batteries have bluetooth. Can you check the cell volatges and see if any alarms have tripped?

When I charged them, they both showed something in the LiTime app that they stopped charging so they wouldn't overcharge. I don't see anything that looks like an alarm. The app has Balance, Cells, and BMS. When I click each of these, it shows "normal" for all on both batteries.

[os1r1s]

So the app won't let you see values of the cells?

[DCPAS]

The batteries do not draw down evenly. I asked Li Time about this and their reply was that minor differences in resistance within the batteries affect how they draw down. I have two and one is always well ahead of the other and then sometimes the other starts drawing down more.

[MSL]

Originally Posted by os1r1s

So the app won't let you see values of the cells?

No, .no details on individual cell values.

[MSL]

Originally Posted by DCPAS

The batteries do not draw down evenly. I asked Li Time about this and their reply was that minor differences in resistance within the batteries affect how they draw down. I have two and one is always well ahead of the other and then sometimes the other starts drawing down more.

Hmm, that seems very strange. Thank you for the info though.

[DCPAS]

Originally Posted by MSL

Hmm, that seems very strange. Thank you for the info though.

What is a bit worse is that I ran one down to where it shut off while the other had about 30% left. When one shut down, nothing went through that battery. I had them wired as you do and so it shut my system down entirely. I now have bus bars so that the power of one battery does not need to go through the other battery.

[MSL]

Originally Posted by DCPAS

What is a bit worse is that I ran one down to where it shut off while the other had about 30% left. When one shut down, nothing went through that battery. I had them wired as you do and so it shut my system down entirely. I now have bus bars so that the power of one battery does not need to go through the other battery.

I don't understand. Any chance you have a photo you could share of the wiring of your batteries?

[DCPAS]

Originally Posted by msl

i don't understand. Any chance you have a photo you could share of the wiring of your batteries?

[DCPAS]

Originally Posted by MSL

I don't understand. Any chance you have a photo you could share of the wiring of your batteries?

In my Li Time manual, its example of a parallel connection uses bus bars, not batteries connected together as in the OEM wiring.

[DCPAS]

Originally Posted by MSL

I don't understand. Any chance you have a photo you could share of the wiring of your batteries?

Better look at the bus bars: https://www.amazon.com/dp/B07C6483RC...n_title_1&th=1

[kb0zke]

Bus bars are definitely the way to go. You can go cheap with just a pair of copper bars all the way up to the Victron Lynx Distributor that adds fuses for each battery and everything in between. I used the Lynx distributor in my previous trailer and I'm going that route again.

[MSL]

Originally Posted by DCPAS

Better look at the bus bars: https://www.amazon.com/dp/B07C6483RC...n_title_1&th=1

Thanks for the photo and additional info. I get it now. I have to admit, I saw the bus bar reference in the manual, just didn't think it would make any difference. I don't think I'll have time to make the change prior to my trip, but will definitely do it when I get back.

I heard back from LiTime, and they told me it was normal as well, although I don't understand the reason they gave, below:
From LiTime: "If you connect your batteries in parallel, it is possible that the APP shows only one battery is discharged (like your battery at 68% SOC).
It's reading both batteries as a single unit. We have checked with our technical colleague that it is a parallel bias current phenomenon, which is normal, please don't worry."

The point is, it's not just that the app is showing it that way, one was lower than the other. Although when I checked the voltage of each (disconnected from each other), they were 13.27 and 13.28.

So, I'm not going to worry ... sort of.

After two nights of running lights without charging, I'm charging this morning. The batteries were at 66% and 70% this morning. Now, charging at about 20A each, one is 78% and the other 82%.

Thanks everybody.

[DCPAS]

Originally Posted by MSL

Thanks for the photo and additional info. I get it now. I have to admit, I saw the bus bar reference in the manual, just didn't think it would make any difference. I don't think I'll have time to make the change prior to my trip, but will definitely do it when I get back.

I heard back from LiTime, and they told me it was normal as well, although I don't understand the reason they gave, below:
From LiTime: "If you connect your batteries in parallel, it is possible that the APP shows only one battery is discharged (like your battery at 68% SOC).
It's reading both batteries as a single unit. We have checked with our technical colleague that it is a parallel bias current phenomenon, which is normal, please don't worry."

The point is, it's not just that the app is showing it that way, one was lower than the other. Although when I checked the voltage of each (disconnected from each other), they were 13.27 and 13.28.

So, I'm not going to worry ... sort of.

After two nights of running lights without charging, I'm charging this morning. The batteries were at 66% and 70% this morning. Now, charging at about 20A each, one is 78% and the other 82%.

Thanks everybody.

I got a similar response from Li Time which did not make too much sense to me, but I have used the batteries for nearly a year now without problem. At their recommendation, I created a "system" in the app to see combined numbers. For some reason, you use 2P1S (2 parallel one series) to create a system. Then you see combined capacity, charge, and load. It's easier than looking at the batteries individually.

[MSL]

Originally Posted by DCPAS

I got a similar response from Li Time which did not make too much sense to me, but I have used the batteries for nearly a year now without problem. At their recommendation, I created a "system" in the app to see combined numbers. For some reason, you use 2P1S (2 parallel one series) to create a system. Then you see combined capacity, charge, and load. It's easier than looking at the batteries individually.

Thanks again. I had already set up the "system". Good to see you're happy with the batteries.

I see that the bus bar makes sense, but it doesn't seem it would make enough of a difference in how the current is drawn. But, this electrical stuff is not my strong suit.

The Lifeline batteries have a 25+ page manual, that seemed overkill to me, but it had every bit of info you could want. The documentation from LiTime leaves a bit to be desired.

Anyway, many thanks for your help. Mark

[JeffKim]

Bus bars are certainly a good way to go, but more easily you could just beef up the wiring. I also doubt bus bars would do much better with only two batteries. What gauge are the cables now?

I have 2/0 AWG connecting my four lithium batteries. But since I don't have Bluetooth batteries, I'm not exactly sure if the charging is balanced. If you don't want to make up cables there are a number of vendors online that make custom cables.

Also, just wondering do you have fusing? I couldn't tell from the picture. If you use a MRBF, there should be two. One for the inverter cable and another for the positive bus bar DC loads.

[gypsydad]

I just ordered buss bars along with the magnet threaded studs to use to mount from Amazon. My LiTime are now 8 months old, and holding up well. I do see one from time to time a bit lower than the other using their APP, but the overview always says everything at 100% Ballance, even if the capacity is down on one or the other. They always seem to come back to 100% when plugged in. Here is the thread I have been following with good info on buss bars and magnet mounting hardware: https://www.airforums.com/forums/f44...ml#post2773322

[DCPAS]

Originally Posted by JeffKim

Bus bars are certainly a good way to go, but more easily you could just beef up the wiring..

That's not the problem I addressed by installing bus bars. With the OEM parallel wiring (batteries connected together) and the batteries not drawing down evenly, when the BMS of more discharged battery shuts it down because it gets too low, no current flows through that battery and so the power from the battery with some charge remaining is not available (unless you want to re-wire your circuit to take the dead battery out of course). I believe inconsistent drawdown is typical of LIFO4, and while I do not know how other BMS work, I do know the Li Time BMS will shut down the entire battery system when one battery shuts down. The bus bars should avoid that outcome.

[JeffKim]

Originally Posted by DCPAS

when the BMS of more discharged battery shuts it down because it gets too low, no current flows through that battery and so the power from the battery with some charge remaining is not available I believe inconsistent drawdown is typical of LIFO4, and while I do not know how other BMS work, I do know the Li Time BMS will shut down the entire battery system when one battery shuts down. The bus bars should avoid that outcome(unless you want to re-wire your circuit to take the dead battery out of course). .

I'm puzzled by this comment. They are connected in parallel so even if one goes dead the other is still connected to the circuit.

LiFePO4 batteries should charge and discharge just about equally if they are hooked up in a balanced topology which from the OP's picture it looks like they are. Yes, they will do best with bus bars, but with big enough cables I'm saying there shouldn't be much of a difference than with buss bars. For example 2/0 AWG is .08 Ohms/1000ft or for a 2ft connection .00016 Ohms which isn't zero but I'd argue pretty negligible.