LiTime 12v battery showing 18.0v resting

[IGBT]

If you get the balancer or similar you should never need to break down the batteries and parallel them once hooked up. Needs to be an active version like this that can transfer 10amps verse a passive one that only does an amp or less.

LiTime 48V Battery Balancer for 24V/36V/48V Battery Bank

The LiTime 48V battery balancer is suitable for multiple battery types on the market, including LiFePO4 and lead acid. Compatible with 24V, 36V, and 48V battery bank.

www.litime.com

Does it have any parasitic draw? This bank is on our sailboat and might sit for a month with no charge. I wouldn't want the balancer to be drawing 50 watt-hr a day for a month.

 

[robbob2112]

Does it have any parasitic draw? This bank is on our sailboat and might sit for a month with no charge. I wouldn't want the balancer to be drawing 50 watt-hr a day for a month.

This is from their page - 5mA which is about as low as one of these goes. Thas is per battery so
12.8v * 0.005a = 0.064W
0.064W * 4 = 0.256W/hr
Now over 24hours that means 6.144 Wh

Times 60 days = 368Wh

Your total battery has 11776 Wh - so over 60 days that is 3% loss unless you disconnect the leads or turn the unit off - I am not sure if it can be turned off or if there is a draw when off.

If you are worried about it put an in-line glass fuse on each positive lead and disconnect it when you put the boat in storage.

 

[IGBT]

Almost convinced! I have $30 off at Li-time from points, so could just about get one for free to try out. The only thing holding me back is the first time I cycled these as a pack, after charging them all up exactly equal, they were so consistent in discharge and recharge. Now, I realize each battery (and cells in said battery) is going to have a different internal resistance, so this balancer might be key. On the other hand, it is just one more thing to malfunction, which is the only reason I am just a tiny bit resistant if the current bank can stay within a few % of balanced over, say, 20 cycles. That would represent quite a few excursions and wouldn't be horrible to manually rebalance afterward.

 

[KnobCountry]

I run 3 of the isunergy balancers and haven't had issues. Occasionally I see them blinking but rarely. Battery bank is always within .09v

They may fail in a few years but they're also fairly cheap and I check the batteries often enough that I usually know where the soc is.

 

[Dave911]

I run 3 of the isunergy balancers and haven't had issues. Occasionally I see them blinking but rarely. Battery bank is always within .09v

They may fail in a few years but they're also fairly cheap and I check the batteries often enough that I usually know where the soc is.

Go with a balancer. I think one company makes most of them. The reviews are pretty good. I have three from Ecoworthy I believe. Id pull your batteries in the winter and store them inside. Your in Alaska right? Its gets chilly up there.

 

[Alkaline]

Thanks for your reply. To update I had a secondary charge controller connected to a small array that was still feeding a very small amount of current into the batteries at that point when I took the voltage measurements.

With that little bit of current going in the voltages are:
13.3
13.3
13.3
18.0

With all loads disconnected the voltages are:
13.3
13.3
13.3
12.8

The problem is I don't have a proper 12v charger for LiFeP04 batteries. The EG4 will only connect to a 48 volt system. I do have a very large roll around style 12v automotive charger with 10/25/50/225 amp settings, but I have no way to control the voltage.

It appears 3 of the batteries are at or near 100%. I will put the 4th battery on a low charge and see if it comes up. Then I will parallel them together and see if I can get them to balance properly.

Will test and report back.

I connected my automotive charger. I set it on it's lowest 10a setting. The voltage comes up from 12.8v to 14.1v but almost zero current is flowing. If I up the charger to the 25a setting the voltage rises further but the clamp meter still reads 0a flowing into the battery.

The batteries rested for a good 6 or so hours today before attempting to charge the battery.

Bro,


Return that battery don't even bother diagnosing, you paid for a new working battery you should get a new working battery. let Li time pay shipping both ways or better yet ask them for a replacement battery. They will probably ask you to throw away the defective battery anyway.

 

[Dave911]

Bro,


Return that battery don't even bother diagnosing, you paid for a new working battery you should get a new working battery. let Li time pay shipping both ways or better yet ask them for a replacement battery. They will probably ask you to throw away the defective battery anyway.

I don't see how you can get 18 volts out of those cells. The only way is if the BMS has partially shutdown.
Seeing that he is in Alaska, he might want to try some other things.

 

[ericfx1984]

Sounds like classic battery imbalance. First, MANY NEW LFP batteries suffer from internal cell imbalance due to several factors that are unavoidable. This occurs with premium batteries as well. Second, when stringing 12V together to make higher voltages, each battery needs to at 100% SoC to make certain what has happened to you doesn't happen.

You need to charge each to full individually as 12V before placing them in series.

The battery voltage didn't spike. The inverter did. I suspect the 18V battery hit BMS charge protection, stopping the inverter from charging instantaneously, and the inverter over-volted because there was nowhere for the charge current to go, and it needed a few milliseconds to respond and shutdown the charger. In that brief period of time, the charger over-volted.

Recommend you break down the bank, place them in parallel and charge them to 14.4V and hold for 4+ hours.

The 18V is odd. Many will drop to a slightly lower but normal voltage for a 12V battery, like 12.5-12.9V.

Sounds like classic battery imbalance. First, MANY NEW LFP batteries suffer from internal cell imbalance due to several factors that are unavoidable. This occurs with premium batteries as well. Second, when stringing 12V together to make higher voltages, each battery needs to at 100% SoC to make certain what has happened to you doesn't happen.

You need to charge each to full individually as 12V before placing them in series.

The battery voltage didn't spike. The inverter did. I suspect the 18V battery hit BMS charge protection, stopping the inverter from charging instantaneously, and the inverter over-volted because there was nowhere for the charge current to go, and it needed a few milliseconds to respond and shutdown the charger. In that brief period of time, the charger over-volted.

Recommend you break down the bank, place them in parallel and charge them to 14.4V and hold for 4+ hours.

The 18V is odd. Many will drop to a slightly lower but normal voltage for a 12V battery, like 12.5-12.9V.

Eggo... Lol I must read way too many of your posts because honestly as soon as I read the OPs post I started thinking almost exactly what you were writing.. Then I read your post it's already done

 

[robbob2112]

Almost convinced! I have $30 off at Li-time from points, so could just about get one for free to try out. The only thing holding me back is the first time I cycled these as a pack, after charging them all up exactly equal, they were so consistent in discharge and recharge. Now, I realize each battery (and cells in said battery) is going to have a different internal resistance, so this balancer might be key. On the other hand, it is just one more thing to malfunction, which is the only reason I am just a tiny bit resistant if the current bank can stay within a few % of balanced over, say, 20 cycles. That would represent quite a few excursions and wouldn't be horrible to manually rebalance afterward.

If it fails for some reason you can just disassemble the string and parallel the batteries.

Math shows if the charge and discharge is identical every day the batteries will slip out of sync very quickly. Add a little chaos into the system and it lasts longer, the more random the more they stay in balance.

If you are worried about failure carry a second one in a dry bag to hookup. Use fuses or water tight plugs to connect the wires to make for quick changes.