LiTime 12v battery showing 18.0v resting

[donsolarak]

My 4x 230ah LTCP 12v LiTime batteries finally arrived here in Alaska.

I checked each of the batteries when I first unpackaged them and they were all roughly 13.1v. I connected them in series and connected them to my new EG4 3kw 48v all in one unit. Everything worked as expected. I connected the unit to shore power and put the batteries on a 20amp charge. LiTime recommended charge rate is 46amps. I put them on the lower rate as I need to upgrade some of the wiring size from shore power.

They charged fine for a number of hours (5 or so) until the EG4 stopped charging due to an over voltage condition. I checked each of the batteries while resting. 3 of them show 13.3v and the 4th battery is showing 18.0v.

thoughts?


Edit: when they were first charging the system voltage was in the high 53v range with constant current. Over the next several hours the voltage rose into the low 54v range as expected. Current was steady. My guess is the 1 battery had a sudden voltage spike which caused the EG4 charger to turn off.

 

[sunshine_eggo]

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.

 

[donsolarak]

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.

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.

 

[donsolarak]

I verified that the charger, volt meter, and clamp meter all work as intended on the other batteries. That battery however does nothing.

 

[Supervstech]

Yikes.
I would go on amazon and order a desktop power supply.
I built my own from buck converters, but im a little crazy.
You ABSOLUTELY POSITIVELY have to get all 4 perfectly charged up to 14V before you connect them together.

 

[Supervstech]

I verified that the charger, volt meter, and clamp meter all work as intended on the other batteries. That battery however does nothing.

Looks like that battery has disabled charging. Bad bms, contact the company.

 

[donsolarak]

Yikes.
I would go on amazon and order a desktop power supply.
I built my own from buck converters, but im a little crazy.
You ABSOLUTELY POSITIVELY have to get all 4 perfectly charged up to 14V before you connect them together.

I checked the voltage of all the batteries and they were all 13.15v out of the box. I know resting voltage is only an approximate SOC but it's hard to believe voltage that close would result in massively unbalanced batteries.

The manual states they are 100% SOC at 13.33v so I'm not sure how I get them to 14v resting.

Crazy that in all the years of using lead acid batteries at my offgrid homestead I never had to ensure battery voltage was "perfect" before connecting anything.

 

[sunshine_eggo]

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

Ah... the 18V may be a "forced" voltage if the system voltage is 13.3+13.3+13.3+18.0=57.9V by the inverter/charger. Since "18V" refuses to pass charge current, the charger is holding peak voltage with 0A. Since the other three batteries aren't out of the charge circuit, they're reporting voltage. Since the 18V battery is effectively out of the charge circuit, it's reporting the remainder voltage.

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

Now, this is typical of a battery in charge protection mode.

Given the above explanation of the "18V" phenomena, I am reassured that everything is as I described.

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.

I made it clear that the "18V" battery was in charge protection mode. Why would you try to charge it? The other three batteries need to be charged.

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

Did you do this?

Looks like that battery has disabled charging. Bad bms, contact the company.

Why? This is normal for a battery with the BMS in charge protection mode. All the evidence points to:

"18V" battery is "full" and in charge protection mode (12.8V when disconnected).
3X 13.3V batteries are not full.

The battery in question may have cell imbalance, but that's very common on new batteries, and a long charge at 14.1V or so will rectify it.

 

[donsolarak]

Did you do this?

No I have not. Thank you for the further clarification. I can wire them in parallel and charge them but I can't use the EG4 since it only supports 48v sized batteries. I do have the "dumb" 12v charger but I cannot control the voltage output only the current. Again it's the style of charger you would typically find in an automotive shop on two wheels with a big handle. I has 2 knobs. One for current and one for a timer. I can set it to 10/25/50/225 amp. I'm typing this from the middle of nowhere near the arctic circle. I'm not certain I could find a charger locally where I could fine tune the output voltage. It took nearly a month just to get the batteries here from the lower 48.

I can try wiring them in parallel then putting them on the low 10amp charge but the voltage will rise over time.

 

[sunshine_eggo]

No I have not. Thank you for the further clarification. I can wire them in parallel and charge them but I can't use the EG4 since it only supports 48v sized batteries. I do have the "dumb" 12v charger but I cannot control the voltage output only the current. Again it's the style of charger you would typically find in an automotive shop on two wheels with a big handle. I has 2 knobs. One for current and one for a timer. I can set it to 10/25/50/225 amp. I'm typing this from the middle of nowhere near the arctic circle. I'm not certain I could find a charger locally where I could fine tune the output voltage. It took nearly a month just to get the batteries here from the lower 48.

I can try wiring them in parallel then putting them on the low 10amp charge but the voltage will rise over time.

You've established that the charger will charge to 14.1V and hold there at a 10A setting. That's a million times better than a swift kick to the nuts. Go for it!

Since you basically have about 200A charge capability on the four in parallel, I wouldn't hesitate to try the 25 and 50A settings once the 10A settings has topped out. They may drive to higher voltage. Ultimately, the BMS will protect the batteries if the charger voltage goes too high.

Before charging, it might also be worth discharging the "18V" battery with some kind of 12V load (load tester, 12V automotive bulb, etc.) to restore a true terminal voltage. It might take a few minutes of discharging to restore the actual voltage. The 12.8V is what the BMS is reporting, not the actual voltage of the battery.

Since you've already had to be a patient man, to minimize future pain, you might want to simply leave them on the charger at 14.1V for 24 hours to give the batteries time to internally balance their cells to minimize future protection events/spikes.

Set bulk/absorption voltage to 55.2V and float to 54.0V. These settings will fully charge your batteries and reduce/eliminate the tendency for spikes due to cell imbalance.

Lastly... you may want to consider something like this:

https://www.amazon.com/iSunergy-Battery-Equalizer-48V-Balancer/dp/B0BDF68PRJ

It will monitor the individual 12V, give you a reading for each and work to keep their voltages identical by transferring charge from higher voltage 12V to lower voltage 12V.

Otherwise, you may need to periodically break your battery down and charge the individual 12V to full.

 

[donsolarak]

Before charging, it might also be worth discharging the "18V" battery with some kind of 12V load (load tester, 12V automotive bulb, etc.) to restore a true terminal voltage. It might take a few minutes of discharging to restore the actual voltage. The 12.8V is what the BMS is reporting, not the actual voltage of the battery.

I had already wired them and had the charger on them before I saw your reply. I was able to charge at the 50A setting. The voltage started at about 13.5V and rose steadily. In less than an hour it made a sudden voltage jump, and then a second one. After that the clamp meter showed zero current coming from the charger. I assumed the other batteries had also gone into protection mode.

After I turned the charger off I saw the voltage at 13.4V and then minutes later it was up to 13.6V My guess is one of the batteries came out of protection.

I unhooked them and tested each. The suspect battery was still showing 12.8V. The other batteries were showing 13.4V+. I hooked up 40w of LED lights to the 12.8V battery and after a few minutes the battery came out of protection mode as you stated it would.

I reconnected the batteries in parallel and I could see almost 10A running between the batteries with the clamp meter as they were equalizing.

Currently all 4 batteries are out of protection mode. The parallel array is at 13.39V. The current flowing between the batteries is decreasing fairly quickly. I'll give them a half a day or so and go from there.

These batteries are very different than dealing with lead acid where all I have to go on are charging/discharging/resting voltages and specific gravity. I assumed since the one battery was showing significantly lower voltage (12.8) that it was undercharged, not fully charged. I see now in the manual there is a sentence stating as such but it's so poorly worded that unless you already knew about protection mode you would very likely not understand the sentence as I did not despite the fact that I read the manual first.

Thanks again for your help!

 

[Q-Dog]

If you can tolerate slower charging the batteries should balance after a few charge/discharge cycles.

 

[robbob2112]

Unless I am badly mistaken you should get an active balancer with 4 leads on it so it can keep the batteries in balance while wired in series. Otherwise you will have to periodically hook them in parallel to let them balance.

I'm sure the others will chime in if this isn't the right idea

 

[Will Prowse]

My 4x 230ah LTCP 12v LiTime batteries finally arrived here in Alaska.

I checked each of the batteries when I first unpackaged them and they were all roughly 13.1v. I connected them in series and connected them to my new EG4 3kw 48v all in one unit. Everything worked as expected. I connected the unit to shore power and put the batteries on a 20amp charge. LiTime recommended charge rate is 46amps. I put them on the lower rate as I need to upgrade some of the wiring size from shore power.

They charged fine for a number of hours (5 or so) until the EG4 stopped charging due to an over voltage condition. I checked each of the batteries while resting. 3 of them show 13.3v and the 4th battery is showing 18.0v.

thoughts?


Edit: when they were first charging the system voltage was in the high 53v range with constant current. Over the next several hours the voltage rose into the low 54v range as expected. Current was steady. My guess is the 1 battery had a sudden voltage spike which caused the EG4 charger to turn off.

What you need to do is not use 12V batteries in series. Purchase a 48V battery for 48V inverter. Would solve this issue.

 

[shvm]

I see now in the manual there is a sentence stating as such but it's so poorly worded that unless you already knew about protection mode you would very likely not understand the sentence as I did not despite the fact that I read the manual first.

Does the manual says anything about access to the BMS?
If you're able to access individual cell voltage reading of the fourth battery, this job would become so much easier.

 

[Q-Dog]

What you need to do is not use 12V batteries in series. Purchase a 48V battery for 48V inverter. Would solve this issue.

You are not wrong. Much better to use LiFePO4 batteries at system voltage.

But, LiTime specifically says if you want to run their batteries in series you MUST first charge them up fully, individually, then connect in series. It's all in the manual.

 

[Will Prowse]

You are not wrong. Much better to use LiFePO4 batteries at system voltage.

But, LiTime specifically says if you want to run their batteries in series you MUST first charge them up fully, individually, then connect in series. It's all in the manual.

Yes absolutely. Needs to be charged to 100% for a day or two before connecting.

 

[MattiFin]

You are not wrong. Much better to use LiFePO4 batteries at system voltage.

But, LiTime specifically says if you want to run their batteries in series you MUST first charge them up fully, individually, then connect in series. It's all in the manual.

In the long run it would be a good idea to install battery balancer suitable for 4x 12v batteries. Cell level balancing for the entire 16s set would be better of course but not easy to do.

 

[sunshine_eggo]

I had already wired them and had the charger on them before I saw your reply. I was able to charge at the 50A setting. The voltage started at about 13.5V and rose steadily. In less than an hour it made a sudden voltage jump, and then a second one. After that the clamp meter showed zero current coming from the charger. I assumed the other batteries had also gone into protection mode

probably.

After I turned the charger off I saw the voltage at 13.4V and then minutes later it was up to 13.6V My guess is one of the batteries came out of protection.

Yep.

I unhooked them and tested each. The suspect battery was still showing 12.8V. The other batteries were showing 13.4V+. I hooked up 40w of LED lights to the 12.8V battery and after a few minutes the battery came out of protection mode as you stated it would.

Glad to hear.

I reconnected the batteries in parallel and I could see almost 10A running between the batteries with the clamp meter as they were equalizing.

Currently all 4 batteries are out of protection mode. The parallel array is at 13.39V. The current flowing between the batteries is decreasing fairly quickly. I'll give them a half a day or so and go from there.

Sounds like a plan.

These batteries are very different than dealing with lead acid where all I have to go on are charging/discharging/resting voltages and specific gravity. I assumed since the one battery was showing significantly lower voltage (12.8) that it was undercharged, not fully charged. I see now in the manual there is a sentence stating as such but it's so poorly worded that unless you already knew about protection mode you would very likely not understand the sentence as I did not despite the fact that I read the manual first.

Sadly, the manuals are usually poor, and one already has to know what they're looking for.

Thanks again for your help!

Unless I am badly mistaken you should get an active balancer with 4 leads on it so it can keep the batteries in balance while wired in series. Otherwise you will have to periodically hook them in parallel to let them balance.

I concur:

Lastly... you may want to consider something like this:

https://www.amazon.com/iSunergy-Battery-Equalizer-48V-Balancer/dp/B0BDF68PRJ

It will monitor the individual 12V, give you a reading for each and work to keep their voltages identical by transferring charge from higher voltage 12V to lower voltage 12V.

Otherwise, you may need to periodically break your battery down and charge the individual 12V to full.

What you need to do is not use 12V batteries in series. Purchase a 48V battery for 48V inverter. Would solve this issue.

Given that it took a month for him to get what he has, this is probably a use what you have situation.