LiFeP04 trailer battery

[TREVTRAVELER]

I have a 2021 Imagine 22MLE XLS travel trailer. About 8 months ago I installed a LiFeP04 battery for the 12-volt system. It has worked fine until about a week ago. It was discharged so I removed it and charged it with a conventional battery charger. It registered 12.3V on a multimeter after charging. I just purchased a new smart charger designed for lead acid, lithium, and LiFeP04 batteries. When I hook it up to the battery, it will not start charging (the display stays at OFF). So, 2 questions: what would cause the discharge and why won't a "smart" battery charger charge it. Any thoughts would be appreciated!

[Hoopy Frood]

What were you using to charge the lithium battery while hooked up to shore power? Was it charging the battery to a full SOC? How did you know it was discharged, and how low was it? What kind of "smart charger" are you trying to use? Some aren't all that smart, and use the "smart charger" as a marketing ploy.

[TREVTRAVELER]

Appreciate your questions Hoopy Frood. The battery was charged by the trailer's standard WFCO converter and it was charging to full SOC according to the sensor in the trailer. When I pulled it out, it was at 5V. I am using a HTRC
20-Amp Smart Battery Charger, Lithium, LiFePO4, Lead-Acid (AGM/Gel/SLA..) from Amazon. When I attach it to the battery, the screen appears on the charger and says OFF with a blinking battery icon next to it. The battery is at 21.1V currently. The user manual does not address this issue.

[Hoopy Frood]

The standard WFCO converter may not have been charging the lithium battery to its full potential regardless of what the sensor said. I believe the lithium batteries can be charged up to around 14.5V. From the sounds of things you'll need a person more familiar with lithium batteries than I. Only having 5V when pulled doesn't sound like it was charging, and I have no idea why it would now be showing 21.1V.

[Riverbug]

The OEM charger was definitely not charging to full capacity on a lithium battery, it just doesn't have a high enough charge rate to do that. I know because I was running my 206AH SOK lithium battery using the stock charger/converter as well. You can expect that it has only ever charged it to about 65%-75% capacity. That doesn't damage the battery but the problem is that the cells never really get balanced because it never gets to 100%. Now if you're also not depleting it routinely, that's not really an issue either. You're just not taking advantage of the full capacity, along with the slow rate of charge compared to a lithium compatible charger.

Anyway, now it sounds like you have depleted it to the point that the lithium charger needs to be tricked into seeing more voltage so that it will kick into charge mode. All you have to do it hook up your lithium charger to the battery, then connect an additional charger (such as the stock charger in the RV), once the lithium charger sees enough voltage it should begin charging. If not, unplug it for a minute and plug it back in to let it reset. Once it begins charging, you can disconnect the other charger.

Give it a try and please report back.

[Redapple63]

Appreciate your questions Hoopy Frood. The battery was charged by the trailer's standard WFCO converter and it was charging to full SOC according to the sensor in the trailer. When I pulled it out, it was at 5V. I am using a HTRC
20-Amp Smart Battery Charger, Lithium, LiFePO4, Lead-Acid (AGM/Gel/SLA..) from Amazon. When I attach it to the battery, the screen appears on the charger and says OFF with a blinking battery icon next to it. The battery is at 21.1V currently. The user manual does not address this issue.

Hi Trevtraveler,

First, check the voltage at a resting state (minimum of 15 minutes).

The 21.1v is not possible on a 24v battery. It is possible on a 24 volt battery.

Please verify the battery voltage for us, both designed and measured.

I sm familiar with the charger you have. It is supposed to auto detect the voltage, but manually have to select the style.

When connected to the charger, make sure the battery charger is set to Lifepo4 and the correct voltage.

Bill

[Redapple63]

The OEM charger was definitely not charging to full capacity on a lithium battery, it just doesn't have a high enough charge rate to do that. I know because I was running my 206AH SOK lithium battery using the stock charger/converter as well. You can expect that it has only ever charged it to about 65%-75% capacity. That doesn't damage the battery but the problem is that the cells never really get balanced because it never gets to 100%. Now if you're also not depleting it routinely, that's not really an issue either. You're just not taking advantage of the full capacity, along with the slow rate of charge compared to a lithium compatible charger.

Anyway, now it sounds like you have depleted it to the point that the lithium charger needs to be tricked into seeing more voltage so that it will kick into charge mode. All you have to do it hook up your lithium charger to the battery, then connect an additional charger (such as the stock charger in the RV), once the lithium charger sees enough voltage it should begin charging. If not, unplug it for a minute and plug it back in to let it reset. Once it begins charging, you can disconnect the other charger.

Give it a try and please report back.

Yep, this is called waking the battery up. When batteries are inactive they go to sleep. Low voltage does not mean it’s dead.

Bill

[ddurig]

What Riverbug said and knowing the battery type and temp you are trying to charge at has impacts as well. Depending on the battery the BMS may not allow you to charge if below freezing.

[Ynot4me2]

I think OP meant to type 12.1 not 21.1 but I could be wrong. Let's hope he can wake it up.

[TREVTRAVELER]

Thanks Happy Frood. A typo on my part:I reported 21.1V and I should have reported 12.1V. This is more in liine with everything that is going on.