LiFePO Batteries ???

[bruceb58]

I was thinking about doing the jumper cable thing, but concerned about the amount of current that the LFP batteries would soak up.

Also, the folks at LiTime recommended their 20 amp charger w/ activation feature. I'll probably buy one from them, because they were so nice.

Actually, a thin cable would be the best...it would limit the current. You are just trying to hit it with a high enough voltage to trigger the BMS. Your biggest issue is if its a really low cell that is causing the issue. If it is, you may not be able to recover.

I helped a friend of a friend recover a battery. On that battery, I was able to get inside and charge each cell up individually with a power supply. It was the only way to get it to recover. No external charger was going to wake it up. I actually disconnected the BMS in order to do this.

 

[airshot]

I do store mine at that level but if you don't, might get 2,000 cycles instead of 3,000 cycles.

On the Rivian, in the lower range models that use LiFePO4, Rivian suggests keeping them at 100% so they don't get out of balance.

You have a manual form Timeusb that shows they recommend a certain storage level? I have heard various issues with Timeusb BMS not allowing you to get full advertised current output. Wonder if they have started putting in a better BMS. They also have a recommended charge current of only 20A for a 100AH battery...that's lame.

Not sure what the recommendations are on the 100 ah battery, I bought the 140 and went with their recommendations on a charger, I figure they made them, they should know what is best ! The 140 ah battery does come with a bigger BMS unit with more safety features, so their advertising states. Having researched for almost 6 months, about 99% of what I found with Time USB was all positive. Time will tell, but so far, it has behaved as advertised..

 

[airshot]

I was thinking about doing the jumper cable thing, but concerned about the amount of current that the LFP batteries would soak up.

Also, the folks at LiTime recommended their 20 amp charger w/ activation feature. I'll probably buy one from them, because they were so nice.

That is why I bought the charger Time USB recomended, it has the wakeup mode. When folks are spending big money on these batteries why scrimp on a charger that is known to work correctly. One thing I gave learned in my 15 plus years of Lipo battery experience, don't cut corners if you want them to perform as advertised!

 

[bruceb58]

Not sure what the recommendations are on the 100 ah battery, I bought the 140 and went with their recommendations on a charger, I figure they made them, they should know what is best ! The 140 ah battery does come with a bigger BMS unit with more safety features, so their advertising states. Having researched for almost 6 months, about 99% of what I found with Time USB was all positive. Time will tell, but so far, it has behaved as advertised..

LOL...The people you talked to didn't make the battery. They hired a supplier in China and plastered their name on it.

Believe it or not, charging a LiFePO4 battery is not rocket science. You charge at a bulk rate(constant current) until it hits and absorption voltage(typically around 14.2V) and you let it charge at constant voltage until the current goes to close to zero. At that point you can float it at around 13.4V. Almost every charger made does this exact process.

The recommended charge current for the 140A is 28A...that's just pathetic. Very similar to what LiTime suggests which makes me think it's the exact same company. You look at the spec page and they look like they are written by the same person. Probably made in the same factory in China. These are low budget batteries and it shows.

 

[cyclops222]

When the battery company has a defective run of rejects.
Who eagerly buys them up for pennies on the dollar value.
Then sells them anyway.

 

[airshot]

LOL...The people you talked to didn't make the battery. They hired a supplier in China and plastered their name on it.

Believe it or not, charging a LiFePO4 battery is not rocket science. You charge at a bulk rate(constant current) until it hits and absorption voltage(typically around 14.2V) and you let it charge at constant voltage until the current goes to close to zero. At that point you can float it at around 13.4V. Almost every charger made does this exact process.

The recommended charge current for the 140A is 28A...that's just pathetic. Very similar to what LiTime suggests which makes me think it's the exact same company. You look at the spec page and they look like they are written by the same person. Probably made in the same factory in China. These are low budget batteries and it shows.

Time USB claims a much higher charge rate up to 2c can be used but will shorten overall life of the battery. Their recommendations are used for longest life span. All my communications with them have come directly from China according to their addresses. They have responded quickly to all my questions and concerns. To those that own one if their batteries, they have all spoken very highly of the mfgrs responses, even when they had an issue. One person had a real issue with his battery and they shipped him a brand new battery within 5 days and no need to return the faulty unit. Sounds like good service to me !!

 

[bruceb58]

Time USB claims a much higher charge rate up to 2c can be used but will shorten overall life of the battery. Their recommendations are used for longest life span. All my communications with them have come directly from China according to their addresses. They have responded quickly to all my questions and concerns. To those that own one if their batteries, they have all spoken very highly of the mfgrs responses, even when they had an issue. One person had a real issue with his battery and they shipped him a brand new battery within 5 days and no need to return the faulty unit. Sounds like good service to me !!

You can’t charge at 2C. The BMS doesn’t allow it!

 

[tpenfield]

There are a couple of videos reviewing the Time USB batteries. I watched the more recent one (Jan 2025). Overall the reviewer thought it was a good battery and the testing met the spec's.

It seems to me that many of the so-called economy battery brands have upped their game over the past few years.

Anyway, I got to start ordering my boat prep stuff, so I'll get the LiTime charger on order. Once I get the batteries active again, I'll let the Xantrex and the solar charger do their thing.

 

[airshot]

You can’t charge at 2C. The BMS doesn’t allow it!

Only repeating what the advertising material states...Not sure why I would need to charge at that rate anyway.

 

[cyclops222]

I have a very smart charger. It is old. I have it set for the A123 "D" sized cells used in my tool packs. It charges at 30 amps. NO problems with battery life at or above 90 %.
The REAL danger is if the battery leads are shorted for a split second. The insulation melts off. The heat is so intense it will cause severe burns. Be very careful with the batteries.
I use a correct sized fuse to protect all the other wires in equipment. Fires ARE a very real danger with these A123 batteries.
The BMS protection IS IS required to prevent fires.

 

[tpenfield]

I received the LiFePO4 charger today. So, I put it to work bringing the batteries back to life.


.
It does a low current charging to wake up the battery, then it goes into the bulk and absorption stages, like other chargers. Not sure how long the wake-up will take.

I'm thinking that over the next winter, I'll just take the batteries out and keep them in in a heated area.

 

[cyclops222]

That is excellent for any battery.

 

[tpenfield]

Quick update . . .

I had some trouble waking up the batteries . . . not sure if it is the charger or the battery. Anyway, I connected a trickle charger to the batteries . . . one woke right up and the other is still sleeping.

Anyway . . . I got the Xantrex charging the good/awake battery and the other will be tomorrow's project.

I've been in touch with LiTime Tech support throughout . . . they have been helpful.

 

[airshot]

I received the LiFePO4 charger today. So, I put it to work bringing the batteries back to life.

View attachment 407210
.
It does a low current charging to wake up the battery, then it goes into the bulk and absorption stages, like other chargers. Not sure how long the wake-up will take.

I'm thinking that over the next winter, I'll just take the batteries out and keep them in in a heated area.

Appears to be the exact same charger I got from TimeUSB for my battery !

 

[bruceb58]

Only repeating what the advertising material states...Not sure why I would need to charge at that rate anyway.

Show the link where it says that.

 

[tpenfield]

I've got the one sleeping battery sitting in the sun to see if a little more temperature will help wake it up. Otherwise, it my be going back to LiTime . . .

 

[airshot]

Show the link where it says that.

Go to the Time USB website and look it up, better yet message them and do your own detective work.

 

[bruceb58]

Go to the Time USB website and look it up, better yet message them and do your own detective work.

I went on there...there is no mention at all of 2C charging. It does however say the BMS can handle 100A but they recommend 20A.

 

[bruceb58]

I've got the one sleeping battery sitting in the sun to see if a little more temperature will help wake it up. Otherwise, it my be going back to LiTime . . .

That won't do it. One or more cells are toast from over discharge.

 

[tpenfield]

That won't do it. One or more cells are toast from over discharge.

Yes, the battery appears to be dead. (I've tried a bunch of things)

I'm thinking that the BMS did not protect the battery (cells) to the extent that it should have. The other battery (it's twin hooked in parallel) came to life with just a quick touch of the trickle charger. and was sitting at 11.5 volts after activation . . . now fully charged.

So, the (bad) battery is going back to LiTime for replacement. 'RMA' is in process.

If I took the batteries out over the winter, I could probably have avoided the whole process of waking them up. But . . . maybe the (now) dead battery would have failed at some point.

I've been contemplating getting another battery, so as to have 3 of them once the return/replacement is done. For now, I will run the 'house' circuit on a single 100 Ah battery.