[Help] Can't charge LiFePO4 Battery.

[mateusleo]

I bought a 48v 20ah battery from sun-thing28, had my first ride and everything. But the problem is that when i connect the charger to the power and then to the charging plug, it doesn't do anything. The red light goes on and i tested its voltage, it works good. The charging plug also gives good voltage. The cooler of the charger doesn't get started and it doesn't warm up, it seems like it's not charging the battery. What should i do?

You can find more info (and pictures) in this post i made few days ago: http://endless-sphere.com/forums/viewtopic.php?f=4&t=51112

 

[defuzo]

Give it time.

Or break the circuit, measure the current (Amp).

Or, make ur own charger, cascading 2-3 laptop charger, pluss a current limiter (with say lm317). Alittle extreme proposal.. (if the chargers are galvanic isolated its maybe okey. If they are of bad switching type, additional filtering maybe suitable=

 

[mateusleo]

Give it time.

Or break the circuit, measure the current (Amp).

Or, make ur own charger, cascading 2-3 laptop charger, pluss a current limiter (with say lm317). Alittle extreme proposal.. (if the chargers are galvanic isolated its maybe okey. If they are of bad switching type, additional filtering maybe suitable=

I just measured the current comming out of the charger. 0,5A. I can't understand why its so slow, it should be 5A...

 

[defuzo]

Give it time.

Or break the circuit, measure the current (Amp).

Or, make ur own charger, cascading 2-3 laptop charger, pluss a current limiter (with say lm317). Alittle extreme proposal.. (if the chargers are galvanic isolated its maybe okey. If they are of bad switching type, additional filtering maybe suitable=

I just measured the current comming out of the charger. 0,5A. I can't understand why its so slow, it should be 5A...

I guess its near full then.
(the last few %, takes little amps, but lots of time)

 

[mateusleo]

Give it time.

Or break the circuit, measure the current (Amp).

Or, make ur own charger, cascading 2-3 laptop charger, pluss a current limiter (with say lm317). Alittle extreme proposal.. (if the chargers are galvanic isolated its maybe okey. If they are of bad switching type, additional filtering maybe suitable=

I just measured the current comming out of the charger. 0,5A. I can't understand why its so slow, it should be 5A...

I guess its near full then.
(the last few %, takes little amps, but lots of time)

I ran for 15,6 kms with it. Is that considered near full for a 20ah battery? I'm going nuts LOL

 

[defuzo]

if u say so. Put whatever equipment in use that deliver, u said 5A.
(just monitor that the cells doesnt get hotter than 10C above surroundings, or 50C)

 

[mateusleo]

if u say so. Put whatever equipment in use that deliver, u said 5A.
(just monitor that the cells doesnt get hotter than 10C above surroundings, or 50C)

I guess i should leave it charging at 0,5A all night long, because by what i know, the charger will but off the power when its full. Then i'll completely dischage it and then charge again. BTW, this is the first charge.

 

[999zip999]

No need to completely discharge as don't. Do light discharges at first with lot's of time on the charger.

 

[d8veh]

I ran for 15,6 kms with it. Is that considered near full for a 20ah battery? I'm going nuts LOL

You can check whether it's charged by measuring the battery voltage. Anything over 55v is pretty well fully charged. The charger should have its charge voltage on it - probably 60.0v, so that should be your battery voltage when you measure it directly disconnected from the charger (fully charged).

 

[dogman dan]

If you got a bad charger, you surely are not the first one to have that happen.

Check your battery voltage with a voltmeter. If near full, a very low amps is normal. But if you are at 50-55v and it's not charging full amps, then you have a bad charger. My very first ebike, with sla's in the kit came with a 36v charger that put out only 18v. Eventually, the seller got me a new one. It happens.

If you can, scare up a 48v charger locally ( like in your country) to use while you deal with the seller for a replacement. Even a 2 amps sla one will work for a while. It won't completely balance the pack, but at least it will get it back to full enough to ride some.

 

[mateusleo]

If you got a bad charger, you surely are not the first one to have that happen.

Check your battery voltage with a voltmeter. If near full, a very low amps is normal. But if you are at 50-55v and it's not charging full amps, then you have a bad charger. My very first ebike, with sla's in the kit came with a 36v charger that put out only 18v. Eventually, the seller got me a new one. It happens.

If you can, scare up a 48v charger locally ( like in your country) to use while you deal with the seller for a replacement. Even a 2 amps sla one will work for a while. It won't completely balance the pack, but at least it will get it back to full enough to ride some.

I got a 48v SLA one, but can i safely use it on a LiFePO4 battery without damaging the cells?
New info about charger: I left it charging all night long and the charger still has same stats: intense red light and green light with a very small bright and the battery gave me 52.5 volts.

 

[dnmun]

you may have thrown the pack way outa balance when you discharged it first before charging it. you can measure the cell voltages and see if there is one cell shutting off the charge. you can measure the gate voltage on the charging FET to see if it is on. you can measure the charging current with an ammeter or watt meter.

 

[dogman dan]

Now you have me confused. Now you have both red and green light on. That's very very different for diagnosis than what you said in your first post.


That green light often just indicates the charger is unplugged rather than done charging. So look for faults at the plug, because 52v is definitely not done. It could be anywhere, including from the bms to the pack. Start by making sure you have pack voltage on the battery side charger plug. If so, that end is OK, and you shouldn't have to dig into the battery or bms. It could be an intermittent bad connection, often caused by a poor solder at the plug, or even inside the charger.

Still possible you just got a bum charger. When you get red light only, it should be pushing out 5 amps at 58v or thereabouts.

Since you have a 48v sla charger, you could try that and see if it works. It could help a lot to isolate the problem to has to be a problem with your new charger. BE VERY SURE you have that plug wired same as your other charger before you plug in the sla charger.

If it won't charge with the other charger, then I'd for sure suspect what he said above is the problem. The bms is breaking that connection, making the charger turn on the green light. Wouldn't that make the battery side charge plug read 0v when unplugged from the charger? or something less than 52v?

What voltage is the charger putting out? You said good, but it should be a lot more than 52v. 58-60v is typical for 16 cell, 48v, lifepo4.

 

[dnmun]

i think he started using the SLA charger. there was nothing wrong with the other charger because he said it was pushing 500mA close to the end of charge. that is why he only got to 52V because he started using the SLA charger i think. no way to know with no info. or pictures.

 

[mateusleo]

i think he started using the SLA charger. there was nothing wrong with the other charger because he said it was pushing 500mA close to the end of charge. that is why he only got to 52V because he started using the SLA charger i think. no way to know with no info. or pictures.

I never plugged the SLA charger to this battery. Just checked the LiFePO4 charger and it gives me 55,6v.

I took some pictures so you can see the status of the charger. The red light is intense, but the green is so weak that i had to turn the flash of, so the camera could capture it. Both of the pcitures were taken at the same time, one with flash on and on with flash off.

Should i plug the SLA to test if it will start charging the pack?

 

[999zip999]

The light green glow can be from the red led. Check the voltage on the sla charger before plugging it in. It might be 54.3v if it's o.k. It would be o.k. at 58v. Aways check with meter for right polarity. The battery has a lot of stored energry so do be careful. Go slow. Charge the battery and don't test the range... Do not fully discharge the battery now.

 

[mateusleo]

The light green glow can be from the red led. Check the voltage on the sla charger before plugging it in. It might be 54.3v if it's o.k. It would be o.k. at 58v. Aways check with meter for right polarity. The battery has a lot of stored energry so do be careful. Go slow. Charge the battery and don't test the range... Do not fully discharge the battery now.

Well, SLA charger worked, but the polarity was inversed so i couldn't leave it charging. I made this to "plug" correctly and avoid short circuit:

Now i have some guesses about the charger. It says 220/110 and something in chinese, But sun-thing said he thinks it is 220. My home has only 110, tomorrow i'll go to a place that has 220 and test it. Should i avoid using the battery for now? What do you guys think that may be wrong with my LiFePO4 charger?


Btw, heres the chinese instructions, maybe someone can help haha:

 

[999zip999]

You should answer the question what voltage does your sla charger put out ? I'm glad you checked polarity.

 

[mateusleo]

You should answer the question what voltage does your sla charger put out ? I'm glad you checked polarity.

I measured it. Got like 54,6v. I'm glad i have this forum xD I'll spend a lot of time here as soon as i get time. Engineering is killing my time.


Should i fully charge it with my sla charger? Should i avoid using the battery until i find whats going wrong with the lifepo4 charger?

 

[dogman dan]

It could be that your basic problem is your sun thing charger is 220 and you are running it at 110. But I know squat about chargers. It might be putting out the right voltage, but won't push any amps unless it gets 220.

That weak green light is not the charger shut off, or disconnected signal. Again I misunderstood, I thought you said it had bright both lights. Many chargers do this, the led's are close, and one turned on sends some light to be seen in the other.

Does the sla charger run ok and eventually shut off? It won't completely charge the battery, but better than leaving it sitting around way discharged. It won't get balanced at that voltage, but at least it can be used a little bit, for short rides if you get it 80% charged.

 

[mateusleo]

It could be that your basic problem is your sun thing charger is 220 and you are running it at 110. But I know squat about chargers. It might be putting out the right voltage, but won't push any amps unless it gets 220.

That weak green light is not the charger shut off, or disconnected signal. Again I misunderstood, I thought you said it had bright both lights. Many chargers do this, the led's are close, and one turned on sends some light to be seen in the other.

Does the sla charger run ok and eventually shut off? It won't completely charge the battery, but better than leaving it sitting around way discharged. It won't get balanced at that voltage, but at least it can be used a little bit, for short rides if you get it 80% charged.

I'll find a 220v plug asap to test it.

 

[DAND214]

If that charger pluged into the 110 then it should not plug into any 220v outlet.
Contact the seller and have him send the correct one.

The sla charger will charge the battery fine, will not fully charge it since voltage is below balance voltage.

Get a new one, now!

Dan

 

[999zip999]

You need to keep an eye on it and check the battery voltage. You just can't walk away and forget it on the charger. I know the charger shuts off at 54.6v. BUT. I mean it took you awhile and money to get it so be careful.
We all have walked away from are batteries at the wrong time.

 

[dogman dan]

Yeah, watch any new battery charge the first few times. Once it passes the test that it shuts off at all, the lead charger should be safe to use temporarily.

 

[mateusleo]

I'm charging it right now with the SLA 48v 2A 15Ah charger, and i'm watching it. Actually its right on my side in my room =P


Edit:
I got someone to borrow me a 220 outlet and now his house is on fire. Nah, just joking. It works like a charm at 220v, the charger doesnt have any problem. The label says 220v but for some reason i saw 220/110, noob thing maybe? So all my worries were my own fault LOL. The quality is simply impressive. The battery has a good price, arrived in perfect conditions and i have nothing to complain about. Well, if you need a 30A max current battery, go for sun-thing.