LifePo4 charger question

P

praskal

1 W
Joined
Dec 25, 2007
Messages
60
Location
Corvallis, Oregon
I finally joined the 21st century and got a 48V 10ah LifePo4 pack. I am using it with a road runner front hub motor and a 48V 25amp controller. It is really nice. I used to ride around with 72V SLA and a rear X5 beast. It was too much. Now I feel much more nimble and I don't think I have sacrificed anything for speed with my new set up.

Anyhoo, I have no idea how to know when the charger is done charging? The 48V LifePo4 charger has a red and green light which are ALWAYS ON. And it has a fan which is ALWAYS BLOWING. Can anyone suggest any bit of knowledge in this respect?
 
Do you mean that both red and green lights are on at the same time? If so, that doesn't sound right. Normally the red light is on when charging and the green light is on when it is not. The red light may come on again for a while (as mine does) while the cells are balancing. I leave mine on overnight for the cell balancing as this can take some time. It is always green in the morning and the fan is off.
 
Something aint right if both red and green lights are on all the time. If you have an sla charger around at the right voltage you could try using it, and see if it does the same thing?

Normal would be a full discharged 10 ah pack would take at least 6 hours to charge, red light showing, followed by at least in the beginning, many hours of green light for a while, then red awhile, as the pack balances. In the first week, asumming the charger is functioning ok, leave it charging overnight so it can continue to balance better. Personally I do this all the time, since I would have to get up in the night to unplug, and a timer would use more power than the charger left on green light.
 
Thanks for the replies. Ok, I will keep it charging overnight and then see if the red light and the fan shut off. If not, I suppose I could try the 48V SLA charger that I have. Is there anything specific that I should watch out for with using and SLA charger for Li?
 
The 48v sla charger will be fine, exept that it will not balance the pack properly, since it will have a couple volts less than the lifepo4 charger. I'm still confused, are both green and red on, or it is just the red and it doesn't seem to stop. If the thing is charging, the fan will blow, but it should stop when the green light goes on. You may have just caught it charging , red on, while it was doing the red awhile then green awhile thing, while balancing. A fully discharged 20 ah lifepo pack can take over 12 hours to charge, and when new , several more hours of balancing, so you may just have not charged so long as you think if you plugged in after dinnertime. To break in a new lifepo4 pack, leave it charging as long as possible on the lifepo4 charger. Even after obvious balancing is done, and the green light is on, some balancing still happens since the charger is on constant voltage mode, and some weaker cells can still come up a tiny bit more. After about 10 cycles of 50% discharge your pack should be at its full capacity, whatever that ends up being. At that point, you can stop leaving it on the charger all the time. With my bike, I end up leaving it on charge any time it's not being ridden, since I get up ride to work, charge all day there, and the returning home, put it on the charger, where it would be done at around 2 am, so it just stays on it till I wake up. Ends up to be about 21 hours a day on the charger.
 
"I'm still confused, are both green and red on, or it is just the red and it doesn't seem to stop."

As soon as I plug in the charger the red and the green come on. The fan also comes on. I let it charge all night (12 hours) and when I saw it this morning it is the same: red and green lights on, and fan on. Absolutely no change at all. I unplugged it. I know something is not right. I have been emailing with the ebay guy who sold it to me. This is what he said:

"hello my old friend,
1 two red lights will be on when it is charging and when it is done charging the geen light on.
2 when it is fully charged you can leave it plugged in about one hour, then after one hour you unplug the charger is the best."

I sent him a reply stating that if this is the case, then mine definately is not working right. I have not gotten a response yet? Damn...
 
Hang on to your shorts, and read the battery threads about freeshopping, Jimmywu, you may be dealing with mr lau. It looks to me like you may need to just get a charger from Ping. He has a new pingbattery website. Another option that works is to get a soneil charger, and adjust the voltage up to what you should have for a lifepo4 battery. There is a little screw inside that can be adjusted. Threads on that in the batt section too. And some of the bike sellers like ebikes ca might have chargers . Meanwhile try charging it on the sla charger, it won't hurt it, and see if it acts the same, or vice versa, try charging a lead pack if you have one of those around and see if that charger does that with the lead. If you have a mr lau pack, multiple things could be wrong with it. If you have a voltmeter, it would also be interesting to see if the charger is putting out any at all.
 
I bought the 48V 10ah LiFePo4 pack from zhimingok12345@126.com on ebay. I don't know if he is masquerading as mr lau or not. He had good ebay reviews and comments. I did check the charger with my voltmeter and it is spitting out 56.6 volts. I suppose that is good that we at least know it is working, right? There weren't any chargers on Ping's website, so I sent him a direct email about chargers. No reply yet. Also no reply from zhimingok12345 yet either.
 
Well his feedback does not display the classic pattern for mr lau's new ebay name, but maybe he caught on to us not wanting to buy from somebody who's entire feedback was one dollar or less items. There seem to be a lot of pretty sketchy 18650 cell packs out there though, and nobody knows where they come from. They could all be from the same place, or some of them could be from the defect dump at the factory. No way to tell which vendor has good ones and wich has bad. Ping uses a different cell with a much better track record.

Good luck, I hope all you have is a bad charger or a bad bms. Does the pack seem to have a full charge? If so, you might be able to use it with your sla charger for awhile. Just keep the rides pretty short till you sort out what the problem really is. Have you looked at the connections at the battery yet? I am assuming its wired right, all the ones I have seen have a seperate wire for the charging negative.
 
As I said, I checked the charger with a voltmeter and it is putting out 56.6 volts. The pack seems to be charging up appropriately. Though I'm not sure about balanced charging and all that LiFePo4 stuff.

Are you saying that this could be a BMS problem instead of a charger problem?
 
Just grasping for possibilites, but if the bms wasn't letting power flow into the battery, the charger would of course keep on running trying to charge the battery. Lotsa possibilites. Usually when chargers don't work the magic smoke lets you know something melted.
 
Ok, I just got this reply from zhimingok12345: "hello my friend, if in this case, you can pluck out BMS to charge about half-hour, not more than one hour, after that, plug into BMS to continue charge. it will be normal. if this is still not help you. please email me again, i will let my engineer to help you! thank you!"

And I replied with this: "Oh no. The BMS was not already connected? I have been charging the
pack without the BMS connected at all. Have I ruined the whole thing?
You need to know, I barely know anything about electrical things,
especially lithium battery packs.
Ok, I just connect both connectors to the BMS. I then plugged the
charger back in. The red light and the green are both on. The fan is
on. Should I leave it charging all night with the BMS connected?
Patrick"

I had absolutely no idea that the BMS was not connected. Have I ruined it??
 
I doubt it, but you still may have something wrong with the charger. Lifepo4 is pretty tolerant of overcharging. The both lights lit thing is really wierd. You might want to open up the thing and see if both led's light, or just one, which may be positioned wierd and shining light into both jewels. If the pack and bms is ok, your other sla charger will shut off when it finishes. So trying that charger and seeing if it ever shuts off may at least tell you whether it is a problem with the pack or just the charger.
 
Thank you so much for all your help. Ok, here's the latest reply from zhimingok: "hello my friend,
my engineer (give) directions:
1 when charging, two red lights on.
2 when charged, one red and one green light.
it is to say, one red light on always, when charging, another one is red, after charged, another one change green.
do you understand? now things is one red lingt on and one green light on, it is mean that the battery charged fully.
i am sorry i can't explain clearly to you.
when you received the battery from us, the battery is fully charged, and you can use it till energy is left unused, you can to charge it.
thank you!
if you are still clear, please let me know.
best,"

Maybe I'll ride the ebike to drain the batteries, and then charge with the SLA to see what's up. I sent an email back to zhimingok stating: "Thank you zhimingok,

I still think there is a problem. After discharging while riding my ebike, I plug in the charger and you say that two red lights should be on. But this is not happening. There is one red and one green light on, and the fan is on (even when the battery pack is low on charge). This does not change. I let it charge (12 hours) all night and this morning same thing: one red light, one green light, and the fan on.

I think either the charger or the BMS is not working correctly."


Hey, I'm just glad the guy is responding and trying to help, and that he has an "engineer".
 
Does the charger do the same thing when the pack is disconnected?

To try and figure out if it is a charger problem or a BMS problem, it may be useful to measure the pack voltage directly on the cells when charging to see if the charger voltage is reaching the cells.
 
Good question. I had a broken wire in the plug giving me a led saying the pack was charged once, but it that case, the fan stopped, so plugged in and not plugged in were the same, as far as the charger could tell. Too wierd, the charger saying charged, but the fan keeps running.
 
Well, if I plug in the charger when it is not connected to the LiFePo4 pack, the red light and green light come on. Also, the fan comes on the low speed. When I plug it into the batt pack, the red and green stay on, and fan fan ramps up to the high speed. What do you think this means?

Also, I notice that the charger puts out 56.6V. and after leaving the charger on for several hours the pack is fully charged - around 54 volts. And the BMS is hot.
 
It sounds to me like a new charger is in order. If the sla charger puts out the same voltage, you could just use that.
 
Should I plug in the 48V SLA charger when the BMS is connect, or not connected? Or does it matter??
 
bms connected.
 
By the way, I finally talked the LiFePo4 ebay seller to send me a new 48V charger. Yay. I hope this one works.
 
I've stopped using the BMS altogether on my battery. It was doing something similar when I tried charging my battery.

Total life cycles are certainly improved with a good bms; but even if I get half of the 3000 anticipated life cycles of LiFePo4 ... 1500 is more than 5 years of charging... even if i drained the batteries every single day. By then, I would hope better batteries would be on the market, and it would be time to get new ones anyway.

I've noticed a few other people out here that have dumped their BMSs as well... that made me feel confident to bypass it altogether.
 
Hi
i have the same problem with two chargers i buyed (one 12V and other 48V) !

:(

all are turning ON the green and red LED at the same time but they dont turn on the fan!

:( :(

what can it be?
 
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