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Help! Battery not charging without a reason I can see.

#1
Hi, I am beginner rc flyer and got a strange thing, with multiplex L-703 EQU Multicharger. Yesterday I charged the battery all ok, with the same charger and everything was ok, it didn't overheat or anything. After flight the battery got slightly warm but not too much, I think it was normal. And I don't think I deepdischarged it, motor was just barely losing power when I got it down, and after landing it was still capable to turn the main motor. Today I was putting it to charge, and what happend is strange for me. On standby(not charging mode) charger was ok, but when I put battery on instead of two led cell indicators going on red (as normal charging indicator) all the 3 cell indicators started blinking red. The instructions don't say anything about this, so now I don't know what to do... I found on inernet forum about this, but they are not shure about this thing. I have only one battery and charger so I can't test other battery or charger. On battery there is no any visual damage. Sorry about bad english, hopefully someone can help.
 

DamoRC

Well-known member
Mentor
#2
It's possible that the battery voltage is too low for the charger to start charging. I don't have this exact model but I have a similar cheap-and-cheerful unit. Do you have a voltmeter / multimeter to check the cell voltages?
 
#3
Yeah, I have, and I'll check it later, but it would be strange if it would be, because of the fact it was capable of turning the engine. Before I have managed once to discharge it to be not capable of turning it and then it was perfectly charging.
 

DamoRC

Well-known member
Mentor
#4
It could also mean that the pack is significantly out of balance. This pic from a manual for a similar charger (I looked at a couple of different ones and they both state the same thing)

IMG_4324.PNG
 
#5
Well, this may be, although it flashes once in one second cycle (may be slightly different system) why would that happend? And what do I do if its unbalanced? Can it be fixed by someone who knows what he is doing or is the battery dead if its unbalanced?
 

FDS

Well-known member
#6
You use a balance charger, it charges the pack then spends the last third of the cycle balancing the cells. You can get plug in balancers as a separate item if you don’t have a balance function on your charger.
Getting cells un balanced indicates you may have worked the pack too hard, watch out for running it down below 3.5v per cell, as that can permanently damage the battery. Use a battery alarm and land as soon as it beeps, even if the beep stops when you throttle back.
A good lipo cell checker is a vital and inexpensive tool too. You can buy combined cell checkers and balancers.
The charger you have is not very good, it lacks both a balance function and storage. I like the IMAX B6 for cheap chargers, and the Accucell S60 for slightly more expensive. I don’t like chargers without a proper display or balance and storage modes, they are not suitable for beginners IMO.
 
#7
Well, my charger only charges via balancer (not main output as some big batteries need) but via smaller cable, the one that has one wire/cell, which as I know is the balance charging. I am not shure, I will check everything out. But thanks for reply! :)
 

FDS

Well-known member
#8
You are just charging all the cells slowly through the balance lead. Get a lipo checker/balancer then you can read the voltage of each cell in the pack. You want them all within +/-0.1v to be balanced.
 

FDS

Well-known member
#10
If you have a combined balancer/checker you could keep using that charger. Cheap chargers in bundles often don’t represent a good deal!
Check the pack before you fly again. You can read the cell voltages with a plain multi meter provided you are very careful not to touch the ground and positive probes together when you push them onto the balance connector pins. The black wire in the balance connector is ground, the other ones are the +ve from each cell. Don’t short + and - on any part of a lipo.
 
#11
Well, i don't have a balancer, only a general multimeter, so i will need to buy one, i'll be in contact with local store. I am avare of short circuits, I have a radioamateur license but still will be careful :)
 
#14
If a cell drops below a voltage that some chargers "see" as too low, USUALLY, it will not charge the pack.

You can try to revive it.
I have done this many times to LiPo's that have been given to me by friends, and customers, and have been able to revive at least 80% of the packs.

... !!!!! DO NOT DO THIS IF YOU HAVE ANY DOUBTS !!!!! ...

... DO NOT LEAVE THE BATT/CHARGER UNATTENDED WHILE DOING THIS !!!! '''

... Obviously, I am NOT responsible for any damage this may cause. ...

If your charger can charge other battery chemistry, you can set it to NiMH, adjust it to a low amp setting (start with half C), and charge for 60 seconds. Then set it back to LiPo, and the correct charge rate, and try to charge it again. If it is still too low to charge, ...repeat. If you begin to feel an increase in heat while trying to revive the pack on NiHM setting, ...STOP. Better safe, than sorry. If the pack only has a low cell, and is undamaged, at some point the cell will reach a level the charger will charge, you will be able to BALANCE CHARGE it on LiPo setting again.

I have never had a pack cause a fire, or any other damage, BUT, I certainly don't want it to happen to anyone else. Please, be cautious.

I've had a lot of success doing this, and hope it helps you, too!
 

Hoomi

Well-known member
#15
These battery checkers are cheap, and accurate enough for our purposes. You can set them to alarm when a cell goes below a threshold voltage, and leave it connected to the balance connector while the battery is in use in your plane. With my hearing (40+ years of working around noisy equipment), I can't hear the alarm in the plane while it's flying, so I use the timer on my Tx, but they are also useful for doing a quick check on your batteries at the field.

When I first started flying, I was using the cheap 'n' dirty chargers that came with my RTF planes. The trouble with those is they ONLY charge, and if I got to the flying field and wasn't able to fly, I had no convenient way to discharge the battery afterwards. It's bad for LiPo batteries to store them fully charged, so I invested in a charger that also has a discharge and store function. The store function sets each battery cell to the proper level for safe storage, whether it's already discharged from a flight, or still at full charge from a missed flight. I figure the money it will save in potentially damaged batteries will be more than the cost of the charger. There are quite a few such chargers out there, and I'll echo the advice to look into getting one soon. If you're like the rest of us, it won't be long until you have more planes and more batteries. These silly things are kind of addicting.

LiPo Battery Checkers
 
#17
These battery checkers are cheap, and accurate enough for our purposes. You can set them to alarm when a cell goes below a threshold voltage, and leave it connected to the balance connector while the battery is in use in your plane. With my hearing (40+ years of working around noisy equipment), I can't hear the alarm in the plane while it's flying, so I use the timer on my Tx, but they are also useful for doing a quick check on your batteries at the field.

When I first started flying, I was using the cheap 'n' dirty chargers that came with my RTF planes. The trouble with those is they ONLY charge, and if I got to the flying field and wasn't able to fly, I had no convenient way to discharge the battery afterwards. It's bad for LiPo batteries to store them fully charged, so I invested in a charger that also has a discharge and store function. The store function sets each battery cell to the proper level for safe storage, whether it's already discharged from a flight, or still at full charge from a missed flight. I figure the money it will save in potentially damaged batteries will be more than the cost of the charger. There are quite a few such chargers out there, and I'll echo the advice to look into getting one soon. If you're like the rest of us, it won't be long until you have more planes and more batteries. These silly things are kind of addicting.

LiPo Battery Checkers
Thnx for the link I'll check it soon! :)
 
#18
You use a balance charger, it charges the pack then spends the last third of the cycle balancing the cells. You can get plug in balancers as a separate item if you don’t have a balance function on your charger.
Getting cells un balanced indicates you may have worked the pack too hard, watch out for running it down below 3.5v per cell, as that can permanently damage the battery. Use a battery alarm and land as soon as it beeps, even if the beep stops when you throttle back.
A good lipo cell checker is a vital and inexpensive tool too. You can buy combined cell checkers and balancers.
The charger you have is not very good, it lacks both a balance function and storage. I like the IMAX B6 for cheap chargers, and the Accucell S60 for slightly more expensive. I don’t like chargers without a proper display or balance and storage modes, they are not suitable for beginners IMO.
Hey, how about the imax b-6? Does it include 2cell balance charging cable? And does it need to be always charging via main port? My connector on main port of battery is kind of hard to get with theese crocodiles, it has 3 small contacts on plus and 3 on minus, I cant simply push the crocodile in it as you could if there would be 1 contact/wire...
 
#19
Ok, now I am even more disappointed, one cellwire showed 2,8 volts. The other one showed about 6,2 which is also same at the main output wire. Smells like short circuit, but there is no any sign of damage, maybe somewhere inside the battery, but I don't see a reason for it, even though landing weren't prettiest...
 

FDS

Well-known member
#20
You measured one cell then the pack voltage, both combined. If you are under 3v anywhere then it’s dead.
IMAX B6 is a fine starter charger, it needs a 60-80w laptop PSU for mains use. I had a clone one for a couple of years, it worked fine.
The cause was likely you flew too long, drawing too much from the battery.