lipo...3.7v and 4.2v?
12-12-2011, 11:00 AM
#1
Thread Starter
lipo...3.7v and 4.2v?
ok, so ive had this happen in the past, and now i just got 2 used lipos pack with the same issue.
my charger reads both cells, and will charge the pack. but once its done(charger times out at 1&1/2 hours) the total voltage is a hair over 8v.
my blinky balancer shows cell 1 @ 3.75v and cell 2 @ 4.22v
same with the second pack. and the pack provide plenty of power....but only for a couple of minutes before the ESC's LVC kicks in.
Why is one cell taking a charge...but only to 3.7ish volts? what causes a cell to only charge to that point. its like it works but only half way.
my thunder ac6 charger and my common sense RC balancer cannont get that 1st cell to go above 3.8v. doesnt matter how long i leave it on the balancer.
my charger reads both cells, and will charge the pack. but once its done(charger times out at 1&1/2 hours) the total voltage is a hair over 8v.
my blinky balancer shows cell 1 @ 3.75v and cell 2 @ 4.22v
same with the second pack. and the pack provide plenty of power....but only for a couple of minutes before the ESC's LVC kicks in.
Why is one cell taking a charge...but only to 3.7ish volts? what causes a cell to only charge to that point. its like it works but only half way.
my thunder ac6 charger and my common sense RC balancer cannont get that 1st cell to go above 3.8v. doesnt matter how long i leave it on the balancer.
12-12-2011, 12:01 PM
#2
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RE: lipo...3.7v and 4.2v?
I believe that is not good at all to have the two cells that far apart from each other. It is pretty dangerous to do that. You need a lipo charger that has a balancer. I don't know a lot about lipos I have one and i am kind of new to them but i think that your batteries are going bad, how old are they? If the cell won't charge any higher than 3.7v then it is prob bad.
12-12-2011, 12:26 PM
#3
Thread Starter
RE: lipo...3.7v and 4.2v?
i figure the cell is bad. i want to know why?
usually if a cell goes bad then it wont charge at all. this one will charge, but only to 3.7ish volts.
the previous owner used a slow balance charger. and my thunder ac6 is also a balance charger. but no matter how long its on there, it wont balance the cells.
sucks to get 2 used lipos and have them both be bad.
but im not out too much. i bought a RTR volcano epx pro(brushless) with the lipos for $85 shipped! The truck runs great, just ran it with one of my other lipo packs. lots of power and fast. the volcano epx pro is $185 new, and the one i got looks to be in really good shape. just wish the pair of lipos had been good.
usually if a cell goes bad then it wont charge at all. this one will charge, but only to 3.7ish volts.
the previous owner used a slow balance charger. and my thunder ac6 is also a balance charger. but no matter how long its on there, it wont balance the cells.
sucks to get 2 used lipos and have them both be bad.
but im not out too much. i bought a RTR volcano epx pro(brushless) with the lipos for $85 shipped! The truck runs great, just ran it with one of my other lipo packs. lots of power and fast. the volcano epx pro is $185 new, and the one i got looks to be in really good shape. just wish the pair of lipos had been good.
12-12-2011, 02:20 PM
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RE: lipo...3.7v and 4.2v?
One's full and one's empty. The cell's have no choice in the matter especially when they are in series.
The full cell can be discharged OR the discharged cell can be charged. Ideally they should be both balanced at 4.2 volts before evaluating them as a pack.
If the same cell in two packs reads the same then the voltage measurement may be suspect. Try to use the SAME EXACT device to measure each cell's voltage. In otherwords pin out cell 1 then move it to cell 2 then 3 and then 4.
The full cell can be discharged OR the discharged cell can be charged. Ideally they should be both balanced at 4.2 volts before evaluating them as a pack.
If the same cell in two packs reads the same then the voltage measurement may be suspect. Try to use the SAME EXACT device to measure each cell's voltage. In otherwords pin out cell 1 then move it to cell 2 then 3 and then 4.
