James c harrell

My Feedback: (18)

I bought a new Zippy 5200 30c 2 cell lipo for my R/C car. I charged it on a 2 amp balance charge and all looked good. Went out and ran it and it did O.K. but when I went to charge it back, after it cooled off , the cells were not the same. One was .3 volts off. During the charge they balanced back out but I kind of think that means one is a little weaker. Any input??

chuckk2

What did the lipo look like before you charged it?
Were the cells in balance at about 3.8V or so?
If not, and there was a significant difference, the lipo was iffy to begin with.
You can try to charge and discharge the pack a few times, and see if it improves.

For reasons unknown, I've had similar problems with 5000mah 6s lipos.
One Pulse brand ballooned slightly on initial charge at 5A.
At the time I didn't think to check the cells before I started a balance charge.

Now, I check for proper cell voltage and balance before I leave the store.
The worst I've encountered from a reputable distributor was .3v low on one cell.
It was just within minimum storage range, and while the lipo is serviceable, it
does have a "weak" cell.
Having learned a few things since, I also check cell voltages under load whenever possible.

James c harrell

My Feedback: (18)

When I got it the cells were both at storage. 3.8 on the nose. First charge, 2 amp balance charge, charged fine. After that first run was were I saw the imbalance. I charged it back up and it balanced fine. Ran it again today for a short run. My Husky needed some exercise! Put it back on charge and it was 3.89/4.00. Would have ran it down a little more but the dog was out of shape. When I put it on the charger it came right to even while on charge. The only reason I am worried is that I have 6 cell batteries in a Telemaster that never have any difference in the cells and I am not used to seeing this unless I have a swollen pack. This one is not going to swell or give any warning because it is a hard-case battery. Battery lasts fine as far as run times and has good power. So ???

trax de max

my zippy's did that too, it took about 8-10 uses to get them pretty much close together, I didn't cycle them a few times when i bought them, I just thought for the price, just charge and run. But they did get a close reading.

Rodney

You just have cells that are not well matched, the one with the low reading after use just has less capacity than the other cell. Still safe to use as long as you don't pull the weak cell to low.

James c harrell

My Feedback: (18)

Good thing I turned up the cut-off on my ESC as high as it will go. Cuts down on run time but I don't like pulling my batteries that low.

chuckk2

3.89 to 4.00 is acceptable. 3.88 or less and 4.00 might be an indication of mismatched cells. Remember that a voltage of exactly 4.00 might actually read more or less, due to measurement device accuracy. Cell checkers and chargers use slightly different circuit paths from each cell, so that can also be a contributor. A fair number of the cheap RTF "come with" chargers for 1 and 2 cell lipos didn't have balancing built in. These can create problems with the two cell lipos if the cells are not well matched.