charging lipos

[bwells]

I'm currently charging my second 7.4 5000 MaH lipo after running them yesterday for 21 minutes. The first one took 173 minutes and consumed 3878 and final voltage is 8.43. Thats 6 hours to charge batteries for 20 minutes of run time. Is there a better way? (nitro)

[egneg]

Don't run them so long and they will charge faster.



What charger are you using?

I have a Triton charger that ramps up to 2.5 amps and then back down again. I have had them take that long as well and it takes about an hour just to top them off from a short run. I usually charge them when I am putsing around the garage working on other stuff. Other chargers can charge at much higher rates and 2 at a time but they cost a bunch more.

[bwells]

It's an Electrifly triton eq and is capable of 5 amps and 6s, I was thinking of something like charging in series set at 4s and 5 amps but the balancing plugs won't work unless I make an adapter or parallel the batts, that would half the amps but I think that would be okay. Anything to cut down on the time. It appears to take the last hour at .2 amps to gain a minimal amount of charge. I guess I can yank them at 2 hours and call it good!

[bwells]

After 60 minutes on the second battery, I have hammered in 3638 MaH! I will keep an eye out for the last charge time but I would assume 2 hours to get another 200 MaH is a bit much. I'm guessing it is in top off mode now but not sure>

[bwells]

update: 66 minutes and 3685 on the second battery. That sounds a lot better and I can deal with the time. I do notice that one battery always seems hotter than the other, by 20 degrees, but I will now pay more attention as to the placement in the series, my guess is the first one,i.e. neg lead, is going to be the hottest.

[egneg]

The last bit of charging is the most important ... you will not get the batteries full capabilities if you pull them off the charger early. Wait until it says it is done.

[bwells]

Okay, I can see that but why would one tale 173 minutes and the other 66 minutes? Is one of them bad? I have only ran them twice but they are zippies!

[egneg]

Are they in series or parallel?

[bwells]

series and the temp between the 2 batteries, whether it be NiMh or lipo, is always 20 degrees different. I need to pay more attention as to the placement in the series and try to figure out why, or not. There has to be a reason. I've got the batts numbered so I will pay more attention as to which is hotter and in which position(1st/last). Someone has to have had this same question!!!~

[Brushless55]

Are you charging both batteries at 5amp?
possibly the one is taking a loooong time to balance?

[bwells]

Nope, 4 amps to start with and then the charger drops from there. The difference in charge time and temp after runs is what I was wondering about. I think I need to get more specific info as to batt placement in the series thing. Someone out there has to have the same issues. I would say the battery that has the neg from the ESC is more likely to discharge faster than the other one and don"t have a clue why! I will definatley pay more attention to where I place the batts as I have them numbered. Kind of an interesting experiment unless someone else has already done it!

[Brushless55]

Are you charging your batteries one at a time or in series?
a lipo battery should not get warm durring charging

[Boatman]

I had the same deal with some polyrc packs. They were getting weak, or at least one was. They had been overheated and swelled. They were the first pack to shrink after it cooled so I kept an eye on it and it lasted and lasted. However it always came back hotter and took longer to charge. I would recommend getting a new set or as you say watch which one is the "hot" one and replace asap.

[Boatman]

Hmm, after reading about the "NEG" side always being the hot side check you solder joints on the esc and your connector. May have a weak connection there. Goodluck to ya

[bwells]

Sorry on the mislead, the batteries are 20 degrees different when ran in series but charge at a totally different rate and time but I have only done it once with the lipos so I will check it out. I have noticed the temp difference on both lipo and NiMH SO I don't think it is my solder joints. 2 batts in series,neg lead first is the hottest when ran and requires the most charge is my assum
ption and have not proven it.In the telecommunication industry, the saying is "it's battery looking for ground" and the tip(neg) side goes open first. I'm thinking this side gets hammered and has the most draw in a series setup, one has to take the heat and the first one on the neg side is it,help me out here you electonic guys, I know you can explain it better than I can