bit of a battery issue?

[SwampDawg]

lastnight i charged my 7.2 3300MaH stickpack for hours and the battery never even got warm, nor charged a helluvalot??

so what happened here, a collapsed cell or something else?

[AreCee]

Did you check to see if you have voltage at the connector? If yes, recheck your charger. If no then you may have a short.

Stick packs are throw aways. Either they work or they don't, it would be a pain to fix it if it is even fixable.

[SwampDawg]

yea....just odd?
worked just fine the day before, then noticed the battery wasnt getting warm during a charge session?
there is voltage at the cannector, and the RC will run...but for a very short time, so i guess the sticpack is history lol
time for a new one...ugh!
right after we just spent hours building the start of our new track this happens?

[Trubble]

Originally Posted by SwampDawg

lastnight i charged my 7.2 3300MaH stickpack for hours and the battery never even got warm, nor charged a helluvalot??

so what happened here, a collapsed cell or something else?

What charger?
What charge rate did you select? (amps)
Did your charger (false) peak shortly after starting?

[SwampDawg]

okay....after testing many things out.....

Pulled out my NVS and plugged in the ESC & Steering directly into my Rx......still the same issue.

Charged battery again for HOURS......put it down and it ran somewhat alright for a minute or two before coming to its death again. Threw on the voltameter to the 7.2v sticpkack to discover it was at around 6.2v and slowly was recovering on its own back to 7.2v, so i think the battery is ok??

the VXL3S is new as of a month or less.

The Tekin 13.5t is new as of like a week ago.


WTF?

[AreCee]

If the charger is working with other packs I would suspect you have a bad battery.

[Trubble]

Originally Posted by SwampDawg

Charged battery again for HOURS......put it down and it ran somewhat alright for a minute or two before coming to its death again.

Sounds like its not an issue with the truck or a battery issue (yet), but a charger issue.

What charger?
What charge rate did you select?(amps)
Did it false peak on you shortly after starting the charge?
Did remember to press "START"?

[SwampDawg]

Originally Posted by Trubble

Sounds like its not an issue with the truck or a battery issue (yet), but a charger issue.

What charger? Hotbodies micro charger
What charge rate did you select?(amps) 2A
Did it false peak on you shortly after starting the charge? N
Did remember to press "START"? Y

now id believe that comment had it not been at 7.2v at the stickpack.

[Trubble]

Okay, I was looking for why it was charging so long. Usually, if I have a cell get sulfated or shorted, my charger'll kick off after only a minute. Even on a good day it'll take you an hour and 40 mins to charge that battery at only two amps.

So the 'only running for a minute or two', and the charger never getting to a 'finished' status does sound like a bum cell in the pack. The part that was throwing me was that typically bad cells will heat up and you'll get a localized hot-spot within the pack. Two amps must be under the threshold of causing too much heat, or the charger's reducing the amperage as the pack's internal resistance increases.

At this point, short of cutting off the shrinkwrap and checking the voltage on idividual cells, I'd tend to agree with your original diagnosis of a dropped cell. For what it's worth, I've used THESE packs and really liked them (if you're looking for a 'budget' pack). I also have THIS & THIS, and like them too, but there's no way I'd recommend them with that charger. And to be honest, if you have to buy a different charger anyway, I'd think about maybe going LiPo at that point.

[SwampDawg]

i have to agree with you now, i think its the stickpack.
i think its time for me to join the future and go LiPo.
these NiMh are just not enough for todays esc & motors.

[AreCee]

Originally Posted by SwampDawg

these NiMh are just not enough for todays esc & motors.

Not really true. Stick packs still provide voltage which is all the ESC and motor care about regardless of the source.

Lipos have the advantage of providing the same amount of power in a smaller, lighter package. Also the discahrge curve is better with Lipo, however, unlike NiMH batteries you cannot discharge Lipos below 3.0V/cell.

[spillproof]

Originally Posted by AreCee

Not really true. Stick packs still provide voltage which is all the ESC and motor care about regardless of the source.

ESC and motor care about more then just voltage. There is a huge difference based on the amount of amperage a battery can provide. A 5000mah 60c lipo is going to make a ton of amps available (300a), where nimh and such have a much lower discharge.

If your motor wants to draw 100 amps at 15volts, and your battery can only discharge at 20 amps, your gonna be a sad panda. Not to mention you will probably make the stick pack pretty hot.
You can control the volts, but the motor pretty much chooses how much amperage, and it's up to your battery to provide it