Batteries way too hot!

[makin' waves]

Hi guys,

after a 2 to 3 min run the temps on one of my 7cell 5000mah intellect nimhs was around 240*!

it has melted some of the plastic wrap on the batteries, tho the cell is not out of shape.

Would it be safe to use this again? (i've not even tried to charge it, just in case)

my setup is

ammo 2300 motor
42x55 prop
7 cell nimhs,
Stock Esc

All the other temps motor/Esc are fine around 80/90*s and the boat was flying....
so the question is how do i keep the temps on my batteries down?

Thanks
Tone

[Fluid]

Was it a single cell which was so hot, or a whole pack? How did you measure the temperature, 240*F is REALLY hot. If the other pack was fine, then I'd toss the 'hot' pack (not in a landfill!).


.

[Duster19]

Not trying to steal this thread, but I have a similar question about batteries. I just got a used Supervee 27 and with it came a Twin Peak Charger (will not charge Li-PO batteries) and 2 Power-Max Pro 3000 mah Ni-MH packs. When I finish charging them they are warm to the touch. I'm getting about 3 min. run time and they are hot to the touch. They can be held, but my 13 year old gave me the "wow" those are hot when he picked one up. I have no clue how hot they were or if they were too hot. The engine (upgraded 6 pole gold color Aquacraft) was pretty cool to the touch. Is a 3 min. run time about right for these batteries (running an x440/3 prop)? I also have the upgraded 45amp ESC with the built in water cooler.

My questions to you all is if, I don't really want to upgrade to Li-Po (charger and batteries at this time), what Ni-MH pack is the best on the market and what run times should I expect to get? Or would it be a better investment to just switch to Li-PO?

Thanks,

Dave

[makin' waves]

Hey Fluid,

Yeah it was just one end cell (one furthest from the connectors) That was 240*f. The rest of the pack was hot but not as hot.
I used a infared digital thermometer, so I'm trusting it was fairly accurate.

Yes i agree I'm definately not going to use the pack again, and I will dispose of it properly.


Tone

[makin' waves]

My questions to you all is if, I don't really want to upgrade to Li-Po (charger and batteries at this time), what Ni-MH pack is the best on the market and what run times should I expect to get? Or would it be a better investment to just switch to Li-PO?

Hey Dave

Batteries will get fairly warm to the touch when you charge them, and they will be warm when you use your boat, my temps are usually around 110*F.

The time of your run lasting depends on how hard you drive the boat, I can usually go for about 4/5 mins max and i'm pretty much full throttle the whole time.
Are you using 7cells?
Duratrax 7cell 5000 mah batteries would be a good buy. Basically you want batteries that have them all the same way in the pack, with battery bars along
each side..(these are usually better quality batteries.)
I have heard from others once you go lipo you won't go back. But others say the 27 was designed to be run with nimhs...its your call buddy!
Hope this helps

Tone

[Duster19]

Tone,

Correct me if I'm wrong, but wouldn't a 7 cell batter be 8.4 volts? Can these be used on my Supervee? I thought you could only run 7.2 volt batteries?


Dave

Sorry for being such a noob :)

[makin' waves]

Yeah mate,

7cells are 8.4v, I run these with no probs atall, I don't think you can run any more than 7 without upgrading the ESC.

You WILL notice a big difference from 6 to 7 cells. I only buy 7cell batteries now.

I just place the batteries slightly more forward (about 1 cell) so to keep the COG good.

Tone

[mappo]

Was it a single cell which was so hot, or a whole pack? How did you measure the temperature, 240*F is REALLY hot. If the other pack was fine, then I'd toss the 'hot' pack (not in a landfill!).e pack

.

I had similar situation with many of my nimh packs and fount that if you charge at 50-100mah for an hour then charge the pack at higher amperage, the one cell will balance out with the whole pack. try my method before tossing.

[makin' waves]

I had similar situation with many of my nimh packs and fount that if you charge at 50-100mah for an hour then charge the pack at higher amperage, the one cell will balance out with the whole pack. try my method before tossing.

Thanks for the advice mappo,

I'm new to all r/c stuff, does charging @ 100mah mean charging @ 1 amp?

I usually charge my batteries @ 4 amps for a few times and then charge @ 1amp. I heard that this can prolong
the life of the batteries.
Thanks

Tone

[mappo]

Thanks for the advice mappo,

I'm new to all r/c stuff, does charging @ 100mah mean charging @ 1 amp?

I usually charge my batteries @ 4 amps for a few times and then charge @ 1amp. I heard that this can prolong
the life of the batteries.
Thanks

Tone

100mah is just that,- 1000mah = 1 amp. if you want to prolong the pack you will have to charge at lower than 4 amps