How hot should NIMHs get?

[R.C.Hole]

Anybody have an idea how hot NIMHs should get?
I'm running a D4 with a 5700kv brushless (approx 6T) on a 7.2v 4000mAh pack and depending on the surface I'm running on I can burn myself on it (even worse with my old brushed 15T).
I only bash for now and its the only pack I've got so i don't have experience with lots of batteries.
Also does anyone know a max safe discharge rate (before you start to damage them) all Lipos have it marked on them but I can't find any info for NIMHs;

Any help would be great.

[ianhaye]

you shouldnt burn youself from the batterys thou its ok for the to get hot after a hard run, sounds like your motor is pulling more power than your batterys can handle, whats you motor temps like?

[R.C.Hole]

My Brushless temp is ok, never gets too hot. The wierd thing is I'm only running a 18T pinion and there's still sod all punch, top speeds good but it's crap on start up (for punch my brushed was better).

Shouldn't NIMH be able to handle brushless? Or is mine screwed?

The problem is my brushless is sensorless and if you go hard on the throttle from a stop it just stutters -you have to really roll the throttle to get it to start.

At the moment I'm running without a shell, I've tried putting it on and the batteries just cook!

[ianhaye]

u sud no way have to run without a shell, just a thought but how hot do they get when being charged? how old are the batterys and have been sitting for a while, if u can check each cell with a voltmeter and report back you findings.

[R.C.Hole]

Now and then they get really hot when charged but recently they haven't even got warm.

They're orion sport 4000s and I went to orion's site and they have a new sport battery range now, mine are from the old range but I don't now how old they are.

I checked the voltages a while back after running and they seemed fine and they're all the same.

Any suggestions?

[ianhaye]

i would try and borrow a set of battery of someone and give them a try bud,

[R.C.Hole]

Only guy I know who has an RC car is my brother and he's running 8 cells. Do you run NIMHs or Lipos?

[slow bob]

i had the same problems with my nimh s when running brushless off them i also had a set of orions but i had the top speck 4200 mached set and i was running a sensorless 7400kva mamba brushless system

i got about 12 runs with them on differnt days before i had the same problems as you

then i swiched to lipos with a high c rating and havent had any problems with the car since apart from smashing it into things at 70mph lol

[ianhaye]

before using 8 cell check that the esc specs allow them, if not ull be fine using lipo but just rember you wount have a cut of for low voltage if the esc is lipo ready, so only run it quickly to test it..

[R.C.Hole]

Problem is the D4 uses saddle packs, ESCs not a problem its fully programable.

Do you think NIMHs will handle my motor if I bought a new pack? -love to get lipos (looking at the trakpower dark series) but it comes to about 100 euros + 50 for the chassis trays +my charger can only charge at 2.5amps!

If not do you know of any mid range lipo saddle packs? I want 4000-5000mAh but I don't think I need 40c discharge (160amps continuous!) -at least I hope not!

Might try rigging it up with the 8 cell to see how much current it pulls on start up.

[ianhaye]

if u are going to buy new its silly to buy nimh again to be onist everyone is fading them out in the shops and lipos are so much better. check out hobbyking if u dont mind waiting to come from hk, tons of batterys on there, will easyly lose a hour or to looking through that lot, but gotta be done for there bargin prices

[R.C.Hole]

Wow thats alot a batteries! narrows it down looking for saddle packs though.

Great, thanks for all your help.

[ianhaye]

if you idealy try another set before you buy just to conferm that it is these causing the prob and dont fancy u cursing me if it ant them lol.

[R.C.Hole]

I'll try the 8 cell today

Don't worry mate, if thats the case I was the bloody idiot to listen to ya!

[R.C.Hole]

double post oops!

(anybody know how to delete them?)