batteries
 

my batteries keep dying in the middle of races i am wondering if it is my pinion or my batts



thanks dan

what batteries you running & what gear?

i have 4200 batts and i 16 tooth spur and a 6.5 motor

how do you charge them also? is the transmission on the car free or stiff?

i put then on a cycle charger and diss charge

and yes the diff is free

how old are the 4200's?

they are not very old

what amp's you charging at? or what cutoff is your esc set at?

hard to say really. I run my d4 with a 4.5 on a 16 tooth and it will do 5 mins on some older 3300 cells. Is you motor getting hot? You could try a bigger pinion i guess like an 18 but not sure if that would help.

i charge them at 3 amps and i dont know what the cut off point is

what charger do you use? does it tell you how many milliamps are going into the cells? Or how long do they take to charge at 3A?

is the entire transmission free, not just diffs? take off the pinion and roll the car along the floor, it should run along happily, not stop abruptly.

i would try 4.2amp
and deffo try to find the cut off point as it may be cutting out on you hence its stopping half way through
what esc you running?

i use a cml charger it is like the venom charger . it take just over a hour to charger the batts

the cells should be taking over 3000mah then, which is enough for a 5 min race easy. does the motor or speedo get really hot during a run? do you mesh your gears properly and not too tight?

Does it do this on more than one pack of cells ? You could have a bad pack or bad cell within the pack ?

ok then i will try thank you very much

yes it does do it on more than one set of batts

Id try a diffrent charger for starter's more like a protrak i have for sale (http://www.oople.com/forums/showthread.php?t=24597)
As your cells may dump due to lack of charge in them?

ok thank you

While that makes it less likely to be the batteries it doesnt rule it out as my ip NiMh's failed for fun.

If you can, when the pack dumps measure the voltage across each cell, they should all be pretty close.

ok i will do that thank you

before you spend out on a new charger charge your packs as normal and test each cell with a volt meter each cell should have 1.2 volts minimum you could have a duff cell in each pack i would recomend you charge them a little higher 6 amps or so with a cut off of about 3mv from a fresh discharged pack you should be getting a goo 4000 mah in them. are you discharging with a single cell discharger or doing a pack discharge a pack discharge could also be the problem as you may not be taking all the power from the all the cells and when you charge again you will get a false peak as one or more cells have hit the delta peak early and shut the charger off. i hope this make sense

the best advise i can give is if your gonna spend money on a charger you will be better off getting one pack of lipos and a lipo charger it will prob cost about £100 but agro free.

stu rand

Exactly how far would you say the car should roll? carpet or smooth?

Building a brand new D4 atm. :)