ljn521

Can anyone tell me if there is a way to perform a load test of my batteries? they show approx 8vdc and the battery is a 7.2vdc 1500mah. as i said it shows the voltage. however, when installed in the car. it only runs very slow at best. thanks, Larry

samguan

maybe pull full throttle on the car while on a stand. Then check the voltage to see if it drops alot.

ljn521

Thanks samguan i didnt even think of doing it that way. will try it thanks again.

sheograth

The best way to load test is to use the proper test/measurement equipment, some high end chargers also have this function.

Smiff 24

will the ICE or superbrain 989 load test a pack ?

Access

I use the Intellipeak ICE and it will do discharge testing up to 8A for most of the lower voltages, ie. 2-cell LiPo or 6-cell NIMH.

samguan

What is the proper discharge rate to simulate a load test as if the battery was powering a car.

Access

Well for 1/10th scale hard acceleration can pull 60A or more, holding a constant but high speed that will drop to 8-24A.

If you look at the thread where I tested LiPo batteries I actually built a fan-cooled 0.125-ohm load test device but that is probably beyond what other people wish to do. If you want an estimate you can assume a constant internal resistance for the battery which means voltage drop varies linearly with the current drawn. Ie. if open-circuit is 8.40A, 8A draw takes it down to 8.2V, 24A draw would take it down to 7.8V. If you just want to know if you are overstressing the battery, run it hard, take the temperature every minute and chart that. For NIMH if the battery is too hot to touch after the run, you are running too hard.

Here is a pic of the test setup I use, 60A or so is a lot of power to dissipate and you're not going to find a charger that can actually do that for you.

sheograth

A while back I rigged up a propeller on motor shaft as a load. You can also also have a marine propeller on a shaft dipped in water.