Fully charge the battery, checking the SG for a constant (best) reading - (this may take a while) and for good indication of SG strength.
Get hold of a battery heavy discharge tester and test each cell - results will confirm if cells good or bad individually. 1 poor cell = poor battery performance overall
Fleettech,
Use a volt meter and check the voltages on the battery cell to cell, should read 2.5 each cell. Also if you check your voltage reading of the battery while you are traveling, it should not drop below 35 volts, normally a fully charged battery when traveling will read 36 volts. As Mr. Fixit points out, sound as if you have a bad battery.
Are you sure you have 36 volts with a load on it, like pulling the tilt lever? The symptoms are of a bad battery.
Thanks for the response. Nothing looks out of the ordinary on the brushes. I've removed the lift motor and sent it out to be tested. Still waiting to hear back from the motor shop. Here is the model and serial. Thanks Again!
Model: ERC040AGN36TE084
Serial: A814V05105X
Another thing to check would be the power cables going to the motor,make sure is no ground faults to frame causing the contactors to drop out. Check cables for rubbing and cracking that would expose the wiring.
Could be a weak contactor coil,how are the motor brush's looking, they okay? Might be helpful to post the serial number of the machine also. What control system does this truck use?