On one of my trucks, which has four batteries, two positive and two negative cables going to the starter, I'm losing too much voltage, the batteries check ok, and I can load test them with a simple tester, but when we try to start the truck at the batteries and at the starter, when cranking the engine, we drop to 8 volts, everyone seems to think we have bad cables, how can I determine if its the cables or the starter or something else. The cable ends are clean and tight, nothing gets hot anywhere when cranking. We've cleaned the grounds and other than pulling the starter and putting on all new cables the only other thing I can think of trying it to remove one or two batteries from the battery box and hooking up considerably shorter cables and checking those for voltage drop or see it that fixes the problem. Anyone have any idea's or suggestions?
Have you checked that little jumper bar from the solenoid to the starter? Had that problem once myself.
Try to put jumper cables on the starter itself. If it turns over good it should rule out starter problem, if starter still drags I'd look at the starter. Just be sure to use good enough cables and enough battery on the jumping vehicle to make sure you get sufficient amps to the starter. That's what I'd try first.
Now that you mention it grandpa, I didn't do that, I'll check into that, thanks, at least it gives me something to try.
Mark, to keep the cables shorter, we were going to hook a battery up under the truck, its over my service pit, and that way, I should have enough amps to do it, I've got a couple short made up battery cables laying around, that was on my list to try tomorrow.
Randy try holding your load tester leads on each battery post not the cable end and let somone try to start it look for one that does not drop to the 8 volts ,sounds like a Mack here that turned out to be a broken cable inside the rubber end.
Before you go to that trouble, check the voltage drop from the batteries to the starter. Either put test leads on the starter and ground, and compare that to the battery voltage. Or test each battery cable individually, one test lead on each end and read the voltage. You either need more than one volt meter, or you need to repeat these measurements, with the starter engaged obviously. When I read your post a second time this sounds like exactly what you did: "when we try to start the truck at the batteries and at the starter, when cranking the engine, we drop to 8 volts, everyone seems to think we have bad cables" if you have 8 volts at the battery and 8 volts at the starter, there's no drop so it's not bad cables. Maybe crank it and see if the starter gets warm, or hook up a good warm battery with some good short cables and see if there's any improvement. My guess is old batteries or weak starter, but it never hurts to check the oil in the engine? maybe even alternator bearings locked up?
Shopguy, we did that to all four batteries, each had the same voltage drop. Delmer, your saying that if the drop is the same at both the battery and at the starter, the cables are fine. I'd never been told that before as a way to rule out the cables. I've had the alternator off recently to have it checked over, can't imagine it could be that, but never say never, I"ll check tomorrow. We plan on doing the short cables and battery tomorrow and we'll go from there, thanks for the input guys.
Yes, if there's no voltage drop the cables are doing their job, assuming you have a tester that's accurate enough. Is the 8 volts read off of the load tester or a digital multimeter/volt ohm meter? Either the batteries aren't putting out the amps, or the starter is taking too much amps and not putting out the power (or the engine is "tight"!). You said nothing heated up, which tells me the connections are good. Maybe it's just weak batteries? usually a starter drawing too much amps will warm up even good cables.
Took the starter off yesterday and took it in, my guy got right on it and got it done, the starter was totally shot, he ended up with about all the internal components new, the armature was shot, along with the brush holders and the bearings, starter drive and also the solenoid was shot, it was too late last night to get it back on, so that's todays project, but I'm thinking I found the problem. He said he was surprised it even turned over at all for as bad a shape as it was in.
Checked over all the batteries, the brand new one I put in last fall was bad, all the others were good, put the rebuilt starter in, and she fired right up, took some tests of the system and voltage drop at the batteries when cranking was to slightly over 10 volts, actually it started up so fast we had a hard time seeing what the voltage drop was, so it was a success all the way around, thanks for everyone's input.