Odd starting problem; Bobcat e42 excavator

[KeithT]

Need some help from TBN community….

2016 Bobcat E42, new battery installed 3/2024.

Will not start unless I connect my jumper box. However, both advance auto parts in Napa have tested the battery and the results have been the same, It’s a good battery.

With my multimeter I’m getting full battery voltage to my starter. I have checked all the grounds that I can find on the machine. I have cleaned all the connections on the starter. I even installed a battery from my boat which I just use for a week solid on vacation without any issue And excavator behaved in the exact same way. -when I turn the key on, I do not get any lights to light up nothing at all. Even though the battery is reading 12.4 to 12.6 V. As soon as I hook my jumper up though. Everything lights up and it easily starts.

Any ideas? Really scratching my head in this one

 

[gengine]

A fully charged 12v battery should test at 12.7v-12.9v. The charging system, by way of the voltage regulator (built into the alternator), should be testing between 13 and 16 volts, dependent on what the battery needs. 16v seems high to me, but that's what I was taught in a class. Normal high to me is 14.5v. Anyway, corroded wires and/or terminals will keep the amperage needed for starting from getting to the starter. Grab a battery terminal brush and clean the battery posts and the clamps, the shinier the better. If there is one of those replacement battery cable clamps, where you strip the wire and clamp the copper strands to the battery clamp, replace it with a solder type and heat shrink tubing. Also check the negative wire at the battery and the engine block, making sure they are clean and shiny. But, since it starts with a boost, its almost certainly a connection problem between your battery post and your cables. I usually find that someone has over tightened the clamp, so instead of full contact all the way around the battery post, the clamp is "egg" shaped, only making good contact at two points on the battery post. A multimeter will show you getting full voltage, to the starter, but your amperage can't get there. Think of water in a hose. Yes, you have water from the battery to the starter through the hose, but with a slight kink in the hose, (the egg shape on a round post vs. full contact around the entire post) the volume of water (amperage) can't get to the starter.

 

[KeithT]

Thank you for your reply, I’ve cleaned and re-cleaned the battery terminals. And I’ve taken every ground off that I can find and clean those as well. I guess it’s possible there could be some corrosion in the positive terminal. Where is connected to the wire? It’s the stock Battery cable not a replacement terminal clamp.