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Tuesday’s Heavy equipment question?

ThePanzerFuhrer

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I know it’s Wednesday but I’m having a charging issue on one of my excavators. This is a cat 350l excavator so it’s dumb as a box of rocks. The charging system is a one wire brushless alternator hooked to the positive side of starter. I have been burning up alternators faster than I can change them.

this thing doesn’t use my power as the only electrics on it are a throttle control and a small brain box to control the pumps. TheIf there was a dead short the batteries would blow the fucking wire up. This guy has 4 4d batteries on it.


The only thing I can think of is there is a small parasitic draw that drains the batteries a bit when off. You start it up and the alternator go balls out to try and charge 4 4d batteries and fries itself.

has anyone ran into a issue like this? I’m thinking about removing 2 batteries from the machine completely.

Is there such a thing as a dc clamp on amp meter?
 

swtfman

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Use a multimeter on the 10A current setting in series after the batteries on the positive side to check for a draw with the machine off. Don't turn anything on though or you'll probably pop the fuse in the meter.
 

Muckin_Slusher

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I know it’s Wednesday but I’m having a charging issue on one of my excavators. This is a cat 350l excavator so it’s dumb as a box of rocks. The charging system is a one wire brushless alternator hooked to the positive side of starter. I have been burning up alternators faster than I can change them.

this thing doesn’t use my power as the only electrics on it are a throttle control and a small brain box to control the pumps. TheIf there was a dead short the batteries would blow the fucking wire up. This guy has 4 4d batteries on it.


The only thing I can think of is there is a small parasitic draw that drains the batteries a bit when off. You start it up and the alternator go balls out to try and charge 4 4d batteries and fries itself.

has anyone ran into a issue like this? I’m thinking about removing 2 batteries from the machine completely.

Is there such a thing as a dc clamp on amp meter?

Yes, the fluke 337 (or 337A) is an example of a 1000 amp rated ac/dc clamp meter, I've got a couple of them, they're good, but the resistance measurement isn't as great as the 87V.
 

Muckin_Slusher

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Use a multimeter on the 10A current setting in series after the batteries on the positive side to check for a draw with the machine off. Don't turn anything on though or you'll probably pop the fuse in the meter.

I concur, although be aware the draw could possible be more than 10 amps.

It's a quick and easy 2 second check to see what the voltage is before you start the machine. Check after shutting it down for the day (should be high since they've just been charging). Then check again a few hours later. Then check again just before you fire up. Then check again what voltage it's actually charging at (most 1 wire alternators need to be revved up to initiate charging).

Oh, and shitcan the stupid 1 wire alternator, replace with a proper alternator, they're better and worth it.
 
Last edited:

billybob_81067

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Use a multimeter on the 10A current setting in series after the batteries on the positive side to check for a draw with the machine off. Don't turn anything on though or you'll probably pop the fuse in the meter.

You can also pull the ground and jump between it and the battery ground with a test light to see if it lights up. If it does that indicates a draw.

Another thing I would do is disconnect all the batteries from each other and do a load test on them separately. If you have one battery with an internal short that could drain the others. I have had that happen a few times. If you can also check the specific gravity of the cells that would help to narrow down a bad cell.

On our old 920 CAT loader we were having issues with the alternator needing rebuilt frequently and the batteries just not lasting very long. It's about as dumb as a box of rocks too. Finally pulled the starter and had it rebuilt. It was still cranking fairly well but was using so much juice it was just hammering those poor fucking batteries every time we started it up. After it came back from the rebuilder it cranked a lot faster and easier and we haven't had issues with batteries or the alternator since!
 

Beast

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If it is a parasitic drain, I'd just throw a night switch on it and save myself the headache of trying to chase it down.
 

Pukemaggots

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Check the resistance of the wire between the alternator and starter, if the resistance is high it could be causing the alt to charge at full field and be burning it up. A bad ground will cause the same issue.
 
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Check the resistance of the wire between the alternator and starter, if the resistance is high it could be causing the alt to charge at full field and be burning it up. A bad ground will cause the same issue.

Check grounds, had a grader do something similar. Cleaned up the grounds and it was fine.

Also, make sure if it had a master switch that it is turned on. I’ve seen a machine cook wires after accessories were added with grounds added directly to the battery. With the master switch off these wires became the main starter ground wires. Could be trying to ground through the alternator somehow,
 

Landslide

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Check grounds, had a grader do something similar. Cleaned up the grounds and it was fine.

Also, make sure if it had a master switch that it is turned on. I’ve seen a machine cook wires after accessories were added with grounds added directly to the battery. With the master switch off these wires became the main starter ground wires. Could be trying to ground through the alternator somehow,

Yep, I had a battery negative ground wire that was barely loose in the lead battery cast post clamp. Took a bit to find that fucker.
 

PAE

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Yes there are dc clamp on amp meter they are very expensive and hardly anyone has them in stock.

Ill call my ex boss and get the name and model #.
 
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