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 Not to long ago I did the w-t ground mod with the 150amp breaker on the charge lead from the alternator to the battery (pass side) and it tripped a couple times shortly after install. On the advise here I disconnected the relays for the grid heaters and no more trouble until yesterday. Grid heaters still disconnected, I fired up the truck to run to town, made it about a mile when I noticed the "check gauges" light and my voltage was down to around 10 volts according to the dash gauge.

 Popped the hood and found the breaker tripped, not sure why. Did not have the lights on, a/c was off. Shouldn't have been any major power draw at the time. 

 

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Typically, the charging system has to work the hardest for a few minutes just after you start the truck.  Even without grid heater operation, the starter draws a lot of power from your battery.  Once you start driving, the alternator has to carry the electrical load, plus the make up load for the partly discharged batteries from starting the engine.

 

I would check your 150 amp circuit breaker connections for building heat while the alternator is charging.  A loose connection (if it is near the circuit breaker) will build heat quickly and that heat could transfer to the breaker causing it to trip.  It is very easy to do a voltage drop test at those connections while the engine is running .  It will clearly show whether or not the connection is good.  If you need help with the voltage drop test, let me know.

 

It could be that you just have a weak breaker.  It might be worth installing another new breaker while you are diagnosing the problem.

 

- John

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I agree with @Tractorman that the breaker might be weak.  When I was doing the charge line protection part of the W-T mod some members went with a fuse due to certain circuit breakers being of poor quality and tripping prematurely.  I opted for a 150 amp inline fuse with a spare in the glove box.

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More often they trip the more likely they will trip again too. So I also went with fuses to both my trucks because some people tested the breakers and found a lot of them tripped at even half the amps they were rated for. That was not good.

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Posted (edited)

I tried the cheaper resettable breakers Like mentioned, hated both. Bought an Eaton hi-amp marine breaker (150 amp) for around $70 and still have yet to have it trip. The only 2 times it has tripped is when I did it just to make sure the truck sensed it. 
eaton part #82150

Edited by Towrigdually
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I concur, my breaker tripped after I started the truck after sitting for awhile.  Truck reved up to shift and breaker popped.  Reset the breaker kept the RPM below or at 2,000 RPM and continued on my trip.  Long Term, I'll be looking for the Eaton breaker.

 

Michael : - )

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would be nice if you had a clamp on DC amp meter with max/min and you would see the max readings that the truck is drawing. but I think you are safe in getting a good breaker as a replacemnet

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First off the max output of the alternator is 136 Amp period. The only way this could be happening and reaching over 150 Amp and popping is the alternator has issues with shorted diodes. Stock Fuse is only 140 Amps. The side problem is placement of the breaker. If the location is to close to heat source it could trip the breaker. 

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There is the chance of a faulty alternator and a bench test would show that problem; but how many of140amp alternator fuses in the PDC have we heard about blowing?  None that I can recall.  So, I'm thinking It is an inferior circuit breaker and high heat can exacerbate the problem.

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 Ok, just gonna ask this, would the fact that both batteries are 6 years old? They both have date stickers showing 2014. Maybe they draw down more than they should while starting and then the alternator is working hard to recover? By watching the volt meter it seems to recover quickly. 

 Is there an accurate way to check the amps? I have a clamp on meter but AC power only. (I tried)

 Once I get a few minutes I will test the batteries. I recently bought a battery load tester. Good time to try it out.

This is  the breaker I used.

 

Screenshot_20200708-213225.png

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Posted (edited)
2 hours ago, Doubletrouble said:

Ok, just gonna ask this, would the fact that both batteries are 6 years old? They both have date stickers showing 2014. Maybe they draw down more than they should while starting and then the alternator is working hard to recover?

 

Always a possibility, but I think unlikely.  Remember that no one seems to ever had a problem with the factory 140 amp fuse and that fuse has operated under all kinds of undesirable battery conditions.

 

- John

Edited by Tractorman
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I'm sure my issue was low batteries and a weak Circuit breaker!!  I'll try the Eaton version, as soon as it gets here.  With this Covis-19 Crap I haven't been driving the Truck, and the batteries get flat from sitting.  Heck we drove the wife's car for the first time in 2 months and the tires had flat spots from sitting.  We did practice social distancing for the 4th.  Drove up in the mountains and went 14 miles up a forest service road and had lunch at the crest of a hill, no fireworks but a Heck of a view!!

 

Michael :- )

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Weak or damaged batteries with bad cells tend to generator extra heat. Being part of that load is convert to heat as it attempts to recharge bad cells. I've got 8 years on these batteries and starting to see sign that life is getting short for them. I'll keep you all updated as mine start to wear down.

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