jlsmithivan
New Member
just looking into best ideas for wiring/grounding my new mechman 250A alternator to better charge my slide in camper's agm batteries. got a bit lost in the 2018 thread on big 3 upgrades and thought I'd ask for help.
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06 duramax charging system upgrade.
- Thread starter jlsmithivan
- Start date
Nothing wrong with simply asking in a post the good questions you have.
A Big 3 upgrade is generally:
Ground strap from engine to frame, Ground strap body to engine, and ground strap frame to body. Further some upgrade the charging wire size from the alternator.
Now you are wanting to wire in a camper.
First you need something, battery isolator, to disconnect the "house batteries" in the camper from the truck with the engine off. Otherwise you drain the truck batteries with the camper batteries if they are not isolated. You don't want the camper batteries helping start the truck, but, your wire size make this concern moot.
Example:
stingerelectronics.com
Now wire the camper ground to the engine. Then the camper positive after going through the isolator and a large fuse goes to the alternator. (Fuse? Yeah, alternator diodes short out now and then and if there isn't a fuse to pop the truck becomes a "Real GM Blazer" model and burns to the ground!)
The alternator is generating the charging voltage/current so why screw around taking the power from anywhere else adding resistance of small or longer wire? The other wires are also "busy" running the ECM and charging the truck batteries and maybe even the glow plugs/grid heaters. At 50% Depth of Discharge the AGM batteries can take 100% of the alternator output and be all like "That All You Got!?"
No, you don't connect the positive to the "+" battery post on the truck.
Ignorant or misunderstood advice from mechman that deprives the truck battery of it's charge. DO NOT CONNECT ANYTHING TO BATTERIES!!! Ground loops were covered in the other thread and this battery connection could be a positive loop. After starting the engine and carrying the grid heaters/glow plugs all storage batteries are is a 6A+ "load" on the alternator. Again get power from where it's being generated: the alternator.
Why ground to the engine and not the alternator bolt/bracket? It's a trick to knock down alternator noise. The engine block is essentially a dead short for grounds, but, items mounted on the same ground as other things or the alternator bracket pickup more noise than a separate dedicated ground location. Experiments with a Big 3 ground strap and noise from OnStar are my reference: more noise when ground strap on existing stack of grounds on a fender and/or big 3 strap on alternator bracket.
A Big 3 upgrade is generally:
Ground strap from engine to frame, Ground strap body to engine, and ground strap frame to body. Further some upgrade the charging wire size from the alternator.
Big 3 upgrade
Hello all, I am currently working on doing the big 3 upgrade on my 06 LBZ. I bought Knukonceptz kolossus flex 1/0 OFC, ring terminals, wire loom and a fuse for the alt portion to complete the task. In looking at the stock wiring setup though I think I'll end up rewiring all the battery...
www.thetruckstop.us
Now you are wanting to wire in a camper.
First you need something, battery isolator, to disconnect the "house batteries" in the camper from the truck with the engine off. Otherwise you drain the truck batteries with the camper batteries if they are not isolated. You don't want the camper batteries helping start the truck, but, your wire size make this concern moot.
Example:
200 AMP RELAY AND ISOLATOR
$114.00 Prevents primary battery discharge Maximum current transfer Ideal for 2nd audio battery isolation from vehicle systems High current relays are the most reliable and efficient way to add secondary batteries to your system Compatible with all types of alternators and charging systems...
stingerelectronics.com
Now wire the camper ground to the engine. Then the camper positive after going through the isolator and a large fuse goes to the alternator. (Fuse? Yeah, alternator diodes short out now and then and if there isn't a fuse to pop the truck becomes a "Real GM Blazer" model and burns to the ground!)
The alternator is generating the charging voltage/current so why screw around taking the power from anywhere else adding resistance of small or longer wire? The other wires are also "busy" running the ECM and charging the truck batteries and maybe even the glow plugs/grid heaters. At 50% Depth of Discharge the AGM batteries can take 100% of the alternator output and be all like "That All You Got!?"
No, you don't connect the positive to the "+" battery post on the truck.
Ignorant or misunderstood advice from mechman that deprives the truck battery of it's charge. DO NOT CONNECT ANYTHING TO BATTERIES!!! Ground loops were covered in the other thread and this battery connection could be a positive loop. After starting the engine and carrying the grid heaters/glow plugs all storage batteries are is a 6A+ "load" on the alternator. Again get power from where it's being generated: the alternator.Why ground to the engine and not the alternator bolt/bracket? It's a trick to knock down alternator noise. The engine block is essentially a dead short for grounds, but, items mounted on the same ground as other things or the alternator bracket pickup more noise than a separate dedicated ground location. Experiments with a Big 3 ground strap and noise from OnStar are my reference: more noise when ground strap on existing stack of grounds on a fender and/or big 3 strap on alternator bracket.
- Staff
- #3
There was a dual alternator option with the plow prep package. That might be an idea.
- Staff
- #4
I think the dual alternators were 105A each giving you 210A.
The regular standard alternator was 140A.
Upgrading the cable size helps transfer current better.
The regular standard alternator was 140A.
Upgrading the cable size helps transfer current better.
Will L.
Well-Known Member
OP sent pm before posting here. I just replied same stuff yall know.
But just added a useful link.
www.engineeringtoolbox.com
But just added a useful link.
12 Volt - Wire Gauge vs. Amps
Maximum current (amps) in a 12V electrical circuit vs. size (AWG) and length of wire.
www.engineeringtoolbox.com
jlsmithivan
New Member
I had been talking to will and did not realize it was a private conversation. I am now putting this in the general thread so others can help steer me. here are the current facts: I have an 06 duramax with dual batteries. the original stock alternator is still in place. the stock charging system has not been modified. My 4 wheel slide in camper came with a 10 gauge harness for up to the engine compartment. the camper mfr had suggested it run off the + terminal of the battery with a 30 amp auto reset breaker between the battery and the + cable running back to the camper's onboard battery isolater and on to the 2 agm camper batteries. After reading camper blogs about voltage drop over the 24 foot run back to the camper I decided to upgrade to 4 gauge for that run. it is already routed and both + and - run are enclosed in 3/4 pex to protect it further. my dmax is getting old and I was going to replace the alternator as preventative medicine and ended up going with a US made mechman alternator (250 amp) as it was a direct plug and play for my truck requiring no belt changes. my truck has a new belt, tensioner and idler pulleys. I already have and can not return the alternator which I bought 6 months ago. Mechman told me that for my application 2 gauge from the alternator to the + of the driver side battery and 2 gauge for that battery's ground would be sufficient for my application with the camper. they also suggested I just leave the factory charging cables alone. Then I just happened upon the 2018 thread about the big 3 upgrade and realized I was not as sure as I wanted to be before actually hooking things up. that is where I am at right now.
With the engine off and camper wired up, again, you need a battery isolator. Otherwise all 4 batteries including the truck batteries get drawn down.
Take the camper power from where it's made: the alternator. Even the "lug" in the charging wire as noted in the other thread is better. A battery is NOT the correct source and merely a big fat connection point to tempt you.
30 amp fuse/breaker?! You have a 250 amp alternator. The fuse will be constantly open! I would suggest a 300A breaker or fuse minimum.
Here is my RV project moving the 60A charger/converter closer to the AGM batteries with thick wire. 44.6A is getting near the limit of the 60A converter limited only by the AGM batteries not being discharged that much. That 30A fuse would be T O A S T here.
Take the camper power from where it's made: the alternator. Even the "lug" in the charging wire as noted in the other thread is better. A battery is NOT the correct source and merely a big fat connection point to tempt you.
30 amp fuse/breaker?! You have a 250 amp alternator. The fuse will be constantly open! I would suggest a 300A breaker or fuse minimum.Here is my RV project moving the 60A charger/converter closer to the AGM batteries with thick wire. 44.6A is getting near the limit of the 60A converter limited only by the AGM batteries not being discharged that much. That 30A fuse would be T O A S T here.
- Staff
- #8
Just thinking outside the box here.
What about running a power inverter in the Duramax?
Also Mechman now makes a 400A alternator. Not sure if that helps or not.
What about running a power inverter in the Duramax?
Also Mechman now makes a 400A alternator. Not sure if that helps or not.