DC to DC wiring and rating?

[GeekyGuy]

I have a 2022 Greyhawk 29MV, with solar panel, dual house batteries. Solar controller will recharge both house and coach batteries.
I'm upgrading to lithiums (200ah) and will use the Progressive Dynamic Pendant to help better charge them when on shore power, using the standard converter/charger. (force it to 14.4V manually)
I'm also installing a DC to DC charger to fast charge when driving and protect the alternator.
20 or 40A?
Where to connect it so I don't mess up existing setup like Boost to start if coach battery is dead...?
Thank you.

 

[Kevin Cooper]

If you have boost to start, then you already should have house battery charging from alternator. In our Alante, it is located next to house battery, but I’ve heard in the class C the solenoid is under the hood. The solenoid will have two larger cables going to the two bolt studs, and two smaller wires for control. If you find it, one stud will be chassis battery voltage, and the other stud will be house battery voltage. When your engine is running, it automatically closes and puts alternator power to the house batteries. If you measure the voltage to ground with engine running, you will have alternator voltage both studs. I put a resettable circuit breaker on mine to charge the chassis from the plugged in RV by the converter.
And ours is 50 amp I believe.

 

[dvspl]

I use a similar setup; the PD remote pendant when connected to shore power and a DC-DC charger to protect my alternator from high amperage output. What's the rated capacity of your alternator? If it can take the added 20 amps, a 40 amp charger will charge your batteries twice as fast. That might be helpful if you discharge your batteries deeply and only have a short drive. I have a 50 amp DC-DC charger in my 2019 chassis and haven't had a problem. Mine also has a bluetooth connection so I can reduce it's output if I choose to. If I'm going to be driving a long distance so have the time to charge it more slowly, I often reduce it to 20 or 30 amps for less load on the alternator.

I wired mine by just putting the DC-DC charger in the line coming from the battery boost solenoid to the coach batteries. As you've already concluded, that effectively disables the boost function to use the coach battery to start the engine. There are several threads on here with more elegant solutions that use switches and relays to make that functional, but I chose to just carry a small jump box to jump start the engine if necessary. I haven't had to use it yet for my coach, but it has come in handy for a couple of other nearby campers.

 

[billcf7]

I have a 2022 Greyhawk 29MV, with solar panel, dual house batteries. Solar controller will recharge both house and coach batteries.
I'm upgrading to lithiums (200ah) and will use the Progressive Dynamic Pendant to help better charge them when on shore power, using the standard converter/charger. (force it to 14.4V manually)
I'm also installing a DC to DC charger to fast charge when driving and protect the alternator.
20 or 40A?
Where to connect it so I don't mess up existing setup like Boost to start if coach battery is dead...?
Thank you.

Swapping out your BIM for a LIBIM would be much easier. Precision Circuits Inc makes a 160 amp Part Number: 00-10041-260 and a 225 amp Part Number: 00-10041-261 LIBIM. Below is a link explaining how they work. Direct replacement for your factory BIM
https://www.precisioncircuitsinc.com...i-BIM-Rev1.pdf

 

[GeekyGuy]

Swapping out your BIM for a LIBIM would be much easier. Precision Circuits Inc makes a 160 amp Part Number: 00-10041-260 and a 225 amp Part Number: 00-10041-261 LIBIM. Below is a link explaining how they work. Direct replacement for your factory BIM
https://www.precisioncircuitsinc.com...i-BIM-Rev1.pdf

Yep, I read it, I sent them an email asking them about it. Is it simply a question of removing the existing one and installing this new LiBIM one and then no issue with overcharging or stressing the alternator. No idea on price and shipping to Canada, which is often crazy expensive. Thank you.