Renogy DC to DC battery charger and emergency start circuit

[dougybug]

We are looking to change out our house battery on our Jayco Redhawk 24B from a wet cell to LiFePO4. We contacted Jayco and they said we could switch our onboard converter/charger to a Lithium profile, but we would need something (DC to DC battery charger) to go from our alternator to the house battery that could change to a Lithium profile and control draw on the alternator to prevent damage. Since we have a 210A alternator on our motorhome we figured the Renogy 40A DC to DC charger would be the ticket.

Now the rub, our RV has an emergency start circuit that when activated would attempt to change the current flow from the house battery to the chassis battery through the charger. The charger does have reverse protection, but it would defeat the emergency start circuit. My thought is to use the emergency switch to close a parallel circuit that would by passes the charger and would still facilitate an emergency start, rather than have the switch operate the solenoid normally controlled by the battery isolating circuit.

Any thoughts? This makes sense in my head, but I am a mechanical engineer. I always appreciate input from the electrical guys.

 

[Weru12]

You might want to look at this fellow's video on his LiFePO install. He had similar issues.
Protect Your Alternator After Battle Born Batteries Install li-bim 225 Battery Isolation Manager - Kevin Caudill

 

[muzakmon]

We are looking to change out our house battery on our Jayco Redhawk 24B from a wet cell to LiFePO4. We contacted Jayco and they said we could switch our onboard converter/charger to a Lithium profile, but we would need something (DC to DC battery charger) to go from our alternator to the house battery that could change to a Lithium profile and control draw on the alternator to prevent damage. Since we have a 210A alternator on our motorhome we figured the Renogy 40A DC to DC charger would be the ticket.

Now the rub, our RV has an emergency start circuit that when activated would attempt to change the current flow from the house battery to the chassis battery through the charger. The charger does have reverse protection, but it would defeat the emergency start circuit. My thought is to use the emergency switch to close a parallel circuit that would by passes the charger and would still facilitate an emergency start, rather than have the switch operate the solenoid normally controlled by the battery isolating circuit.

Any thoughts? This makes sense in my head, but I am a mechanical engineer. I always appreciate input from the electrical guys.

You just need to clip one wire off the aux start switch to disable it from combining the batteries while the ignition is on. Retains some of the aux start function.

 

[jdfrye]

not sure this will help, but this is what I did which now has disabled my Emergency switch. I dont want my lead and lifepo4 tied together. I pulled my battery and house supply off the solenoid post
Buty then I noticed the solenoid was very hot to the touch so I disconnected the small wire that was at the base and the solenoid disengaged and cooled down..so I left it off.
check the picture