dc to DC Renogy charger

12thgenusa wrote:
I'm thinking of installing one for my 5th wheel. Concerned about the extra 30 amp draw on the alternator, long run of large gage wire (at least 6 ga) and an additional disconnect on the tow vehicle.

My oem feed to the battery bank is #8. Therefore I chose #8 for feeding the dc to DC charger, and #8 from the new charging device to the battery bank. Ampacity of #8 is 40 amps.

The path to feed the dc to DC is about 8 feet. From under the seat to the house batteries is at least 12 feet and perhaps longer. The alternator is not direct connected to the new charging device. The feed is from the starter battery.

I do have an ammeter that measures flow to and from the house battery bank. My meter falls over at 70 amps. When I had flooded marine jars (875 amp-hours), I did have occasion to exceed 70. I had added 2nd charging path from the starter battery to the house jars.

When I switched to telcom batteries (for the house) the alternator ceased charging them. Their voltage was too high I guess. I attempted to fix this by moving to an agm for the group 65 starter battery, which changed nothing at all. Hence my desire for the dc to DC unit.

If concerned about the alternator, add a switch to manually control the "feed" of power to the house bank, and a volt meter to let you know the starter battery is not being charged enough by the alternator. My control switches can be operated while I'm in the drivers seat.

My alternator is 130 amps. (stock Ford oem)

I did deliberately get the smallest dc to DC charger that I could find--for the same reason. Burning out an alternator is not my
cup of tea.

I left the oem charging path alone--and leave it switched off. It does give me the ability to have a "poor man's" boost if the need should ever arise.