AC to DC converter

roycej

New member
Nov 4, 2022
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I've started digging into my recently-acquired '76 Birchhaven RB. Onan generator is currently non-functional. It has a 30 amp plug for shore power. When plugged in to shore power, the 120 volt outlets inside are live, but there is no 12VDC. I have no coach battery at present, but as I understand it, the converter should supply the 12 volt system even without a battery. Earlier I had connected a spare battery to the coach system and 12v lights and the furnace blower were operational.

The converter looks fairly ancient. The front cover is missing and the label inside reads Series 6300 Model 6332. Apparently made by Magnetek. I assume a new converter is indicated. A couple of questions: For the time being I'll be using a regular deep cycle battery, but in the future I'd like to upgrade to lithium batteries and add solar panels. So I'd like a converter that's "future-proof" in that regard. What's recommended? Second question: In the original Coachmen owner's manual it shows a manual switch on the breaker box to switch between shore power and the Onan. This coach has a box labeled "Automatic line/generator transfer switch". Since the Onan doesn't run, I can't test this switch. Is it likely to be a problem?

All comments appreciated, thanks!
 
I can't answer to the transfer-switch question (stock GMC coaches didn't have them; just plug the breaker box into the generator or to shore-power). But, I'm using an AC/DC converter/charger with a switch for lead-acid/Lithium/Fixed-voltage output. Just select your battery-type or fixed-voltage if you prefer.
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Yes, I had to replace the AC outlet with a 20A outlet for the higher capacity converter (the wiring is already 12ga on a 20A breaker).
 
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Yes, it sounds like you need a new converter/charger. While you get overall things operational, you don't need much for battery - you can look for a used 12 volt at local store, swap in your lawn mower starter battery during the winter, etc. If you have shore power while you are doing stuff, the house battery just acts like a reserve/buffer for 12 volt, and if you need to test some things short duration pretty much any ole' battery will do. Then you can do your research, meet other folks, and decide your long term plan - like lithium, dual 6 volt golf batteries, a single low expectation 12 volt (any healthy car battery will work if you are only at home, on the road to an electric site, and camping plugged in), or you can get a massive 12 volt or marine deep discharge type.

As to what type and capacity house battery system you need, that answer is determined by your intended use. Almost always plugged in don't need much. The more you boondock and how much is running on 12 volt, the more battery you need. Fridge, heater blower fan, lights (led are 1/10 the power load as filament), any hope of an inverter, etc can rack up need for amp hours quickly. (I love my 12 volt electric blanket, takes 3 amps lo, or 7 amps hi; over 8 hours that difference can be as big as 56 amp hours - which is full usable capacity of a 100 amp hour lead acid- down to just 3 amp hours if I use it one hour on low to heat the bed before I get in) Do the math on what you want to run, get at least a $50 battery shunt style monitor, and then get after the research of how each type meets those demands.

I don't think Coachmen installed any automatic transfer switches, my Royale has an either/or on the fuse panel for shore or gen, and a separate on/off switch for gen to rear AC, neither is automatic. You should always familiarize yourself with the systems of a your particular coach and check for tightness of wire connections and proper installation. If your onan does not run, as long as the transfer switch is in the shore position and does not get thermally too hot while in operation (indicating corrosion or failed contacts), it's ok to leave in for now. Test it later when gen is happy, if that will be a while straight wire/bypass it.