MtnDon wrote:I thought there was somebody on the forum who had already done just what you are thinking of, but I can't find it. Maybe I'm dreaming or confused about where I saw it. As I think I recall, the person used it mainly while traveling. If the intent was to also use such a system while parked I would only recommend doing that as a last resort and only if a generator and charger was not available. It would be a fuel waste to run a TV engine while parked.
That was probably me, Don. It's in the Charge While Towing topic. Here's my experience:
It's roughly 30 feet from my TV battery to TD battery, so an inverter in the tongue box cut that distance in half. Because I only had LED lighting and the Fantastic fan, things were fine with 10AWG wire supplying a 300W inverter and a 7.2 amp charger. That was until I added a 12V Indel refrigerator. Then things started getting undersized in a hurry. Now a fully charged TD battery was good for about 2 days, and I was staying at IRG for 4. Charging from an idling TV didn't do all that much good, but back on the road things worked. However, the AGM battery had just sustained the first of several death blows.
First I replaced the 7.2 amp charger with a 25 amp one and the 300W inverter with a 600W one. Well, the 25A charger just dragged down the 600W inverter, so I settled for a 15A charger. The inverter kept giving a low voltage warning, and would cut out. I also got a small gas generator just in case. Just-in-cases turned into the "usual." The generator would run for hours just to bring the battery to Stage 3. Good Grief, I hated that genny. They may be quiet, but they're not silent. With the generator, beer stayed cold, but the AGM was taking some more hard hits.
This last summer, I went out to SoCal in the height of the heat wave. Total system failure. The heat was just too much. I'm pretty sure the problem was the inverter, but no way to test on the road. Ambient temperature this summer was hotter than the inverter was rated. So now the AGM won't run the fridge at all, and I'll be re-doing the whole setup and adding solar.
THE MORAL OF THE STORY is that DC-AC-DC charging has to be sized just as critically as your solar setup. Any weak link will result in great annoyance and warm beer.