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Best charging method?

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Given this scenario -- Been dry camping, just woke up to find house batteries kinda low (12.3V) due to lots of furnace use through the cold night. We have two options -- turn on the genny and let the 45-amp converter pump up the batts, or turn on the engine and let the alternator do it. I think the engine solution is best, as the alternator can push out a lot more current than the converter, and simultaneously heat the coach, too. Anyone ever looked closely at this?

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Given this scenario -- Been dry camping, just woke up to find house batteries kinda low (12.3V) due to lots of furnace use through the cold night. We have two options -- turn on the genny and let the 45-amp converter pump up the batts, or turn on the engine and let the alternator do it. I think the engine solution is best, as the alternator can push out a lot more current than the converter, and simultaneously heat the coach, too. Anyone ever looked closely at this?

We really need a little more information to be able to give you reasoned advice.

First, we don't know what engine you have. The amount of fuel used at high idle by, say a Cummins B engine is a LOT less than by, say a GM 8.1 liter gas engine. What engine do you have?

There are significant differences between 45 amp converters. "Smart" converters start in bulk mode which is at higher voltage than standard converters. Said another way, they can get closer to really putting 45 amps into deeply discharged batteries. What converter do you have and does it have a smart feature/module?

Also, be aware that it is better on batteries to charge them at a lower rate-- so 2 hours at 45 amps would be a lot easier on them than 45 minutes of charging with a 150 amp alternator.

If you have a larger output generator, run it for 2 hours. Plug in an electric space heater to provide heat and load. The generator is better off working under a load. Of course, if you have a small portable generator, the converter may provide adequate load.

The more information you give us, the better we can advice you.

Brett Wolfe

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Thanks for the info, Brett. Engine is a 460 Ford, 1995. Converter is a 9245 Progressive Dynamics, with the dongle. After reading your response, I'm believing perhaps a half hour charging off the alternator followed by a long charge off the converter might be the way to go. Any thoughts?

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Thanks for the info, Brett. Engine is a 460 Ford, 1995. Converter is a 9245 Progressive Dynamics, with the dongle. After reading your response, I'm believing perhaps a half hour charging off the alternator followed by a long charge off the converter might be the way to go. Any thoughts?

The fuel your 460 will burn in 30 minutes would run your generator for many hours. With a smart charger, that's the way I would go.

Brett Wolfe

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We do nothing but dry camping and our coach has a very high load on the DC system, with everythig off it will drain batteries (4- 440ah) in less than eight hours. The coach (90 Wanderlodge) came with two 45 amp converters and went through batteries like a kid goes through candy. When camping we use hte generator almost constantly and at home the coach is always plugged in.

The problem (in my analysis) was that the converters took the batteries to 12.6 volts; they just kept them up, not fully charged (whether on generator or plugged in to shore power). The idea was that the alternator would fully charge the batteries when the coach was driven. The problem with this is that the load when driving, especially with four hydronic heaters blowing, plus the front heater and defroster, plus the load on the inverter, plus... the voltage when driving (due to IR drop) was only about 12.7 so the batteries never got fully charged. The problem was solved by installing a 3-stage inverter/charger that fully charges on generator or shore power. Batteries now last an hour or two longer when generator is off and life of the batteries is at least four or five years instead of less than a year.

For dry camping I highly recommend getting a good charger with a pulse desulphation feature; plug it into 110 and use hte generator to charge the batteries, etc. This will improve both the performance of your batteries and their longevity. The pulse desulphation really works (I have performed experiments that verify this) and keeping the batteries at full charge keeps them from dying due to the number of and depth of discharge cycles.

The Bounder has a lot less load on the batteries than the Wanderlodge. On our Bounder, driving would charge the batteries adequately and when camped we always use the generator. I mounted a couple of 1 amp BatteryMinder desulphating chargers and used them when it was plugged into shore power.

Our experience and experiments indicate that the desulphation chargers extend the cycles a battery can take, even when they are deeply discharged.

A side benefit of using the generator is it helps assure long life for the generator. Most generator problems come from lack of use (dried out seals etc.) not overuse.

Jim Magowan

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For dry camping I also use a Battery Minder Plus connected to the house battery and plugged into my outside 110 outlet, I run the generator in the morning during breakfast and during dinner in the evening. The battery stays charged and desulphated.

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I strongly recommend an Charger/Inverter/Transfer by Dimensions, Inc. to handle this problem along with your generator. I have a coach with such a system and used it for 6 days in the snow in Yosemite with no more than 2 hours a day with the generator. If you are interested in obtaining one I have a spare for sale very cheap. Larry

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