I'm going to install a converter/charger in my van, primarily for the purposes of: (1) providing 120 AC for AC outlets in the camper, (2) converting the AC to 12V DC to run lights and appliances that need DC (water pump and fan) and (3) charging the house batteries.
Right now, the van has an auxiliary battery and an "isolator" to keep the starter battery from discharging when using the aux. I assume that if the converter/charger is hooked up to those wires, it will not charge the starter battery.
Do converter/chargers only charge the "house batteries" or do they have a set of wires that bypass the "isolator" to charge the starter battery?
In general, the converter/chargers do not have separate outputs to charge the chassis battery. You can have separate AC and DC distribution plus a deck mount converter/charger or you can get them in a combined unit technically called a power center.
If you will have AC power for charging the aux battery for extended periods, you can add a Trik-L-Start for about $50, and it will transfer charging voltage from the converter/aux battery to the chassis battery. There are other devices that do this, too, but generally are more complex and higher cost.
I suggest you look at power centers with multistage chargers:
1. The WFCO 8700 and 8900 series power centers. The 8700 series are smaller and have capacity to charge one or two batteries RV/Marine deep cycle batteries.
2. The new Xantrex power centers.
You can see all of these here: Best Converter. On the left side are links to the pages for WFCO, Xantrex and Trik-L-Start. There should be links to the instruction manuals for these or a link to the item's website where manuals are available.
Mel & Mary Ann; Mo'Be (More Behave...) and Bella
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73 Kountry Aire 31.5 ft (semi-retired) TT
90 Champion LaSalle MH 29 ft P30 (89 Chassis)
Thanks for the explanation and additional information. I had previously purchased a small (30 amp) Elixer single stage converter/charger power center, but aml now thinking of selling it and buying the three stage WFCO 8735 for a pair of 6V AGMs.
"Converters" where used in RV's until about 1990, when electronically controlled and well regulated battery chargers became less expensive, lighter and more reliable.
Converters did not have a adjustable voltage output, so if plugged into 120 volts it might overcharge the batteries, and if plugged into 105 volts it would not charge much at all. They typically had a 40 amp and 5 amp output, where the 5 amps is connected to the battery to charge it, and the 40 amps was the most you could use at any given time before blowing a fuse and shutting it off.
You are asking about a Converter/charger. The "Correct" term is a charger. But you also want 120 volt output - so that would require a inverter or inverter/charger. A combination inverter/charger is more expensive than a single converter and a small wattage inverter.
My suggestion is using a portable 400 watt inverter to power whatever 120 volt things that you want to run from the battery. Running a microwave from a inverter less than $800 is inpractical, because microwaves don't like modified sine wave inverters, and sine wave inverters are really expansive!
Also you stated you want to use AGM batteries. These require closer regulation of the charge rate. You really don't want to expose them to 14 volts that the alternator can sometimes put out, so a #10 gauge charge wire from the battery to the isolator relay to the battery will limit the charge rate, and keep the batteries cooler while charging.
If you could mount the batteries outside, with good ventilation, then lead acid batteries are more economical and longer lasting batteries, but they will require adding water to them every couple of months. Lead acid batteries can also be charged and discharged at a higher amperage rate.
A 400 watt inverter can be fed with #10 gauge wire and a 20 amp fuse. This will allow up to 200 watts output at one time. This is plenty to run a TV, laptop, cell charger, camera charger, and DVD all at once.
If the Elixer charger is not to expensive, it could be used to recharge the engine battery with a timeclock. Only turn on the charger for about 15 - 30 minutes per day, that will give it plenty of charge without overcharging to the point of boiling out any water from the battery. Also if your main charger happens to fail, you will have a back-up one.
The three stage charger that can be programmed to charge the AGM batteries are a great choice. I would use a Procharger 20 by the same designers of the Prosine 2,000 watt sine wave inverter. They are well regulated, and if plugged in for over 30 days will raise the voltage for a few hours to de-sulfate the batteries automatically. If you will be using a generator as your primary recharging than the 40 amp model will lower generator run times.
You can also go with solar panels, but they will be more expensive than a 1,000 watt Honda generator. The Honda 2000 watt will run a microwave or small window type A/C unit, up to about 9,000 Btu's.
If you are going with AGM batteries, make sure the batteries you purchase have charging requirements that are met by the converter.
All brands of AGM batteries don't have the same charging requirements, and the common converters are designed for the wet cell batteries. You might do OK, or you may destroy the AGM's fairly quickly.
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