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puterbug's avatar
puterbug
Explorer
Jun 21, 2013

TMI about batteries? My brain is saturated.

My old set up:

Two Interstate 12v batteries in parallel, and they were connected to this relay thingy that I can flip on or off with a switch on the wall. There is another switch on the dash that allowed me to use the coach batteries as auxiliary start if the chassis battery died.

Onan genset and an outdated obsolete Magnetek 6345 series converter/charger.

I don't think my old converter hurt my old batteries because they lasted me 7 years, and even at that, I only had one dead cell on one of them, so I'm not complaining, and I think I have the "care and feeding" of batteries down... I just want to upgrade stuff, since replacements are needed, and am trying to plan ahead for solar.

Until "solar happens" here, my current worst case scenario is 2 weeks without power because of a storm. Until then, the only other boondocking I plan to do is enroute somewhere.

Within my budget, so far I have updated the following:

Because I am working my way up to solar, I decided on the Sam's Club GC2s rated at 232 AH/20 amps and bought welding cable and built my own 2/0 battery cables. I am careful that the batteries are the same distance apart and the cables are the same length. Also the cable is protected from oil and grease with sleeving, because it is my understanding it will damage the welding cable insulation.

I plan to install a Tiger Claw 1500/3000 pure sine wave inverter within 3 feet of the batteries (actually closer to a foot and a half), but outside the battery box), and also with 2/0 cable.

I bought a 6 volt battery charger/tender for the GC2's and have not yet connected them to the old converter/charger.

After lots of reading, I am thinking that allowing ANY RV converter to charge these batteries might not be a good idea, and certainly not before I buy a new converter.

There's a switch on the wall that activates a relay under the step that allowed me to 1) start the generator. 2) draw amps out of my batteries at will and 3) use the coach batteries as an aux start for the engine. There is another switch on the dash that also allows me to do that from the driver's seat without flipping the wall switch. I have to hold that one down while starting the engine for that to work, it can't be left on.

I don't "think" the switch on the wall disconnected the "charging" part of the old converter, but only disconnected the batteries from providing power. I always did hook the old batteries up to a regular charger after I checked the water levels, and they never seemed to need too much of a charge until that one cell went bad.

So I am wondering if there is any way to hook these new batteries up to a new converter, so I can flip that switch to get the power from them when I need it (say to start the generator) and prevent the converter from charging the batteries? I'm thinking I only want the correct charger charging them.

Or will it not hurt my new batteries to just let the converter do it's charge thing when I am disconnected from shore power, and just disconnect that cable to use my 6 volt charger when they are "stored"? (Everybody else is doing it, why not me? Right?)

The other thing I am wondering is if I have messed myself up with regard to being able to use that "aux start" on the dash and starting my generator since the GC2s don't have CCA? Should I not plan on being able to do that with the GC2's? Do I now also need a spare marine battery to start the generator? (OR am I completely misunderstanding that switch on the wall???)

Appreciate your insight!

19 Replies

  • I think you might be confused a bit. Newer converters would work fine on those batteries for charging and floating. The issue with newer converters in general is they don't really get your batteries back to 100% by themselves. Some of us use separate chargers with manual control or equalize functions to get that last few percent in there.
  • Puterbug,

    You are working way too hard and even out-thinking the problem to many extents.

    The GC2s in series are a 12V bank, threat them that way. Don't bother breaking them up for the maintainer. Just use them and enjoy the power. Think of them as one BIG 12V bank. It may not say it but it probably has an actual CCA of 12~1400. (Think that will do?)

    There is nothing wrong with any Onan as long as you do the required maintenance to keep it reliable. The Magnatek is another issue, rip that babe out of there at your first opportunity. Put in a new Progressive Dynamics, Iota or other three stage smart converter/charger and then keep about a 1qt bottle of distilled water because that is all the GC2 will need in a year or more. Until you get the new converter, never leave the coach on shore power when you are not using it.

    Don't sweat the welding cable. All of the new stuff is neophrene jacket and oil in things won't bother it

    You have made a lot of very good choices. Keep it up.

    Matt - the guy that does this work on really expensive yachts.
  • It is just a 12v wet cell battery. They will operate just fine with existing systems.

    Take the 6v charger back for a refund unless it is also a 12v charger and you need a portable.
  • How do you use a 6 volt charger with both GC2's wired in series? It sounds like a converter upgrade is in your near future. If you have everything set up right, your new GC2's and the converter should be controlled just like you had everything previously.
  • the bear II wrote:
    Sorry my brain hit full about the time I read your third paragraph....


    And yet, you felt compelled to respond.
  • HiTech wrote:
    Golf cart batteries have a CCA they can provide, it is just hard to get it out of the OEM. They will work fine to start your genset.

    Jim


    Thanks. What are your thoughts about allowing them to be charged by the converter? Ever or Never?
  • Golf cart batteries have a CCA they can provide, it is just hard to get it out of the OEM. They will work fine to start your genset.

    Jim

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