Tom,
I'll still maintain that as long as the recommended charging voltagesare pretty close, I
wouldn't worry about it. Remember that they're in parallel anyway,so the applied voltage is
actually the same. Unless your isolators are something unusual, theyonly prevent one battery
from backfeeding another, they really don't do anything for the charging.

With your type of travelling, I can see why you want a good electricalsystem, but you were
certainly abusing it by running the water heater! <<grin>>

I'm now off to look at the sites you listed below, thanks for the info!

<<Jim>>

Tom H. wrote:

> Jim,
>
> The rated charging voltages is pretty close but the internal resistancesand capacity are
> not. However, perhaps my concern is overly cautious although I havealways understood that
> mixing different battery types and sizes is not a good idea.
>
> As far a being a moot point, in fact the situation of normally runningoff of batteries and
> moving often is a situation that I often find myself in. Since Iwork full time, our trips
> are typically logistically planned so that we cover a lot of milesin the beginning and
> often stay at boondock sites since we are only stopping for sleep.I have been in
> situations several times over the past couple of years where we diddelete the batteries
> and were only able to recoup small recharging from the tow vehicle.However the major
> reason for this deletion was that my previous hot water heater waselectric only, which we
> used through an inverter, and thus this would rapidly run us down.Just this week I
> finished final installation of the PrecisionTemp 500 LP continuous/instantaneouswater
> heater. Everything appears to be working well and we'll be testingit next week on a 10
> day trip to FL (our first trip since November '98).
>
> The E-meter that I have discussed was actually purchased at http://www.rvsolarelectric.com/
> although I have since seen this same meter at West Marine and atJade Mountain. It is
> described on the Jade Mountain web site (http://www.jademountain.com/metr.html)as:
>
> E-Meter: New reading as a % of charge with digital precision. A breakthroughin
> versatility, information and cost. Complete, accurate (99.95%) dataon your battery bank.
> Displays amp hours, volts, amps, kilowatt-hours, state of charge,consumption rate, and
> more. Also acts as a digital ammeter, letting you know how much powereach DC load draws.
> Optional RS-232 computer output. 0-50V, requires 500 amp shunt. Excellentall around meter:
> highly recommended!
>
> I am very impressed with this meter as I can program it for instantaneousreadouts of A-hrs
> as well as remaining A-hrs in the battery bank. As you surmised,it uses a shunt to
> measure the current while the battery bank data was input by me asdenoted in the battery
> information. I am not using the RS-232 output because I am satisfiedwith the information
> I can presently get from the meter as it is.
>
> Tom H.
>
> Jim Dunmyer wrote:
>
> > Tom,
> > The rated charging voltage of those batteries is probably prettyclose, and actually
> > MUST be identical because you have only one source, and they'reessentially paralleled
> > while charging. It is not a problem to parallel different batteriesas long as the rated
> > charging voltage is the same. Note that you cannot place mismatchedbatteries in SERIES
> > (such as 6-volt golf cart batteries), even to the point of havingthem differ
> > significantly in age.
> >
> > The forklift battery connector that I mentioned is a 2 pole, heavyplastic job, with a
> > big handle to pull it apart. The contacts are huge, plated, spring-loaded,and "wipe" as
> > the connector is engaged/disengaged. Depending on size, they'llhandle handle a couple
> > of hundred amps for lengthy periods of time; forklifts often have#4 cable going to
> > these connectors. This connector wouldn't replace the Bargman,but supplement it.
> >
> > The whole thing might be moot anyway: a fancy hookup to the vehiclewould be needed only
> > if you are normally running off battery power and are moving oftenenough to charge it
> > up. Plus, using a lot of battery, and driving for only a few hours.I'd think that
> > extensive boondocking would warrant solar panels or perhaps a smallDC genset. (in case
> > anyone is interested, there's lots more to them than simply beltingup an old car
> > alternator to a lawnmower engine!)
> >
> > Did you say that you have one of those "E-meter" gadgets? Can youelaborate on how it
> > works and what it does for you?

--

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