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 I workfull 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 at JadeMountain. 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, consumptionrate, 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, ituses 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're essentiallyparalleled
> 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'll handlehandle 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, butsupplement 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?