Re: [A/S] Electrical Independence

[Bob Kiger <myairstream@xxxxxxxx>]

At 09:40 AM 5/7/01 -0400, <<Jim>> wrote:
>Bob,
>  Please go back and re-read what I said:
>
>You most definitely CAN charge batteries from the vehicle's alternator.
>You CAN'T do it at a decent rate through the #10 wire that's typically
>used for hookup, you need to have very heavy cable. If you're unfamiliar
>with #4 welding cable, it's a bit over 1/2" OD and the wire itself is
>about 3/8" diameter. It sells for between $.50 and $1.00 per foot, and
>you need about 75 feet (2 conductors), plus a connector that will run
>you maybe $25.00.
>
>As I said, the problem is voltage drop across that #10 wire. The
>vehicle's alternator regulator sees the vehicle's battery voltage and
>cuts back on the charge rate, so little goes to the trailer. IF the
>vehicle's battery was disconnected AND IF the regulator had a connection
>directly to the trailer battery to sense the voltage, THEN YES you could
>successfully charge it like you want to.

So I would build a crossover switch between my alternator and puller's 
battery.  When I throw the switch the alternator's output is redirected 
through #4 wire to a plug installed very closeby. on the front end of the 
puller.

I park the vehicle next to the trailer's special battery charging plug.  (2 
of the new high tech 12 volt batts.) and boost the idle speed to 1500 
rpm?  Assuming I have a big 125 amp hour alternator, should I not be able 
to get a decent charge in an hour or so.

>You're envisioning operating on your batteries for a couple of days
>until they get "low", then plugging in your umbilical cord and running
>the truck's engine for a couple hours to recharge them. From my own
>measurements, you'll remove about 60 AH from the batteries over those
>couple of days and will return maybe 10 AH or so in a couple of hours.
>Look at those numbers and tell me what you think is going to happen.
>
>                                    <<Jim>>

How is it that a 125 amp hour generator hard wired to the Airstream 12 volt 
batteries only gets 10 amp hours of charge in 2 hours.?

I used to charge two twelve volt batteries up enough to function for the 
night in my camper van.    I remember that after using my 600 watt invertor 
for the microwave for 12 minutes the invertor alarm went off.  That meant 
low battery power.  So I turned on my van and let it idle and Bingo, I 
finished out my night in comfort.  That would be defined as small 5" TV and 
an occasional light.

Thanks as always.
Bob