what a combiner?

[al chernoff]

Would be glad to... but gene fisher can probably explain it better.

> I have to admit I never heard the word before. Some 20 years ago I installed
> 4 golf cart 6v batteries and two gages to show amps one to house batteries
> and one to the engine battery After I replaced the isolator with a ford
> starter solenoid. I got twenty amps more charge out of the alternater . That
> was with the old eighty amp alternator. I now run a one hundred amp
> alternator. When we dry camp for a few days and I start the engine the amp
> gage will show thirty amp charge and the house batteries will show seventy
> amp charge. I think the old isolator robed at lease 20% of the amps. I guest
> that why they have a heat sink. I don't have a generator I took it out the
> first week I had the motorhome.I find that if we camp over three days I can
> recharge house batteries by letting the engine idle 45 to 60 minutes and its
> much quitter than any generator. I replace the golf batteries after 5 years I
> never had one go bad. I can honestly say I never ran out of house battery
> power yet. I seldom use campgrounds with hook-ups we went to Alaska and back
> and total camping fees came to $17.
> Jim Anstett Loveland Colorado
>

 

[henry davis]

>Would be glad to... but gene fisher can probably explain it better.

Take a look at my site:

http://www.henry-davis.com/GMC/electFAQ.htm

I have some helpful definitions there including combiner.

Henry

 

[henry davis]

>

>
> > I have to admit I never heard the word before. Some 20 years ago I
> installed
> > 4 golf cart 6v batteries and two gages to show amps one to house batteries
> > and one to the engine battery After I replaced the isolator with a ford
> > starter solenoid. I got twenty amps more charge out of the alternater .
> That
> > was with the old eighty amp alternator.

Isolators work by employing diodes to block current flow. They work quite
well for this job. However, they do have a diode drop of at least 0.8 volts
and some have more. The voltage drop is dissipated by the isolator as heat.
For the OEM isolator in the GMC I think that you lose about 10% of the
capacity of the alternator in heat. So, an 80 Amp alternator is limited to
72 Amps of usable current.

I'm not sure why you saw a 20 amp increase unless there were other problems
with your isolator.

> I now run a one hundred amp
> > alternator. When we dry camp for a few days and I start the engine the amp
> > gage will show thirty amp charge and the house batteries will show seventy
> > amp charge.

The automotive regulator is the limiting factor in recharging battery banks
using the engine alternator. A multi stage regulator will recharge your
batteries in the most efficient fashion - automotive regulators tail off
pretty rapidly so that they avoid boiling batteries that are nearly charged
(and because the electronics to do multistage are more expensive). FWIW,
your 100 AMP alternator is sized pretty good for 4 golf cart batteries.
Assuming T105 batteries, your alternator is just about 25% of the total
charge capacity of your batteries.

Henry