Mark,
I can only partially answer your questions from experience, but with your
willingness and ability to improvise & experiment, that shouldn't be a
problem. ;-)
The alternators you're considering should certainly handle your load and
they've apparently avoided any mounting problems. My concern would be with
the V-belt drive. I have no experience with double belts, having run
serpentine belts on both the 455 and the 500. Those have performed
perfectly, but I have no idea where to find a reasonably simple and priced
setup for the 455 -- mine was custom from someone else and that on my
Cad500 is my own design. We've got a lot of GMCers running dual V-belts --
they'll advise you whether to expect reasonable performance under twice the
load.
Yandina.com has 200+ Amp combiners, as I'm sure all of the suppliers do. I
tend to recommend those because that's all I've ever used. I was an early
adopter of them and, AFAIK, Yandina Marie Foster, the inventor, was the
only supplier at that time. She (he, at the time) invented it for marine
use on the houseboat/yacht she lived on in Beaufort, SC -- to provide a
little useless information.
Incidentally, there are higher-capacity options to consider vs your
"cooling pack". For example, we had, years ago, a lawyer-GMCer in Alabama
who had no roof air on his personal GMC (his wife, also a lawyer, had her
own personal GMC -- more useless info -- 83 yo's tend to provide that).
He'd had a household unit modified with the evaporator under the sink in
the rear bath of his 23'. I don't know the capacity, but it was probably
15K BTU or better. I no longer remember where he had the condenser and
compressor, but they were concealed somewhere inside (probably to the rear
of the Onan since that's about the only free space).
Please keep us all posted on your progress.
Ken H.
On Tue, Nov 17, 2020 at 11:53 AM Mark Sawyer via Gmclist <
> Sorry I took so long to get back to this thread... Got busy with work and
> some other issues with the coach...
>
> So Ken: to answer your question, the coach currently has a 100 amp
> isolator on it.... And I never even thought far enough to look into
> changing it out
> for a combiner... Since I want to go with a larger alternator, I only
> looked into a larger isolator to go along with it....
>
> I'm actually not super knowledgeable about RV electrical systems... Let
> me back up and describe the system on my coach, and why I am looking to
> increase the capacity of the alternator...
>
> So the coach currently has a 4K onan, 4 6volt GC2s... One set in front,
> one in back by the genset... Instead of the stock buzzbox, the coach has a
> 2500 watt inverter/charger. There is also a perko switch linking the 2
> banks together, an isolator as already mentioned and a 100 amp 10SI
> alternator.
>
> So the reason for me wanting an upgraded alternator was linked to project
> to add some additional cooling. The coach has a working dash air,(still
> running R12 but with an updated Sanden SD7 compressor) and a single 15k
> btu Atwood rooftop AC in the center roof position.
>
> Being in Texas, I had originally planned to add some additional AC
> capacity to the rear passenger area to keep my kids cool when on the road,
> without
> having to fire up the generator and rooftop ac. The plan was to add an
> additional evap under the fridge area, with the vents pointed to the dinette
> area. But the more I thought about it, it seemed like a lot of resources
> (space, $$ and effort) for an AC that can only be used when on the road.
>
> What I ended up doing, is buying this portable spot cooler:
>
>
>
https://www.globalindustrial.com/p/hvac/air-conditioning/commercial-portable-ac/portableairconditioners-spotcooler-etl-approved-796000?infoParam.campaignId=T9F&gclid=Cj0KCQiAhs79BRD0ARIsAC6XpaXpz5tM4f0tGglkxSvjOFqtEaJqsq-q1QuV3jCbn9dAQtdPXK0BGD0aAnqWEALw_wcB
>
> I had switched my propane fridge out for an electric unit a few years ago,
> and I was able to install this spot cooler in the unused space behind the
> fridge. It uses the old propane fridge vents to move air over the ac
> coils, and exhaust the heat outside. It also runs fine on my inverter...
> Uses
> about 6-700 watts running. I have a 5" vent in the fridge wall near the
> door (standard 73 26' layout coach) pointed at the dinette area plumed in to
> the spot cooler outlet hose.
>
> It's not a huge amount of cooling, but with the dash air on, I can run in
> the mornings and evenings without firing up the generator and the rooftop
> unit. It will also stay running on the battery during fuel stops when the
> engine is shut down, which is kind of nice. And if I need some additional
> cooling on hot Texas summer days, the 4K onan will run the spot cooler and
> the rooftop unit simultaneously... And of course I can run both units off
> of shore power as well. As a bonus, vs a coach with dual rooftop ACs, I
> was able to leave my front and rear fantastic vents in place.
>
> However, as you may have already figured, it's really maxing out the stock
> alternator charging when I'm on the road, and I don't really feel
> comfortable running it for extended periods... So I was looking at
> changing to maybe a 200 amp alternator... And the current, 100 amp
> isolator to
> something larger, along with it.
>
> I welcome any input and am open to suggestions on anything about the
> current system, or what I am planning with the alternator.
>
> Ken, do you still recommend a combiner over an isolator for what I am
> running? How about the alternator capacity I am thinking of? Figure
> 180-200
> amp should cover the loads with some excess capacity to spare, without
> overtaxing the engine or alternator too much. Already running a dual belt
> alternator pulley.
>
> I'm not set on what alternator to run either... Was looking at some of
> the upgrades from these guys:
>
>
https://www.qualitypowerauto.com/category_3/GM-Alternators.htm
>
> But was also considering adapting a high output alternator out of a late
> model truck and modifying it to work in my coach...
>
> Again, I would love any thoughts, suggestions or inputs anyone can provide.
>
> Thanks
>
> Mark
> --
> Mark S. '73 Painted Desert,
> Manny 1 Ton Front End,
> Howell Injection,
> Leigh Harrison 4bag and Rear Brakes,
> Fort Worth, TX
>
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