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boomvan · 03-02-2012, 01:04 AM

Hello,
Our 1986 Jayco on a Ford E350 chassis, 460 gas engine, has its alternator on its last legs. While its out, we are planning on upgrading from the externally regulated 55 amp to a modern internally regulated Ford 3G 130 amp alternator. This will require a battery isolator upgrade also. However I'm confused on the models of isolators. Which group model isolator do I need? Which one from the list on this page should I look at?
Battery Isolator - Marine Battery Isolator - Sure Power Battery Isolator

Thanks

MattC · 03-02-2012, 07:48 AM

Boom,

You confusion is understandable. You know need the 130 amp rating (buy more, it's cheap), but you don't know if you need series 1, 2 or 3? I don't know the Ford 3G series real well, and my books are here, but this might help:http://www.allbatterysalesandservice...on-180012Q.pdf

I'm thinking it is a series 1, but this should answer the question.

Matt

Quote:

Originally Posted by boomvan

Hello,
Our 1986 Jayco on a Ford E350 chassis, 460 gas engine, has its alternator on its last legs. While its out, we are planning on upgrading from the externally regulated 55 amp to a modern internally regulated Ford 3G 130 amp alternator. This will require a battery isolator upgrade also. However I'm confused on the models of isolators. Which group model isolator do I need? Which one from the list on this page should I look at?
Battery Isolator - Marine Battery Isolator - Sure Power Battery Isolator

Thanks

Bilito · 03-02-2012, 07:59 AM

where would a battery isolator normally be located?

Dave78Chief · 03-02-2012, 08:30 AM

Groups 2 and 3 are for Delco Alternators with external sense leads. A 130 amp Ford 3G alternator does not use that so you need group 1.

Better to get larger amperage (reduced stress on components) by getting the 160 amp model (Sure Power 1602 Battery Isolator)

I take it you have researched all the information about how to convert from a 1G (external regulator) to a 3G (internal regulator) alternator setup?
Unless you have a serpentine belt, the fan belt size of the 55 amp 1G is not really big enough for a 130 amp 3G.
You will need to upgrade the Alternator BAT lead to 4 gauge wire and install a 175 amp fuse.
OEM Amp meter (if installed) in dash will no longer work. You will need to get aftermarket gauges.

Dave

Ragingbull · 03-02-2012, 08:31 AM

Quote:

Originally Posted by Bilito

where would a battery isolator normally be located?

Mine is located on the right side firewall facing the grill.

Dave78Chief · 03-02-2012, 09:02 AM

Quote:

where would a battery isolator normally be located?

Some older rigs used the electronic Battery isolator, others used the AUX Start Relay. Today they (coach mfgs) mostly just use the Aux Start relay. If installed, it (either an electronic isolator or Aux start solinoid) would most likely be under the front hood on your Oshkosh chassis. Many of todays (and many older) rigs use a BIRD controller to control the AUX start relay. On my old 78 Chieftian I have the manual implementation (Dual/Norm/MOM switch) for Aux Relay control. The reason a solinoid is preffered over the electronic isolator is there is a 0.7VDC voltage drop across the isolator diodes therfore the batteries never really get the proper charge voltage (13.4 vs 14.1). The Delco group 2 & 3 versions, the fourth post is used to compensate for that voltage drop given that those alternators have the external sense. Whether the original rig had a solinoid or a used the Aux Start relay was up to the coach mfg (not the chassis mfg).

Dave

ImagineIF · 03-02-2012, 09:04 AM

The wire size used for the old alternator is likely not sized for the new alternator.

ahicks · 03-02-2012, 01:31 PM

Quote:

Originally Posted by ImagineIF

The wire size used for the old alternator is likely not sized for the new alternator.

Another reason to scrap the electronic/diode type isolator and go to a relay type as Dave is describing above. Relay type are much more reliable, and much easier for most to troubleshoot should problems arise.

ImagineIF · 03-04-2012, 06:21 AM

BTW,

Some will say this product is too expensive, I think about $200, but I would say it does everything in one simple to install box and it comes from a reputable marine product supplier, so need to worry about the environment it will be used for in an RV. It combines, isolates, and provides forced start combining.

ML-Series Automatic Charging Relays (Magnetic Latch) - PN - Blue Sea Systems

Gil

MattC · 03-05-2012, 05:55 AM

I do/did boat work.
I've been watching this device for a while. It is possibly a good device if you always leave the coach on shore power. But even the (less than) 10ma drain (like your propane, smoke and CO detectors) on the house bank and the ECU keep alive on main engine bank, it will deplete a battery over a long period of un-use.

Matt

leadman · 03-15-2012, 01:50 AM

There is also a manual switch available with positions to charge different batteries.
You can select #1 battery, #2 battery, or both #1 & #2. If you don't want to mess with a manual switch The solenoid set-up is the least expensive and most reliable in my experience.
I worked for a large Municipal fleet (4,700 vehicles) and the isolators always gave us charging problems and short battery life.