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ntrsandman · 03-09-2012, 08:43 PM

A friend's toyhauler has a generator starting battery and isolator that was installed by the previous owner. We were discussing the isolator function after the generator was started. (or on shore power). MY question is:

IF the house batteries and starter battery are isolated, how does the converter/charger "sense" the required charge needed to charge and maintain a set of deep cycle batteries and a standard starting battery with generator or shore power?

I found this isolator site
Hellroaring Battery Isolator/Combiner notes for Multi-Battery isolation in RV/Camper/Trailer Applications

It has diagrams, but not one for an RV with a gennie.

I think it would be an advantage to have a starting battery for the gennie. I think there is more to the install than wiring and an isolator. I wish it could be that easy. Then again, I do over analyze things

Any input or info would be appreciated!

Full.Monte · 03-16-2012, 07:27 AM

My generator seems to start off of the engine battery rather than the house batteries.

In answer to your question...an isolator is essentially a diode that allows electrical current to flow in one direction only. Once the voltage on the input side of the system exceeds that on the battery side of the system, current flows, thus charging the battery. There is one caveat to this. There is a voltage drop of as much as .7V across the diode/isolator. This means that if there is an isolator, the batteries will always see less voltage than might be necessary for a full charge.

Dave78Chief · 03-17-2012, 06:54 AM

In order to answer your question we would need a drawing of how this setup is connected. Additionall, given the PO installed this setup himself, is this a aftermarket generator that comes with a battery in it? Is this a diode or relay isolator? If diode, is the 12VDC charging output from the generator the isolator input? What type/model generator? Far to many possible varibles

Dave

ntrsandman · 03-17-2012, 07:46 AM

The toyhauler (5th wheel) came from the factory with a 4k Onan. Which was started with house batteries. The PO added the starting battery and isolator which appears to be an off the shelf "blue" type. The converter was also upgraded to one with float charging capabilities. I will try and find out the exact make/models of the parts.

I do understand how this (basic) system works in a motorhome. Would like to know how it would/should work in a generator only, 2 separate battery bank system in a towable.

Thanks for the responses!

Dave78Chief · 03-17-2012, 08:04 PM

Some Onans do not have a 12VDC charging output so the converter would be the primary charging source (input to isolator). For Onans that do have a 12VDC charging circuit, it is only rated for 10 amps so you may still want the converter to be the primary input to the isolator.

Dave

Qwert66 · 03-18-2012, 12:04 AM

See if this meets your needs - includes a wiring diagram and description of how it allows charging either set/bank of batteries from either the engine (alternator) or converter (powered by either genny or shore pwr) by automatically and manually (with a dash switch) determining when to tie both sets/banks of batteries together for charging and/or emergency starting with 1 hi power solenoid. This is what our RV came from the factory with.

http://www.intellitec.com/pdfs/BATTE...300839.100.pdf

RV Wizard · 03-18-2012, 04:28 AM

Why not just installing a Battery Minder, Battery Tender or similar charger for this added starting battery and make life simple.

HotMech · 03-18-2012, 09:49 AM

Most likely, the PO, got tired of not being able to start the Gen if the house batteries were low, and since it does not have a starting battery, (Trailers have no engine)
The PO simply added a starting battery for the Gen. The isolator is to keep the starting battery from being drrained with the house batteries, while still being charged by the Converter. That way, if he were to drain the house batteries, too low, ( I know, bad for the batteries, yes) he could still start the Gen.
K.

ntrsandman · 03-19-2012, 07:10 PM

Quote:

Originally Posted by RV Wizard

Why not just installing a Battery Minder, Battery Tender or similar charger for this added starting battery and make life simple.

WOW! How simple is that! I feel so Homer Simpson! DOH!

That sure does make sense. I am sure someone will or has devised a isolating method that I was thinking about. Let someone else buy it. Keep it simple! Thanks Mr. Wizard!

RV Wizard · 03-20-2012, 04:17 AM

Your welcome.

Dr4Film · 03-20-2012, 04:33 AM

Quote:

Originally Posted by RV Wizard

Why not just install a Battery Minder, Battery Tender or similar charger for this added starting battery and make life simple.

I would recommend installing a Trik-L-Start versus a Battery Minder or Battery Tender. They are great keeping two sets of separate battery banks fully charged at the same time.

Ultra TRIK-L-START Starting Battery Charger/Maintainer

Dr4Film ----- Richard