AGM Batteries

First before you spend the cash, email Redarc and explain to them what it is you want to do, ask them the direct question is a Redarc solenoid actually "recomended" by them to be used with two different types of batteries, their reply will change your decision.

yes you can use it with two different batteries and you can also drive in the right lane of the freeway, but it's not recomended either!!!

Who cares what the maunfacturer says the fact is it works just fine. If the manufacturers of products knew everything they'd never have to ask the consumer for feedback would they. I work for a manufacturer and I'm damn sure the company doesn't know everything about our product. Theory is one thing, real life experience is the real test.

Ray,
The facts are its not "recommended" by Redarc for a valid reason, hence I have posted "ask them for their reason"

To my knowledge, in no present advertising for the Redarc Smart Solenoid is there any reference at all to them being used and/or recommended with any other than two identical Cranking batteries, prior to my contact with the CEO of Redarc they did imply two different types of batteries could be used, that has since been negated.

Various Electronic Isolator manufacturers do recommend their Battery Isolator can be used with any combination of Cranking battery and AGM or Deep Cycle batteries.

That's because Redarc's technical dept aren't up to play with the latest theory about dual batteries, not their fault because the myth that only identical batteries should be paralled is all over the web, even some battery manufactures aren't up with the play yet.

norm ,
Excuse my ingnorance but when you say wet cell, do you mean normal acid type dc batts ? if so i always thought you couldn,t parrell different types of batteries.
because my conundrum is i have to 2 agm (extreme orbitol 55ah) one as my crank and one as my aux and also 65ah dc acid battery sitting in the shed doing squat , almost brand new.
it would be nice if i could put in my ct to run parrell with my aux, via anderson plug to charge up while driving along your thoughts most appreciated
thanks tony

"i always thought you couldn,t parrell different types of batteries."

- yet another "well-known" battery myth.

Lead-Acid batteries (wet, agm, starting, deepcycle) can be charged with a constant voltage. It doesn't matter how many other batteries are connected to that same voltage. But keep in mind that some battery types need different voltages (e.g. calcium-calcium)

Mike

Tony, Correct. By Wet cell, I mean normal vented (not sealed) lead acid Deep cycle. As Mike has said, the 'theory' that you should not connect different battery types in parrallel has been dubunked for some time. Many people on this forum have successfully mixed batteries. AGMs and normal vented batteries are no problem. The only potential problem I am aware of is that since an AGM can take large charging currents, it may 'rob' the charging current from the normal (vented) battery so that the normal battery does not fully charge. This is only likely to happen if you do lots of short trips and no extended running. I have never had the problem, and as far as I am concerned, it remains an unconfirmed theory (although the theory is sound).

I've heard that theory also Norm but if using a good isolator that doesn't bring the second battery in until the main is charged that potential problem is overcome.

"since an AGM can take large charging currents, it may 'rob' the charging current from the normal (vented) battery so that the normal battery does not fully charge"

- if this happens then you just don't have enough charging capacity - to fix that you need to either increase your Alternator current capacity or reduce the amount of current you are drawing. Fiddling with batteries is just re-arranging the deckchairs on the Titanic.

Mike