Mixing AGM and Flooded Cell Batteries

Read what WA8YXM wrote.

I do this for cruising boats (or did before the depression). Many owners have reported how the two separate systems saved their buns on occasion. AGM and Flooded Cell can be charged by the same system. (Gell Cells get a little picky.)

A rolled cell AGM (looks like a 6pac) is just the best starting battery you can get. Real good CCA. Not much for AH, but you don't need that to start. It can be put anywhere. If you want to go with a maintenance proof battery, that will work too, but it has to have a box and be upright.

Anybody's golf cart batteries are great for the house(hotel) bank. You can beat them up real bad and they just don't seem to care very much.

My coach actually has three banks. Main engine, hotel and one just to start the Genset. Why, because the Genset(APU) is all the way at the other end of the coach from the other batteries.

Matt

To answer the "Why do you need separate chassis battery" question.

This is from personal experience...

I have, in my 8.5 years of driving this house....

Left the headlights on (The alarm is faulty) and run down the chassis battery, Thankfully the house batteries were isolated and started the engine.

I have also accidentally let the house batteries run down. But I was able to start the main engine, then the generator and bring 'em back.

Having independent batteries for engine and house means your chances of getting stuck due to dead battery are far far far lower and jump starts are almost as expensive as the battery itself.

Now to the O/P.

You do not need an AGM battery.. Standard Maintenance free is likely good enough EPICALLY if you install a vented battery box to put it in.

And that is what I did with some aux batteries.. I put in a vented battery box.

MrWizard wrote:
i think the 4 GC's would start the v10
how ever, i would never CHOOSE, to wire everything house and chassis to (1) set of batteries

keeping chassis and house separate gives more redundancy/backup and more options when something goes wrong, with one side or the other

X 1,000

There is a reason why you have separate battery systems! Do what you were planning on doing - just make sure the AGM is a starting battery and not a deep cycle battery.

i think the 4 GC's would start the v10
how ever, i would never CHOOSE, to wire everything house and chassis to (1) set of batteries

keeping chassis and house separate gives more redundancy/backup and more options when something goes wrong, with one side or the other

It will charge. I paralleled 1 flooded starter with 3 coach AGM because starter one was dying and didn't charge well on its own.
The combo of 3 AGM + 1 starter behaved normal, charging and floating. I didn't try cycling it too much, my goal was merely to restore the wet cell and charge it fully.

I only have a tiny 175W inverter that is used an hour or two a day and only when batteries are floating.

I don't think the starter batt - no matter if it's an AGM - will enjoy deep cycling if forced to do so due to being parallel to coach batts.

Also, voltages will be averaged between AGM and flooded, so your setpoints will be screwed up a little. Trik-L-Start may help with this, didn't try it.

Equalization of a wet cell is a separate issue, this will likely require disconnecting the flooded from all the loads and from AGM.

BFL13, you raise an interesting scenario. Maybe I don'tneed the AGM chassis battery but I have no idea if 4 X6 volt GCs have enough CCA to start the Ford V10 in my 2013 Sightseer.
Can anyone else answer that question?
I am puzzled by the connection arrangements. Now the two systems are seperated from each other except when you manually deploy the interlock switch when a boost is needed. As it comes from the factory the two systems are isolated from each other. This protects the chassis circuits from the high voltages your inverter/charger puts out in the equalization mode. Is this an important issue or does it not matter?
Another question that I should have raised originally is whether to abandon my very expensive, 6 month old, Trojan group 27 12 volt deep cycles rated at 130 AH each and replace them with 4 new 6 volt GC's or keep the two existing 12V group 27's and just add two more of the same to give me a total of 520 AH? The 6V golf carts hooked in series / parallel would give me 440 AH but is there a benefit, others than cost, that would suggest the 4x6V GC's over the 4x12V group 27's?
Mr Wizard, you also have extensive experience in these matters so I would appreciate your opinion as well
To be honest, I appreciate every ones opinion and wish to tnank you all for your feed back.
Lloyd

That should work just fine. On our coach we have just the opposite situation: four Lifeline AGMs for the house and two Interstate wet cell starting batteries. Our Magnum inverter/charger is set for the AGMs and the starting batteries get charged by the alternator or shore power when their voltage drops below the house batteries voltage using a Trik-L-Start.

StarBurst
you are correct

Why do you need the separate chassis battery? Won't four 6s provide enough CCA to start the engine?