Give Feedback on initial House Batt charging upgrade plan

Thanks for the feedback so far. A couple clarifications and thoughts:

- The storage barn is not mine, no chance of solar
- I actually pull the batts while in long term storage, keep them in my heated garage and charge them periodically (boat and rv batts) (December-February)
- The RV is used at 2 to 3 weekends per month, so when the batts do sit they are only sitting for a few weeks with them disconnected

- Let's rule out 8D, However I'm still out on 2 6v or 1 12v or agm/wet. Let's set price at $200 tops for batts (I think this puts me in the 2 6v league because I can get 220AH for about $190)

- Isolator questions: Matt_Colie: I'll check on my isolator. I guess my big thought was without the ProMariner my alternator (160 amp) will always feed both batts even possibly overcharging as the internal voltage regulator on the alternator is not that smart. (perhaps undercharging if I have a voltage drop on the isolator). With the ProMariner it will send the full alternator current possible to the battery that is in most need and also switch it off when it is charged.

- My overall theme here is how do I walk into my RV that may have been sitting for two weeks, drive it about 4-6 hours then boondock for 1-3 days. I've even looked at DC to DC chargers (marine stuff). Using this as a reference any more great thoughts/concerns? (don't worry I'm not buying a DC to DC charger).

If the ProMariner is going to help get me that last 2-3% of charge on my House batts I'll make the investment.

Again thinks for the dialogue this is all great stuff! I had never even known about 8D batteries until now....

Two decisions again:
1. Wet/AGM 6v/12v on a $200 budget
2. ProMariner at $130 worth the investment (even if small)

oh yeah...some won't like but I am putting a $8 digital voltmeter in my control center to see my batt volts (I have the chart for under load, and sitting with no load) for now the $8 is what I'm willing to invest....I have to get my boat prepped for summer....

I like BFL13's answer best.

I like the solar on the barn idea a lot. I have installed similar on the winter storage shed for some boats. It worked well. It will not take a lot of solar to do a good job as you will have lots of time at low load to charge the house bank.

If your coach currently has a dual diode isolator, then leave it alone. Systems that have that also have a voltage sense on the engine side of the isolator so the diode drop (0.6V) is no longer an issue. If it has a single diode isolator (only two posts - very rare) then by all means, replace it with a contactor.

Depending on the main engine alternator, you may or may not be capable of doing significant recharge on the road. Alternators can be upgraded, but if you have to go past the largest parts store unit, this gets expensive in a hurry.

An 8D in AGM will use a lot of your budget and be very difficult to more (~170#). Yes, golf cart batteries will have more junctions to maintain, but at least you can more one without a crane.

Plan to install a Trimetric or Xantrex battery monitor. This will tell you what you need to know when you need to know it. Unfortunately, this will burn half your budget in one shot. Maybe plan it for next year.

We did this sort of work for the owners of expensive boats for years before the depression ended the business and all the big boats that could left the area.

8D AGM is a good battery, no question there, but it is HEAVY over 2x the weight of each of those six volts he has and over 2x the price too. SO what he has gives far more "Bang for the buck" and far less likely hood of medical problems

(The joke I say is that with two six volt GC batteries in series you get one big 12 volt battery,, With the same size (it is between a 4D and an 8D) 12 volt battery you get ... A hernia.. That said, I can indeed lift an 8D with no danger and have carried the equivalent more than once).

And the alternator very likely can not provide that much charge to the batteries to make that big a difference..

Finally, Xantrex recommends the same max charge rage for "Generic" AGM as they do for Flooded wet cells.. LIFELINE is the only one I have seen who recommend more and then only for their AGM product.

Check out the 'public lands/boondocking' forum here. THOSE people know every which way to Sunday to assist/boost battery charging and RV'ing as long as they can off the grid! Lot of good info can be found from them.
http://forums.woodalls.com/index.cfm/fuseaction/listings/forum/35

BFL13 wrote:
Long time storage between trips, no power, inside barn. Low batts from self discharge on way to camping. No power when camping. Not there to do any generator/converter charging while off doing activities (--solar?)

-AGMs have way less self-discharge, so better for storage time (Wet 6s have high rate of self-discharge)
-Put solar on roof of barn to maintain batts in RV inside the barn? Make that solar portable and lash it to the roof of the RV for any trips?

X2

Long time storage between trips, no power, inside barn. Low batts from self discharge on way to camping. No power when camping. Not there to do any generator/converter charging while off doing activities (--solar?)

-AGMs have way less self-discharge, so better for storage time (Wet 6s have high rate of self-discharge)
-Put solar on roof of barn to maintain batts in RV inside the barn? Make that solar portable and lash it to the roof of the RV for any trips?

Your plan sounds good, but I would go with a single 8D AGM battery. You will get more efective charge times at a slightly lower voltage. You need to find a way to make sure the battery is fully charged during storage. That is the only way ypu will get the cycle life out of the battery.
MM49

Hi,

An ordinary continuous duty solenoid will do a great job of charging the house batteries at a much lower cost than the promariner

My OEM battery compartment had room for 3 group 29 12 volt jars. That's about 50% more capacity than twin six volts.

If all you are trying to do is get more voltage (and current) to the house batteries, from the engine alternator when driving, you should forget those fancy isolators and install a simple switch controlled continuous duty solenoid between the chassis and house batteries.

About $24 for the solenoid and maybe $10 worth of cables.

You probably already have a solenoid installed for your aux/emrg start function. Just add a toggle switch to parallel the aux start temporary contact switch.