Seeking advice on 12v upgrade- Ch. 1: Batteries

Ductape wrote:
Do I need to ask vendors about date codes before ordering from websites? I would not like to end up with batteries that were 2 years on the shelf. Searched and did not find any discussions about this. Maybe it's not an issue with this brand.

I'd ask but when I ordered mine three were only a couple weeks old and one was a month old.

When you are on the road, the alternator voltage regulator decides who gets what by presenting a set voltage.

When you are camped underhood temperature is at ambient so dedicated temperature compensation is moot.

Lifeline isn't going to be handled by a flake outfit. Choose a major retailer because their inventory turns over fast and there is not a lot of leeway in the price. Myself I would be selfish and telephone the vendor and ask them to select a battery for you that reads 12.80 volts or higher. They aren't going to do it of course -but- a yellow flag gets hoisted and the office tells the warehouse crew "Pick a fresh one for this order". (insider's secret).

Do I need to ask vendors about date codes before ordering from websites? I would not like to end up with batteries that were 2 years on the shelf. Searched and did not find any discussions about this. Maybe it's not an issue with this brand.

Hi,

I just use Napa switches.

Unless you have massive solar, I think putting the sensor on the set of batteries that will be coldest may be enough.

I will use a marine A-Both-B-Off battery switch for the feed to the chassis. For the solar side I'll need to study up on and select a solar controller, and see what it will take to switch the temperature sensors, since I'll have two of those and I want one switch to handle the current and the sensor. Outcome is I'll have the same switching options for the solar. May have to buy a configurable industrial switch, I don't know yet on that.

Any problems with that setup?

Hi Ductape,

I chose to go one step farther and used the same battery for the chassis, so I applaud that decision

How will you arrange your switches?

Thank you everyone for your advice. I'm a bit slow to reply since work has demanded my full attention lately. :)

I've decided to go with four of the GPL-6CT. Two under the hood as one bank and two in the basement as a second bank. That will give me 600 AH in total, and if I need more I can always add another pair in a third location.

I thought it best to keep all the batteries the same size, that way as they age and ultimately fail, I can mix and match between the two banks to keep similarly aged batteries in pairs. If they were dissimilar sizes then one bad battery in each bank would force me to replace all four.

Keep us posted on your choice in batteries.

Hi,

My two banks "meet" at the inverter. The OEM bank powers the 12 volt side of the RV.

I chose the Magnum 3000 watt hybrid--so I can now charge either bank at up to 125 amps. I left the OEM 40 amp converter in place and tend to use it when I have 30 amp shore power.

I use the Magnum when I have 15 amp shore power as it is possible to "dial" the input to 15 amps--which means I don't blow a breaker--but the hybrid lets me run the RV as though it were on 30 amps.

I also use the Magnum if I plan on generator recharging--though so far that has happened exactly once. (solar is a gooooooood thing!)

I also have switches so I can charge either bank from solar, and either bank from the alternator.

Definitely reinforce the storage area for the new bank. I'd also consider having a 12 volt in the OEM location. It is rare for an RV to have too much storage.

Thank you all for the helpful advice. For some reason I had not thought of doing two banks :S but that is an obvious solution to the temperature and potentially size difference between the location in the engine bay and in the basement, yes? Just run a temperature sensor to each bank and a switch to select which bank the charge controller is monitoring.

To clarify on the space, I *can* actually fit either the GPL-4 (220 AH) or the GPL-6 (300 AH) pair in the engine compartment. There is even space for the GPL-L16 pair up there with a slight mod of the rack, however IMO the 16's are tall enough that blocking air flow to the radiator is a concern. So I conclude that the 300 AH pair is the max for the OEM location.

The storage bin has the converter and separate inverter in it now. There is adequate additional space for all the batteries mentioned, although if two 16's go in then I'll want a sliding tray to make it easy to roll them out to access the other equipment.

I plan on making the solar inputs as large as reasonably feasible, within practical limits. This is a 30' roof and has a lot of penetrations now with dual air and satellite etc. And it will be flat fixed mounting. I don't want the remaining roof mounted equipment to be unserviceable... When we go FT I suppose a portable setup to supplement could be an option.

I accept that the genset just has to make up any deficit, and I'm in full agreement with Mex, no generator loafing. So the 80 amp converter is not set in stone either.

Based on what I am hearing sounds like the best solution is the two separate banks. Adds complexity, but with proper fusing and selection switches as suggested it will also pay for itself when (not if) a cell fails.

Someone mentioned how long to keep the rig? We expect 10 years or so. Of course if that changes I can always transfer the gear to another rig.

I'm a bit concerned about the floor of the storage bin. Probably need to reinforce and put in a sliding tray to support the 16's if I do that. A pair of those is 238 pounds.

PS- 8D are a bit wider and don't fit either space. I have more height available but am width constrained in both spaces.