Need new batteries

[stew47]

Well our new to us 98 Winnebago 35 adventurer needs some new batteries. I'll rattle on with a few questions and if anyone has some better ideas fire away 🙂

I pulled one of the house batteries out last fall cause it seemed to be heating up and losing cranking amps. I figured one would work. It has but I think I'll be going back to two and using group 27 deep cycle. Any problems with rural kings $69 special?

Next chassis battery is down to 3 to 4 volts after trying to charge it. Sounds like shorted or just needs replaced. It takes a group 58 and I'm thinking of just putting in a group 27 deep cycle for it too. Might even rotate with house batteries if makes things last longer. Any issues?

Also I figured out that converter doesn't charge my chassis battery. Which is better for the battery keep trickle charger to it or use a jumper to the house batteries? Thanks in advance.

[stew47]

Makes so much sense now that I've been told lol. More capacity has to come in handy. I don't have a SAMs club membership but I can change that.

[wa8yxm]

If you have two group 27's you have less than 200 amp hours total

Replacing them with a pair of GC2's (A bit taller but smaller at the base) and some shims (Boards) will get you 220-230 amp hours of DEEP CYCLE battery, this means you can safely use half, a better chance of recovering if you go over that and possibly a longer life,, Get 'em from Sam's. and they (if you are a member) are about the same price. This is a far superior battery to what you have now.

As for the chassis battery,,, Replace it, I leave the choice up to you.

[stew47]

jrnymn7 wrote:

stew47 wrote:
So 2 cg2 Duracell 6 volt golf cart batteries for 170$ seems like a decent way to go. Ventilation and access are both good. Oh and thanks so much for the solar info. Will dig in later.

Just keep in mind, you may need/want to expand, in the future. In that case, would four GC2's fit?

I will have to do some measuring but they might. Be close.

[pianotuna]

Hi,

Much as I would love to take credit--it is from N8GS--not me. (I'm spreadsheet challenged.) I've corrected my original post to make that clear.

OldGreaser wrote:
Hey Pianotuna,

I read this thread because I have a house battery on its last legs, and stumbled over your solar work. VERY Impressive, especially the spreadsheet. I may not convert my present rv to solar or install a residential fridge but I've stored your documents in a very honorable and dignified location on my hard drive.

Thanks for sharing!

[jrnymn7]

stew47 wrote:
So 2 cg2 Duracell 6 volt golf cart batteries for 170$ seems like a decent way to go. Ventilation and access are both good. Oh and thanks so much for the solar info. Will dig in later.

Just keep in mind, you may need/want to expand, in the future. In that case, would four GC2's fit?

[OldGreaser]

Hey Pianotuna,

I read this thread because I have a house battery on its last legs, and stumbled over your solar work. VERY Impressive, especially the spreadsheet. I may not convert my present rv to solar or install a residential fridge but I've stored your documents in a very honorable and dignified location on my hard drive.

Thanks for sharing!

[stew47]

So 2 cg2 Duracell 6 volt golf cart batteries for 170$ seems like a decent way to go. Ventilation and access are both good. Oh and thanks so much for the solar info. Will dig in later.

[jrnymn7]

Like westend said, stay away from hybrids, i.e.; marine/rv batteries... unless, of course, you plan to over-inflate your tires and strap a trolling motor on the back of your rig. 🙂

6v deep cycles are the way to go, unless space is an issue, then look at deep cycle 12v's. If ventilation and/or access is an issue, consider going AGM. And for the best of the best, look into LiFePo4, but compare overall, long term cost; i.e; fuel savings, if charging with a generator while dry camping.

[westend]

The Rural King battery is not a deep cycle battery and, for $69, probably not good for more than a garden tractor. Standard lead acid starting batteries are not a good choice for RV use and deep cycle batteries are not that good for starting tasks. The cheapest solution for deep cycle batteries (not hybrid and not starting batteries) are 6V golf cart batteries sold at Costco or Sam's club. For the vehicle's system, look for the most weight/$$. FWIW, I payed more for a replacement battery for my truck than was necessary but chose the same Motorcraft battery that was original. My choice was based on the 10 yrs, 1 Mo. of service I had with the original.

[pianotuna]

Here is a simple flow chart.

Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT. What ever type of controller is chosen, make sure it has adjustable set points and a temperature probe that is on the battery.

One rule of thumb is between 60 and 150 watts of panels per 100 amp-hours of storage. The smaller the battery bank the higher the wattage needed (per 100 amp-hours). Here is a link to the rather special spreadsheet which includes an energy audit, that N8GS has created to help size solar battery charging systems!

Solar Spread Sheet by N8GS

For a nice explanation of solar, try this link:

Golden rules of solar

stew47 wrote:
Any advice on solar charging set ups?

[KD4UPL]

For what it cost to buy a little 15 watt "charger" solar panel, plus the trouble of installing it, you would be better off buying a 100 watt panel and have it be actually useful for camping.
Those tiny little 5 to 15 watt panels are pretty useless.

[stew47]

Any advice on solar charging set ups?

[pianotuna]

Hi Stew47,

5 watts will do nothing for you.

[stew47]

Thanks for the replies. Thought about a 5 or 7 watt trickle charging solar panel sitting on the dash.