Modifying for 2 batteries

[michelprevost]

Hi all,

I want to add a second battery. The current one is a 12 V 60 Ah, so I wanted to add another one of same type, in parallel, which would bring it to 12 V 120 Ah. The dealership told me to use instead 2 batteries of 6 V, in series. Those batteries are 130 Ah.

I am wondering why? What is the benefit? If I go with their solution, I will have to buy 2 new batteries, instead of 1. And those batteries cost over 200 $ each. And at the end, the same power output.

Anyone knowledgeable about this?

 

[KillerIsMe]

Not an expert here. I have one 12V battery in my fifth wheel and have not used 2 6V's before but I've been on this forum long enough and have read enough to give you a very simplistic answer.

6V batteries are generally much higher in amp-hours than 12V's and they can take many more charge/discharge cycles. If you have 1 12V battery at 60 amp-hours and add another of the same you will double your amp-hours at the same voltage - so still 12V but now 120 amp-hours. If you were to switch to 2 6V batteries at 225 amp-hours the voltage will be double but the amp-hours remain the same - so 12V at the same 225 amp-hours. You'll have more hours on a more durable and longer-lasting battery.

If you never leave the convenience of plug-in power it won't benefit you to spend the big bucks upgrading but if you boondock and therefore recharge frequently it will.

That's the laymen's simplistic answer. Many more folks on here are much more knowledgeable and will undoubtedly explain better.

Tom

 

[Vicr]

What RV do you have and how much room for batteries is there? Do you dry camp often?

 

[videoarizona]

I bought 2 6 volts at Costco. Sam's Club has similar. They are GC (golf cart) deep cycles made by Interstate. Around $100 plus bux each.I was able to mount them side by side on my TT. Had to modify the battery cases by cutting the lid a bit so they would fit snug on the battery rail. I then wired them for 12volts, added a battery disconnect on the right side case and 2 charging/tap posts...one on each case for positive and negative solar charging as well as for use as a battery tap off for air compressors,etc.. Very happy with arrangement as it more than doubles my available DC power. And being golf cart batteries, I know they can handle the discharge better than any combo battery or car battery.

 

[michelprevost]

The 6 V batteries the dealer had were 130 Ah

 

[michelprevost]

We intend to boondock more, with solar panels, but want more battery power, for rainy days

 

[michelprevost]

@videoarizona I cannot read the Ah rating on the pictures.

 

[KillerIsMe]

The 6 V batteries the dealer had were 130 Ah

Reading comprehension

Seems expensive, $200 for 130 Ah. I'm looking at one right now that's 239 Ah at Lowes for $144. It's $300 for the upgrade but the golf cart batteries should last a while.

Tom

 

[Murff]

If you are near a battery distributor, call them and ask if they have any "blems" (batteries with blemishes). These are missing labels, mis-labeled or may have a crease in the case. Usually are 30 to 50% off of the price of perfect batteries and still have the same warranty.

If your current 12 volt battery has a few "miles" on it and you buy a new "like" battery, the batteries will discharge at different rates and will not work well together. Always best to replace two at the same time.

Murff

 

[videoarizona]

@videoarizona I cannot read the Ah rating on the pictures.

210amp hrs @20 amp/hr rate
\
https://www.costco.com/Interstate-6-Volt-Golf-Cart-Battery.product.100476406.html

 

[Subaru297]

I have never heard of a 130Ah 6 volt battery. It probably exists but the common 6v battery used in RV's is 205 to 230AH depending on the brand you go with. If you are planning on boondocking with solar I would highly recommend going with two 6v GC2 type batteries.

And don't buy them at your dealership! You will overpay.

 

[Screwby]

Hi all,

I want to add a second battery. The current one is a 12 V 60 Ah, so I wanted to add another one of same type, in parallel, which would bring it to 12 V 120 Ah. The dealership told me to use instead 2 batteries of 6 V, in series. Those batteries are 130 Ah.

I am wondering why? What is the benefit? If I go with their solution, I will have to buy 2 new batteries, instead of 1. And those batteries cost over 200 $ each. And at the end, the same power output.

Anyone knowledgeable about this?

You can get 6v batteries with 200 amp hours for around $100 all day long. So for $200ish you’ll have more amp hours with batteries that have thicker lead plates inside so they will last longer. Mine are Duracell brand that I bought from a local battery retailer.
Whoever is charging you $200 for a 6v battery that small is crazy

 

[Camper_bob]

I agree that around $100 for a 6V GC2 battery is about right. My local Sam's Club has them in stock all day long (Duracell) for $89.99 (plus core on each if you're not giving them a battery).

I can't remember what the AH rating on those is, but I'm sure it's north of 200.

I'm thinking of putting a pair in my MH, but DW needs to clear the $$ for the project since I'll have to make a few mods for them to fit.