Confused on batteries

[GENEDANIELS]

We havwe a 1997 national 36 ft tropi-cal. When purchased it had 6 volt chassis batteries. Two of them. They have gone bad. Is it possible to replace them with two 12 volt batteries in in series.

[MrWzrd]

Originally Posted by GENEDANIELS

We havwe a 1997 national 36 ft tropi-cal. When purchased it had 6 volt chassis batteries. Two of them. They have gone bad. Is it possible to replace them with two 12 volt batteries in in series.

no and yes.

The two 6 volt batteries where probably wired in series (plus to minus, chassis is connected to unused plus and unused minus) to give 12 volts.

If you do that with two 12 volt batteries you will get 24 volts. This would be bad for all those 12 volt devices in the RV. (remember that electrical things run on smoke and if you let the smoke out, they stop running)



If you decide to replace the two 6 with two 12 volts, the 12 volt batteries must be wired in parallel. (plus to plus, minus to minus, chassis is connected to either plus and either minus)

[Dixierail]

Remember that 6v batteries generally will have a deeper capacity in pairs than a single 12v. If you do alot of boondocking or use those coach batteries a bunch, you probably want to stay with the 4 - 6v setup. Check youtube for some great explanations and comparisons of both systems.

[twinboat]

If you replacing the chassis ( starter ) batteries, you would be better off using 12 volt batteries.

Most 6 volt batteries are deep cycle and for house loads. Use a portion of there power for a long time.

12 volt batteries that start engines will have a CCA rating ( Cold Cranking Amps ). They are for a big surge of power needed to start an engine. It depends on your engine size as to how much CCA you need. Most gas engines will get by with 750 or so. Diesel engines need 1000 or more CCA to get going.

The 2, 6 volt batteries were probably thrown in by a previous owner just to get it sold.

If you feel the need to use 6 volt batteries for starting your engine, there are some available. Check with Tractor Supply for 6 volt starting batteries.

[chboone]

My 99 Dolphin has one 12 V chassis battery. It originally had two 6 V house batteries. All three were under the entry step.
BTW, I now six 6 V house batteries.

[wa8yxm]

First all batteries in RV's are 12 volt. So you would never put 12 volt batteries in SERIES

Two Six volt in series makes one 12 volt battery

Usually the chassis battery is a single 12 volt not two sixes in series.

HOUSE however often use two six volt in series. Reasons.

For starting the engine you need LOTS OF AMPS for a very short time.. So often you have a fairly small. say 75 Amp hour (C/20 rate) STARTING battery but it can deliver 100,200, even 300 amps for a brief burst to fire up that big honking engine.

But for the house you need like 20 amps for many hours. So they use a true DEEP CYCLE battery like th GC-2 Six volt which they use in pairsm in series This pair of batteries holds about 220 amp hours (Way way more power) and since it is a DEEP CYCLE you can run it down to half full before serious aging happens. A Starting battery at 50% may well not recover band need replacejent but for DEEP CYCLE this is the design point

You would never put 12 volt batteries in series as that would give you 24 volts. You put 'em in parallel

Finding 12 volt DEEP CYCLE is possible, but not easy (Usually special order) and EXPENSIVE Most 12 volt's used in RV's are either full Starting (Chassis) or MARINE/deep cycle which is still a Starting battery..

I would recommend you stick with a pair of Six Volt in series for house batteries.

IF they put those in for chassis. You can go to 12 volt in parallel there (IF you need that many Cranking amps) but .

Well I have an 8.1 L Chevy Vortec, one of the biggest gas engines made (Along with the ford V-10) NOTE thre are bigger, but they are rare.

It uses a 73 Amp Hour startring battery.. Same as my little 4 cylinder car .

[MSHappyCampers]

Hi ! Welcome to IRV2! We're sure glad you joined the gang!

I can't add to what others have said.

Good luck, happy trails, and God bless!

[RBC2017]

My coach originally came with two unbranded 12-v house battery’s. I only have space for two battery’s, and wanted to obtain maximum amp hours. After researching 6-v and 12-v battery’s and there respective amp hours I installed two new Interstate GC 12-HCL-UTL 12V battery’s with 150 Amp hours @ 20 hr rate each. Giving me 300 AH@ 20 hr total. Cost of battery’s was under $200.00 each. I don’t believe I could get that 300 Amp hours at 20 hr rate out of two 6-v battery’s that take up the same space. Just passing this info on for others that have limited space and want max amp hours.

[Smitty77]

Originally Posted by RBC2017

My coach originally came with two unbranded 12-v house battery’s. I only have space for two battery’s, and wanted to obtain maximum amp hours. After researching 6-v and 12-v battery’s and there respective amp hours I installed two new Interstate GC 12-HCL-UTL 12V battery’s with 150 Amp hours @ 20 hr rate each. Giving me 300 AH@ 20 hr total. Cost of battery’s was under $200.00 each. I don’t believe I could get that 300 Amp hours at 20 hr rate out of two 6-v battery’s that take up the same space. Just passing this info on for others that have limited space and want max amp hours.

This is an example where the desire for higher total AH battery bank with the same number of batteries, is rewarded by using the 12V vs 6V. Yep, as mentioned, you really need search hard for them, and make sure they're true deep cycle. And yes, you pay more for this set up then say X's 4 GC2 6V's.

Another popular 12V deep cycle, besides the Interstate above, is the Trojan T-1275.

It all comes down to space, vs price, vs what is important to the RV owner!

Best to all,
Smitty

[jeepfamRV]

Just looking for some opinions. Getting ready to dump my junk 24dcm napa batteries

Lets say I am choosing between going with 2 of the GC 12-HCL-UTL 12V or 4 of the GC2 6V's.

The total cost of the batteries is roughly the same so thats not a factor. And I have plenty of room for either, so that isnt a factor. The only factor would be the initial install. The 12v would drop right in but the 6V's would take me a Saturday afternoon to rerun some wires and move the chasis battery. Either of which is not a big deal to me. I am a moderate electric user meaning a few lights, run the water for showers, and furnace at night.

Which would you choose? Why?

It seems to me that the 4 6v's would give me longer amp hrs but is it worth the trouble of moving things once for the long term gain or is the long term difference not that much.

2nd question. Would adding solar down the road change what you would choose?