house batteries

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b-love508

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Hello all, I am trying to add a new 2nd house battery to my rv and was wondering what gauge battery cable I should use? I have to run  about 5-10 feet of positive and negative cable to wire into existing system case I'm mounting second battery into a side capartment behind driver door. So I was wondering out of 6, 4, or 2 gauge wire is should use? Any help would be greatly appreciated!
 
Hard to know without some estimate of the amps that will flow between the batteries, but 2 gauge will handle over 120 amps across a total (round trip) distance of 12 ft. I'm guessing you aren't expecting to run a 3000 watt inverter with just two batteries, so 2 ga should be plenty.  So would 4 ga.
 
No I will only be running a 750 watt/1500 watt peak power inverter. The rest of the power coming from batteries are the led over head lights and water pump and fridge etc. I also have a set of solar panels on roof so the can "trickle" charge all day
 
The answer depends on the RV, so long as you are not running a big (1,000 or larger watt) inverter you should be good with standard Starter cable from your local auto parts store

IF you are running a big inverter.. Use the same size cable as the wire that connects to the inverter.  OR LARGER.
 
That inverter can pull 70 amps or so to produce 750 watts, but that current comes from two batteries combined. If they are 6v's in series, that could put 70+ amps on the connecting wire, but it sounds like they are 12v's in parallel so the load would typically be shared. The rest of the stuff is small or intermittent, so not of much consequence.
 
Try a welding shop for cable. They can make you up whatever length and gauge you need and crimp ring terminal ends on them. Plus welding cable is more flexible than starter cable.
 
X2 on the welding cable,, the very fine wire in the cable makes for more flex and better conductivity, its also more expensive but worth it.>>>Dan
 
I just bought 50feet of red and black 2 gauge welding /battery cable for 75$ off eBay so hopefully that will do it.. thank you all for feedback
 
Gary RV Roamer said:
That inverter can pull 70 amps or so to produce 750 watts, but that current comes from two batteries combined. If they are 6v's in series, that could put 70+ amps on the connecting wire, but it sounds like they are 12v's in parallel so the load would typically be shared. The rest of the stuff is small or intermittent, so not of much consequence.
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Gary is correct.. HOWEVER I think he overlooked something.

Batteries have assorted failure modes.. ONE mode is HIGH RESISTANCE, when this happens the battery is effectively NOT THERE.  Thus you assume when batteries are in parallel. EITHER of them may need to provide the maximum load.

So, you join them with a cable at least as large as the largest wire connected to them.. For a 70 amp load, Common Starter Cable (4ga) should do the job.
 
Assuming I didn't miss something along the way in reading the thread, did anyone determine if the OP is adding a brand new second battery to mate with an existing house battery? I don't see a mention of the age of the existing battery. Can cause problems if this configuration is fact. I don't recall reading any mention of type/age of RV.

Maybe more specifics are in order.
 
I'm getting rid of the old house battery and buying two new deep cycle batteries and putting right next to each other in a side capartment
 
Making progress.
Now, what type of camping do you want to be prepared for? Any boondocking? Got your heart set on 6v or 12v batteries? How much power usage are you expecting on a typical trip?

My point is that you may be at a point to build a battery supply that more compliments your style of camping. Specific power wants/needs are direct clues to what you should have to fill the bill. BEFORE you spend money on something that still doesn't work for you.

I'm not trying to nitpick. I am suggesting that you may be in a position to build a battery bank, with the correct wiring, that will fulfill your power needs on your future camping trips. It sounds like you're planning to buy 2 new batteries anyhow. I think you will be happier with the results.

My 2 cents. 
 
denmarc said:
Making progress.
Now, what type of camping do you want to be prepared for? Any boondocking? Got your heart set on 6v or 12v batteries? How much power usage are you expecting on a typical trip?

My point is that you may be at a point to build a battery supply that more compliments your style of camping. Specific power wants/needs are direct clues to what you should have to fill the bill. BEFORE you spend money on something that still doesn't work for you.

I'm not trying to nitpick. I am suggesting that you may be in a position to build a battery bank, with the correct wiring, that will fulfill your power needs on your future camping trips. It sounds like you're planning to buy 2 new batteries anyhow. I think you will be happier with the results.

My 2 cents.
Click to expand...



Well I bring this camper on the beach. So no power hook ups. So there for (like my father's camper) I'm going to have two 12v deep cycle batteries ran parallel  with two solar panels charging them. I'm running a 1500 peak watt inverter all the dome lights inside (which is switched out to led's) the fridge and TV when needed. 6 volt batteries are for one dam expensive and weigh a hell of a lot and not trying to go in and reinforce my side capartment to hold that much weight. For years my father has ran two 12v batteries and 3 solar panels on roof charging them and has had plenty of power. So like I said this goes on the beach and I am sometimes 2 days,  3days, sometimes 4 days on beach.
 
Don't get me wrong, I know what you're talking about now. I boondock 100%. Genny power available when needed. I use 2-12v 4-D's for a battery bank. Parked out in the woods. Solar not an option for me.

What saves my butt is a good 4-stage charger and LED light conversion in the TT. Still using an old 13"  AC/DC CRT TV for late nite viewing. Otherwise, power only fires up the stereo while we are outside around the campfire.

You are correct about the 6v Trojans. I wouldn't call the cost too expensive. Depends on application.  But they are the best bet for the money if you are in a situation to rely on them for power for a length of time. They are truly built for deep use and recharge.
However, if you are only talking about 2-3 days with a 12v bank complimented with solar, you will be just fine. In your case, keep a close eye on the new batteries. Keep them healthy and get all the life out of them you can.

 
I think there are some misconceptions here. First of all, 6v and 12v battery weight is essentially identical if they produce the same amp-hours of power. There is no getting around the physics of a lead-acid battery - it takes so much lead plate area to produce so many amps. 2 x 6v GC2 (golf cart) batteries in series will yield about 225-230 AH. Two 12v deep cycles that produce the same AH would be a pair of Group 27 size and both batteries will weigh in at about 61-62 lbs each.

Generally, 6V GC2 deep cycles are cheaper than similar quality 12v deep cycles, simply because the larger golf cart markets drives a higher volume of production and more competitive pricing.

If you are finding 12v batteries cheaper than 6v, then I think you are looking at the so called marine deep cycle, which is a hybrid of a car starting battery. Their useful life will be much less than half what a true deep cycle will provide. Perhaps as little as 1/4.
 
Gary RV Roamer said:
If you are finding 12v batteries cheaper than 6v, then I think you are looking at the so called marine deep cycle, which is a hybrid of a car starting battery.
Click to expand...

My thoughts also. But it sounds like the 2-12v set-up works for the OP. It also sounded as if the cost was a factor.
As far as weight per battery is concerned, all I can tell you is my 4-D's weigh a freaking ton! Glad I only move them twice a year!  :eek:
 
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