Where to install an extra Battery?

I understand adding batteries, but don't overlook changes to reduce your power usage and existing battery. If you haven't made the switch to led, do it! It makes a major difference. The other big change we made is adding reflectix to compartments and cutting it to go in windows at night. It's made the furnace run much less. Finally, you might not be able to put two batteries in the compartment but make sure you have the battery with the most amp hours since all batteries of the same group are not equal. Measure the compartment to make sure you have the largest most powerful battery possible.

Blanco1,

Refer to your original thread topic question.

Please go measure one adequate 6 volt battery for size and check it's weight. Then double it as you will always need 2. Where will you put 2 of them and at 65 years plus in age, who or how will you lift them or move them around or replace one as it always takes 2 of them to produce 12 volts. Remember that if one 6 volt battery fails, you have NO usable battery current at all for your 12 volt system. Finding a matching 6 volt battery to your remaining 6 volt battery is usually very hard to find in most areas. Therefore, you will likely need to replace both 6 volt batteries with ones that will physically fit or just replace with one or two 12 volt batteries as they are about everywhere. Cost is a factor also.

Having a 12 volt battery/batteries it's not only easy to find but with two of them and should one go bad etc, you still have usable 12 volt battery power. Just not as many amp hours available but can go right on with your camping by simply un hooking the bad one.

We had two 6 volts in one of our motorhomes, virtually no difference in usable charge life from always having 12 volt batteries as amp hours are simply amp hours, period, and we learned this one battery failure lesson the hard way! Like the saying, once you'd burned your fingers you should know better than to put them on a hot things again!

Only 12 volt batteries were or will be used ever since in our RV's and boats and of course, all our vehicle also! Yet some RV'ers still like 6 volt batteries in series for 12 volts. Larger motorhomes and some 5th wheel have more room to use multiple larger 6 volt or 12 volt batteries but TC's and the average TT's usually do not. Why make matters more difficult by throwing a "red herring" into the mix of what's really simplicity?

Food for thought. It's your own decision to make.

joe123 wrote:
I installed two 6 volt batteries in the box beside the camper in their own battery box the ran new wiring into the camper battery compartment which had one twelve volt 100 amp hour battery this gave me 300 amp hours of reserve power another advantage is that its clean up out of the dirt and dust, also you should install a battery watering system make it easier to keep the water level in the bank up.

I have heard going with 2 6volts vs a single 12 volt is a better way to go?

I hear what you are saying and agree exceot it would take a sizable solar unit on your hood to keep 2 large capacity batteries at full charge for your Dmax engine. Remember that I also have a Dmax too and they take a lot of amps to turn them over for starting due to the very high compression in a diesel engine.

Just wondering why can you only charge one battery at a time? Hook 2 or more batteries together with standard battery cables "positive to positive" and "negative to negative" and then hook your charger clamp positive (red) to the positive post on one battery and the negative charging clamp to the other battery's negative post and it charges both batteries at the same time. This is hooking/coupling the batteries in "parallel" and the voltage remains at 12V DC while the amp hours (capacity) multiplies and that's what you want.

DO NOT hook the batteries in series (positive to negative on the next battery etc as the voltage multiplies (12v becomes 24V for 2 batteries and 36V for 3 batteries hooked together in "series" and burns the 12V items out. Also it's fruitless as the amp hours remain the same as if it was just the one battery.

I have coupled up to 7 batteries together in parallel for over 30 years now and it's yet to not re-charge all of the batteries fully as long as the batteries are of the same group size, close in amp hour rating, and in good condition. I have a 50 amp plug into 110 AC charger I use or use or the dual alternators in my Dmax engined truck when driving to re-charge them. Consistantly get 6-7 years of use out of my group 31 batteries (225 minute draw amp capacity at 23 amp draw for each battery in the cabled together battery pack) before replacing and they still hold a good charge.

Not about to wait until one battery dies or shorts out as it's murphy's law that it will happen when not near a plsce to replace it or at what cost? This happening also usually ruins the other batteries in it the group and that makes it VERY expensive! The total amp hour draw ability is not what you go by as you should only draw them down to 50% charge (capacity) before re-charging. If you draw down until depleted, your battery useful life will be drastically shortened by more than 1/2. A very expensive lesson learned!

Don't knock being an over 65 female because my wife is nearing 74 and still learns a lot additional every day. She wants to know so she can make good decisions if something should happen to me as I'm almost 3 months older than her yet! It makes me so proud of her as always in our 54 years of being so happily married. 2 old farts in the same pea pod!

We do Park in shade as much as possible unless it's cold weather, then the more sun the better. We don't camp much in Oklahoma but it does get hot in other places too. With or dogs along shade is important so solar really isn't on the radar. The idea for extra battery capacity for us is more of an emergency thing. If there were an issue with the truck batteries it takes two to start the diesel and only one can be charged on generator at a time. If the generator runs out of gas then there's no battery charging. Chicken or the egg thing I guess. Our Duramax was built in September of 03 and sold as an 04 model to us in December that year. Don't know if that addresses the spare wire issue. The label on the wiring harness stated the extra wire not needed for any other light functions hooking up to the camper, everything else on camper works as it should, was an ACCESSORY wire. In my book it states that wire should be for major add-ons like PTO or snow plow, but nothing mentioned battery charging. It also said, like someone else mentioned, NOT to install the relay fuse unless it was wired to something active. Obviously I'm no expert and being left handed, dyslexic, female and over 65 doesn't help one bit. As everything stands so far there hasn't really been any need, but it only takes one time. Maybe just get a solar battery charger to put on the hood poking out into the sun to keep truck batteries charged and call it good?

trailgranny50,

If your extra wire in your truck's wire harness is kind of aa light blue, it's likely for backup lights. Very easy to check out to be sure by connecting a ground with to a bare metal spot on the truck or to the negative terminal on the battery with the other end going to the outside metal on the bulb. Then touching or connecting a wire from the extra harness wire to the center bottom of an 1141 or 1156 12V light bulb and usually with the engine running and foot on the brake, put the transmission in reverse to see if the bulb lights up. I use alligator clips as they leavr your hands free. Can use a volt meter to check also if you have one.

On some models the light blue wire was for the center rear upper brake light and I can't remember exactly which models it was or which years. Yes, some models the wire was for accessory positive current which was usually controlled by the ignition switch so it was live only when the key was in and turned to on to prevent a dead battery scenario. The changes were mostly in the 2003 and 2004 years.



Just speculating on what financial outlay you will accept to help your situation. Only you can determine if you want or need additional battery reserve availability vs costs. Just be sure the RV and added battery/batteries disconnect fram the truck batteries when the ignition is off. All the isolator really is is a solenoid type switch whether it be mechanical or electronic. With only one RV battery, you must be careful as to amp draw. If I understand you, your generator is a stand alone not built in which means it's likely a pull cord starting and not requiring battery amps to start it.

If your generator is 1000 watts or more, you could use perhaps a 40 amp stand alone plug in battery charger instead of running the big diesel engine at idle (700 rpms or less) which with one alternator will not spin it fast enough usually to put out 40 amps to recharge the battery very fast. Much depends on how loud your generator is as the cheapies are usually much louder than your truck's idling diesel engine. We all think different and what works for me may not be what you want or is best for you.

Adequate solar power system is not cheap to purchase and then you need to park in full sun on your roof to get the best charging watts. By the same token, after paying for an adequate solar syatem, the sun's energy is free but comes with a trade off of a hot RV being out in the sun and Oklahoma is very hot in the summer so that's something to consider, not only what a solar system costs. Just bet you always like to camp in the shade in the south in summer!

My added extra battery reserve system was cheap to build and only needs to be made once. It goes from truck to truck very quickly when buying a new truck etc. Why Not? I use existing holes to mount things on so no or hardly any new holes are added or all new holes are in hard to see areas. Doesn't de-value the vehicle.

So glad the battery thing came up on the forum at this time. Get a cup of coffee and a cozy seat as this question is going to take a while, or just skip it! We've been using our TC without any onboard battery since we bought it last year. We have a 2004 Chevy Duramax 3500 long bed DRW. It was built to haul a camper from the factory with extra suspension and had the wiring harness taped to the frame. We'd never undone it since the truck was a work truck all the years since we bought it in 03. When we did the labeling was still intact so the function for each wire was easy to be determined. The camper actually had its paperwork as well after 24 years and included a wiring diagram which matched the plug and wiring hasn't been altered from the factory. Made the hook up easy. While doing this there was an extra unused wire from the truck that was labled as "accessory" within the harness. Would this be the battery charge line? Everything in the camper matched up with the truck and worked fine so we simply taped it over and then taped it in with the other wires. Evidently this camper was not designed for a house battery as there is no compartment per se but afloor door on the driver side in front would give access for one there. The converter in it is 45amp, old but functioning fine, has 12v and 110 circuits. It was pre-wired for roof AC at the center vent, which we added, and it works fine. There are two 110 outlets at the front of the camper one a above the sink and another on the other, passenger side, above the dinette area. These 2 are, apparently, wired on one circuit and to the AC as well within the walls somewhere, no way to seperate them as I'd like. Right now the camper runs off the truck batteries for everything 12v, 110 only available by unplugging the truck and plugging into the generator or shore power with the land line. Keeping truck batteries up requires starting and running the truck every couple days for 30 min or so or simply by driving from place to place each day if we don't have shore power or choose to fire up the generator. The fridge is on propane unless we are plugged in to a 110 source and all lights have been switched to LEDs. We don't camp in the dead of winter so the heater doesn't cause a problem and we run a small ceramic heater again when on 110. My question is should we proceed to add a battery or two, and all the other extras to charge and use, isolate specially or just unplug as we do when on shore power, etc.? Is there any real need for more stuff? We get off the grid some but not lots, have the generator for TV, microwave and fridge if on electric, DH coffee water. The water heater is manual gas only, no auto start, just the Bic lighter initially. I've done a major rewiring on a Polaris Razr but I'm NOT touching hubby's truck wiring myself! So what would the concensus be? I hate to put the extra bucks into solar on such an old camper when the 12v issue hasn't been a biggy, yet. Just not keen on waking up to dead batteries one day on the truck. Had an issue with them going down over a period of time with everything off and camper totally disconnected, but fixed that I think, so I've gotten a bit parinoid. Any thoughts from more tech savvy folks before I do something unnecessary or really stupid?

Blanco1,

Just additional info.

If only adding one up to group 31 deep cycle or marine battery in size. #4 ga fine strand welder wire can be uses instead of #2 ga if the wire length is a max of 10 feet long.. Saves a little extra $$$. I always incase my high amp battery cables in the simple very incepensive split black plastic sheaths and run then plastic cable tied along side the truck frameso they done hang below the bottom of the truck where they can get scraped or damaged. I bring them up into the bed thru the drain hole at the front of the truck bed. That way no need for drilling new holes. Some truck bed drain holes may be so small in dia that they will need to be drilled larger. Make sure there's no burrs left to cut thru the wire insulation and short out the positive wire.

May be wise to use a plastic or rubber grommet in the hole thru the bed to insure no wire insulation wear as as there's very high amperage involved. My beds have sprayed in Rhino liner which stays pliable and acts as a grommet but LineX usually gets very hard and can cut thru. Choices, choices, choices!

I installed two 6 volt batteries in the box beside the camper in their own battery box the ran new wiring into the camper battery compartment which had one twelve volt 100 amp hour battery this gave me 300 amp hours of reserve power another advantage is that its clean up out of the dirt and dust, also you should install a battery watering system make it easier to keep the water level in the bank up.

Blanco1,

My 2 bed batteries stay with the truck no matter what RV unit is used or even none at all. This gives 2-7 added battery versatility for so many uses. I also have a short #14 gauge red wire with small alligator clips on each end made up that jumps the positive side of the solenoid which energizes the solenoid to connect the bed batteries to the truck engine batteries should I ever have dead truck batteries. Because of the #2 welder cable used providing the ability to carry so many amps, no HD jumper cables would be needed to start the diesel engine as the bed batteries will in spades and even provide all 12V DC needed to operate the truck normally for driving.

Again, totally self contained and with simple built in redundancy! The GM dual alternator option allows normal truck operation even if one alternator should fail for any reason. Simply carry an OEM serpentine belt under the seat for a one alternator OEM configuration. 5 minutes and you are good as new and on your way! Like a good boy scout, Be Prepared! Not fun being in nowhere with a vehicle that won't start or get you back to civilization! Food for thoughts!