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Where Is The Best Location To Put 3 To 4 House Batteries In The Brand New Interior Of An 18' Sunrader?


Stevo

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Where is the best location to put 3 to 4 house batteries (possibly sealed 12 volt Group 29's) if you were starting new with the gutted interior of a 1982 18' Toyota Sunrader? Forget the area behind the drivers seat because thats where I built the new bathroom. I can put one battery under the hood but what about the other 2 to 3 batteries? I'm thinking weight distribution here...if it matters.

Thanks
P.S. I just asked this same question at the Toyota motorhome Yahoo group too.
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Estimate what you are doing with the center of gravity of the vehicle.

Above the rear axle or slightly forward will give you better handling.

A large weight aft of the rear axle, the camper feels like it does not want to come out of a turn.

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Thanks. Thats what I thought but someone on another thread on this forum about axles said to NOT put weight over the rear axle and no one challenged him on it. I read his post in the email notification I got but didn't have time then to respond so let it go. Do you know if its a problem with wiring to put one house battery under the hood (because there is a bracket already there for it) but have the other two to three batteries in the back somewhere?

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I'm with Derek on this one. As far forward of the rear axle as your cabin design allows and think about side to side balance too.

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And what do you think about putting one of the house batteries in the extra bracket under the hood and the other two to three in the back? Does separating one battery from the others create problems when it comes to wiring them?

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I would keep them close together and near the power center. The guys here have gone over current loss with longer wiring many times. I don't think the weight over the rear in a gutted shorty Sunrader is an issue at all. Lots of the 21ft Sunraders have the bathroom with holding tanks, plus the coach battery back there and they are way farther behind the rear axle. You need a vented space. Do you still have a storage compartment on the rear drivers side. Mine has a generator in there so it's already vented. You could easily cut some louver type vents in the existing door. That's where I would put them. My generator has died and I may just add a couple there anyway

Linda S

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Yes and he said it was STRIPPED. I didn't say where to put the batteries, but to put them as far forward as he COULD within the limits of his redesign. AND don't forget the vertical

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And you know that the thicker wire compensated okay for the longer length to the engine compartment? Its difficult to tell by the photos but how many batteries do you have in the back? Do you still have one in the engine compartment too?

I relocated my batteries to a rear storage compartment and added a vent to the door. I also upgraded my wiring to 4awg to account for the added wire length. I am super happy with the results.

It was/is stripped but the bathroom behind the drivers seat is rebuilt so no batteries can go in there and directly across will be a 36" tall cabinet with counter for the sink and stove. The closest forward I can put them is one in the engine compartment and the other two to three either over the rear wheels on top of the wheel wells or just behind the wheel wells. And by vertical you mean to have one battery above the other?

Yes and he said it was STRIPPED. I didn't say where to put the batteries, but to put them as far forward as he COULD within the limits of his redesign. AND don't forget the vertical

Yes that is correct.

Yes but read what he wrote.....he has an 18' Sunrader. On the driver side the bathroom is in front of the rear axle. On the passenger side the entry door is right in front of the rear axle.

Can you explain exactly how he would physically be able to put the weight in front of the rear axle and distribute it side to side when there is zero room for that scheme? Once again we see theory in a head-on collision with reality.

Please people think about what the person is asking/saying before we hop on down the bunny trail....

You might be right about putting them together and the distance but I hope you are wrong. :-) I might use sealed batteries so no vent required. If I go with vented then I'll build a sealed compartment with a small vent to the outside. The vented compartment and all other compartments are long gone.

I would keep them close together and near the power center. The guys here have gone over current loss with longer wiring many times. I don't think the weight over the rear in a gutted shorty Sunrader is an issue at all. Lots of the 21ft Sunraders have the bathroom with holding tanks, plus the coach battery back there and they are way farther behind the rear axle. You need a vented space. Do you still have a storage compartment on the rear drivers side. Mine has a generator in there so it's already vented. You could easily cut some louver type vents in the existing door. That's where I would put them. My generator has died and I may just add a couple there anyway
Linda S

Not possible in my rig and pretty sure thats not possible in factory interior cuz of all the junk inside unless they built a battery compartment forward. I'd like to build a rack under the chassis which is what they did with the Yota 4x4 at www.VanSpecialties.com. They are just aft of the rear axle though but nice to have them totally out of the interior and the weight down low.

If I was looking to add batteries, my first choice of location would be in front of the rear axle, not over or behind the rear axle. There's already more than enough weight (~2/3 of total!) on the rear axle.

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I have two six volt batteries that give me 225 amp hours for the coach and one regular 12 volt under the hood for the truck. I used high quality 4awg in place of the stock 10awg, this more than compensated for the extra wire length. I also upgraded my ground to 0awg and used high quality connections on the wire. My volt meter showed no addition voltage loss due to the relocation.

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Thats good to know and thanks. I was thinking of getting Trojan T105's which apparently give 225 amp hours each, if I read that correctly, or maybe they meant it was 225 amp hours with two of them?? I guess with six volt you always have to pair them up, right? No odd quantities like three six volt batteries or five? What kind of six volt batteries do you have?

I have two six volt batteries that give me 225 amp hours for the coach and one regular 12 volt under the hood for the truck. I used high quality 4awg in place of the stock 10awg, this more than compensated for the extra wire length. I also upgraded my ground to 0awg and used high quality connections on the wire. My volt meter showed no addition voltage loss due to the relocation.

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I bought the Costco ones, much cheaper than others and still great quality. With 6 volt batteries you do not combine the amp hours like 12 volt batteries. Each six volt gives you 225 amp hours which you have to pair up to make 12 volts but the amp hours stay at 225 not 450.

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too bad you don't combine the amp hours with 6 volt batteries! Costco online doesn't show any 6 or 12 volt batteries on their site and I don't have a Costco card now, but I can get access to one. Do you remember what brand, size, and how many amp hours your 6 volt Costco batteries are?

I bought the Costco ones, much cheaper than others and still great quality. With 6 volt batteries you do not combine the amp hours like 12 volt batteries. Each six volt gives you 225 amp hours which you have to pair up to make 12 volts but the amp hours stay at 225 not 450.

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Real quick and dirty battery math.

6v batteries hook in series (+ to-), voltage adds, 12, 18, 24 volts etc. Amp hours remains the same. Batteries should be same AH.

12v batteries hook in parallel (+ to +), voltage stays the same, AH increases x the number of batteries.

So for a 12v system you need 2 6v batteries. With 4 6v batteries you make 2sets of series and then parallel those 2 sets, for example with four 6v T105 you would have a 12v 450 ah battery bank.

See clear as mud.:-)

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Yes that is clear. thanks.

Hmmm, just doing the math here...

Three 12 volt AGM batteries weighing 105 pounds each = 420 pounds. 170 amp hours X 3 = 680 amp hours. Cost for four is: $540.

Four Trojan T105's weight 62 pounds each = 248 pounds. 225 amp hours X 4 = 450 amp hours. Cost for four is: $560.

So for $20 less I'd get 230 more amp hours with the three 12 volt batteries but at 420 pounds they'd weigh 172 pounds more. Aaargh!

What would you guys do? And what about the weight of these batteries with a lil 22R pulling a frikkin house?

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Basic question.... What do you need so much freakin power for???

There people who removed the stove because it weighed to much at 10lbs, and your asking about 400lbs

You are aware that a 1000watt Honda generator weighs about 40 lbs?

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Here is my UPDATED energy usage to reflect the same in Post #28

- 12 Volt Fridge/Freezer: 24 watts = 2 amps x 24 hours per day = 48 amp hours. www.TruckFridge.com says "average consumption" for this model is 24 watts an hour. If I buy this fridge, I'll add an extra 2" of insulation to the top, back, sides, and bottom (excluding around the compressor) to reduce its energy consumption. I'll be traveling alone and opening the fridge only a few times per day and not one to leave the door open any longer than necessary. Lastly, and I'll have this figured out very soon, I might build my own super insulated chest fridge box which could cut the fridges energy consumption in half with one of those easy to install "plug and play" refrigerator/freezer kits that require no soldering. Cruisers and stink pot owners use these kits all the time.
- iPad Charger: 8 watts = .67 amps x 2.5 hours per day = 1.7 amp hours
- iPod Charger: 2 watts = .17 amps x 2 hours per day = .34 amp hours
- Apple Airport Time Capsule: 14 watts = 1.17 amps x 1 to 4 hours per day = 1.17 amp hours to 4.7 amp hours
- MacBook Pro 17: 51 watts = 4.25 amps x 1 to 8 hours per day = 4.25 amp hours to 34 amps
- Waring 12 volt Blender: 200 watts = 16.7 amps x 1 minute per day (.02 hours) = .334 amp hours
- Electric Razor Charger: 8 watts = .67 amps x 8 hours = 5.36 amp hours (only twice a month)
- Android Phone Charger: 2 watts = 1.7 amps x 2 hours = 3.4 amp hours
- Fantastic Vent Fan: 3 watts = .25 amps x 1 to 14 hours per day = .25 amp hours to 3.5 amp hours
- AA & AAA Battery Charger (for LED lights): 1 watt = .083 amps x 8 hours = .7 amp hours
- *Juicer (AC 110 volt): 150 watts = 12.5 amps x 10 minutes per day (.2 hours) = 2.5 amp hours
- *External Monitor(AC 110 volt): 40 watts = 3.33 amps x 1 to 8 hours per day = 3.33 amp hours to 27 amp hours
- *Inverter: I don't know how many watts/amps but only need this for the AC juicer and AC external monitor - IF I don't replace my current 24" AC 110 volt monitor with a smaller DC 12 volt monitor.

Minimum amp hours per day: 16 amp hours + 48 amp hours (12 volt TruckFridge) = 64 amp hours per day.

Maximum amp hours per day: 84 amp hours + 60 amp hours (12 volt TruckFridge) = 144 amp hours per day.

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Thats a good deal!

For some reason Costco does not have their Golf Cart Batteries online, they are Costco branded with 225 AH. I think I got mine for $80.00 each, so $160.00 for 225AH is hard to beat. Best bang for your buck.

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I thinks we have a math problem, watts and amps is different critters.

Volts x amps=watts. So using your fan as an example 48 watts is the max power consumption. That translates into about 3.5 amps. You take 3.5 x the numbers of hours it is going to be actually running. Say 10 hours a day. That comes to about 35 amp hours (AH) per day.

At low speed it is using about .3 amps, so for the same 10 hours it would use about 3 AH per day.

That is the number, AH per day, you need to use to figure out the size your battery bank needs to be.

So ONE of your 12v 170AH batteries would safely run the fan on low speed for 10 hr per day for 28 days.

More fun battery stuff, for max battery lifespan do not discharge it much below 50%

Thus 170 x 50% = 85 AH ÷3= 28 days

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And specifically what is the "math problem" you're speaking of? Is there something wrong with my list? Thanks.

I thinks we have a math problem, watts and amps is different critters.
Volts x amps=watts. So using your fan as an example 48 watts is the max power consumption. That translates into about 3.5 amps. You take 3.5 x the numbers of hours it is going to be actually running. Say 10 hours a day. That comes to about 35 amp hours (AH) per day.
At low speed it is using about .3 amps, so for the same 10 hours it would use about 3 AH per day.
That is the number, AH per day, you need to use to figure out the size your battery bank needs to be.
So ONE of your 12v 170AH batteries would safely run the fan on low speed for 10 hr per day for 28 days.
More fun battery stuff, for max battery lifespan do not discharge it much below 50%
Thus 170 x 50% = 85 AH ÷3= 28 days

A mini motorhome would be too small to grow pot in! I'd buy a big giant cheapo Class A off of Craigslist like the one they used in Breaking Bad. I haven't smoked pot in 14 years and if I started now I'd NEVER finish rebuilding this Sunrader! =;^P

This conversation reminds me of another member who was trying to charge a big bank of batteries up with solar so he could run a large quantity of LEDs for a mobile pot farm.

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Your list is fine, but you talking watts with your list and trying to size a battery bank in AH. What your missing is time. Right now your talking apples and oranges. Watts is a power right now measurement. AH is power supplied over a specific period of TIME

Using the formula I gave you, you can rearrange it, to convert watts into amps. Then you multiply by time to get AH, then your talking apples and apples.

Then add up each items AH to see how many AH you will need to operate your RV for one day. Then multiply that by the number of days you want to operate WITHOUT RECHARGING.

Think of a load as something draining a battery (-), if you can charge your battery (+) with a generator, solar panel, drive your RV or what ever, you will be putting AH back in the battery. The larger the charger the smaller the battery can be. If your roof is big enough you can have enough solar power to power things forever with a small battery bank.

The basic battery rating means that a 170 AH battery will provide 1 amp of power for 170 hours

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Yup, I am what you'd call severely electrically challenged! I refigured everything and converted watts to amps with this online calculator. Can you tell me if this is correct when you get a chance please?

- 12 Volt Fridge/Freezer: 24 watts = 2 amps x 24 hours per day = 48 amp hours. www.TruckFridge.com says "average consumption" for this model is 24 watts an hour. If I buy this fridge, I'll add an extra 2" of insulation to the top, back, sides, and bottom (excluding around the compressor) to reduce its energy consumption. I'll be traveling alone and opening the fridge only a few times per day and not one to leave the door open any longer than necessary. Lastly, and I'll have this figured out very soon, I might build my own super insulated chest fridge box which could cut the fridges energy consumption in half with one of those easy to install "plug and play" refrigerator/freezer kits that require no soldering. Cruisers and stink pot owners use these kits all the time.
- iPad Charger: 8 watts = .67 amps x 2.5 hours per day = 1.7 amp hours
- iPod Charger: 2 watts = .17 amps x 2 hours per day = .34 amp hours
- Apple Airport Time Capsule: 14 watts = 1.17 amps x 1 to 4 hours per day = 1.17 amp hours to 4.7 amp hours
- MacBook Pro 17: 51 watts = 4.25 amps x 1 to 8 hours per day = 4.25 amp hours to 34 amps
- Waring 12 volt Blender: 200 watts = 16.7 amps x 1 minute per day (.02 hours) = .334 amp hours
- Electric Razor Charger: 8 watts = .67 amps x 8 hours = 5.36 amp hours (only twice a month)
- Android Phone Charger: 2 watts = 1.7 amps x 2 hours = 3.4 amp hours
- Fantastic Vent Fan: 3 watts = .25 amps x 1 to 14 hours per day = .25 amp hours to 3.5 amp hours
- AA & AAA Battery Charger (for LED lights): 1 watt = .083 amps x 8 hours = .7 amp hours
- *Juicer (AC 110 volt): 150 watts = 12.5 amps x 10 minutes per day (.2 hours) = 2.5 amp hours
- *External Monitor(AC 110 volt): 40 watts = 3.33 amps x 1 to 8 hours per day = 3.33 amp hours to 27 amp hours
- *Inverter: I don't know how many watts/amps but only need this for the AC juicer and AC external monitor - IF I don't replace my current 24" AC 110 volt monitor with a smaller DC 12 volt monitor.

Minimum amp hours per day: 16 amp hours + 48 amp hours (12 volt TruckFridge) = 64 amp hours per day.

Maximum amp hours per day: 84 amp hours + 60 amp hours (12 volt TruckFridge) = 144 amp hours per day.

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Much better, apples and apples. Now all you need to do is figure how many days do you want to run with out recharging AND how you plan to recharge.

Paper napkin math shows that 200 w of solar will produce between 40AH and 80AH a day depending on how much day light you get.

A Honda 1000w generator will give you close to your 144 AH max with a 2hr run time each day.

A last comment..... DUDE you do realize that your CAMPING. Electric razor, A juicer and a blender???? 2 computers and a storage device????

Like really.... :glare:

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Hah hah, camping is sleeping under the stars or in a little tent man! This little Sunrader is going to be my home for an indefinite period of time as I travel through the US, Mexico, Central America and South America so I need to take stuff like a razor, computer (just one computer for work so I can pay for my travels), and a blender and maybe an external monitor and maybe a juicer. The juicer is still up in the air because of the space it would take and because I'm not sure yet how the availability of fresh greens to juice will be down south. The Apple Airport Time Capsule is a 2 to 3 TB hard drive with its own built in WiFi network that I'll load with movies so I can watch em on my iPad without internet. Cool eh?

Thanks for explaining the math in your post #26 cuz it helped a lot. :-) Next I'll figure out how many days battery storage I want and then on and upward for the solar panels and controller.

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Sure you can run an A/C off a battery bank with a big inverter. The proposed battery bank here, 400lbs, $550, would power a 9K BTU AC for about 2 hr.

It would take a 200w solar setup about 3 days to recharge it for the next 2hr of run time. A generator would recharge the batteries in couple of hours, but if you have a generator why run the AC of batteries?

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I might install AC in the front cab but I won't have AC in the back.

I think I might be using Crown golf cart batteries and 4 of them will weigh about 250 pounds. Still high but a lot lower than 400 pounds but my interior should end up being substantially lighter than the stock Sunrader interior because all that factory BS has been yanked out and I'm making my cabinets out of 1/4" plywood that is glassed in specific areas with epoxy for strength.

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I'm not sure of the clearences involved, but could you build pockets in the floor and put the long axis of the batteries parellel with the drive shaft and not drag the batteries???

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I was looking underneath the Sunrader today and it seems the best places to put the batteries below the floor is either between the differential and spare tire in the center, or forward of the differential on the drivers side next to the drive shaft with the batteries oriented parallel like you suggested. That could require a heat shield between the batteries and the muffler though. Now that I think about it, it might not work to put them forward of the axle because I think the bathroom is in the way. I'll look again tomorrow.

I haven't looked at the numbers yet but two ways that should reduce my energy usage substantially would be to replace my current LCD display MacBook Pro 17 for an MBP with an LED display and the same goes for the external monitor. As spoiled as I am for using an external monitor the last 5 years, it might not happen cuz I don't know where the heck I'd put it.

What do you mean "not drag the batteries?" You mean if a branch or something got caught under there and dragged them out of the rack? I was thinking that whatever rack I build for the batteries should have a "V" shaped steel front to deflect junk to the sides so the rack won't get damaged and I end up dropping batteries along the way. Aaargh!

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Are you familiar with the concept of being High Centered? It when you drive over a big bump an your front goes over fine but the bump hits the frame and lifts some off wheels off the ground.

So a skid plate would be a good idea. Be sure to keep the bottom of the batteries above the bottom of the frame.

If you just can't fit the batteries in front of the rear axle, then behind the axle will have to do and as close the axle as possible.

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Well I am saying this again. His shorty Sunrader is stripped. Stock on my same model Sunrader there is a 30lb propane tank, 60 lbs when full, a 150 lbs of generator, a 12 gallon grey tank, a 20 gallon fresh water tank,a dinette, a spare tire, a furnace and a fridge all behind the rear axle. When I'm camping add to that 100lbs of inflatable boat and motor on a hitch carrier. I have never had any problems with the weight. I really don't think a few batteries are going to be a problem.

Linda S

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