House Battery Upgrade - Where to put 'em??

[travelingbard]

Hi all! We're getting ready to upgrade our house battery setup (adding a nice pure sine inverter, etc).

We're in a 2003 Fleetwood Flair 33R. It has the stock pair of 6V batteries. They're doing fine for now, but getting a little old. Since we're about to add the inverter, it's a great time to go ahead and replace them, but we're wanting to REALLY beef up our boondocking power at the same time (TX and FL in the heat of Summer means AC at night!).

I'm still running the math to see how much juice we'll need, but running an AC unit, computers (desktops in some cases), and keeping up with our geeky TV shows will have a draw. May end up popping 6 6V batteries in to cover it.

That being said, the Flair's stock batteries are under the hood, so we'll definitely have to relocate. Any opinions on the best place to put the new bank? Storage compartments are reasonably roomy, so not sure we would "have" to use a sliding tray...

Thanks for any insight!
Chris

[bobthegod]

Well if you want to run AC all night and use as little power as possible. You got to go to you tube and check out a "Red Neck AC".
You may laugh and you may thing its stupid but those damn things work, and they work great!!! I sure you already have all the parts you'd need sitting at home. I made one and it'll run for hours at 32 degrees.

[tahiti16]

One that I didn't see asked yet is do you know your weights, front, rear and side to side? Batteries are heavy so make sure you know where you have capacity left for all the extra weight.

[JiminDenver]

It took me a year to figure out just which 5000 BTU window shaker used the least power. That's a Frigidaire energy start unit and it pulls amps in the mid 30's @ 12v/ 450w when the compressor is on and the pressure is up. I can run it off of 750w of solar but just don't have the kind of battery needed to run it at night.

[Chandalen]

I looked at Lowes yesterday. They have 3 portable AC's 8k, 10k, and 12k.
The 8k would be the best bet as it claims at worst it will need 12 amps.

Conservitive numbers...

1450 watts, 135 amps.

Still very hefty.

[pianotuna]

Hi,

Look at the hybrid models. Magnum and Victron are good names and there are some others as well.

I am able to run my air conditioner on the battery bank. I'd love to redo or add to my existing solar system.

If you are starting from scratch, consider a 24 volt battery bank.

travelingbard wrote:
Looking at the 3000 watt inverter models...

[pianotuna]

Hi Chris,

You will need to weld on a brace to use the storage compartments. They are not meant for the large weight of a multi battery bank.

travelingbard wrote:
Storage compartments are reasonably roomy, so not sure we would "have" to use a sliding tray...

[Chandalen]

Its not realistically feasible to run an AC off the batteries. You 'could' for a little bit... hour or two.. but the drain on the batteries is going to be amazing. Having Solar would help a little, but the batteries will need a REAL charge afterwards.

Now.. option B. A portable AC is more realistic, the kind that has an exhaust tube (like a dryer).

You are still going to use a lot of juice, but it may be closer to your goal than the RVs AC.

I actually made that pinterest AC thing out of a Home Depot bucket, a DC fan, and ice. It freggin works. The down side is the ICE. We have an ice maker, and last year we had 15a service so that could keep running as I couldnt run the AC.

[westend]

travelingbard wrote:
Looking at the 3000 watt inverter models...

This would be the correct size of inverter.

About the AC math: a conventional 13.5K BTU air conditioner may draw up to 25 amps of current at 120V when starting from lock rotor position. It probably operates at close to 15 amps when running. That is 15 amps at 120V. You can interpolate that to 12V through the inverter by a factor of 10X, allowing for inverter loss and wiring. You're looking at 150 A of draw from your batteries. A 6 fold GC2 6V bank would have a capacity of (3x225AH)=675AH at the 20hr rating. Traditionally, batteries are only allowed to be drawn to 50% of capacity, in the above example, 337 AH. After allowing for the Peukert effect of the large draw and the lock rotor draw, you may get 2 hrs. of run time from that bank but real life use tells me it would be less because the inverter will shutdown when you approach 11 or 11.5 volts DC. The above considers no duty cycle but a continuous run time. It also assumes a 12V battery system. That may or may not be typical use in your location.

If you need off-grid power from batteries to run an AC unit, you should be looking at LIthium technology, IMO. There is a Forum member that does accomplish what you envision but they limit the use of the AC to a few hours a day.

To your original question--put the batteries where it's convenient to service them and as close as possible to the 12V distribution panel, the converter, and inverter. GC2 6V's weigh 70 lbs. A sliding tray would be a great thing to have.

[travelingbard]

Looking at the 3000 watt inverter models...

[2oldman]

travelingbard wrote:
I'm still running the math to see how much juice we'll need,

Keep running.

[Grandpere]

How big and inverter are you getting that will run an AC unit? I for one would think that the draw on the batteries would be enormous and the batteries would last like 10 minutes, not all night.

[ScottG]

You cannot realistically run AC. It would take a trailer load of batteries to run it any length of time.
Since AC will be important to you, either a generator or hookups is the only way to go.