Charging house+extra batteries

[ksaltman]

Hi -

I am awaiting delivery of my 2014 38FL and am starting to work out the details of how I want to configure my off-grid power. I've done a little bit of the math and given the limiting factor being water based on previous experience my wife and I can comfortable live 3 days on 100 gallons of fresh water, probably more depending on what we are doing.

So if I can configure my power source with enough to cover 3 days off grid then we'll be really happy.

With that said, I've done a bit of the math and unless we are in a very hot climate and need to run both A/C units 24/7, a set of 2 100Ah lithium batteries will more than cover our power needs. (Of course more experimentation required, but for now that is my #)

So as it would happen the cost of 2x 100ah batteries from http://www.lithiumion-batteries.com actually cost less than the Onan 5.5k generator, are smaller and 1/2 the weight. So far no down side....

There's the back story, now my question, if I place these batteries in the area designated for the generator (yes they will fit very comfortable and I ordered the 38FL with hen-prep option), how do I charge them from my truck. I ordered the F350 with dual alternators so there theoretically is 384 amps to go around from the truck, but I'm a little lost how I get that power from the truck to the generator compartment.

Yes I know there is some power available in the 7 pin connector that runs the coach lights, charges the house battery and so forth, but I have no idea what the gauge of the wire is or how much current is available for charging other batteries.

Any help would be appreciated.

[johnboytoo]

Wowser, ambitious project !!! subscribing

I;m still trying to get my 38gk to keep my res fridge going for a few hours !!!

[ksaltman]

We opt'd for the normal 3 way RV fridge setup because we know we need to keep it running while not plugged into shore power.

I recall RW puts in a second battery dedicated to the res. fridge. Do you know what type & size it is? Also I'm wondering what type/size the standard house battery is in the RW.

I know its a expensive option but you might look into a larger capacity Lithium battery, perhaps something like what are on http://www.lithiumion-batteries.com.

If you don't already know the power consumption of the fridge go on amazon and have a look at "P3 International P4460 Kill A Watt EZ Electricity Usage Monitor". Basically you plug the monitor into the wall outlet, the fridge into the monitor and run it for a few days on shore power. It will tell you exactly the amp hours used so you can calculate the battery size you need. I've got one and it is very handy and pretty cheap.

When sizing the battery I only count on about 80% of the battery rating as usable because the inverter is not 100% efficient and over time the battery will loose capacity but other than that it's pretty straight forward math.

Hope this helps keep your beer cold .

[jhardin]

What about the battery fumes? They are explosive and need vented.

[JellyStonePark]

Hello Neighbor, After posting a fairly lengthy posting on the other site I opened this site and here you are working on the same questions. I spoke with Leaonard at Crossroads about this same question today. Bottomline, they have now decided "Not" to install the third battery on our coach.

So I am now considering installing a Solar System on mine to the tune of almost 3 grand. Ouch. We do have a Honda 3000 which is plenty to just charge batteries when Boon-docking. What have they told you about whether your unit will have two or three batteries? Looks like so far you and I will be the only ones at the Rally with 38FLs.

Have they said yet when you can expect to take delivery of your Coach? The wait is unbareable at times. But gave my wife lots more time to shop for stuff.

[sinder]

ksaltman - check out this website. Click on "learn about batteries" in the menu bar at the top. You may find your answers in the articles or you can use the forum to get additional information. http://batteryuniversity.com

[Steve & Linda]

We have a 38GK on order with the Residential Appliance Package option. When ordering, our salesman at LifestyleRV, whom I trust, said they would provide the 2nd and 3rd batteries needed for that option, and they would be the good ones.

[ksaltman]

Hi JHardin,

The batteries I'm looking at are based on Lithium Iron Phosphate chemistry. That are considered the most safe version of current lithium battery technology and are commonly used in EVs (Tesla, LEAF, Volt etc) and other things like battery power tools. They also have built in circuitry to avoid over charging, over discharging or over heating. Given they are designed as drop in replacements for auto and marine applications I feel pretty safe using them.

Wrt to the venting, good point. My thought was since I plan on installing them in the space designed to hold the generator it should have some ventilation already designed in. I may need to have a small fan to move the air around especially in warmer conditions but that should be easy to accommodate.

Thanks for your feedback and I'll keep you posted.

[ksaltman]

Hi Sinder,

Thanks for the pointer. This looks like an interesting read. Yes I'm a geek, just ask my wife .

[Adamsvr]

Originally Posted by ksaltman

Hi JHardin,

The batteries I'm looking at are based on Lithium Iron Phosphate chemistry. That are considered the most safe version of current lithium battery technology and are commonly used in EVs (Tesla, LEAF, Volt etc) and other things like battery power tools. They also have built in circuitry to avoid over charging, over discharging or over heating. Given they are designed as drop in replacements for auto and marine applications I feel pretty safe using them.

Wrt to the venting, good point. My thought was since I plan on installing them in the space designed to hold the generator it should have some ventilation already designed in. I may need to have a small fan to move the air around especially in warmer conditions but that should be easy to accommodate.

Thanks for your feedback and I'll keep you posted.

The generator compartment only has a hole in it for the generated tailpipe. Otherwise, it's sealed. You'll have to be creative to vent the batteries. The house batteries have covers over them and a tube leading to the outside air.

[atom ant]

Yes the house battery boxes are vented out the bottom and out the top - as required for non-mechanical ventilation.