New battery location options in 2018 320S

subfreq111

I've decided to put two LP tanks up front and move the battery(s) under the right side bench along the wheel well in my 2018 320S. I like this location because it's centered over the axle (won't affect tongue weight) and on the opposite side of most of the other heavy stuff. The space I have to work with is roughly 8" wide by 30" long by 12" deep. I want to go with deep cycle AGM batteries this time around but may switch to Lithium down the road. I'm leaning towards two of the Weize 100Ah batteries (12"x6.6"x9.2") on Amazon for $169 each. This will get me 200AH for $340, but doesn't make use of all the space. I'd like to get more capacity if I can find a battery combination that will fit for a reasonable cost. For example, I also considered the Powerstar 4D 200Ah (21x8x8.5) for $300. I just decided that for the same capacity saving $40 wasn't worth wrestling a 126lb battery. Would love to get about 300Ah in this space if anyone has any ideas. I know AGMs can be mounted sideways but I'd like to keep the connections on top for ease of wiring. I may also consider putting a battery or two behind the Alde. The point of all this is to support daytime air conditioning while boondocking in conjunction with 370W of solar and a 2000W inverter. Please let me know if anyone knows any battery sizes to fit more capacity in this space. 

pthomas745

Remember:  your 200AH of battery means you have 100AH to use, since  you will get longer life out of your batteries if you only discharge them down to 50 percent. 

Long story short on Daytime Air Conditioning on Battery power:  you need more solar panels, and a lot more battery storage. 

subfreq111

Good point, DoD is another reason to eventually go to lithium, just not in the budget right now. But for daytime use wouldn't production, as in solar, be more important than storage? What's a normal percentage of time for A/C to be running in say, 90 degree temps cooling inside to around 75? Around 25% of the time seem right? It looks like the A/C draws around 500W while running, and a 5000 BTU unit should cool a 60 square foot room pretty quickly, since that size unit is adequate for 150 square feet. 

Cbusguy

Running AC battery is possible just not practical yet.  I have done the math.     your 500w estimate is at 120 volts not at 12 volts.    I don't remember the exact numbers but running the ac in my 2020 320 took about 80 amps at 12 volt dc.    

Going long on the numbers,   if you ran the AC for say 6 hours you are looking at 480 amp hours.   in lead acid land you need 1000 amp hours of batterys.   in Lithium you would need about 600 amp hours.   High current draws are tough on any battery regardless of the chemistry.
  

dCliffhanger

I think what you're looking for is a very compact nuclear reactor. A/C is just too power hungry to be supported by a battery\solar array that would fit on or in a Nucamp space. If A/C is a must then shore power or generator will be required. For off grid cool, perhaps less clothing and a fan.....

GatorEgg

Not even close on amp hr capacity required for ac operation. Get a genset.