Looking to build a 12 volt System for a VW Westfalia.

[blackcatracing]

After multi searches (feeling even more confused) I am still searching for a system for my VW Westfalia.
What I am hoping for from the perfect system. The ability to boondock for up to 3+ days in cold weather. My electrical needs for that time would be split between my Engel mt45f-u1 12 volt Refridgerator, an Espar D2 diesel furnace (the van is a diesel so fuel supply is not an issue), and the plethora of laptop charging, phone charging and lighting. I will be cooking with propane.
Looking for advice on amp hour battery size and matching charging systems. I currently have a Victron 75/15 MPPT controller. 3 100 watt solar panels (all Renogy) that can be incorporated into the system. Hoping to install the system and monitor it lightly.

Any and all help would be greatly appreciated.

 

[Short_Shot]

My first suggestion would be to do a thorough energy audit. If you have a system with a shunt present you can monitor your actual needs.

From there sizing a system is easy.

And there are options to get wild amounts of solar on top of a vehicle that can be looked at later.

 

[blackcatracing]

Unfortunately, I do not have the ability to do an energy audit at this time. I did google the average of real use energy consumption for both big energy draws I would be using.

Engal mt45f 12 volt fridge is
9.93 KWH = 9930 watt-hours
9930 WH ÷ 745 hours = 13.3 watts
13.3 W ÷ 12 volts = 1.1 amps
run for 24 hours -> 1.1 A X 24 hours = 26.6 amp-hours

Espar D2 diesel Furnace

Heating level	Low	Medium	High	Full speed
Heat output (Watts)	850	1,200	1,800	2,200
Electric power consumed (Watts)	8	12	22	34
Diesel fuel consumed (litres/hour)	0.10	0.15	0.23	0.28

If the heater had to run at full speed for 10 hours, it would need 34*10=340 watt-hours, or 28.33 amp-hours at 12 volts.

I cant see the heater running at full speed so at the worst-case scenario I am thinking 20 amp hrs.
Lights, computer/phone charging, ect. 5 amp hrs?

Looking for a battery for 50 amps hrs x 3 days 150 amp hrs?

So maybe a heated 200 amp hr lithium battery with an equivalent 120-volt to 12-volt charger recommendation?

 

[Short_Shot]

I could agree with 30ah per day for the fridge. My iceco is about the and size and uses about that.
I have a Chinese deisel heater as well and expect 1.5a draw typically if it's particularly cold out.

Charging a laptop and phones may be more than you think.

My cell phone has about an 18wh battery on its own. My light Lenovo laptop is a 60w draw at load while my big gaming laptop is 180w. Lights are pretty... light on power but even my tiny two led dome lights pull half an amp.

My roof fan pulls up to 2.5a, though I usually run it at speed 7 for 1a draw. I run mine even in the winter with the lid down to circulate air and help with my lack of insulation causing cold spots.

If I were to size your usage, which is similar to mine (and I have) I'd get a 280ah pack. That would be close for 3 days of "regular" use but a bit of solar makes it easy.

Your 300w in the winter might be enough to offset the heater no problem. In my case I've got only 150w but have a dc-dc charging option.

I'm currently discharge testing a 280ah pack for almost the same load as youre describing.

 

[blackcatracing]

So did you buy the 280ah hour battery that you are testing or did you build it? I am looking to buy one that is reliable with a heater. Any recommendations would be appreciated. Plus a good 120-volt charger that would mate up to it nicely.

 

[Short_Shot]

So did you buy the 280ah hour battery that you are testing or did you build it? I am looking to buy one that is reliable with a heater. Any recommendations would be appreciated. Plus a good 120-volt charger that would mate up to it nicely.

Build.

Pre-built ones will take up more space and I can't afford that.

I'm also planning to work heating pads into it, but I'll have to see how well it all fits where it has to go first. I have a thread on it, but it's less of a build thread and more of a dump for what I'm doing.

 

[McCarthy]

What Short_Shot said, 280 A will fit your bill with a little spare, and solar will recharge the battery so you won't need the battery capacity alone.

Build your own, Will has plenty of videos up showing how to build and balance them.

Buy 4 quality grade A 280 A cells from a US based seller, maybe through eBay, an Overstock 4s BMS, 1/4" threaded steel rod, some 1/2" plywood, 1/4" nuts and washers for a compression frame, and a box that fits it all.

 

[blackcatracing]

I am a carpenter and could easily build a nice box for it. The rest of it I am not so sure. I was looking for grade A cells and see that they are about 2/3 of an already built battery. The added cost of a BMS, heating pad, the equipment to charge and balance it right I think it would be better to buy my first battery. I will keep researching though.

 

[chrisski]

I installed PV on my RV last year. This year I’m upgrading the battery pack. The upgrade to the battery pack with making lithium cells is about as hard as the PV build. Every single part of the battery is ordered by you and cut and designed by you. It’s more of a time and patience thing.

What I will add is I was told to plan on 250 watts to charge a laptop (20 amps), but for me it worked out to 120 watts (10 amps). How long its plugged in, especially at night makes a huge difference.

Phones and iPads take about 1 amp to charge.

Without a good energy audit, the best you can hope for is to fill your roof up with panels. I don’t know ho Whig your van is. You can always have a plan to put it some portable panels to get more than just the roof if you need to.

 

[bulamatare]

Hello, I have a 1985 Westfalia. I am looking for a 100ah battery to fit under the drivers seat. I have read on samba, (150Ah LiFePo4 flat under driver seat + swivelectomy) that the 100ah renogy smart battery will fit in this space without modification. Although a very tight fit if placed on it's side with terminals on top facing the front of the van. The terminals can then be accessed thru the cubby after removing the swivel seat. I am ready for an upgrade. I will be purchasing either a renogy 100ah smart lithium or the Aolithium 100ah lifepo4 battery for this space. Both have similar dimensions.
My question being, has anyone tried the 100ah Aolithium lithium lifepo4 in this space under the drivers seat?