Roughly How Much Drain on Battery?

[jopparocks]

I'm going away at Easter and will be staying in a couple of sites which don't have hookups and so I have a power capacity query. It might be cold as we'll be going to the top North of Scotland (outside John O Groats).
I have two 110 amp batteries and two 75 amp solar panels. We will want to use the blown air heating from my Truma heating system on my 1997 Hymer S650.
We'll no doubt be putting the telly on at night (a12v Avtex) as well along with led lights and will want to run the heating maybe sometimes in the day too. There's a fridge which will be running and possibly charging my phone through a small invertor as well. We like to be comfortable
On this set up how long do you think the batteries will last? Will be going for lithium if my set up is not up to it.
Cheers Martin

 

[autorouter]

I'm assuming the fridge is electric only as I don't see any option for switching to gas. Seems to run nicely on 12v when not on hookup.

You need to find out if it's a 3-way fridge (mains, 12V, gas) or a compressor fridge. Apart from the gas setting, the big difference is that a 3-way is silent in operation, and a compressor has a motor you can hear when it's operating.

A compressor fridge takes maybe 30 to 40 Ah of charge per day to run (the figure will be in the manual somewhere). A 3-way fridge on 12V running from the battery will take 100Ah per day if you're lucky, which is why they are normally run on gas. I'd think you'd need at least 200W of solar panel to keep a compressor fridge happy without other charging methods. 300W is usually enough for the fridge and other hab circuits.

 

[jopparocks]

You need to find out if it's a 3-way fridge (mains, 12V, gas) or a compressor fridge. Apart from the gas setting, the big difference is that a 3-way is silent in operation, and a compressor has a motor you can hear when it's operating.

A compressor fridge takes maybe 30 to 40 Ah of charge per day to run (the figure will be in the manual somewhere). A 3-way fridge on 12V running from the battery will take 100Ah per day if you're lucky, which is why they are normally run on gas. I'd think you'd need at least 200W of solar panel to keep a compressor fridge happy without other charging methods. 300W is usually enough for the fridge and other hab circuits.

I'll have a look at when I get the van back from the body work shop but I can definitely hear it running when its on so prob compressor. Berni19 suggested trying it out on the drive so will do that.

 

[acropolis22]

Yes now its pointed out to me it does seem daft. I'll get there in the end!

You need something called a buck converter. To take 12V off the cigar lighter and convert to 5V for the phone. And there are plenty of gadgets that do exactly that on eBay.

 

[autorouter]

You need something called a buck converter. To take 12V off the cigar lighter and convert to 5V for the phone. And there are plenty of gadgets that do exactly that on eBay.

If it's a modern phone you would be better off with a proper USB socket, preferebly one that is QuickCharge3.0 (QC3) or better. Depending on the exact phone model, it will increase the charging amps and voltage from the standard 5V to 9V or even 12V. That's the standard rectangular (Type A) socket. If it's a USB-C then a proper USB socket is definitely a good idea.