suitable axillary battery

One blog to read is John & Val's: Electricity for Camping

Hope that is a good start :)

Andrew

Hello Dave,

because your 64W solar panel delivers all the juice for the one fridge plus a bit extra, two solar panels will keep you going equally well with two fridges.
Since there's not much useable solar for 16 hours every day, your battery's got to bridge this gap.
Looking at the Ah from two 64W panels reveals you get close to 40Ah useable solar energy out of them every day.
Your battery has to be able to supply at least two thirds of this (16/24) before it gets re-charged, or 26Ah.
Aiming for a depth of discharge of 50%, you're looking at a 52Ah battery capacity or better.

If you don't mind the extra weight (33.5kg) of a good 100Ah deep cycle AGM battery, get one of these.
If weight is an issue, I recommend another AGM type battery: spiral wound pure lead/tin with superior electrical and chemical properties and improved service life.
E.g. a 50Ah unit will do this for you comfortably and it only weighs 18.5kg.
And when you come back from your trip, don't forget to fully charge your battery using a good mains powered charger.
Not doing so, will jeopardise the wellbeing of your valuable battery.

There is more info in my profile, and here.

For any other questions, just let us know.

Best regards, Peter

Dave,
Your 1 meter square (1.36 x 0.74) solar panel delivers a maximum of 64 Watts and 3.9 Amps, however various other brands of same physical size, will deliver ~120 Watts and 7+ Amps.
You can add one of these higher producing power panels, instead of using another lesser power unisolar panel to your existing unisolar panel and you can then expect a much better performing system.

AGM batteries are definitely the way to go with a solar system because they will charge fully and much faster too.
You will also need a good solar controller now with a much larger power rating.

Maîneÿ . . .

Hi David,

A freezer will obviously use more power than a fridge, perhaps up to twice as much, perhaps even more.

With this in mind, and as I'm also planning to add a second fridge as a freezer, have if you looked around for something more efficient than an Engel ?

Trailblazer and Explorer both have more insulation than Engel/Waeco/Evacool, and while this makes them bulkier, it also means they use less power. I imagine there are more options than these two, especially since Explorer seem to have ceased trading.

When considering batteries, remember that they are all fussy beasts - even the best brands need to be looked after to perform well.

Deep Cycle AGM batteries arte definitely the way to go and as for regulators, MPPT delivers at least 25% more power.

MH

no - 25% + more power. Morningstar claim up to 35% more power for their MPPT regulators but we are a little conservative and like to say around the 25% mark.

We have strong anecdotal evidence from those who have fitted Morningstar MPPT regulators to support the fact that they deliver a phenomenal amount more power.

The way MPPT is designed/set up you should be able to gaurantee at least 21% more power, and Don's electrical engineering mind tells me that you should be able to take that up to around 25%.

We haven't bench tested it, but believe the claims are true.

cheers

mh