size of battery needed for my solar panel

[Harry Bloomfield]

Watts = Volts x Amps x power factor, the latter in DC is 1, so amps = watts/volts so 45/12 = 3.75 amps. It is just simple maths now we know the unit being used.

Granny and eggs, I think!

 

[muckington]

* Power Converter Output Voltage: 12V
* Power Converter Output Current: 25A
So if the mains to 12 volts unit is 25 amps, then it can clearly run with a battery able to deliver 25 amps.

There is no mains charged involed for me like the poster above. it will rely on battery solo

If only wanting to spend a couple of hours then down to around 12 Ah. Deep cycling, a car battery, is not recommended, the active material will fall off the plated, so looking at a traction battery which in the main today are AGM (VRLA).

I was told somewhere ells that the plates are all the same size now. will I need a greater amps/ hour if using a car battery then a leisure battery?


Found this one! its on offer

Lion Sealed Marine Battery - 120Ah | Euro Car Parts

Lion Sealed Marine Battery - 120Ah at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

 

[Harry Bloomfield]

I was told somewhere ells that the plates are all the same size now. will I need a greater amps/ hour if using a car battery then a leisure battery?

You should not be using a battery, at all, designed as a car battery. Car batteries, are designed to support a short, high current discharge, followed by immediate recharge. A leisure type battery, is designed for long slow discharge, then a full recharge - which is what you need. A car battery, will seem to work for a while, but will soon be wrecked by such treatment.

 

[ericmark]

Reference to mains, was to show maximum draw, or start amps. Lead acid batteries come in a few flavours, the traction battery is designed to be deep cycled, and toped up, used in fork lifts and milk carts, the vehicle battery designed for high current, and the leisure battery halfway between.

But there is a new technology, the valve regulated lead acid or absorbed glass mat, these batteries are not flooded with electrolyte, they only just have enough, and are totally sealed could be used on their side, in fact in stair lifts they often are, but the charging needs a special charger as over-voltage will damage them. Used with all sorts from stop/start cars, mobility scooters, house alarms, from around 3 Ah to 110 Ah.

So flooded batteries (can be topped up with distilled water) can use any type of charger, but AGM needs a special type, the same problem with Lion batteries, sometimes the controller is built into the battery, but if not, the chargers can be expensive. As to the Lion battery you link to, since we don't know if the charge controller can be used with Lion batteries we can't advise.

In the main they are better, as can be left for years half charged, but depends what the charge controller says.