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Falstaff

PV Battery charger

What do we think - I'm wanting to go away for a couple of weeks and charge a leisure battery so we can have a bit of lighting and charge laptops, maybe even watch the Grand Prix ? (Low energy TV reckons to run at 13 watts ! )

SO I want a PV or wind generator to bang as much grunt into the battery as possible without breaking the bank or being too huge.

I'd seen a 1.5 watt trickle charger - then this

http://www.ebay.co.uk/itm/NEW-20W-12v-Energy-Solar-Battery-Charger-Polycrystalline-20-watt-TUV-ISO-UK-/252028959055?pt=LH_DefaultDomain_3&hash=item3aae18b94f

Can anyone point me at anything better ?
dpack

the laptop thing is the problem ,mine flattened a 120ah leisure battery in about ten hours,lights (and a low energy tv etc)is easy

for what would seem low use on mains(lappy) you probably need the sort of panel that is normally seen on a house roof unless you recharge from a vehicle engine
dpack

ps the little panels will cover loss in waiting but dont cover use.
vegplot

20 watts (if that is what it will provide) will give you around 120Whr per day (give or take). That will allow you to run a 60W laptop for 2 hours. Reality maybe different.
Falstaff

We already have one of those little 1.5 watt ones sitting on the bulkhead and it seems to keep the battery alive for lights etc.

The one I linked to is rated 20 watts or 1.5 amps so in 10 hours would contribute 15 Ah in theory.

There is an alternator on the engine, and that keeps the Power battery charged reasonably well. After an hour or so I usually switch over so it charges the Leisure battery as well - but the Voltage drops quite significantly when it is charging both batteries. (Down to around 11 volts)

I'm sure you're right about the laptop. I wouldn't be using it for long - maybe an hour or so a day - but it's an old Sony (which heats the room !) and the battery is knack'd - to make matters worse - the Transformer is saying it outputs 19.5 Volts. That means it would need to be chopped to flatten down to 19.5 or so, with all the attendant losses in an inverter.

It looks as though I'll be taking paper and pencil with us then !

But what about this panel ? Is it worth spending the 30 or so "just for if..." or shall I just do without ?

Oh I also have another decent power battery that I'm taking for "a spare" - that would get no charging at all - unless it were hooked up to something like this.

Edited to say - Thanks vp Cool
dpack

the small panels are ideal for keeping a battery "full" when in long term storage(or for running a very low input thing such as an electric fence)
RichardW

1, We already have one of those little 1.5 watt ones sitting on the bulkhead and it seems to keep the battery alive for lights etc.

2, The one I linked to is rated 20 watts or 1.5 amps so in 10 hours would contribute 15 Ah in theory.

3, There is an alternator on the engine, and that keeps the Power battery charged reasonably well. After an hour or so I usually switch over so it charges the Leisure battery as well - but the Voltage drops quite significantly when it is charging both batteries. (Down to around 11 volts)



1, It might seem to be doing this but unless you are only using a very very low wattage light for a very very short time its not. you eating into the battery storage.

2, Not in the UK it wont. You will not get full output for the entire day. In summer you might get 6 times the peak output over the whole day. So about 96 wh. Also at what voltage is that 20 watts? I would guess 18v so at the 12 to 14.4v you need the actual output will only be 13 to 16 watts.

3, This is really your best option, you have it already, its more powerful than you will need. As its a one off a small amount of fuel cost is still going to be less than buying a substandard solution. When charging both bats iof the V is that low then the leisure bat must be about 10v which it BAD for the bat. If you raise the revs it will up the voltage.
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