More Leisure Battery Questions

[paul_loves_borbons]

Hi everyone,

I have a couple of leisure battery questions and would very much appreciate any helpful info anyone can give me.

I'm planning on installing a 110Ah battery on the left side of the engine bay, underneath the spare wheel well. People have mentioned Lucas and Elecsol batteries on previous threads and I was wondering of anyone had any feedback on these or any other leisure batteries. If I could get a decent 110Ah battery that could fit under the spare wheel well that would be ideal. However, I can always put the leisure battery on the right and the "proper" battery on the left if a decent leisure battery won't fit. Any recomendations on a good battery to go for would be very much appreciated.

I would like to run the leisure battery output into a fuse box, with one output from the fuse box going to a 12v interior light and another output going to a 240v inverter to run some low ampage appliances such as chargers (although I'm sure my girlfriend will try and plug a hairdryer into it if she gets the chance). I've had a quick look on ebay for 12v to 240v inverters and there are several available with different wattages. What difference does the wattage of the inverter make?

Can anyone reccommend a good wattage and/or brand for an inverter to use in a camper? I suppose a higher wattage inverter will generate more heat so that could be a downside. Again, any help would be appreciated.

Finally, should I have a RCD anywhere in the system? There will be a fusebox between the inverter/interioir light and the leisure battery and 30A fuses between the two batteries and the relay but I've noticed a couple of people mentioning them in details of their installs.

Any advice would really be appreciated.

Cheers

Paul

 

[froggy]

Theres no need to use an RCD when running from an invertor, just be aware though that the bigger the invertor the faster it will flatten the battery.
As for install guides have a look in the tech know how guides at the top of the tech page as you will also benefit from a split charge relay to charge the leisure battery as you drive. Also some good ideas in some of the threads in the gallery (think it was in Lards thread)

 

[Graham L]

RCD's are only required on mains hook up installs, not on 12v leisure batteries.

As Simon has said the bigger your inverter the quicker you battery will flatten, they are not really suitable to run things like hairdryers, straighteners and that kind of thing as you will need a mega inverter.

Remember 1000w inverter will only handle 4amps which will power a laptop, maybe a small LCD TV but not a kettle/hairdryers etc.

If you are going to a site that has power its sometimes easier to pay for the hook up and then you can draw 16 amps, doesn't need to be a permanent install can be as simple as a fused 4 way block on one end and a 16a connector on the other to hook up to the supply, lots of caravan suppliers sell portable power blocks to use in tents with RCD's built into them.

 

[paul_loves_borbons]

Hi guys,

Thanks for the advice. I was only joking about the girlfriend plugging in the hairdryer although I would never be 100% sure she wouldn'gt give it a go. I've done some research on the inverter front and think I've got it sussed now.

The wattage drawn from the battery can be calculated by multiplying the batteries voltage by the current drawn. I will have a 12v leisure battery and I guess it would be wise not to draw more than 30A for safety reasons. I'm therefore limited to a maximum of 12x30=360 watts that can be drawn from the battery if I want to keep the current below 30A. It would therefore be sensible to get a 300 watt inverter and only use appliances that draw less than 300 watts of power.

A 12v, 110Ah battery will provide 12x110=1320 watt hours of power. Assuming the battery is new and is fully charged I should be able to draw 300 watts for 1320/300=4.4 hours.

Obviously there will be a fair ammount of reduction in the power available from the battery as it gets older and there will be energy lost at various points in the system which I haven't taken into account above. It's nice to have a rough idea of what's actually going on with all those bit's of wire and magic black boxes though!

Thanks

Paul