Caravan / Leisure Batteries

[cqueen]

Hi,

Quick question, think I already know the answer but giving it a try..

I will soon be doing some marquee events and need quite a bit of power to run my gear. We're talking 25amps @ 230v for approx 5 hours. That would equal 125 amp hours?

Is this beyond the realistic reach of what leisure battery can cope with?

Thanks

[volks al]

Thats going to be rather a large leisure battery. Surely a little generator would work better? Draining a leisure battery down like that will need a decent charger to bring it back to full health I would say. Also it would be affected by ambient temp, so if its outside, night time and colder then its going to have less juice to start with by my understanding.

[Fishtigua]

Try this marine guide for ideas.

http://www.westmarine.com/webapp/wcs/stores/servle...

On boats, we fit banks of batteries that can last for days with no charge but it does get pricey. Also check what output your inverter will handle.

I would still go for a genny with soundproofing and a good silencer.

[cqueen]

For a generator I'd be looking for at least 5.5Kw, for that I'm probably looking at the best part of £1000. Was hoping the battery option would be cheaper and more mobile!

[R TOY]

There is a big difference between 25a @ 230v and 25a @ 12v iirc. If you have a huge inverter that can handle 25a @ 230v (5.7kw) you will need a v large bank of batteries to handle the load.
A 12v battery inverted only gives around 250w output so you would need 23 leisure batteries to produce the power. How long for ?? beyond me.
Bottom line you need a geni ! Rent one for the day for £25
What do you need to power? It may be worth conecting things up and measuring the load on each appliance.

Edited by R TOY on Saturday 7th July 14:50

[cqueen]

R TOY said:

There is a big difference between 25a @ 230v and 25a @ 12v iirc. If you have a huge inverter that can handle 25a @ 230v (5.7kw) you will need a v large bank of batteries to handle the load.
A 12v battery inverted only gives around 250w output so you would need 23 leisure batteries to produce the power. How long for ?? beyond me.
Bottom line you need a geni ! Rent one for the day for £25
What do you need to power? It may be worth conecting things up and measuring the load on each appliance.

Edited by R TOY on Saturday 7th July 14:50

That's a good shout. I would hope that most events will have a mains supply available. Occasionally there wont be so renting a big gen for a few days a year will be much easier and much more cost effective than buying one. Cheers!

[abbotsmike]

As RTOY said, I've just done the maths on that.

25A @ 230V = 5750 Watts (roughly)

5750W / 12V = 480A

480A * 5 = 2500Ah

480A, whilst not impossible to draw/supply from 12V is well beyond the capabilities of any leisure battery!! It would require a very large bank of batteries, and even then they'd only be good for short bursts, not 5 hours or so!

I would say Genset hire would be your best option. Unless you are only running basic lights, I would recommend going for a diesel with Voltage Regulation, and if you are running funny loads (motors, Flourescent lamps, anything that switches rapidly) allow enough overhead to run a few 500W halogen flood lamps on it to help stabilise it. A generator can ramp up from 10% to 80% load much faster than idle to 80%, this helps to reduce voltage drops.

Edit: Just noticed the portable bit, and as I'm bored:
A 115AH battery being driven that hard is going to lose some capacity, so for sake of ease we'll say 100AH useful capacity (Being very generous there) at 25kg a battery, you'd need 25 batteries, so in excess of 600kg in batteries alone! A generator would probably weigh less to boot!

Edited by abbotsmike on Thursday 26th July 00:06