Leisure battery and electrical questions

[dirtydog]

I'm looking to get a leisure battery for the back of my van to run my 1000w inverter, will mostly be using it to charge my tools, run a mains power tool now and again and to run a kettle.

What size battery will I need? and where's the best place to get one from?

I'm going to be fitting a split charge relay thing to keep it charged from one of the starter batteries, i'm going to need to run some cable for it so what size do I need? I had a look on maplins website and the they measure it in AWG rather than amps they had some 4AWG will that be ok or is it too thick?

Thanks Adam

[MrMPuk]

I've never had much luck charging tools from my 1000w inverter for some reason and it wont run most kettles as they are well over 1000w.

[dirtydog]

I've never had much luck charging tools from my 1000w inverter for some reason and it wont run most kettles as they are well over 1000w.

Ah ok scrap the kettle thing (a quick look shows they're all over 2.2kw) will carry on running my little 12v travel kettle

What's the issue with the charging power tools? I've not actually got my inverter wired up yet.

[angeleye]

think 4 awg is about 80 amps (American Wire Gauge) its there system of stranded wire carrying capacity incorporating several factors,have to make it complicated dont they,smaller the number the bigger loading it can carry

[sidspop]

I believe you can get lower wattage kettles, or a camping stove is probably easier.

The charger thing could be down to the way the waveform is created.
Proper mains is sinusodal. I wont try to describe a sinusoidal waveform, easier for you to look it up. #inverters struggle to make a waveform that looks sinusoidal, so they generally produce pseudo sine wave. Looks like a bit of brick wall, that is stepped, and not smooth. It is ok for most things, but chargers nowadays are not the old fashioned tansformer type, they are switch-mode, and switch mode psus like sine waves.

Does any of that make sense, or have I confused everybody more lol

[MrMPuk]

So you're talking about modified and true sine wave.

[dirtydog]

think 4 awg is about 80 amps (American Wire Gauge) its there system of stranded wire carrying capacity incorporating several factors,have to make it complicated dont they,smaller the number the bigger loading it can carry

That's probably a bit heavy for what I need, will get the 8AWG. Anybody see any issues with that?

[angeleye]

I believe you can get lower wattage kettles, or a camping stove is probably easier.

The charger thing could be down to the way the waveform is created.
Proper mains is sinusodal. I wont try to describe a sinusoidal waveform, easier for you to look it up. #inverters struggle to make a waveform that looks sinusoidal, so they generally produce pseudo sine wave. Looks like a bit of brick wall, that is stepped, and not smooth. It is ok for most things, but chargers nowadays are not the old fashioned tansformer type, they are switch-mode, and switch mode psus like sine waves.

Does any of that make sense, or have I confused everybody more lol

yes sounds like something me old telly used to do ok sidspop whats best way round this,what to fit and how,could be useful if you put a thread in frequently asked questions
just a simple set up to run,kettles ,small ,tv etc
what to buy ,how to install etc

[dirtydog]

I believe you can get lower wattage kettles, or a camping stove is probably easier.

The charger thing could be down to the way the waveform is created.
Proper mains is sinusodal. I wont try to describe a sinusoidal waveform, easier for you to look it up. #inverters struggle to make a waveform that looks sinusoidal, so they generally produce pseudo sine wave. Looks like a bit of brick wall, that is stepped, and not smooth. It is ok for most things, but chargers nowadays are not the old fashioned tansformer type, they are switch-mode, and switch mode psus like sine waves.

Does any of that make sense, or have I confused everybody more lol

Yep i'm confused

So it's not quite the same wave pattern as proper mains power

Will have a look for a lower wattage kettle as the 12v ones takes an age to get hot!

[angeleye]

think 4 awg is about 80 amps (American Wire Gauge) its there system of stranded wire carrying capacity incorporating several factors,have to make it complicated dont they,smaller the number the bigger loading it can carry

That's probably a bit heavy for what I need, will get the 8AWG. Anybody see any issues with that?

be about 22/24 amp best give maplin a call they will advise

[spospe]

If your inverter is rated at 1000 watts then at 12-volts this requires a current of 83 amps, so your cabling needs to be able to supply at least that current.

900-watt kettles are readily available from caravan dealers and these will run quite well off any type of inverter, both pure and modified sine wave.

Beware that if it takes 10 minutes to boil your kettle at a nominal 900 watts this will drain about 20 A/H out of your battery (the simple calculation shows 13.9 A/H, but at these high currents, you should allow for far more inefficiency, so about 20 sounds right).

[dirtydog]

If your inverter is rated at 1000 watts then at 12-volts this requires a current of 83 amps, so your cabling needs to be able to supply at least that current.

900-watt kettles are readily available from caravan dealers and these will run quite well off any type of inverter, both pure and modified sine wave.

Beware that if it takes 10 minutes to boil your kettle at a nominal 900 watts this will drain about 20 A/H out of your battery (the simple calculation shows 13.9 A/H, but at these high currents, you should allow for far more inefficiency, so about 20 sounds right).

My inverter has about 2m of heavy cable fitted to it so will be connecting that to the leisure battery, just after what size cable I should run from one of the starter batteries to the split charge relay to charge the leisure battery

there's a towing/camping shop down the road from me, will pop in there to see if they have any 900w kettles

[spospe]

dirtydog

I would suggest anything rated at about 20 amps would be OK to use to link the engine and leisure batteries via the split-charge relay.

Keep the 12-volt feed to the inverter as short as possible, as that is where the losses are. The output of the inverter being at 230-volts can be as long as you like (or as long as your van ).

[newbie]

i had a similar set in my van i used a set of jump leads 3m long cut the ends off and crimped lugs on the ends connected 1 end direct to the battery and the other end to 2 6v sissorlift batteries which gave me a constaint 900 ah supply to run the inverter because i had the kit on the van i used a manual change over switch one charge on monday on the way to work and it would last all week
i too used a 900w kettle and charged my battery drill and never a problem also used a toaster and microwave home from home

[dirtydog]

Right have got some 8AWG wire, it's rated at 40a max and have ordered the the relay. Just need to get a leisure battery now. The ones i've seen are 110ah will one of them be ok?


Hmmm a microwave eh? Wonder if i cna find room in the van for a small one