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Posted: Sun Oct 25, 2015 6:57 pm
by Forestboy1978
Could really do with ability for constant 3kw. No idea about any of this stuff so don't really know what to do. got a good vehicle elec that'll fit the inverter for 100 but I don't know what to buy or even where to begin.
Anyone got any advice?
Ta
Posted: Sun Oct 25, 2015 9:54 pm
by Exsparky
3kw, or 3000w at 12 volts is 250 amps, plus losses. It would have to be a hell of a big battery to deliver that much current for any time at all. To give you an idea of how much that is, 250 amps is probably what a big starter motor takes, but then, just for a few seconds. The battery would take a lot of recharging, too, which would mean running the van for several times longer than the time you used the inverter for, using the van as a bulky generator set with a very small output.
You might as well just get a generator. Generators are rated in kva. kva is not the same as kw, though both are found by volts X amps / 1,000. Things like electric motors do weird things to alternating current, which means that, say, a 600w motor needs something like 750va from the generator. A 3000w load would need something like 3,750va, or 3.75kva from the generator.
In practise, there are losses and inefficiencies which means that a slightly bigger generator would be needed. 4kva would do it, but would be running at maximum welly with a 3kw load.
I haven't had too much to do with buying mobile generators, but I'm sure others here can advise you on which ones are worth buying.
Posted: Sun Oct 25, 2015 10:01 pm
by GB_Groundworks
get petrol tools?
Posted: Sun Oct 25, 2015 11:18 pm
by rxbren
don't get one of the warrior generators off of ebay or any others that look the same I bought one and it was nothing but misery should have spent a little extra and got a Honda powered generator
Posted: Mon Oct 26, 2015 6:00 pm
by michaelthegardener
http://www.ebay.co.uk/itm/SDMO-2-8kw-pe ... 5b1921da4c
don't know if that's anygood for you but I recommend the seller bought a few mowers from him allways been good quality and service
Posted: Mon Oct 26, 2015 6:48 pm
by Exsparky
Once a year I have to drag a particular generator out and check that it starts. All I do is fill it with fresh fuel and it starts with ease, even though it hasn't run for eleven and a half months. It has a Honda engine. I haven't run one day in and day out, so I couldn't say with any experience that a Honda engine will do that, but others seem to rate them highly.
A friend of mine bought a 1kw gennie for about £120. It seemed not to be working properly, so we connected a toaster to it as a test load. Even before we turned the toaster on, smoke came out of it as soon as the gennie was started. It turned out that the gennie relied on there being a relatively big load to help control the voltage. I measured 275 volts with no load, and the tiny load that the permanently on control electronics made wouldn't make any difference to that voltage, which fried those electronics. Lots of electrical things have circuitry like that nowadays.
My friend doesn't realise that you get what you pay for. What does he expect for £120? He won't be told.
Posted: Mon Oct 26, 2015 7:30 pm
by rxbren
The one I bought the exhaust snapped clean off within two months they never sent a replacement no matter how many times it was chased up, power output isn't as good as a 240/110v inverter breaker would occasionally be under powered, the other fault with it is that the fuel tank leaks so you either have to drain it down after each day or guess how much fuel you will need. I contacted them about the tank and that is apparently a common fault and a replacement tank would be sent with the exhaust. Considering they prided themselves with it being British designed its utter crap
Posted: Mon Oct 26, 2015 9:15 pm
by Forestboy1978
Ta for all the feedback. Lots to think about. cheers Michael that link was nearly perfect for me but I need a little bit more juice.
Exsparky. Cheers for the useful info!
GB - I do have a lot of petrol tools and battery tools but I need something for my gutter vacuum, titan cheepy breaker and my mitre saw mainly. Also charging batteries perhaps.
Posted: Mon Oct 26, 2015 9:18 pm
by Forestboy1978
Exsparky - yeah, some people cannot be told. My brother being the classic. I've got a spinal fuse, we do the same work. Guess who suffers the worst back problems! Not me and he's 8 years younger. Never bends his knees and gets pissed of when I tell him to monitor his posture lol. Just cannot be *****g told lol
Posted: Tue Oct 27, 2015 11:24 am
by cookiewales
Honda sell a fuel additive once a year treatment great for pressure washers and mowers that stand idle and strimers check diesel ones more go and duel power 
Posted: Tue Oct 27, 2015 7:11 pm
by Dave_L
Buy the best generator you can afford, avoid the chinese imports, you'll never get any spares for it. I've got a diesel Lister one on wheels, never fails to start......mind you it's a bit of an art to start it!