Starting vehicle battery with generator?

Ice Rich

Ice Rich

Ice Rich

Soldato
Joined
3 Dec 2004
Posts
2,637
Hi all,

I have a very small generator (petrol) that I'd like to keep in my transit on the rare occasion my battery dies.

I notice on the front there is mention of battery charge so hoping I can buy some leads and then just jump start when needed. Only problem is i do not know the type of leads needed on the generator end. If you see the terminal 'bolt' do not fully unscrew so I presume I need some kind of 'U' shaped connection that I then tighten up on.

Gen1.jpg


Gen2.jpg
 
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You would need something like this
7oEm3.jpg


Available from all motor factors or electrical places.

As for jump starting from that thing, don't even try. It only puts out 8.3 Amps, you van with a flat battery will want somewhere between 125-350 amps - not only would trying it pop the generator circuitry, but you wouldn't be able to connect thick enough wires not to melt them too.

It would however be fine for charging the battery slowly, but it would take quite a long old time if its totally flat.

Better to buy one of these :
https://www.google.co.uk/search?q=j...cp.r_qf.&fp=2942838c3763d6f2&biw=1680&bih=882

Or just replace the battery, if its weak then winter will only kill it anyway!
 
A Jump Pack will be infinitely more suitable for your purpose and take up less space.
 
Thanks guys.
You're right, the leads will be too thin to do any jumping.

Battery booster will be better.

I'll keep the gen just for workshop lighting backup running direct of the 110v connector.
The stated output is 400va - would anyone know what this would roughly give me in watts?

Thanks,
 
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Ice Rich said:
Thanks guys.
You're right, the leads will be too thin to do any jumping.

Battery booster will be better.

I'll keep the gen just for workshop lighting backup running direct of the 110v connector.
The stated output is 400va - would anyone know what this would roughly give me in watts?

Thanks,
Click to expand...

About 250watts
 
The simple answer is that it depends what load you are running.

The formula is Watts=VA x PF

PF is the power factor, which is a value between 0 and 1 and is equal to the cosine of the angle of displacement between the voltage and current wave forms... got that? :P

A resistive load will have a power factor of 1, these are filament lamps, heating elements etc. So 400w if you want such items.

Any thing with a motor in it, vacuum cleaner, power saw etc is an inductive load, the power factor will vary on mechanical load its under but in the range 0.7 to 0.9 wouldn't be far off

Electronic items, computer, power adapters/chargers, LCD televisions etc have a very strange load profile, I don't think you want to assume a PF any better than 0.5 of these even though it probably will be quite a bit better. In addition devices like this may be damaged by the unregulated output from a small gen-set
 
Ahh that's very interesting and I understand that :)
Thanks for explaining so clearly. Never knew of PF before.

I'll look out for the PF rating on devices from now on, are they usually printed on things like drills etc?

Many thanks,
 
Ice Rich said:
I'll look out for the PF rating on devices from now on, are they usually printed on things like drills etc?
Click to expand...

Not usually on marked on domestic items I'm afraid (and as as I said, you drill for example, it'll change with how much load its having to exert). Its often indicated on industrial machinery though

Just remember things which heat up are 1 as are filament lamps, other things are less
 
Sorry to bring this up again and apologies for all the questions :)

I have seen some 110v strip lights (fluorescent) 5ft running 2 bulbs in each unit. Each bulb is 20w. Do you know if it is possible to join the 110v cables together then that way I can connect 2 lights at some time to the generator. Would a simple junction box be ok do you think?

Kind regards,
Richard
 
andy_mk3 said:
And the rest! I've measured a 1.6 petrol pull over 400amps cranking! Van batteries are rated for 600+ cranking amps usually!
Click to expand...


I see, so is it the 'flow' of amps that does the damage if you were somehow holding onto it whilst it started? i.e 12v is not a lot but the rate that it is entering body is to fast to handle?
 
You can get 110v splitters easy enough to connect your work lights

http://www.screwfix.com/p/masterplu...tracking url&gclid=CNT92PmszLICFYcPfAodGSAAmw

Ice Rich said:
I see, so is it the 'flow' of amps that does the damage if you were somehow holding onto it whilst it started? i.e 12v is not a lot but the rate that it is entering body is to fast to handle?
Click to expand...

Its the current which causes the damage in an electric shock, yes, and the levels at which it causes damage is quite low, a tenth of an amp is easily enough to be fatal, a hundereth of an amp is most certainly painful. The time for which the current flows is also important. The work of biegelmeier and lee is important here and forms the basis of how the writers of electrical regulations decide on acceptable disconnection times and touch voltages etc.

Where the voltage comes in, and why your car battery is quite safe to touch the terminals of, is due to skin resistance. 12v simply cannot push a large enough current through a body to cause damage, 230v on the other hand can. 50v is considered a safe level in most situations to humans. This is usually dropped to 25v for more hardardous connditions, or where animals are involved. You 110v site supply from that generator is actually whats called a CTE (centre tap to earth) supply, meaning that between each wire and the ground there is only 55v.... it is impossible to get a 110v volt shock unless touching both wires (which would have to be very bad luck, or deliberate)

Big batteries do have other risks though, if shorted out the current which can flow can cause signicant heating with the associated burn/fire risks from this. The hydrogen from charging can be an explosion risk, and the acid inside presents risks of chemical burns
 
Adam_151 said:
You 110v site supply from that generator is actually whats called a CTE (centre tap to earth) supply, meaning that between each wire and the ground there is only 55v.... it is impossible to get a 110v volt shock unless touching both wires (which would have to be very bad luck, or deliberate)
Click to expand...

It's an isolated generator, there should be zero volts between each wire and ground!
 
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