Variable Supply

Submitted: Friday, Apr 22, 2016 at 11:55
ThreadID: 132203 Views:1583 Replies:4 FollowUps:4
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Finally back on deck & find travelling batteries are all down. To get the generator going can I connect a variable (0-24v) supply in place of the battery? Bill
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Reply By: HKB Electronics - Friday, Apr 22, 2016 at 12:59

Friday, Apr 22, 2016 at 12:59
Can you elaborate a little more on what your trying to achieve?

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Follow Up By: Member - Roachie - Friday, Apr 22, 2016 at 15:23

Friday, Apr 22, 2016 at 15:23
I'm with HKB...

The question simply doesn't make any sense.

You would need to tell us:

What type of vehicle are the batteries in (eg: Caravan, boat, truck etc)?
What is the operating voltage of that vehicle (ie: 12v or 24v)?
What EXACTLY do you mean when you talk about a "variable supply 0-24v"? Is this some sort of battery charger?
What generator are you referring to and how were you going to use it??

My assumption is that you have some sort of petrol driven generator and some sort of battery charger and you want to know if it's okay to connect these to your battery/ies....but there are simply too many assumptions there to be able to give you ANY sort of meaningful response.

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Reply By: Member - bill f (QLD) - Friday, Apr 22, 2016 at 16:53

Friday, Apr 22, 2016 at 16:53
The starter battery on the stationary generator at the shed will not wind it over. I have a variable power supply (240v in 0-24v out) that has been used to power an electric fence & in an emergency a compressor fridge .

The question is can I connect this supply in place of the battery? i.e. red outlet to + ve generator & black to -ve gen with the supply set to 12v.

I reckon it should work but don't want to blow anything up & have to spend the next few nights in the dark. Bill
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Follow Up By: Frank P (NSW) - Friday, Apr 22, 2016 at 17:23

Friday, Apr 22, 2016 at 17:23
If I read you right, you want to crank your stationary generator with your power supply set to 12V instead of using a 12V starter battery..

Have you tried using your power supply to get some charge into your starter battery? Try that first.

If the starting circuit is powered direct from the power supply, it probably won't work. The starting system on the generator will most likely require many more amps than your power supply can deliver.

But if it is a small generator (sounds like it may not be) and your power supply has a high current output (which I doubt, but maybe wrong) I suppose you could try it. If the power supply is a decent one it should protect itself against over-current (an output fuse or circuit breaker). If it doesn't adequately protect itself you will probably fry it.


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Follow Up By: Zippo - Friday, Apr 22, 2016 at 17:26

Friday, Apr 22, 2016 at 17:26
Bill, unless it is a real beefy power supply unit - i.e. capable of delivering CRANKING CURRENT to your genset starter, it won't get you anything other than maybe a cloud of smoke or a showers of sparks depending on how the power supply handles severe overload.
More info on the power supply's rating and the genset details. For instance if it CAN be hand-cranked but needs 12V for auxiliaries, you may be good to give it a whirl.
[Edit]: beaten by Frank
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Follow Up By: Bob Y. - Qld - Friday, Apr 22, 2016 at 20:07

Friday, Apr 22, 2016 at 20:07
Hey Bill, I'd be interested to know what power source you're going to use to run the variable power supply, if you can't start the genny?

Am assuming that the genny is fitted to a motor home/big van, and you'd rather use it to charge the "travelling batteries", if you can get it going. My thoughts after nearly 50 years living with gennys from 3kva up to 255kva, is it would be easier to just get a starting battery out of a vehicle, take it down to the genny in a wheelbarrow or trolley, and jump start the genny, off this donor battery. That's if you can't get a vehicle in close enough to jump start the genny?

If you haven't got a battery charger, then set the power supply to a little over 14v and leave for maybe 4-6 hrs and see if that puts a charge in it. Leave the p/s hooked up as you try it.........depending on the output amps on the p/s.


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Reply By: Member - Roachie - Friday, Apr 22, 2016 at 19:24

Friday, Apr 22, 2016 at 19:24

Basically we need to know what size/capacity the battery is (as that will give us an indication of how many cranking amps the gen set needs)

For the variable power supply, we'd need to know what it's maximum output capability is.

Is there any way you could take the battery out of your car or 4x4 etc to crank the gen set into life?
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Reply By: Member - bill f (QLD) - Saturday, Apr 23, 2016 at 00:33

Saturday, Apr 23, 2016 at 00:33
Thanks everyone for all the advice. The shed is on a country block & was previously wired for & run on 12v with charging of house battery done by the gennie. (5kva) I've just had 240 power put on but until it is all rewired there is only one 15 amp power point in the fuse box outside the shed.

Have to wait for the dozer to remake the track in so at the moment we have to carry everything the last 100metres. Alright for you young fellas but after a bad bout with cancer it's a bit much for me at the moment.

I'll give the battery a couple of hours on the power supply & see what happens. If no joy will have to leave early & bring a proper charger back.

Thanks again Bill
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