I'm looking to make or buy a device which will allow me to power for a brief test run some 24v side and brake lights on a vehicle from a 12v supply. The vehicle might have LEDs, or conventional bulbs, depends on the year of manufacture etc.
Anyone have any ideas of how to test at up to 70w at 24v from a 12v supply on a van ?
This sort of thing, perhaps?
Nick
Something like this?
Will this do? A bit pricey mind...
Tim
NET-POE-12TO24V at
Owain
On Saturday 28 December 2013 22:15 Nthkentman wrote in uk.d-i-y:
Small 12V motorcycle battery in series?
If this is just a brief test of lamps(*) whats wrong with a couple of series connected small 12 V sealed lead acid batteries? 70 W @ 24 V is 3A, not a great current for an SLA, see what is available and at what price in the 2 to 3 AHr capacity. Wall wart mains 12 V SLA charger and charge them individually. In the past I've found that following company offers good service and prices:
No need for the technology of a fairly chunky and expensive DC-DC convertor.
(*) In or out of circuit? I'm assuming out otherwise you'd be using the trucks 24 V battery...
Have you considered simply testing at 12V?
Bill
Um, my linked converter is still sitting at £3.99. It is an auction admittedly but they're not that expensive. A lot cheaper and less clunky than messing about with extra batteries
Tim
In message , Tim Watts writes
+1. You beat me to it (although I wouldn't have mentioned 'small' or 'motorcycle').On Sunday 29 December 2013 08:44 Ian Jackson wrote in uk.d-i-y:
For some reason I was considering something easy to carry :)
An old 12V car battery of course would be free.
Why not just get two batteries, or am I missing something here?
Brian
Well it will give a very basic go/no go but not heat the filament to operating temperature and the stress things properly. Mind you 2 x 12 V batts will have a lower voltage, on load, than the truck with the engine running.
That will be the 24V SDS cordless battery.
I was going to say a small-ish leisure battery as being a bit more tolerant of flattening.
A chopper circuit followed by a voltage doubler
Something like this?
OOOOH! Ta Toby,
That might well do the trick....
This sort of thing, perhaps?
That would be perfect but I suspect my MD might balk at the price... Good idea though, but perhaps insufficient amps to start some of the kit I have. As for testing rear lights on Moffets.... Overkill... But I do like the design
A capacitor switcher wastes 50% of the energy at each stage. (When charging a capacitor, half the energy consumed ends up in the capacitor, and the other half is lost in the circuit resistance.)
A more efficient version would be a Boost Switched Mode PSU
Probably around 40 years ago, Everyday Electronics did a circuit to drive a 24V 50W Weller TCP soldering iron from a car battery, which was based on this AFAICR. I've used it a few times since, although I've built many more Buck Switched Mode PSUs, to drop voltage or provide constant current for power LEDs.
There are loads of 12-24v convertors on Ebay - naturally from China.
A 150watt ones costs about 8 quid with free postage. Will need a box of some sort.
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