Electronics Forum / Electronics / March 2007

Alot of the cheaper UPSs don't have a high duty cycle, they count on the
fact that the battery will go dead within X minutes and design the UPS to
survive X+5 minutes (for example).

If your UPS has the option of adding battery packs then it should be fine
(and probably also too big to keep in your car). If it has a fan then it
might be OK. If its a good brand or you add a fan then its worth a shot.

Of course all of that only really applies if your putting a fairly high
load on it, if you just want to run a fluro light or an FM radio you
shouldn't be pulling enough power for it to even warm up.

-- Michael Heydon

Depending on the model it may need the battery for loading and proper
function

Apart from the duty cycle consideration, it shoud be fine.  I use one to run my
Weller iron in the field.  The only downside is the ferkin annoying beeping
because it's upset at having no mains input.  (The beeper is ferkin hard to get
at to disable elegantly).

Be aware that they DO pull a decent bit of current @12V and cig-lighter outlets
often provide poor contact.

The one I tried to do that with had a 'safety feature' that inhibited the
inverter unless the mains had been supplied and then cut off, the solution
to that was to make a blocking oscillator with the centre-tapped secondary
of the small mains in transformer and power the BO via a push button to fool
the control circuit into thinking mains was supplied and just failed.