Dead UPS

Sounds okay, with several caveats:

Motorcycle batteries are pretty unsuitable for inside use.

Motorcycle batteries are not meant to be discharged beyond a certain point...cuts their lifetime in half...or worse.

UPS batteries are probably not much more expensive than than motorcycle batteries, will fit *inside* the UPS, and will last longer...both per use and total lifetime.

All that said, if you got motorcycle batteries, you don't have UPS batteries, you don't actually 'use' the UPS all that often, (and/or all that long) AND you have the batteries in a well-ventilated area...hydrogen gas is no fun to breath, and is explosive (think: Hindenburg).

...it might just work. Better than nothing, anyway. Sounds risky, though.

jak

some bikes now use SLA batteries. the yamaha XVS250 is one.

All that, plus make sure that your long wiring to the M.C. batteries is of a suitably heavy gauge, and all the connections are really sound. On start-up, UPS's pull monster amounts of current, and any voltage drop across less-than-perfect connectors, or inadequate wire, can cause erratic behaviour, as the UPS thinks that the batteries are in poor condition, and unable to support the current it is looking for. Don't ask me how I know this ... d;~}

Arfa

I want to build my own. I have a 2000 watt inverter I can hook up to one or 2 car batteries. All I need is a relay to cut in the inverter and cut out the trickle charger when the power drops. A time delay relay would be good too so if the power fluctuates on and off several times in a second it don't keep switching and stays on battery. Anybody done this? I'd like more capacity to back up things. Some inverters output is a stepped spike wave instead of a sign wave so that may be an issue with electronics. I'm not sure how much.

Can be quite a lot. Better UPS units put out a smoother wave approximation. Also higher-end units like mine from APC allow you to daisy chain external battery packs to add capacity.

I'm sure you can do what you are attempting, but it's likely to be an ugly implementation which in all likelihood won't save you any money vs. buying a used UPS off of eBay. I bought mine, a 2500VA model, for about $30 plus the obligatory $50-$60 for shipping lead-acid batteries... they're heavy.

Dave S.

worked for me.

i used some 'expired' gel batteries from emergency lighting units or security alam boxes.

they seem to last forever and are 'sealed' or whatever that means. mine have been going good for about 6 years beyond the expire date.

i just doubled up the same size wire from inside the UPS, i have two nicely power drill twisted runs of wire out of the UPS to the batteries.

dont use cheap spade connectors, get the heavy duty automotive ones that can handle 10amps or more

one more thing... add a fuse in line with the connection between the two batteries..

Mark

Yes; those are not deep cycle batteries..

I used two 50AH deep-cycle batteries on my 1200VA SmartUPS. Only issue was a full discharge took days to recharge...

Be sure the jumper between the batteries is fused.

While you're at it, buy some rubber grommets with holes in the middle. Drill your holes larger than the wires and insert the grommets first, then wire through the middle. You definitely don't want a short to the cabinet with that kind of current involved.

jak