My Lister running in full CHP with video - cross posted from VOD

[julesandtash]

If you can get one on the super cheap I would be very very  grateful and happy to give it a go.
The Lister is only good for about 15A so potentially I could sit the UPS next to the Lister and use it to smooth all the power into the house which would be very nice

[rbdazza]

It will likely be free, might cost me a drink...

[julesandtash]

I will buy you quite a lot of drinks if you can get me one then.
Looking at UPS units online, it appears that an online variety would do the job nicely as it will rectify the incoming AC to DC (which should not be too picky with regard to the waveform) and then invert it to true sine wave AC which everything should like.

[photoman290]

i am not sure  trying to use a ups as a signal conditioner will work. you may run into the same problems you did with with the mig. i had a trace inverter with a built in battery charger that i killed by trying to charge the batteries with the genny. the electronics are expecting something like a sine wave. put a triangular waveform in them and you get all sorts of spikes which will kill the fets. using  one as a ups on battery power as a UPS will work,hence the 48 volt 50 amp supply. you could use 4 12 volt batteries and charge them during the time you are on mains power from the internal charger in the UPS.   if you are down this way i have one you can play with.they are heavy around 30 kgs.

[julesandtash]

Thanks Bob. The problem with the Mig was purely that the engine didn't have the power to drive it at high enough current. It would strike and arc and the alternator output would jump massively but soon that initial burst of energy in the flywheel was used up and there was not enough current

It would be nice to try an AVR alternator in place of the capacitor excited one but they are not cheap bits of kit new and not that common secondhand - most spares or repair generators have working engines and dead alternators

[julesandtash]

I suppose a further alternative would be to generate at 48v DC and power an inverter from that

[photoman290]

I suppose a further alternative would be to generate at 48v DC and power an inverter from that

yes that is what i meant. power the UPS from a 48 volt supply. one way to do that would be if the generator has a 110 volt output you could use a  240/110 volt transformer. that would give you give you around 50 volts ac a couple of stud diodes and a bit of ally for a heat sink. i use a transformer with a couple of diodes to charge my battery bank at 50 amps works fine and has done for 5 years or so.

[julesandtash]

Hmmm - it does have two 115V coils. Currently they are connected in series to give 230V but it would be easy enough to wire them in parallel for 115V which, at full output, would be around 30A
I guess all I would need then is a 3KVA or higher 240/110 transformer and the diodes

I will see what Dazza comes up with (and NigelB has kindly agreed to transport from Derby to Cornwall if does get one) and take it from there

[therecklessengineer]

Am I missing something?

110V AC doesn't give you 50V. 110V AC rectified directly would give you about 150V DC.

[julesandtash]

The bit where bob said feed the 110V into a 240v to 110v transformer which would give about 50v ac then recify that.

[photoman290]

you  may need to use 4 diodes and smooth it a bit as well. a  couple of 100 volt electrolytics  should do it  as long as they can handle the current. not sure how fussy UPS's are about the battery side DC. of course 4 12 volt batteries would also work, and may be a bit simpler. 

rewire the genny for 110 volts

use 240/110 transformer 240 side connected to 110volt output from genny

50 volt output from transformer to either 2 stud diodes or 4 12 volt batteries.
if the UPS doenst like halfwave recified AC either use 4 12 volt batteries charged from the halfwave AC or use a bridge recifier and a couple of smoothing caps to supply the UPS with a clean dc signal.

simples ish.....depends on whether high current caps or  batteries are easier to find. 

 

[photoman290]

while checking high power caps and power supplies i came across this. looks quite handy. 80 volt max so x10 probe will get you 800 volts. only 1meg but fine for checking the genny waveform.

http://www.amazon.co.uk/SainSmart-Pocket-Sized-Digital-Oscilloscope-DSO201/dp/B006CQT49E/ref=sr_1_1?ie=UTF8&qid=1415745540&sr=8-1&keywords=pocket+oscilloscope

[therecklessengineer]

Aha, I see.

50V AC rectified will give you about 71 volts DC though. If I've got my maths right then you'll be wanting about 57V to fully charge a 48V battery bank.

[Chug]

Excellent Jules, its great to see it doing what it's supposed to do, some dreamers just let them rot in fields!
I'm turning green!

[julesandtash]

Thanks Chug - yours always starts OK having been abandoned all year so I suspect internally it is pretty good.
With a bit of a service and addition of an alternator, you have a bio fuelled BBB