Generator question

[Nickhlx]

Why are some / most petrol (and maybe others as well) 230V a.c. generators that have a 12 volt output, have this 12 Volt output rated at 100 watts, whether they are smaller ones or larger ones ?

 

Nick

Edited January 27, 2015 by Nickhlx

[Martin Megson]

Possibly due to cable sizes required for larger output. 2kw @ 240v = 8.3 Amps. 100 W @12 v is also 8.3 amps.

[smileypete]

As far as I know it's usually just a basic unregulated output intended for charging flat car starting batts.

 

So the output is sized to a typical car batt, not the generator itself.

 

cheers, Pete.

~smpt~

Edited January 27, 2015 by smileypete

[by'eck]

Many have a dedicated secondary stator winding for the 12 volt charging output.

 

The Honda EU20i for example has only a bridge rectifier between the dedicated stator and the 12 volt output socket. It therfore gives an unregulated output limited in power by the size of this stator.

[Loafer]

It can't be much beyond the wit of man to produce a little genny that has it's own 12V charging curves at max power.

 

Most liverbores wouldn't need a battery charger then, including me.

[rogeriko]

It can't be much beyond the wit of man to produce a little genny that has it's own 12V charging curves at max power.

 

Most liverbores wouldn't need a battery charger then, including me.

 

You mean like these

 

 

[MarkHez]

I made my generator from an old honda G40 I picked up off a farmer, and an alternator that I got for a £10 from a local car breaker. Using jump leads at the moment till I knock some cables with anderson plugs up, but its a damn sight better than a battery charger in my eyes!

 

[Loafer]

 

You mean like these

 

 

 

Yes, I do. Could be my next generator. Thanks!

[Guest]

I have this ancient 12 volt only (well actually 6-12-24, but not 240 ac) Honda genny that can output about 15 amps continuosly. It can also put up to 16 volts across the bank and is good for desulphation purposes. It is unbelievably quiet. I have had numerous attempts of people trying to purchase it!

Edited January 28, 2015 by Guest

[Loafer]

Nice one.

[onionbargee]

The 8 amp 12v winding common on cheap generators is seperate to the main winding, its just a donut sized bit added on to the end of the alternator as an after thought.

 

I have a Honda ED400 like the above, they are good machines, based on Ex650 engines, which means engine parts were easy to source.. They have no charge control though. I've never seen anything off the shelf that could be used with it ? Suggestions please. They go for about £100 on eBay, there's quite often one on there.

 

The yellow Chinese battery charger in the picture has / had a 40 % return rate, I don't think anyone will stock then anymore.

Edited January 30, 2015 by onionbargee

[madcat]

I've got the engine off an old concrete mixer driving a car alternator , works well

[bargemast]

I've got the engine off an old concrete mixer driving a car alternator , works well

 

A perfect solution, cheap and cheerful.

 

Peter.

[onionbargee]

The Honda G40 engined charger in the picture could be improved by a bigger pulley on the engine, 5 or 6 inch diameter. Run the engine at about 2000 / 2200 rpm, for less noise and less wear, and the Bosch alternator at around 5000 rpm, which should get you near full output.

[Loafer]

The Honda G40 engined charger in the picture could be improved by a bigger pulley on the engine, 5 or 6 inch diameter. Run the engine at about 2000 / 2200 rpm, for less noise and less wear, and the Bosch alternator at around 5000 rpm, which should get you near full output.

As long as the engine can produce enough power at that rpm to match the alternator's requirements.

[onionbargee]

In theory 23 amps per hp is an accepted figure for 14.8 v. the G40 engine is 3 .3 hp a 3600 rpm, and that looks like an 80 amp Bosch, so it is too big.

 

You need some kind of charge control to make it work. A car alternator isn't a leisure battery charger .

Edited January 31, 2015 by onionbargee