Micro 12v Generator Project

[mattnj]

So when all is complete are you going to supply us with a list of parts so we can get cracking on ours?
You can sell us an electronics kit so we can develop our circuit board building skills?
Will we then have a good lightweight charger that doubles as a pump?
Can you sumerise why this item ( properly developed and marketed) will be superior to buying a cheapo genny (Sub 1KW and sub £100)
One reson for me buying the cheapo genny was emergency charging the starter battery!
Congratulations by the way!!

sure, because it will be in a box that can be installed somewhere, super light, under 8kg, hopefully more like 6.5kg over 13kg for an EU10i, and about half the physical size, super quiet compared to all the others, you can barely hear it running, its water cooled with water cooled exhaust and electric start (auto voltage sensing so can start by itself)

 

[mattnj]

Peter
http://www.energymatters.com.au/generators-honda-c-159_272.html
About £600ish, they look like good pro jobs.

no electric start, no water cooling on those..they are very noisy, like the SDMO things, cant run them at night....thats the whole point, can run at anytime, without touching it, also cant run the suitcase ones whilst underway, just not the same thing. neither the SDMO or one of these, address what i am trying to do so are therefore irrelavent.

 

[pcatterall]

All good points, those Aussie units seem quite useful even with the limitations you list.
They also seem quite expensive!! What ball park would you say your system might work out at with new main parts and DIY electronics?

 

[2Tizwoz]

Seddons are offering the GX22 engine at £76.63 http://www.seddondirect.co.uk/productDetails.asp?productID=370

The built in fuel tank isn't very large.

 

[mattnj]

All good points, those Aussie units seem quite useful even with the limitations you list.
They also seem quite expensive!! What ball park would you say your system might work out at with new main parts and DIY electronics?

£100 for alternator, £100ish for engine, £50 for pump, electronics, pipe and brackets etc ish. plus £50 for all the bits i have forgotten about.

I have no plans on making more than 1!

 

[Cari bean Pie rat.]

Do not understand what you say when you say :
"with a simple diode mod on the regulator to boost the output voltage."
Diodes do not boost voltage as far as I know and would be intrested to know more as a regulator is as far as I know 1 to 4 diodes in a circuit.

 

[2Tizwoz]

There's a self priming gear pump

good for 10,000 hrs 2 litres /min. against a 1.5m head £18.18 delivered http://cgi.ebay.co.uk/NEW-2L-DC-12V...den_PondsWaterFeatures_UK&hash=item4aa36e63f7 on ebay.

Have you considered putting a coil of say 8mm copper pipe carrying the inward flow from the pump in the box so that the airstream from the fans can be cooled to make it simpler to maintain the cooling water circuit? Engine and alternator cooling circuits are inclined to be a troublesome part of self contained generators. Then into your exhaust injector.

Of course the trickiest part is the electronics with the PIC and various ICs which can make the whole operation self sufficient and regulating.

Will you be making the detail of that available?

The usual rule of thumb for battery charging seems to be less than 10% of capacity to avoid topping up.

What current could the GX25 manage?

 

[Heckler]

There's a self priming gear pump

good for 10,000 hrs 2 litres /min. against a 1.5m head £18.18 delivered http://cgi.ebay.co.uk/NEW-2L-DC-12V...den_PondsWaterFeatures_UK&hash=item4aa36e63f7 on ebay.

Have you considered putting a coil of say 8mm copper pipe carrying the inward flow from the pump in the box so that the airstream from the fans can be cooled to make it simpler to maintain the cooling water circuit? Engine and alternator cooling circuits are inclined to be a troublesome part of self contained generators. Then into your exhaust injector.

Of course the trickiest part is the electronics with the PIC and various ICs which can make the whole operation self sufficient and regulating.

Will you be making the detail of that available?

The usual rule of thumb for battery charging seems to be less than 10% of capacity to avoid topping up.

What current could the GX25 manage?

The usual rule of thumb is 750ish watts = 1 HP. the GX25 is quoted in a quick Google as 1.5 HP
So its capable of 1075 watts ISH! That will be at full chat as well. So 4 amps at 240 volts (before the toothsuckers jump in, I am doing very rough calcs here!)
At 12v of course, ignoring losses, about 90 amps.
But of course, as Matt has found out, put an alternator on, dump a flat battery in to circuit and we have a situation where the small engine cant deal with the load. An age old conundrum, how to deal with light and heavy loads as they present themselves to an engine!
Stu

 

[VicS]

What current could the GX25 manage?

The max power output from the GX25 is a bit less than 1 hp ,,, 720 watts to be precise at 7000 rpm. Equal to approx 52 amps at 13.8 volts

Matt wanted to run the engine at somewhat less than full revs.
but that meant less power output, as you can see giving only slightly more than 0.5 kw at 5000rpm (I forget without reading back through the whole thread what speed he actually wanted to run it at)

The trouble he had with the original alternator was that without any control it could deliver 57 amps at 13.8 volts ( ie over 780watts) at 5000rpm but you cannot stick 500 watts in via the drive shaft and extract 780watts of electrical power from the other end!
That is what gave rise to the need to electronically control the alternator output but in part solved when he found a smaller alternator.

Reducing the alternator speed below engine speed with some sort of reduction gear or belt system would have overcome the problem (contrary to the rubbish he was told in post #2 about it being necessary to increase the speed in order for it to work at all!) but would have compromised the whole concept of building a compact unit .

 

[VicS]

A little later... after watching "Countryfile"

There is also a GX35 engine. It's a little larger and a little heavier but delivers 1.3 hp or 1 kw at 7000 rpm

http://www.honda-engines.com/engines/gx35.htm

It would come pretty close to matching the 40 amp alternator matt subsequently used. Certainly at speeds of 4000rpm upwards.

Matt of course already had the GX25 engine to experiment with but starting from scratch the GX35 and a 40 amp Denso 8172 alternator would look like a pretty good combination.

http://www.brise.co.uk/documents/8172.pdf

 

[saltwater_gypsy]

The GX 22 looks good but there could be some bugs in it!!!!

 

[VicS]

The GX 22 looks good

Whats the differnce between the GX22 and the GX25.

 

[2Tizwoz]

Whats the differnce between the GX22 and the GX25.

GX22

3cc ?

 

[mattnj]

Whats the differnce between the GX22 and the GX25.

as far as i know (could be wrong) the GX25 is the newer GX22, which is not made anymore, the GX25 is euro emissions compliant, or something like that, but basically, same thing.

 

[mattnj]

Do not understand what you say when you say :
"with a simple diode mod on the regulator to boost the output voltage."
Diodes do not boost voltage as far as I know and would be intrested to know more as a regulator is as far as I know 1 to 4 diodes in a circuit.

here you go, i thought originally i "may" need to increase output, but ended up needing to control it completely:-

http://www.smartgauge.co.uk/alt_mod.html

 

[mattnj]

Have you considered putting a coil of say 8mm copper pipe carrying the inward flow from the pump in the box so that the airstream from the fans can be cooled to make it simpler to maintain the cooling water circuit? Engine and alternator cooling circuits are inclined to be a troublesome part of self contained generators. Then into your exhaust injector.

Of course the trickiest part is the electronics with the PIC and various ICs which can make the whole operation self sufficient and regulating.

Will you be making the detail of that available?

What current could the GX25 manage?

Yes, kind of working on water cooling improvements in parallel with the other bits....

Yes, would be happy to disclose the PIC program and full circuit in the future.

From what i have done so far, i reckon it will do 20amps at a nice quiet rpm and a max of 30-35 when flat out, but havent tried it at higher rpm yet.

I am currently tweaking the coupling and alternator mount, have ended up shortening and using a different couling, all needs to be spot on when you start putting 1hp through it for a decent period of time.

 

[mattnj]

A little later... after watching "Countryfile"

There is also a GX35 engine. It's a little larger and a little heavier but delivers 1.3 hp or 1 kw at 7000 rpm

http://www.honda-engines.com/engines/gx35.htm

It would come pretty close to matching the 40 amp alternator matt subsequently used. Certainly at speeds of 4000rpm upwards.

Matt of course already had the GX25 engine to experiment with but starting from scratch the GX35 and a 40 amp Denso 8172 alternator would look like a pretty good combination.

http://www.brise.co.uk/documents/8172.pdf

yes i think the GX35 would be a better choice, think its that same mounts, so hopefully an easy swap if it ends up being a touch under powered, or i just want some more amps for same rpm/noise levels.

 

[2Tizwoz]

The Lucas 17ACR alternator is very common, fitted to many older boats, and less costly than most. Perhaps a close match to the smaller engine.

How to wire it as a motor for starting?

Cut the starter function and return to being an alternator after the engine has achieved some pre-programmed speed?

 

[Heckler]

GX22

3cc ?

I was talking to Charles Sterling a few years ago and he reckoned that he had been experimenting with a std Valeo alternator and had been getting 100amps continuous out of it. Prob is of course that without any decent regulation, as Matt has found out, the little 25cc ish engines struggle to cope. The scenario of a flat battery bank and a std regulator is a recipe for trouble, they cant cope with the start up loads. The beauty of my solution is that the on board charger deals with this situation plus the SDMO regulator/invertor has superb control built in anyway. All in a one handed quiet package ready to go, all I paid for mine was £239!
Stu

 

[VicS]

The Lucas 17ACR alternator is very common, fitted to many older boats, and less costly than most. Perhaps a close match to the smaller engine.

I think the 17ACR will still be a bit too big for the GX25, at least it will be if the speed is to be kept below 5000 rpm

16 ACR looks more reasonable and the 15 ACR looks as though It might even be a goer at 4000 rpm

Must remember that the efficiency of the alternators will be less than 100%. If you stick 500 watts of mechanical power in at one end you are not going to get 500watts of electrical power out of the other end. It is going to consume some of the energy energising its own field windings for a start.

How to wire it as a motor for starting?

Cut the starter function and return to being an alternator after the engine has achieved some pre-programmed speed?

You cannot wire an alternator as a motor for starting ... can you ?