Alternators. Which way round?

[cardiffrob]

I have one of those tiddly little Austin Sevens with the old 3-brush dymanos on it. I've started converting it to 2-brush and 12 volts but have also wondered if an alternator might be a better bet in the short term. Question is...do alternators run both directions? Generally speaking all the ones I've ever played with run clockwise from the pulley end but it would be great if one ran the other way round. Lucas stuff would be affordable but Motorbike ones might also be handy.
Any thoughts?

 

[Seadog]

They're generating a.c. so should work in either direction. The brushes may complain at first if you do reverse one, having bedded down in one direction.

 

[500e]

Will run either direction, in a hot environment the cooling fan could cause problems but in an A7 doubt it.
Kubota make some small units, we did a conversion from outboard to inboard on an Albin sail boat years ago, swash plate pump on 7HP air cooled Robin engine.
The motor on a aerofoil leg with prop mounted on 2 outrigger bearings In alloy housing, all in a Kevlar housing to protect streamline, had to get it all in under the cabin stairs requiring smaller alt & reverse rotation, The reason was the customer wanted diesel not petrol & more MPG he was getting about 6hours at 5 knots in a gallon of fuel the 7Hp petrol OB was swallowing petrol at an alarming rate & the weight over the stern was cut by about 80%

 

[cardiffrob]

Thanks for the info. The A7 uses a flat belt, about 1 inch across. I'm hoping that one of them new fangled multi-groove belts might work.

I've googled the Kubota generator and it looks great but the price is a bit hefty.

 

[rtbcomp]

^^ Turn the belt inside out. An old cam belt might do the trick.

I use a mult-groove belt on my lathe, it goes round a washing machine motor pulley (grooved) and then round the flywheel which is plain. No problems.

 

[Justme]

You can get left & right cooling fins to adapt them.

 

[frank horton]

I've used the Kubota alternators on my old stuff.......keep looking they do come on special, I bought 6 at £75 about a year ago...they were genuine and brand new.......
there is a chinese copy that seems to work well......good price all the time...about £60 if I remember...
is the Lucas ACR series to big ???? u can buy them around the £30 mark all the time......
don't expect to much from the flat belt.....be nice to stick around the 20amp mark any more and the belt will suffer and u CAN'T afford to overtighten the belt....

 

[rtcosic]

20 amps at 12 volts on an Austin 7 would power everything electrical it possessed, and leave a bit left over for battery charging.

 

[Anguz]

you also get little denso alternators on dihatsu charades and the like
use one on my kit car, very easy to mount

 

[8ob]

Thanks for the info. The A7 uses a flat belt, about 1 inch across. I'm hoping that one of them new fangled multi-groove belts might work.

I've googled the Kubota generator and it looks great but the price is a bit hefty.

That denso alternator comes in a few different cases/mounting configurations and pulley types, I would imagine the ribbed belt version would lend itself for mods to flat belt. I collect them for projects and they normally change hands for about £20, thats not bad for a tiny 45amp internally regulated alternator.

Bob

 

[8ob]

 

[RichardM]

I was going to suggest putting a motorcycle alternator on, but the above seems an ideal option unless the mug's massive!

 

[merryman]

Most motorcycle alternator stators bolt into the engine case and the rotor is also the flywheel, attached to the crankshaft.

 

[ibrooks]

Yep those dinky little ones are the best bet. They are fitted on all sorts of small jap stuff. Mine on the GTM came from a Suzuki Alto (and is now mounted to a Nissan CG13 engine).

 

[RichardM]

Most motorcycle alternator stators bolt into the engine case and the rotor is also the flywheel, attached to the crankshaft.

most are but not all, e.g. 1200 / 600 bandit.

 

[Olderisbetter]

I have used these http://www.dynamoregulatorconversions.com/ for info and bits over the years

 

[merryman]

Just one point, the dynamo set up was adequate for daily use in the 1930s, presumably with quite a lot of long winter drives at night. Surely it should be more than adequate for the use they tend to get nowadays, daylight runs on summer days. Particularly if you stick LED bulbs in the lights.

 

[rtbcomp]

A friend of mine had a 3 brush dynamo in a Rover, he ended up changing to a more modern 2-brush type

https://www.mig-welding.co.uk/forum/threads/lucas-3-brush-dynamos.79429/#post-1119010

 

[Stueeee]

Just one point, the dynamo set up was adequate for daily use in the 1930s, presumably with quite a lot of long winter drives at night. Surely it should be more than adequate for the use they tend to get nowadays, daylight runs on summer days. Particularly if you stick LED bulbs in the lights.

The A7 dynamo has a maximum output of 10A, so 60W total, they are "regulated" by adjusting the position of a 3rd brush on the commutator. you can switch from full to half charge using a switch on the dashboard. even at 10A output they are known for throwing the solder off the commutator connections on occasion. Using LED sidelight etc. bulbs does lighten the load, but to get any kind of beam, the headlights do need proper bulbs, and really something a fair bit bigger than the 24W jobs that the factory fitted.

The thing is that as the A7 dynamo is gear driven, and also drives the distributor, it isn't simple to change it out. You can see the issue in this one that I prepared earlier.

 

[ibrooks]

What sort of room is there around it in the bay? There is a belt drive that could be used to drive a dinky little alternator and leave the existing dynamo where it is as a jackshaft.