Genset concept

[Omatako]

I've been talking on the board for a while now about the genset that I am building for my boat. It is based on an old Fischer Panda unit that I bought for a few bucks as scrap. The original alternator was 24v and was trashed but the Kubota engine and the soundproof box are in fine shape.

So I decided that it would be advantageous to rebuild it with two replaceable alternators rather than trying to re-instate the original package. Three reasons were the immediate cost, the fact that I never got the original charge controllers with the unit and the capability to effectively maintain the end result myself wherever I may be in the world.

The generator part looks like this:



The large round flange mates exactly with the engine and centers the whole add-on. The components that were used in this construction are:



The ratio of drive to driven is 2.7:1 so when the engine is running at 2000rpm the alts will be running at 5400rpm. The alternators have twin cooling fans which are straight-bladed enabling the alternators to effectively run counter-clockwise. And then I grafted a Jabsco pump identical in spec to the original electric driven one in here:



The pulley that drives the pump is a Mi-Lock which is a mini Taper-Loc that allows the pulley to be positioned anywhere along the shaft and tightened right there.

Members may remember that I asked the question about the cooling implications of having a pump after the heat exchanger - well this is that pump. I have found a decent solution to the routing of the pipes so it's all good.

The alternators are generic Bosch 120amp units that are used widely in a range of European cars (BMW, Volkswagen, Opel) and should be available just about anywhere in the world. I am also told by more than one Auto Electrician that these particular models are very robust and give very little hassle.



So whaddayathink??

[Hartley18]

I'm impressed!

A mighty fine job you've done there Andre. A lot more compact than I'd have thought possible...

Are you sure the alternators will get enough cooling air?

[centaursailor]

Thats what I call Master Craftsmanship. Neat.

Safe sailing

[Omatako]

Originally Posted by Hartley18

Are you sure the alternators will get enough cooling air?

Thanks for the compliments.

The compactness was the biggest challenge by far. It took several months of modelling and modifying to get it all in. Even now, there are a lot of tolerances that have just a few millimeters to spare - it's really tight. When it's all assembled I'll post some pics to demonstrate.

The original alternator was air cooled and I understand that after that series apparently gave some trouble, Fischer Panda changed to water cooled units. But then it has to be said that they had a very solid, very heavy housing with just a few drillings for air flow and one tiny fan driven at crankshaft speed to cool the whole thing.

I have essentially four fans (two in each alternator) running at 2 1/2 times engine speed so the air flow will be substantially better. Also the alts will be running on internal regulators which will also slow the charge rate when they start getting too hot. I have also made provision if the heat builds up too much to have a large engine blower with ducted fresh air blowing into the enclosure but I honestly don't believe it will get to that.

We'll see.

[Hartley18]

Sounds like you've got it sorted.. Only reason I ask is that I've seen similar setups where all the fans are doing is circulating hot air!

We haven't seen the enclosure, but if there's a fresh air intake at the front of the alternators and the airflow is directed across the top of the engine and out the back, you should be fine.

[tdw]

Impressive, very impressive indeed. Well done Andre.

[christyleigh]

Great engineering job ! You mentioned a small concern about air cooling. It seems to me with all the minimum amp draw fans around these days I would plan on a fan driven cool air input/warm output as an integral part of the plan. The only other comment I have is about the belt you labeled - "Timing belt unknown origin". Do you have 5 of them or know where to get them ? If not ...........

[Omatako]

Originally Posted by christyleigh

Great engineering job ! You mentioned a small concern about air cooling. It seems to me with all the minimum amp draw fans around these days I would plan on a fan driven cool air input/warm output as an integral part of the plan. The only other comment I have is about the belt you labeled - "Timing belt unknown origin". Do you have 5 of them or know where to get them ? If not ...........

No, the comment is simply that I have no idea what vehicle engine it comes from. Now that I have the Gates belt number, they're freely available from almost any auto shop. I believe it to a variant of a Toyota engine but I bought it simply on tooth design and length - the origin was not important.

Also remember that it is an automotive timing belt that will last on an engine for 90000kms which at an average speed of 45 kms/hour amounts to 2000 hours and that is at engine speeds two or even three times what it will do in the genset. I expect it to last for several years.

Nad naturally like all belts I will carry a spare.