Hi,
I have a Bukh DV10 sail drive about 1985 vintage, it appears not to be charging the batteries, I suspect it is the regulator rectifier. before I spend the ridiculous amount Bukh want for a new one does anyone now how to test the old one to make sure this is the problem ? also if anyone knows of an aftermarket or alternative to the Bukh one this would be appreciated.
With the engine running a test meter over the battery terminals you should have about 13 + volts. Check to see if you have a warning light showing before you crank the engine and it goes out when it starts and has a few revs. Best bet is to remove the alternator and have an auto electrician bench test it for you.
Select to expand quoteCowza said..
Hi,
I have a Bukh DV10 sail drive about 1985 vintage, it appears not to be charging the batteries, I suspect it is the regulator rectifier. before I spend the ridiculous amount Bukh want for a new one does anyone now how to test the old one to make sure this is the problem ? also if anyone knows of an aftermarket or alternative to the Bukh one this would be appreciated.
If it cost more than $100 Id go get me self a holden alternator with the regulator built in I bought a new one was around
$200 95 amp
A couple of slight alterations and its done
Thats my old one
Even Ramona suggested to me this as he said
you can drop into any wrecker around Aust and pick up another for $50
I think from memory I just reduced the pivot boss slightly so it was the same as the original alternator the plus is that it doubles your charge rate .
My original I think was 35 amps the holden ( from memory it was around 198 model but you could take it into a retain shop and sort out which holden alternator suits your Bukh and then search for a cheaper one if needed )I bought was 95 amps .
I did change the v belts as well to suit.
Also the holden alternator has a built in regulator. I think I ran an earth and the alternator lead back to the battery and that was it toss and remove your Bukh charging system and your done
The good think about doing this is its a positive not a negative 
your now not repairing your improving your boat
Chariot will know the wiring off the top of his head
thanks Ramona & HG02, but mine doesn't have an alternator, it is a magneto type charging system under the fly wheel, with a regulator rectifier to regulate voltage. it is only charging at around 12.2 volts. I thought about youre idea of bypassing the whole system & fitting a belt driven alternator, probably have to get an electrician in to do that job, as I would have to fit pulleys etc to the fly wheel. a new rectifier from Bukh is around $600.
12.2 Volts on battery, really means ..not charging at all.
It would be complex mechanical modification to fit new style of alternator.
My question is, do you really need engine charge batteries, any solar panel installed.
As I understand, you have old style external regulator. To verify control box
is faulty, you have to measure voltage coming to the regulator box.
Can access wires from magneto and measure voltage.
Multimeter set to AV voltage range and tell us what's AC voltage OUT.
Hi Charriot, you have a point, I suspect the engine has not been charging for some time. I do have a small solar panel, & this does seem to keep Batteries topped up between sailing trips, but while on a 3 day trip from Gosford to Sydney Harbour I accidently hit the switch that turns the solar panel off (without realizing)& ended up with flat batteries, luckily the old Bukh is easy to pull start, this is when I realized that the motor was not charging as I thought by motoring for an hour or so it would charge up. I will try to test as you suggest next time I am out on the boat.
Select to expand quoteCharriot said..
12.2 Volts on battery, really means ..not charging at all.
It would be complex mechanical modification to fit new style of alternator.
My question is, do you really need engine charge batteries, any solar panel installed.
As I understand, you have old style external regulator. To verify control box
is faulty, you have to measure voltage coming to the regulator box.
Can access wires from magneto and measure voltage.
Multimeter set to AV voltage range and tell us what's AC voltage OUT.
Charriot was on the money
Select to expand quoteCowza said..
thanks Ramona & HG02, but mine doesn't have an alternator, it is a magneto type charging system under the fly wheel, with a regulator rectifier to regulate voltage. it is only charging at around 12.2 volts. I thought about youre idea of bypassing the whole system & fitting a belt driven alternator, probably have to get an electrician in to do that job, as I would have to fit pulleys etc to the fly wheel. a new rectifier from Bukh is around $600.
That flywheel looks like it has a V belt pulley on it. If yours has then fitting an automotive alternator with a built in regulator is the way to go. I used Falcon 6's Bosch units in my fishing vessel because they were cheap and easy to rebuild. For my race car I'm building I have a tiny little Suzuki alternator which has a flat pulley, you would either need to change the pulley to a suitable sized V pulley [the alternator needs to be rotating at at least 5,000rpm] or select another suitable alternator. Think along the lines of ride on mower alternators or any of the other small, highly efficient stuff out there.
I had a 3 cylinder Kubota auxillary with a two pole generator like an overgrown pushbike generator and a regulator rectifier and replacement costs were similar to yours. The same engine in tractors had an alternator!
You really need an alternator. There will be occasions when you may have to stop and start your engine and an alternator is the only way you will get the batteries up to charge quick enough.
Waste some time on eBay.
Hello Cowza, I suppose you have already found this but just in case you haven't here is a link to the work shop manual. I had a brief look at other forums and there didn't seem to be an easy fix for your problem (like and off the shelf cheap regulator) so replacing the whole alternator may be the cheaper option. If you are a bit electrically minded the manual has the wiring diagram so you can check the diodes etc.
Cheers
www.boatservicehaarlem.nl/bukh_dv10_dv20_workshop_manual.pdf
Well, manual is priceless
You have to do this test.....than you decide dispose alternator or get new voltage relay
/ off market one should be very cheap /
1/ disconnect Exc wire on regulator
...that's the wire going to alternator
2/ disconnect wire "+"
....that's the wire going to the battery
3 / connect those two wires together
4/ start the motor and measure charging bat. voltage.
if...over 13volts your alternator / diodes are ok, regulator is dead
--- you can charge battery this way but, overcharging can happen, what to do ..later..
if ..you find voltage around 12 volts, ..alternator itself is dead, than recommend disposal
thanks everyone for your input, I am new to this forum, & the responses have been all very helpful. I will do some tests on the rectifier hopefully this weekend, & check if the solar panel has bought the batteries back to life. Ramona, the fly wheel doesn't have a vee belt pulley, its really just a slot to wrap a cord around to hand start. I have just had a similar problem with a motorbike I have, turned out to be the stator, & the rectifier. motorbike rectifiers a soo much cheaper it would be good to find one with the same connections, but the boat rec has 6 wires, & the bike rec's seem to have 5 or 7 wires.
