Electronics wipeout

[al40]

Ah ok - so there is no field coil that a regulator can work on - that explains why it doesn't have one! I guess if the battery is large enough, then 9A is not going to give a huge problem, although it can still boil it! The manual for the motor should spec a minimum battery size (amp-hour) that should avoid problems (hopefully).

I would however try and get a regulator that can work inline. The normal type obviously won't work as these control the field current to vary power from alternator but there are no doubt other types out there that will work directly on the output (maintain a max voltage of 14.4 - ask biggles, as per his post he fitted one to his old merc 50)

The power supply inside the electronics will get pushed a bit harder the higher the input voltage and depending on the type of power supply that's inside, will get warmer. I'd check to see if the high input voltages mentioned in the manual are sustained or peak levels.

I agree tho - if the battery connections are OK then the voltage at the electronics should be nice and smooth - do check your battery connections and cables tho - starting is sometimes possible on a loose battery connection as it will arc and start OK. This happened to me recently - engine would start but wasn't charging battery well. Eventually, I saw smoke coming from battery connection when I spun the starter and sure enough the conneciton was loose......

I still can't think where a damaging spike might come from (Assuming that's what caused the damage)... Coils and inductors can generate huge voltages when current is removed from them (back EMF - basically how an ignition coil works), but I cannot think how an alternator could get into such a state, even if the rectifier was faulty.

Hope you manage to narrow it down / solve the problem!

[al40]

Originally Posted by rickuk3

Older engines did not have alternators, power is produced by coils under the flywheel and just rectified, some instruments are designed to take the higher voltage (Garmin GPS2106 upto 30 volts), but you are always on tender hooks that some thing will blow.

Yes, a really old Volvo Penta O/B of mine had one of these - I think they called it a lighting coil, may not even have been rectified!

[rickuk3]

Originally Posted by al40

Yes, a really old Volvo Penta O/B of mine had one of these - I think they called it a lighting coil, may not even have been rectified!

Mine is a 1990 Mariner 50hp 2 stroke and only has a rectifier

[trentsidetimbo]

As said earlier,,,I think an fitting an extra regulator inline with the instrument loads might be a good idea,,,
There seem to be quite a few motorcycle ones on ebay for a tenner!!
Thinking about it,, 17-12
=5volts to get rid of X 9amps means there is only 45watts to dissipate on full load!!
I am suprised that there is not even a simple zener diode in circuit,, but there must be plenty of these engines about, so the design can't be that bad???

[al40]

yep - that should work well (was just looking at motorcyle dynamos and regulators and seems failry std part). You'll prob be disspating even less than that as it will need to regulate higher than 12v to actually charge the battery - more like 14v

Agreed, there must be 100's of these engines out there - sounds like you just had bad luck.

Good luck!

[trentsidetimbo]

Hi all,,
Thought that I would update you on the wipeout remedy,,
Seem's that the initial problem has been caused by the battery isolating switch being operated whils't the engine was running!!
This allowed the alternator to feed the electronics directly,,causing the lot to commit suicide !!
Be warned ,, apparently a lot of Ribs are wired this way and we have obviously got away with it for many years!!
Anyway, we have since fitted an excellent unit available from Electrex that not only pins the charge voltage down to 14.5 v, but shuts its output down when a battery is disconnected/not present..
http://www.electrexworld.co.uk/erol....k%252Ftoc.html



Thanks again to all who have contributed to this thread ..

[jyasaki]

Selecting the "off" position on a battery switch with the motor running can also take out the rectifier assembly on the motor.

Some battery switches come with a "field disconnect" connection that essentially kills the regulator output when "off" is selected, but the motor has to have the connection as well.

Sorry to hear about your troubles; hope they get sorted out.

jky

[GED]

[QUOTE=trentsidetimbo;187951] Hi all,,
Thought that I would update you on the wipeout remedy,,
Seem's that the initial problem has been caused by the battery isolating switch being operated whils't the engine was running!!
This allowed the alternator to feed the electronics directly,,causing the lot to commit suicide !!
Be warned ,, apparently a lot of Ribs are wired this way and we have obviously got away with it for many years!!


I had a battery isolating switch fail due to damp and salt water...causing my 200hp engine to go on fire at sea now I do not fit isolating switches, just a removable battery post clamp

[Nos4r2]

Originally Posted by GED

I had a battery isolating switch fail due to damp and salt water...causing my 200hp engine to go on fire at sea now I do not fit isolating switches, just a removable battery post clamp

I've stopped using the so-called 'marine' isolators too after frying a VHF from the same cause.
I use an HGV isolator now. It's far more robust and designed to live on the outside of the truck for 1,000,000km+ in all weathers.It doesn't have a removable key either. I've sikaflexed around all the joints in the pressings too just to make sure