I googled “load dump”... got an image of guy sitting on the head ;).
/John > On Sep 27, 2019, at 3:08 AM, Matti Airas <mai...@iki.fi> wrote: > > Hi, > > I'd check the battery and alternator connections carefully. And the main > switches, too. If the batteries get disconnected while the motor is on, the > alternator will create a load dump that can be even over 100V for a fraction > of a second. In principle, automotive and marine electronics should be > protected from that but you never know. I'm only speculating, but if that was > the reason, maybe the voltage spike was short enough that the fuses didn't > have time to heat up? > > Google for "load dump" if you want to learn more. > > Cheers, > > Matti Airas > C&C 36 "Hurma" > Helsinki, Finland > > >> On Thu, 26 Sep 2019 at 22:26, Ian Matthew via CnC-List >> <cnc-list@cnc-list.com> wrote: >> I have been following the list for many years and I enjoy reading the wisdom >> of this group. I have an interesting problem and seek your advice. >> >> I have an very intermittent electrical problem (in fact it has only happened >> twice in the last 7 years. In both cases it has resulted in electrical / >> electronic components becoming 'blown out' with all fuses inline remaining >> good. >> >> The first time I suddenly lost my AM/FM radio and ALL my navigation lights. >> The engine also stopped as I had no power to drive the electric fuel pump. >> This happened when motoring back home at night after a long race. >> Fortunately there was wind and a hand-held VHF and a powerful spotlight on >> the sails allowed us to be seen by commercial traffic. Afterwards, I >> checked - ALL the incandescent bulbs that were on had blown, but the fuses >> were OK. The radio had internal circuit board components blown but again >> the inline fuses (there are 2) were OK. In the case of the fuel pump, this >> had to be replaced. >> Thinking this may have been a spike from the alternator, I replaced the >> alternator. >> >> Last week (3 years later), motoring back in the dark I had a similar >> problem, but this time only my VHF radio 'blew'. Again the inline fuse was >> good. The navigation lights have been replaced with LED lights and the >> AM/FM radio was off. >> >> I often motor after long races and this has only happened twice! >> >> Does anyone have any ideas as to what may have caused this. I am an >> engineer so can diagnose most things but this has baffled me. >> >> I am about to upgrade my VHF radio for one with DSC and internal GPS and to >> add some wind instruments. (I have a Raymarine knotmeter/depth meter >> combined, and a EV-100 autopilot.) I want to separate my electronics >> electrical input and have considered putting them on an isolated battery, >> but charging is a problem. Is there some circuit protector I can put in >> place to stop this happening again? >> >> All suggestions welcomed. >> >> BTW - for those of you with 29 mk 1's - you can race them competitively in >> strong winds (as is usual on San Francisco Bay) - keep the boat flat and >> have a really good crew! >> >> >> -- >> Ian Matthew >> "Siento el Viento" C&C 29-1 >> San Francisco Bay >> _______________________________________________ >> >> Thanks everyone for supporting this list with your contributions. Each and >> every one is greatly appreciated. If you want to support the list - use >> PayPal to send contribution -- https://www.paypal.me/stumurray >>
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