I have 28 volts AC on top of my 12v dc.....

[groundhogyh]

I know... its weird.
Got struck by lightning in north Carolina.
Then while charging my phones and stuff, I noticed odd things were happening like they wouldn't charge
or the phones would act oddly afterwards. That's when I put a multimeter on the 12 vdc outlet and found
the AC.
hmmm....
groundhog

 

[pelagicasd]

Sounds very weird and I have no idea why. Something melted and shorted in the system perhaps? Do disconnect everything though until you figure it out. Check the voltage in the dock outlet. Low voltage means high resistance which can cause a fire due to excessive heat. Are you plugged into a dock line? We had a fire in a marina I used to live in and afterwards one of my friends measured 80 volts in the dock receptacle. Another fire in another marina was at the end dock. The service had been designed for 20 amps and a few of the residents had replaced the 20 amp breakers in the outlets with 30 amp breakers. The wiring and number of outlets were designed as a 20 amp system. The further away you got from the source the lower the voltage dropped. The users at the beginning of the electrical run were drawing more amps than design allowed for and voltage went down. Resistance went up and another fire. Both boats were totaled. Both boats had been running electric heaters. Length and gauge of wire also need to be considered. When my stepson was living on Lyric he was told to never run the electric heater on an extension cord. Did he listen? Nooooooooo. Result was a burnt out outlet, could have been worse. As aside when we were in Mexico we plugged into a dock outlet that had the polarity reversed. Instantly destroyed the battery charger. Any other damage to the boat from the lightning? Be safe, Walt To: AlbinVega@yahoogroups.comFrom: AlbinVega@yahoogroups.comDate: Wed, 29 Jul 2015 21:02:09 -0700Subject: [AlbinVega] I have 28 volts AC on top of my 12v dc.....







I know... its weird.
Got struck by lightning in north Carolina.
Then while charging my phones and stuff, I noticed odd things were happening like they wouldn't charge
or the phones would act oddly afterwards. That's when I put a multimeter on the 12 vdc outlet and found
the AC.
hmmm....
groundhog

 

[groundhogyh]

Hi Walt and Judy,
That's the weird thing. My boat is pretty much off grid unless
I need to run the small electric heater. I have a solar panel mounted on the
arch in back. The solar panel system was my first guess as the culprit, but
when I went over the other day and disconnected it, the 28 vac was still there.
I disconnected all kinds of things and was ready to pull my hair out until I
remembered the cooler of beer and ice....
If I switch the batteries off, it goes away. The solar panel and charge controller
are still happy and working.
gh

 

[Gazuum]

Try disconnecting the positive side of the ac powered battery charger (I assume you have one) from the battery bank. This should get rid of the 28vac but you most likely have a fried charger. Gordon

 

[groundhogyh]

I believe i have everything disconnected except the engine (alternator on beta).Can the alternator cause oscillation? Diodes?"groundhog groundhogyh@... [AlbinVega]" AlbinVega@yahoogroups.com wrote:




Hi Walt and Judy,
That's the weird thing. My boat is pretty much off grid unless
I need to run the small electric heater. I have a solar panel mounted on the
arch in back. The solar panel system was my first guess as the culprit, but
when I went over the other day and disconnected it, the 28 vac was still there.
I disconnected all kinds of things and was ready to pull my hair out until I
remembered the cooler of beer and ice....
If I switch the batteries off, it goes away. The solar panel and charge controller
are still happy and working.
gh

 

[9558345ad3d32553d67b49254fbbb61d]

Does the AC frequency vary with engine revs - if so I would suspect the alternator diodes, maybe one is short circuit. Geoff#################################################Geoff Blake, G8GNZ JO01fq: Chelmsford, Essex, UKgeoff@... or melecerties@...Using Linux: Ubuntu 14.04 on Intel or Debian on UltraSparcand Apple OS X 10.10 Yosemite on my Macbook Pro. Avoiding Micro$oft like the plague.#################################################

 

[groundhogyh]

Put your dvm on your car. You will see it. I think an artifact. Maybe of a cheap dvm"Geoff Blake geoff@... [AlbinVega]" AlbinVega@yahoogroups.com wrote:




Does the AC frequency vary with engine revs - if so I would suspect the alternator diodes, maybe one is short circuit. Geoff#################################################Geoff Blake, G8GNZ JO01fq: Chelmsford, Essex, UKgeoff@... or melecerties@...Using Linux: Ubuntu 14.04 on Intel or Debian on UltraSparcand Apple OS X 10.10 Yosemite on my Macbook Pro. Avoiding Micro$oft like the plague.#################################################

 

[dougpol1]

I can't rember for sure and I don't have my alternater book here at
home but it ssems like an alternat has to make 28volts alternating
and convert that to 14 volts dc. It has to make 28 volts AC to get
14 DC. Wish I had my book?? Doug


On 08/03/2015 09:44 PM, groundhogyh
groundhogyh@... [AlbinVega] wrote:

 

[groundhogyh]

I think it has to do with how a dvm measures ac. Uses a rms formula. Must rectify the ac to an average value. So if u stick 12vdc in, the dvm treats it as ac with a mean value of 12?"groundhogyh groundhogyh@... [AlbinVega]" AlbinVega@yahoogroups.com wrote:




Put your dvm on your car. You will see it. I think an artifact. Maybe of a cheap dvm"Geoff Blake geoff@... [AlbinVega]" AlbinVega@yahoogroups.com wrote:




Does the AC frequency vary with engine revs - if so I would suspect the alternator diodes, maybe one is short circuit. Geoff#################################################Geoff Blake, G8GNZ JO01fq: Chelmsford, Essex, UKgeoff@... or melecerties@...Using Linux: Ubuntu 14.04 on Intel or Debian on UltraSparcand Apple OS X 10.10 Yosemite on my Macbook Pro. Avoiding Micro$oft like the plague.#################################################