A curious thing?

[Andrew_Fanner]

I have discovered, to my mild annoyance, that when I start Jedi's engines (24V system) the GPS and fishfinder shut down. They run off a 12V feed from the main batteries which are specifically set up to take a 12V feed for some of the domestics, or so it seems. Don't ask if both alternators produce 24V 'cos I don't know yet

Only a mild nuisance apart from:
1 The fishfinder resets everything from metres to feet and any other non-default setting
2. Locks require engine shutdown so this ballache could happen every 30-60 minutes or so.

Any ideas electrical gurus?

 

[pheran]

Our last boat had what sounds to be a similar arrangement. It had a device that cut off all ancilliary circuits when the key was turned to start, presumably to ensure that all available battery power was available for starting or to protect them from surges perhaps. I never felt inclined to try and bypass this arrangement so didn't turn the bits and pieces of equipment on until I had started the engines and just put up with the minor inconvenience when restarting later on.

 

[andyball]

fit a separate small 12V battery - charged by a lil 24-12V converter/charger ( yes, they exist, or from 1 alt if it's a 12V one ). If any silly switching circuits, dump em.

Or many boats just run a 24-12V converter especially for the 12V gear, w/o a battery.


My 24V setup spins the motors everso fast- don't think cause a prob even if the gps was run from one of the batts in the 24V bank.



fishfinder totally resetting sound odd tho - perhaps some internal mini-battery to keep settings is u/s?



Of course, best thing to check properly & see how it's really all wired up eh

 

[volvopaul]

I would have thought the f finder etc will be 0 to 36 volt so they can run from 24v, if not then find the 12v supply wire and fit a blocking diode inline. the reason they go off is down to voltage drop, across the batteries, find the supply, disconnect the cables to each battery and drop test them to make sure they are both ok.

 

[silver_boy]

I know that on some starter motors there is a wire attached which sends out a signal to stop all other electrics when the engine is being started. I believe that just disconnecting this wire would stop this happening.