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Charging at 16 vdc - OK?

P

pzvt

Member
Put in a new isolator for 3 batteries. The bow thruster battery is in the bow and only has a # 10 wire to it. Start the boat up and it charges at 16 V for about 10-15 min (checked with my multimeter and the on board gauge). After that it goes down to somewhere between 14 & 15. Does this sound OK. Could it be the resistance in the wire to the forward battery (#10 wire)?
 
IMO, 16 volts is too high!
Isolators are old school technology by today's standards.
There's an inherant voltage loss when using an isolator.

Bluesea offers an ACR that may better serve your purpose.

Also, some are forgoing a battery in the bow for a thruster, and are biting the bullet and increasing cable size so that the charging system can be simplified. The thruster would now be powered from the House Bank.
Food for thought!

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There is a small voltage drop via an isolator simply because of the use of Diodes.
Here is some info:
Voltage drop: 0.7V @ 50% load, 0.9V @ full load.
Note: Battery isolators may not be compatible with self exciting alternators.

Are you by chance using a "gel cell" for this Bow Thruster?

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No gel cell - regular deep cycle I believe. I'm going to pull the alternator and have it tested. I also have a problem with surging that manifests it self in the lights at night when the engine is running (lights cycle from bright to slightly less bright every second)

The only thing that has changed (since now seeing 16 VDC for a short period after starting) are the connections to the loads and the new isolator so this problem may have been there before as there is now less of a voltage drop across all the connections/
 
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