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post #1 of 4 Old 08-11-2011 Thread Starter
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voltage to radio

This spring, I replaced the VHF radio on my Morgan 25 with a Uniden fixed mount radio. My boat has a very old series 27 dual purpose battery which is maintained by a trickle charger while at the dock and charged underway by my Honda 8 h.p. four stroke. The outboard puts out a maximum of 12 amps underway at 3000 r.p.m. (according to Honda). The radio works great as long as the outboard isn't running. When the outboard is running, I get an alarm and a "battery too high" message on the radio. According to the Uniden manual, this means that the radio is getting in excess of 16 volts.

Is anyone familiar with this issue? What changes can I make in order to be able to use the radio while the outboard is running?
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post #2 of 4 Old 08-11-2011
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16 volts is too high for charging and will damage the battery. Max should be about 14.4 volts which will not damage the radio. Not sure why this is happening though. Voltage regulator possibly?

Living aboard in Victoria Harbour
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post #3 of 4 Old 08-11-2011
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Check the voltage on the batteries while the engine is running at 3000 rpm. you should have between 13.8 volts and 14.7 volts . if you charge over 14.7 volts you could overheat the batteries and evaperate out the water.

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post #4 of 4 Old 08-12-2011
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Check the manual on your outboard, some do not regulate the DC vharging voltage as it is meant only for charging, not power.

If the manual (or call Honda) does not warn that it is unregulated, the charge regulator is defective and needs to be replaced. Charging at 16+V as noted will boil out your battery and damage everything else including running lights.

If there is no regulator option for the engine, there are always ways to add an external regulator.
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