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TritonGlenn
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Yes. It's your outboards charging system charging your battery, so you are seeing a voltage jump when you are running and the engine charging system is charging the cranking battery.
All the best,
Glenn
All the best,
Glenn
TritonGlenn
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There ya' go. I fixed my original reply to use the correct terms. 
All the best,
Glenn
All the best,
Glenn
TritonGlenn
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It depends on your battery, but the generally accepted answer is "yes" - 12.5 volts is fully charged.
Lead-acid batteries tend to charge up to a slightly higher voltage at full charge before equalizing during the course of the day. I've read initial voltages somewhere in the 13 volt range on a fully charged lead acid battery, but the battery was initially designed to provide approximately 2.1 volts per cell x 6 cells = approximately 12.6 volts.
Gel cell / AGM type batteries normally will not charge as high as a lead acid variety, which is why I despise having a Blue Top Optima cranking battery in my boat right now. They also do not charge as quickly as a lead / acid battery. It still charges to 12 + volts, but it's known in the marine battery industry that gel cell / AGM type batteries do not normally charge to the level / capacity of a flooded wet cell (lead-acid) type battery. You probably will see a maximum of 12.5 volts when fully charged, dropping during the day to 12 volts or so.
Remember that the voltage you are seeing on your HDS when running is the charging systems voltage. When you shut down your engine, the voltage probably drops back down from 13.4 to somewhere in the 12 volt + range rather quickly.
All the best,
Glenn
Lead-acid batteries tend to charge up to a slightly higher voltage at full charge before equalizing during the course of the day. I've read initial voltages somewhere in the 13 volt range on a fully charged lead acid battery, but the battery was initially designed to provide approximately 2.1 volts per cell x 6 cells = approximately 12.6 volts.
Gel cell / AGM type batteries normally will not charge as high as a lead acid variety, which is why I despise having a Blue Top Optima cranking battery in my boat right now. They also do not charge as quickly as a lead / acid battery. It still charges to 12 + volts, but it's known in the marine battery industry that gel cell / AGM type batteries do not normally charge to the level / capacity of a flooded wet cell (lead-acid) type battery. You probably will see a maximum of 12.5 volts when fully charged, dropping during the day to 12 volts or so.
Remember that the voltage you are seeing on your HDS when running is the charging systems voltage. When you shut down your engine, the voltage probably drops back down from 13.4 to somewhere in the 12 volt + range rather quickly.
All the best,
Glenn
Texas Transplant
Well-Known Member
Generally a really new battery may be a little higher that 12.5 after charging, but not all that much. If you are running 12.5v at the start of the day, and still at 12.0 at the end - you should be good to go.
Tex
Tex
