% of battery charge by voltage

There you are Phil, an electronic tech, using both theory and practical testing, agrees: you get good guidance on battery state of charge from voltage.

The batteries last an average of 7 year

Easy to do if you only leave the dock a couple of times a year!

Phil Fill said:

Sq





I started this disvussion to give a cheap siple way of estimating % of charge left. Not to start a long discussion. I check the batteries omce a month. The batteries last an average of 7 years. Use it. Dont use it. Its up to you.

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Phil,
I had been using "your" method for many years. I installed a Link Lite and used that this past summer, but still fall back to use the voltage method using the Link's readings..
I also get good battery life, so I will continue to use the voltage method.

For folks that wish to use Voltage , it would pay to install a spot or pick up point where even a cheap radio shack $7.00 digital meter can do the measuring.

An analog gauge is usually not accurate enough for meaningful measurements.

BruceK said:

There you are Phil, an electronic tech, using both theory and practical testing, agrees: you get good guidance on battery state of charge from voltage.

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I am an electronics technician also. I just look to see how bright my lights are and how dim they get when the water pump comes on.

For the cost of 50 gals of diesel, you can pick up a monitor and get any reading you want at the push of a button. Seems like a no-brainer when it comes to health of battery banks that exceed $500 in value.

FlyWright said:

For the cost of 50 gals of diesel, you can pick up a monitor and get any reading you want at the push of a button. Seems like a no-brainer when it comes to health of battery banks that exceed $500 in value.

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Yeah. Get a battery monitor.

BruceK said:

There you are Phil, an electronic tech, using both theory and practical testing, agrees: you get good guidance on battery state of charge from voltage.

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So does this one.

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I scanned this thread and see no mention of battery type.

When we installed AGM batteries we were told charging voltage was 14 or so and fully charged seemed to be about 12.8. I think 10.5 was dead.

I usually charge my entire bank of two AGM house batts and one AGM high current start batt when my voltage goes down to 12.2 to 12.5 volts.

If I had standard flooded lead/acid batts all the above voltages would be lower.
One's charger should be adjusted to voltages appropriate to battery type.

All numbers are rough recollection.