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post #13 of Old 07-20-2015
Maine Sail
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Re: charge voltage.

Originally Posted by msogin View Post
I seek advice about my charging set up on a Sabre 426 mk II. After a full day of sailing using the auto pilot, electronics including radar, etc. our charging system delivers between 3.4 and 3.9 volts to our Odyssey batteries (1 starter bank and one 4X battery house bank). The system has a manual combiner switch that we leave in the off position and an automatic charging relay that combines the two banks. The charging system is a Balmar 614 and 100 amp alternator. The Balmar 614 is programed for AGM as recommended by Odyssey. Except when cruising or day sailing, the boat is on a shore charger that delivers 14.6 volts until it reaches the float stage. When we take the boat off the shore charger and start the engine, the Balmar system charges initially at 14.3 volts but as expected soon switches to float. What I don’t understand is why it does not charge at 14.3 volts when motoring after drawing amps from the battery while sailing. I’m especially concerned that we will potentially damage the battery because of the low bulk phase voltage (the 614 display indicates “bulk” phase with a capacity of 14.3 volts) but the actual charging voltage is typically 3.4-3.9 volts. Is this normal or is it possible that something else is wrong i.e a defective ACR?
You are likely experiencing some voltage drop due to your regulator and alternator being wired incorrectly and your setting for the TPPL AGM's is not correct..

Alternators and Voltage Sensing - Why it is Important

The Balmar AGM setting is NOT optimal for your Odyssey TPPL AGM batteries. Using the factory "pre-sets" for Odyssey TPPL AGM's will shorten their life and can lead to irreversible sulfation damage.

With the battery bank discharged...


If your discharged bank of TPPL AGM's comes up to target voltage quickly, with a 100A alt, the batteries have been ruined and are due for replacement..

In bulk charging the voltage is SLOWLY climbing to the Balmar bulk 1 voltage set point (this should be 14.7V). Depending upon how deep you go bulk charging should take you two plus hours before you hit 14.7V.

A 100Ah Odyssey PC-2150, discharged to 11.7V, then charged at 46A (.46C) will not hit 14.7V in less than an hour, unless the battery is sulfated.

You are charging at nowhere close to .46C with a 100A alternator so expect upwards of two+ hours before yous see 14.7V at the battery terminals. With a 100A alt you are likely at about 75A, when hot, so your charge rate on a 400Ah bank of TPPL AGM's is a paltry 18.7% or 0.187C..... Odyssey wants to see .4C (40A for a 100Ah battery or 160A continuous for a 400Ah bank) as optimal charge current.

-Maine Sail / CS-36T

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