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post #2 of Old 12-20-2012
Maine Sail
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Re: balmar mc612 equalizing issues

Your batteries were simply not full. This is very, very typical of alternator charging and improper programming of the regulators... Please do not try to equalize batteries with an alternator regulator.... Save this for dock side...


* Fully charging batteries, to the point where you can equalize them, will take 10+ hours of engine run time unless you have Odyssey TTPL (which can't be equalized anyway) or LiFePO4 (which don't need EQ).

*It requires a properly programmed regulator. 98.5% of the regs I see out there are not properly programmed and are simply using the factory pre-sets. These factory pre-set programs WILL NOT fully charge a typical house battery bank as they go into float mode far to early. At float voltages and "premature floatulation" it can take days not hours to fully charge the bank..

*On top of running your engine for 10+ hours (with a properly programmed regulator) you will then need a minimum of 2 to 4+ hours of lightly loaded engine run time, preferably with no changes in RPM, in order to do a proper EQ cycle, If you then check SG and find a cell still out of balance another 2-4 hours may be necessary.. The last 4-5 hours of the initial charging will also be "lightly loaded" due to acceptance.

*Add all this up and you're looking at 14 - 18 hours of running the engine to do an EQ cycle with a regulator. If doing a large crossing this can be one thing but of course you will want to ideally turn off any electrical devices not rated for 16V, when doing an EQ, so as not to over voltage them. To do this on the hook somewhere is not the best solution and 24 hours of transient dock space would be less costly in the long run.

*The cost of fuel, wear & tear on the engine, alternator, belts etc. etc. all add up to far greater than one would imagine.

I would only ever do an EQ cycle in a real "pinch" and even then I suspect I would hold off until there was an opportunity to do it connected to shore power or via a charger and gen set.

Before and EQ cycle you need to charge the bank until you see 1.0% - 0.5% acceptance at 14.4V (NOT float voltage) before you can even consider an EQ cycle. With many shore chargers this involves unplugging it to get it to reset back into a second round of absorption to fully top the batteries up. Many "smart chargers" are not quite as "smart" as we think they are and have "timed" absorption cycles that may not at all be geared for the bank you have on your boat. These absorption cycle durations, like the factory pre-set regulator profiles, are "generally safe" but do not always charge well or hold the batteries in absorption long enough.. Until your current is 1% or less at 14.4V then you're not ready to EQ.. A truly full battery will actually take less than .5% at 14.4V....

When you do bump the voltage to 15.5V you will see the current go up but it should not be much more than 2-4% of "C".. The best way to EQ batteries is with a lab grade bench top power supply as they allow you to control both current and voltage... The worst ways are alternator followed by solar....

Any EQ cycle should also be temp compensated whether with a shore charger or an alternator or solar system. If you can't guarantee the bank is at 77F during the EQ cycle you risk damaging the bank. I have seen people DESTROY batteries in engine compartments doing an EQ cycle with an alternator regulator that lacked temp compensation. Engine rooms are a HORRIBLE place for batteries but that's an entirely different discussion. As battery temp increases the battery voltage must be compensated and decrease especially when pushing EQ voltages.

-Maine Sail / CS-36T

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Last edited by Maine Sail; 12-21-2012 at 07:56 AM.
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