Is a Battery Equalizer recommended dual batt 24v system?

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TechMOGogy
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by TechMOGogy »

Jimm391730 wrote:Charging an unbalanced pair of batteries (one discharged, one charged) is problematic. The charged one gets overcharged and the discharged one does not get enough charge. A battery equalizer typically takes equal power from both batteries but only returns this power to the more deeply discharged battery; essentially removing energy from the charged battery and giving it to the discharged battery. This is how the equalizer works.

Now let us do a rough thought experiment: If you use a 12V winch for one minute, and it draws 400 amps during that time (not unrealistic!) then that battery is being drained at 400A times 1 minute equals 400 amp minutes. The 6A equalizer will take over an hour (400 divided by 6 = 66.7 minutes) to theoretically bring things back into equalization. Until this time, the alternator is overcharging the upper battery - this creates heat (or at least more heat than "normal"). Heat is almost never your friend; the more heat, the shorter life most things will have. It is possible that a sealed battery might vent during this overcharge and venting is not normal for a sealed battery.

The above thought experiment shows that there is the possibility of damage/degradation even with an equalizer. However, if this only happens a few times per year and not an everyday occurrence, the likelihood of long term problems is probably almost zero - yes, the batteries are unbalanced, but in an hour (or two or three) things get back to an equalized normal. So it becomes a weighted decision to accept some slight possibility of creating a problem with the convenience of a 12V winch. The more you know and understand the better you can deal with the issues: what if you get REALLY stuck, and end up winching for a LONG time? After a bit, swap batteries! Balance their charge that way!

Everyone's "best" solution will be different. I elected to get a 24V winch and not worry about it. YMMV, but be sure to enjoy your choice and your truck!
This is great info
So with a 60amp equalizer all of a sudden we go from 66 mins to about 7 mins. Gets interesting assuming the alt can keep up ;)
72 Pathfinder | 75 710M 2.7i | 96 350GDT Worker
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Jimm391730
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by Jimm391730 »

So with a 60amp equalizer all of a sudden we go from 66 mins to about 7 mins. Gets interesting assuming the alt can keep up ;)
The thing is, the alternator doesn't have any effect. The equalizer gets its energy from both batteries, then redistributes that energy back to the battery that needs it (the one with the lower voltage). So YES, 7 minutes would be all that is (theoretically) needed.

The alternator is charging both batteries and suppling the power that the equalizer looses as heat. A good equalizer shouldn't operate unless the engine is running (that is, that the battery voltage(s) are high enough that it knows that the alternator is charging them). Once the engine is shut off, the equalizer should stop and sleep as to not drain the batteries trying to do the equalization without a running engine. From that perspective, the alternator IS supplying the energy that the winch drained battery needs. Without the alternator the equalizer is stealing power from the upper battery to charge the lower battery.
Jim M.
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