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Unread 27-12-2014, 15:00
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Re: One speed vs Two speed gearboxes

Quote:
Originally Posted by Chris is me View Post
Maybe "mostly" is a strong word, but I could have sworn I've read a bunch of posts about how batteries in FRC are used in a suboptimal fashion by us using them intensely for two minutes then immediately recharging them regardless of how much they had discharged. Probably not something I should regurgitate from memory without a strong understanding of the concept, though.
FRC use is serious abuse to the batteries but it is the deep discharge that causes the problems. Recharging the batteries as soon as practical is the best thing for a lead acid battery. A discharged battery will form sulfates at a higher rate than a charged battery, sulfates increase the internal resistance and lower the battery's output potential.

As Ether mentioned most of the data sheets show the expected battery life in cycles vs the depth of discharge. The lower the depth of discharge before recharging the greater the life expectancy. The curve is just that a curve.

From the Enersys data sheet.

30% depth of discharge 1200 cycle expectancy.
50% depth of discharge 550 cycle expectancy.
100% depth of discharge 250 cycle expectancy.

From MK's data sheet.

100% depth of discharge 200 cycle expectancy.
80% depth of discharge 225 cycle expectancy.
50% depth of discharge 500 cycle expectancy.

A 100% depth of discharge is when the open circuit voltage of the battery after a short rest period is 11.2~11.8v depending on which mfg you consult.
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