Interesting battery charging ideas

stephendv
stephendv Solar Expert Posts: 1,571 ✭✭
in Off Grid Solar & Battery Systems #1
Thanks to petertearai for posting this link to Victron's paper on off-grid living: http://www.victronenergy.com/upload/documents/ElectricityonBoard_rev8_july2004.pdf

A highly recommended read. There were a few points that were quite interesting, especially around battery charging deep cycle FLA batts:
  • They suggest that it is not necessary to charge them to 100% every day. Getting them above 80% is fine and then only charge to 100% once a month (or every 30 cycles).
  • For long term (a few months) pure float service when the battery isn't cycled at all, they recommend a much lower float voltage of 2.17V per cell - combined with a once a month higher voltage charge to bring it to 100% SoC. The rationale is to reduce overcharging with a too-high float voltage.

Thought it might be of interest.
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Comments

  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Re: Interesting battery charging ideas

    Very interesting. Thanks for sharing.
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    #3
    Re: Interesting battery charging ideas

    I agree with their statements as long as FLA batteries are subjected to a full absorb charge once a month.

    2.17 vdc per cell will stress the battery less, primarily lower lead oxide build up on positive plate and positive grid corrosion. However, the lower voltage will mean the negative plate will have a moderate discharge that must be cleared before the lead sulfate crystalizes.

    Float voltage is a compromise between the positive plates wanting a lower voltage and the negative plate wanting a higher voltage.
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