Sol Ark Equalisation Functionality And Battery Spacing.

There is the potential for massive failure of an entire battery bank when certain conditions meet. One of my customers lost an entire battery bank of 16 X S6-460 AGM batteries due to a combination of issues.

The issues that lead to this failure were threefold and are not listed by importance to each other, they only represent the interactions and effects.

  • The Sol Ark 12K inverter has a default programming for a recurring 30 day equalisation charge. When using other than flooded lead acid batteries we usually set the equalisation voltage to the same as the absorb voltage, so no harm done.
  • AGM batteries and also LIFEPO should never be equalized at a higher than normal charge voltage. IN OTHER WORDS, NEVER!!!!!!!!!!!!!
  • Lead acid based  batteries develop higher energy capacity with rising temperature.

Here is what I believe happened, talking to tech support on both fronts, Batteries and Sol Ark.

  • The 30 day equalizing was automatically activated.
  • The battery temperature rose, hence increasing the storage capacity.
  • The pressure relief valves opened to release hydrogen gas.
  • The battery temperature rose to nearly 80 degrees Celsius, accelerating the previously described effects.
  • The batteries started expanding and due to the high temperature the battery cases started fusing together, so they had to be separated with a crow bar after cooling down.

Cause and effect:

  • Battery temperature will rise when charged at a C10 to C20 charge current
  • Batteries, Flooded Lead Acid and AGM develop a higher energy capacity as the temperature rises.

Here are my takeaways on how to minimize battery charging failures:

  • Batteries should according to the manufacturer be placed 1.5 to 3 inches apart to allow the heat to dissipate.
  • Battery boxes should only be insulated to the point that the temperature increase from charging can return to ambient temperature when not charging. In most climates in Canada my opinion would be not to use thermal insulation for the moderate temperature seasons at all.
  • Where charging a flooded battery with a high charge current will cause hydrogen gassing and increased maintenance, an AGM battery will dry out and become useless.
  • The Sol Ark 30 day equalisation time should be set to zero minutes and only activated under supervision and when necessary.
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