markcx avatar image
markcx asked

BlueSmart IP67 Charger Early Float

I haven’t used my BlueSmart IP67 charger for over 6 months as solar has been adequate, but now when I run the charger, it’s only staying in absorption for a maximum of 30 minutes, even though the battery is only at 90% and happily accepting 7+amps. I haven’t changed any settings in this time (only ever used defaults) although there has been a firmware update.

Is there any reason why this is happening?
6 months ago it would stay in absorption for several hours under the same circumstances.

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1 Answer
ciaram-granger avatar image
ciaram-granger answered ·

The absorbtion is adaptive, if only shallow discharges occur, the absorption time is kept short in order to prevent overcharging of the battery. After a deep discharge the absorption time is automatically increased to make sure that the battery is completely recharged.

The maximum duration of the absorption period for the day is determined by the battery voltage as measured just before the charger begins operation (12V battery assumed):

Battery voltage Vb (@start-up) Multiplier
Vb < 11.9V x 1
> 11.9V Vb < 12.2V x 2/3
> 12.2V Vb < 12.6V x 1/3
Vb > 12.6V x 1/6

Its max absorbtion time is 8h

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markcx avatar image markcx commented ·

Ok, thanks. That seems to make sense. The fact that my MPPT is also working (although not doing much at this time of year), means that the Charger sees a higher voltage when it is turned on - what would be the best way to mitigate this?
This doesn’t however explain why the Charger appears to be behaving differently now than earlier in the year, unless adaptive absorption was not part of the previous firmware.

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captain-mike avatar image captain-mike commented ·

Floating early is one of the best ways to shorten the lifespan of an AGM battery. No idea why this logic would not incorporate tail current (which the charger clearly knows based on the display in the app) and only look at start voltage.

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