question

Perryn Smith avatar image
Perryn Smith asked

BMV-700 shows 85% but battery voltage is 11.85V

I've been using the BMV-700 for four months to monitor my 860 ah house bank.

All seemed to be going well-until I discover today that actually the battery bank had been slowly draining, while the BMV always showed a reasonable voltage...usually 80-100%, never lower than 70%.


So what's going on?

BMV Battery Monitor
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1 Answer
Jaco Reinecke avatar image
Jaco Reinecke answered ·

Have you synced it, i.e. charged the batts full, then synced it to 100%?
When last have you Zero'ed the BMV? That is when there is no current on or out, exactly Zero.
Refer to manual on how to do the above on the buttons.

Any other settings you have changed?

BMV's need to be checked regularly and although the settings out of the box is quite decent, it is not necessarily exactly what you bank needs.

For example "The Tail" current:
"Tail current" is basically the current the bank will absorb at almost fully charged.

As your batteries charge they "Absorbs" less and less current. The 702 will indicate 100% charge after looking at the following three conditions. Once all three conditions are met, the BMV will indicate the bank as 100% charged:
1. (Setting 2) Bank voltage at "Float Voltage" or higher
2. (Setting 3) Tail current at less than 4% (In my case 2.8%) of the total Ah rating of the bank
3. (Setting 4) For a set time of ?? Min. (In my case 30min)

It is an idea to check these settings and adjust them to your battery bank.

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