question

markwinship avatar image
markwinship asked

BMV-700 with Solar charger and 200Ah Lithium battery exhibiting strange behavior

In the morning, the BMV-700 indicates a SOC of say 70% with the 200Ah Lithium battery. When the sun comes up, solar charging starts. I have 3 * 120w solar panels charging through a REDARC BCDC1240D charger on a Lithium profile. The strange behavior is that by 8:30am the BMV-700 indicates a SOC of 100%. Now the amps deficit at 70% SOC is about 60ah; with sunrise at 6:30am and a maximum charge of about 20amps, how is that possible? The BMV-700 is all factory defaults except Charge Efficiency is set to 99% and the Peukert's exponent is set to 1.05.

BMV Battery MonitorLithium Battery
1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

klim8skeptic avatar image klim8skeptic ♦ commented ·

"a maximum charge of about 20amps, how is that possible?"

The Redarc 1240D is capable of 40a output.

Post a pic of the BMV settings.

0 Likes 0 ·
2 Answers
John Dickfos avatar image
John Dickfos answered ·

I was having a similiar problem, and had not adjusted the tail current setting (03). Its set at 4% (of battery capacity) by default. The BMV manual on page 18 shows info for settings 01, 02, 03 & 04 that you may need to change from default settings for your installation.

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

markwinship avatar image markwinship commented ·

Thanks; this does make sense.

0 Likes 0 ·
markwinship avatar image
markwinship answered ·

Thanks; I realize that my REDARC 1240D is CAPABLE of 40a output, but this is without being attached to the car, so the only input is Solar. 3 X 120W panels = 360W or 360W / ~18V = ~20a, so how can the 60ah deficit be recovered so quickly when this is the maximum theoretical?

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

markwinship avatar image markwinship commented ·

In addition, when this happens using solar power, even though SOC shows 100%, the BMV-700 shows positive 20a for quite some time before reducing to a couple of amps (presumably when float stage is reached).

0 Likes 0 ·