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Cory Wikel avatar image
Cory Wikel asked

BMV 712 relay not activating when programming matches conditions

I've got a BMV 712 hooked to a Cyrix LI relay but the BMV 712 relay doesn't seem to be following the parameters to open it close the relay as expected.


The only thing that will cause the BMV to change the state of the relay is when I hit the invert relay function. I've tried having the invert relay switch on or off and it never follows the voltage or soc low/high settings configured. The relay stays constantly on or off depending on how I have the invert relay function set... everything else seems to be ignored.


Can anyone shed some light on what I'm missing here? I get absolutely no reaction to any voltage or soc charge low/high events. I've tried different relay modes, disabling the event and enabling it, nothing. Thanks



Set to 24 low and 28 high, charger mode and it looks like it is working because the relay is closed since I'm at 26.9v.

screenshot-20201209-094928.png

screenshot-20201209-094947.png


But then I change the high voltage down to 25v and nothing happens. I would expect it to realize the voltage is high and open but it doesn't seem to care.

screenshot-20201209-095022.png

screenshot-20201209-095036.png


The only time I've been able to change the state is if I turn the invert relay switch on/off... otherwise it never changes state.


BMV Battery Monitor
screenshot-20201209-094928.png (181.4 KiB)
screenshot-20201209-094947.png (161.7 KiB)
screenshot-20201209-095022.png (182.9 KiB)
screenshot-20201209-095036.png (161.7 KiB)
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4 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

I guess in "charger mode" it still uses the default 90% "clear SOC relay" setting even if the "low SOC relay" is deactivated.
So as long as you SOC is below 90% the relay will remain closed.

cory-wikel-bmv-relay-1.png

cory-wikel-bmv-relay-2.png

Try to use the "default mode".


cory-wikel-bmv-relay-1.png (67.0 KiB)
cory-wikel-bmv-relay-2.png (36.5 KiB)
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Cory Wikel avatar image Cory Wikel commented ·

Will do but I've had it on that as well. Will get screenshots again if it's still disfunctional

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Cory Wikel avatar image Cory Wikel commented ·

Same same when set to default or charger mode with the soc at like 93%. Doesn't follow the voltage or soc values to change the state of the relay. The relay works because I can force it changed via the invert relay function and hear the click but seems to ignore all event based thresholds.


screenshot-20201210-135643.png


screenshot-20201210-135330.png


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Cory Wikel avatar image Cory Wikel commented ·

Any more suggestions?

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Cory Wikel avatar image
Cory Wikel answered ·

Here are the sw versions installed if that helps.

screenshot-20201211-064600.png


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Cory Wikel avatar image
Cory Wikel answered ·

@Matthias Lange - DE

Any other ideas? I've also unplugged power to the BMV unit to power cycle it.

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Mark avatar image
Mark answered ·

Your primary issue is that the relay mode must be set to 'Default' for it to respect all the trigger conditions. I still see that you have the relay mode set to 'Charger' in your recent screenshots.

I also just tested it again myself (triggered by low voltage only - per your example) and the relay worked correctly.screenshot-20201225-104848.jpg

screenshot-20201225-104859.jpg


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Cory Wikel avatar image Cory Wikel commented ·

I'll try default when I get back to the rig on Jan 5th.

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Cory Wikel avatar image Cory Wikel commented ·

Same same with mode on default. Set to 27v to flip and let it charge above that and relay is still showing closed.


Below limit it's closed.

screenshot-20210106-102258.png


Current setting should open at 27v

screenshot-20210106-102317.png


After letting it charge up and is above limit, no change... Still closed.

screenshot-20210106-121330.png

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Mark avatar image Mark ♦♦ Cory Wikel commented ·

I can see that you still have the 'invert relay' option activated - unless you really want that behaviour, turn it off.

Also when testing wait for the voltage to get at least 0.1V above or below the thresholds to confirm you have properly satisfied the conditions.

Also the 'closed' threshold (translated to 'open' as you have the behaviour inverted) is currently set to <24V, but you have not shown any screen images showing this condition was ever satisfied.

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Cory Wikel avatar image Cory Wikel Mark ♦♦ commented ·

Enable (closed) is set to less than 24v and disable (open) is set to 27.0v. V screenshot is showing 27.08v. I'll change it down and send another screenshot.. Wired to invert relay because that's the only way I can get it to flip open/closed at all. It's not the Cyrix that's the problem, I'm not checking to see if it is allowing power because I know it does if it's trigger by the bmv relay open/closed.

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Cory Wikel avatar image Cory Wikel Mark ♦♦ commented ·

Here's another set with relay disable (open) set to 26.0v and BMV showing battery at 26.5v. Doesn't change state, closed before I changed the setting and closed still after I changed the setting.


Before changing setting current battery voltage and relay state.

screenshot-20210109-070624.png



Changed really setting to 26.0v.

screenshot-20210109-071105.png


Checking again relay state hasn't changed.

screenshot-20210109-070716.png


I also changed the disabled (open) to 24.5v and it doesn't change state. Only way I can get it change is forcing it through the invert relay function.



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screenshot-20210109-070716.png (160.0 KiB)