BMV 700 settings ?

[Barboots]

I'd rather adjust an actual voltage figure on the BMV-700 than tweak those pesky pots!

Solenoid, diode, and a length of 1.5mm twin core. Sorted.

[Thatbloke]

I might try that lvd when ebay has its next sale, looks simple enough and plenty big enough. Thought this manufacturers discharge graph of my battery may be of some interest

[T1 Terry]

I might try that lvd when ebay has its next sale, looks simple enough and plenty big enough. Thought this discharge graph may be of some interest

Ya gotta wonder when sellers show a graph at 0.1CA (10 amps per 100Ah advertised capacity) discharge rate for a lithium battery, the accepted standard discharge rate is 0.5CA (50 amps per 100Ah of advertised capacity) so anything with a discharge graph showing less than a 0.5CA discharge rate and showing nothing higher than that is not really the capacity advertised, probably more like the point where it crosses the 13v line or in this case about 70% of the advertised capacity.

I'll put up a discharge graph for Winston LYP cells to give you an idea

WB LYP 100AH Discharge chart.jpg

Multiply the voltage on the left hand column by 4 because it requires 4 cells in series to build a 12v battery pack.
Just to put it in perspective, the line for 5CA represents a 500 amp load on a 100Ah battery.

T1 Terry

[Thatbloke]

Well i might be in luck then as my deepest drawdown is the fridge and i think the highest i have seen was about 6amps. I don’t have an inverter either so with the fridge going and maybe a radio and ipad charging i probably won’t see more than 10 amp drawdown.
The whole excercise for me was the weight issue with the slide on, am trying to be a minimalist 🤮
I guess only time time will tell how dumb i might be
Thanks for your graph.

[Thatbloke]

This is wierd; after i turned everything off the bmv was showing -82ah it’s now showing -79ah one day later ???
How could this be when there has been no charging ?

[T1 Terry]

This is wierd; after i turned everything off the bmv was showing -82ah it’s now showing -79ah one day later ???
How could this be when there has been no charging ?

That is how much you are behind each day, but if everything is turned off and there is no charging the monitor must be seeing some charging, enough to record 3Ah over the full day. It is possible the zero current isn't correct, you will need to disconnect the cables from the load side of the shunt, then go through the menu to select zero current and reset that. Reconnect the cables to the load side of the shunt and see if it records any watts either with a (-) sign to the left of the reading or no sign at all. It should read zero if there is no load at all.

T1 Terry

[Thatbloke]

Thanks Terry BUT this hasn’t solved the issue.
I disconnected that cable and reset to zero however the bmv ,even with shunt to load cable disconnected , is till showing a positve 0.16amp input !!! And reconnecting it still showing the same 0.16amp input.
There is definitely nothing sending power to the battery as i have disconnected the start battery input cable to the enerdrive charger and solar is not connected, there is no load as again everything has been disconnected apart from the enerdrive unit which doesn’t create power itself!

Any other ideas?

[T1 Terry]

Thanks Terry BUT this hasn’t solved the issue.
I disconnected that cable and reset to zero however the bmv ,even with shunt to load cable disconnected , is till showing a positve 0.16amp input !!! And reconnecting it still showing the same 0.16amp input.
There is definitely nothing sending power to the battery as i have disconnected the start battery input cable to the enerdrive charger and solar is not connected, there is no load as again everything has been disconnected apart from the enerdrive unit which doesn’t create power itself!

Any other ideas?

Disconnect everything from the load side of the shunt so the only cables are the battery negative cable on the battery side and the small red wire going to the circuit board on the shunt. Now do the zero calibration again and check the readings to see if there is any input/output on the watts menu. If there is, contact Victron, there is a problem with your BMV unit.
The meter should only read negative current flowing through the shunt, if there is nothing on the load side there should be no current flow.

T1 Terry

[BruceS]

Terry is due to hit the road on his way to do an install so if he's already gone he might not answer straight away.
Did you calibrate it?
Read through this thread maybe?
http://www.ybw.com/forums/showthread.ph ... 349cdfb38d

[Thatbloke]

Thanks Terry BUT this hasn’t solved the issue.
I disconnected that cable and reset to zero however the bmv ,even with shunt to load cable disconnected , is till showing a positve 0.16amp input !!! And reconnecting it still showing the same 0.16amp input.
There is definitely nothing sending power to the battery as i have disconnected the start battery input cable to the enerdrive charger and solar is not connected, there is no load as again everything has been disconnected apart from the enerdrive unit which doesn’t create power itself!

Any other ideas?

Disconnect everything from the load side of the shunt so the only cables are the battery negative cable on the battery side and the small red wire going to the circuit board on the shunt. Now do the zero calibration again and check the readings to see if there is any input/output on the watts menu. If there is, contact Victron, there is a problem with your BMV unit.
The meter should only read negative current flowing through the shunt, if there is nothing on the load side there should be no current flow.

T1 Terry

Yep still the pos 0.16amp and showing 2watt pos. Will try and contact victron
Thanks