I just noticed on my newly installed battery monitor - Victron 700 BMV, that it drops the displayed battery voltage by .24 volts when you push any button to light up the display screen. Real example, Battery at complete rest, monitor shows 12.8v but as soon as you light up the screen it shows 12.56 volts. Turning on lights or anything else doesn't immediately show any drop whether screen is lit up or not. When the screen lights up and shows the drop, other volt meters around the place do not drop.
I have just recently installed this unit, and can't say if this difference has been there from day one or not. .24 volt for a display screen??, something seems amiss??
Q1. Is this right?
Q2. If not, what is wrong - how to rectify?
3. Frustrating.
Thanks, Cheers,
John.
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"My mind is made up. Please don't confuse me with facts."
With the monitor unlit it reads .18 volts lower than at the battery and when lit up it reads a further .24 volts lower again. Not right. both sides of the shunt, at the shunt show correct battery voltage.
Actual battery 12.98
monitor unlit 12.80
monitor lit up 12.57
Cheers, John.
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"My mind is made up. Please don't confuse me with facts."
I have a Victron BMV 702, essentially the same unit except it can also monitor a second battery's voltage. Just had a look at my system, there's no change in the voltage shown whether the display is illuminated or not, so afraid I can't help much (at this hour of the night not able to stick a meter on the battery itself). Did you use the shunt supplied with the monitor?
Cheers, Joe
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Thanks for that fellas. So that is one question answered. If the monitor showed different before now I am sure I would have noticed. Yes Joe I used the supplied shunt.
Cheers, John.
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"My mind is made up. Please don't confuse me with facts."
Replace the little glass fuse in the read cable that supplies voltage from the battery to the shunt with a blade fuse. Be sure to connect that cable from the actual battery positive, not some where further up the wiring chain as this will also cause voltage fluctuations.
These little glass fuses were a cause of many a headache in the early days of building systems, especially the 702 version where the other lead was used to measure half battery voltage. Regular alarm trips where there was no real problem, the blade fuse replacement did the trick.
Tried to find the fuse holders we use as an Ebay listing but couldn't locate one, you could even just solder the fuse direct to the cable if you wanted. A 5 amp fuse is about as big as you would want to go, it is to protect that wire and the communications cable that runs from the shunt to the gauge and I believe that is current protected at the shunt anyway.
T1 Terry
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