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Blue Smart IP65 12/15 - odd voltage readings vStart/vEnd

a64891c6-2ba3-4a88-b863-a253629d0ef8.jpegHey there,I wanted to ask, why the Victron App displays odd voltages at the vStart and vEnd readings. The battery in the screenshot was resting for minimum 30 Minutes, at the vStart I got 13,xx V and still it was possible to load in >10Ah? Literally no one could explain why there is a huge difference between vStart in the App and the actual voltage of the battery. I tried it with 3 different AGM-batteries from 2 cars and still, I always got strange readings on vStart.

The second thing is: Am I correct that vEnd is measured right after absorption? Isnt it so that the batt needs to rest for 10-15 min after loading to show the actual voltage?

charger
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Sry, I was unable to put the screenshot at the end of the post. The editor is not very handy within iOS
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Alexandra answered ·

@DocLoboto

The Vstart is whatever the battery voltage was when it started charging. I would expect that one to be varied as that is more how much you used it.

The v end should be related to your settings mine with LiIon reaches 14.4V i set without fail every time.

With AGM do you have equalisation charge in or not? That might explain the one hitting 15V. Also temperature compensation can affect it as well.

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Hi Alex, thx for reply.


Today I tested it with another AGM battery (70Ah) which isnt connected to any consumer. I measured 12,4 V right before plugging in the charger and 13,4 V right after unplugging. For testing I choose „high + recond“ setting to see, how it behaves in recondition mode. The temperature of both battery and charger were about 6°C.

I witnessed two things:

- the vStart and vEnd differs extremely from what I measured (I used a Voltcraft VC290)

584ac981-341b-4368-bacd-79c62f0db137.jpeg

- the current in bulk was really really low (the current is not limited within the settings!)

7dbf6137-3a3c-4748-83c2-3e6cb599d480.jpeg

I still have no idea, what vStart and vEnd wants to tell me or how I should interpret these values. :(


Alexandra avatar image
Alexandra answered ·

@DocLoboto

With agms if the voltage rises in a short period of time, has low AH charging, the battery has high internal resistance which could mean it is near end of life. (There can be other factors for low amp charge)

Temperature compensation makes the voltage higher at lower temps. The graph in the manual does describe the influence of the temp compensation on charge voltage.

If you want to rule out temp compensation.as an influence, then use a lithium ion settings with voltage customised if necessary or disable it in settings.

Leave the charger to do the full bulk abs float charge and see how many AH it has put into the battery.

The manual does describe what Vstart and Vend means.

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