thetechnobear avatar image
thetechnobear asked

Batteries are flat? What has changed?

this morning I woke up to a huge number of alarms from my VRM, basically because the system has been discharging for the last 7 days... from Jul 1 and batteries were at 0% !!!!

Id not really been monitoring actively, as at this time of year in southern spain - we get loads of sun, so charge is not an issue (though im confused why Ive not been getting alarms prior (say at 50%)

when Iook at the VRM, a few things look odd...

prior to 1st july all seemed ok, it was regularly going between 90%-100 doing bulk, abs , float

but after july 1, on july 2 it started keeping the battery % dramatically, and then each day, would only go up a bit... then stop rising, despite solar pv being available... and never got into abs

in fact if I look on the 30 day overview, you can see that except for yesterday, we still were producing the same amount of solar... but the batteries appear to be (largely) failing to charge....

Id be grateful if someone could have a look at the above installation graphs (last 30 day overview and you'll see my issue) - and advise me what to take a look at....

Im really confused.. nothing has changed...

the only thing I noticed is that there was also (coincidentally?) firmware update on 1st July, which is when the problems started!

is it that the batteries having stopped taking the charge for some reason?

would this be the MPPT?

could it be the BMV-702, just acting up an reporting wrong voltages?

what can i check?

for now, Ive put the generator on, even though we have a lot of PV, as an 'emergency' to see if I can get some charge into the batteries, as obviously running this low is very bad....

(of course its sunday, so can't do much today - and not even sure who to call tommorow :( )

any thoughts


system notes:

24 panels


2 x MultiPlus 48/5000/70-100

2 xBlueSolar Charger MPPT 150/70 (VE.Can)

1 x BMV-702

battery chargingfirmware updateHelp
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3 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi Mark,

From the VRM data it looks like the solar production has remained consistent, the batteries are still absorbing charge. The big difference I can see is that your consumption/loads has increased from ~23-24 kWh / day to 29-30 kWh / day.

Nothing appears to be wrong with the system, just an increase in load beyond the system's capacity to supply over several days.

Do an energy audit of the house, check if there are any other users of power and see if they have added any new appliances recently. Begin to disconnect non-essential appliances and see if you can isolate the load that is consuming so much power. Specifically heaters or coolers for an additional load of 7 kWh/ day. Maybe a fridge door as been left open somewhere?

From that data, the firmware update would seem to just be a co-incidence.

There is no surplus PV, it is all being consumed. PV output is maximum and optimal. The loads have increased to the point where they cannot be supplied by the PV anymore and are now coming from the batteries.

The yellow graph here shows a slight INCREASE is solar production, previously the solar panels would reduce output once the batteries were full. Now they cannot produce enough to satisfy the loads and fill the batteries, so production goes UP slightly, but still not enough.

You have doubled the demand coming from the batteries, previously it was 14kWh solar, 6 kWh batteries. On July 2nd that increased to 14 kWh solar and 15 kWh batteries.

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thetechnobear avatar image
thetechnobear answered ·

ok, i can see this on the 2nd and 6th july

but 1st, 3rd, 5th - all showed positive supply overconsumption, yet it still fell

and the 4th was pretty marginal, but again it dropped significantly....

if you look back prior to 1st july, you'll see the only reason we stop charging at around midday usually, is not lack of sun, but because the MPPT moves to abs/float - which its not done since July 1

also the confusing part of all of this is... nothing has really changed, we have not installed anything new to consume more power - and this system has been running for years like this without issue, Ive never see it plummet like this, particularly in the summer months where we have plenty of sun.

but I will definitely go and look to see if we have something that is constantly pull power....
we are completely off-grid, so we go have a lot of pumps for things like the heating/water and pool systems- perhaps something else has gone awry.

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Your AC load has about doubled, from 600W to 1200W, so yes I'd check for things that use more power since beginning of July.

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Previously there was a 600W load that run from 7am to 1pm.

On the 2nd of July that 600W started to run continuously 24 hours / 7 days. I would investigate a pump that has a faulty timer or float switch.

This 600W load (whatever it is) is the cause of your issue. Find it, and investigate why it is now running continuously when it used to stop.

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thetechnobear avatar image
thetechnobear answered ·

thanks @Guy Stewart (Victron Energy Staff) and @Daniël Boekel (Victron Energy Staff),

I really appreciate your support, esp. given its Sunday - much appreciated as its was kind of all a mystery a couple of hours ago!

(the system has been so stable, so this kind of came out the blue!)

indeed, I think Ive found the sensor that has failed, and was causing the issue of running a pump continuously unfortunately at a place on the site, when it cannot be seen easily! :(

ok, I guess my only problem is now...

Why did I not get alarms much earlier? I only got alarms at 2am this morning, when it had hit 0%

yet, I have a BMV702, which was supposed to be firing alarms off at 60% (which would have been 3 days ago)

we can see its connected ok...

yet i see an odd 'warning' on the alarms

also the remote console on the VRM, shows the voltages etc from the BMV, so it looks all ok, in that its seeing it.

also... Im kind of surprised even if VRM didn't send me alarms,
and I didn't get any beeps, or alarms from the BMV or CCGX, I go into where its all installed a few times a day so would have noticed any alarms there)

if I had been warned 3 , or 4 days ago, when batteries were at 50-60%, I would have done something :)

alarm log:

so you can see prior to these alarms, last alarm was 8 may....

and we can also see it was the battery monitor that did report an alarm at 2am today

... but battery monitor did not report low voltage, but the VE.BUS system did, but only at 0%

again, its a bit unclear, why this was so late ?!

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you're alarm rule is for device 256, but BMV is (now) at 258

If you'd set the alarm in the BMV itself, you'd get a general alarm.

So sometime in the past, the BMV got another device number, usually due to switching of cables / adding devices.

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thetechnobear avatar image thetechnobear Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

hmm, perhaps we had a bigger problem quite a while back with the Multiplus and we had a victron guy here - perhaps he switched the BMV as part of the troubleshooting - and forgot to switch it back/setup the new alarms.

ok, thats all cool - Ive now setup new alarms for the BMV, and also put an additional alarm on the MPPT (battery) voltage, so that should prevent something similar in the future.

again, sincere thanks to you (@Daniël Boekel (Victron Energy Staff)) and @Guy Stewart (Victron Energy Staff), I feel much more confident now that all is good - and that if there is a repeat, Id spot in much sooner, and know what to do -

Thank you!

@mvader (Victron Energy Staff) , you have a great support team, top service - thank you.

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