Charge voltage to high

DIY
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1

Hello, i have a setup with agm batteries working with a smartchargecontroller 150/100 for few years now and all worked fine so far

Recently we upgraded and added another smartcontroller 250/100 and a Cerbo GX (latest)

The Cerbo is setup that DVCC is enabled and i even set the max charge voltage of 58.8volts

Also both smartcontrollers are set at max 58.8volts Absorption, still voltage goes as high as 60volts at times, and if i check on my victron connect app all of my devices agree that the voltage is to high, jet the chargecontrollers keep on charging.

It seems that if i lower the voltage settings by 0.7volt on all settings in the 150/100smartcontroller it seems to help,

Is it possible that eventhough it shows that that chargecontroller is giving a to high voltage that internally there is another measurement telling it to charge at a higher voltage?

And why if the Cerbo sees this doesn’t it react?

What is best to do?

All connections are in order

2

It might be the temperature compensation settings. Please check the settings and connection to the temperature sensor

1 Like
3

Thanks.
I left those settings to original settings and we are not using a temp sensor for the AGM batteries.

And settings are equal to both smartcontrollers, but it seems that one regulates differently than the other, eventhough the measured voltages on the screen looks same

4

Because the setting of maximum charge voltage is for " managed batteries", i.e. ones where the Cerbo is forwarding battery required voltage to the MPPTs and the MPPTs are under external control. You do not have managed batteries, the MPPTs are using their own control algorithm.

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5

Ok thank you, than the problem is most sure in the chargecontollers to be found?

Can it than be that eventhough on the victron connect screen they display 59.95volts while both in absorption and doing their best to charge, eventhough their settings for absorption is 58.8volts that somehow there are 2 voltage measurements inside the controllers taking place, in regards 1 to regulate and 1 to show on display?

If so is there a way to reset them or should u than adjust the settings for absorption to 57.7volts in order to get the 58.8volt desired outcome?

6

And also in the cerbo DVCC i set the limit charge current also to max 120Amp so that the batterybank does not exceed its limit, will the Cerbo DVCC also not react to that if it happens?

7

Try and answer both questions.

The DVCC section of the manual states that the limit charge current setting applies to a lead acid battery system.

Do you have shared voltage sense (SVS) enabled on your GX device from your battery monitor. If you do, then the MPPTs increase their output voltage to compensate for voltage drop in the cables, so you ate likely to see the MPPT voltage at 60V now, before without the GX it would be at 58.8V. It regulates to the actual battery voltage now, not the one at its terminals.

In this case leave the settings at 58.8V and watch the battery voltage not the MPPT voltage.

8

Thank you very much,

as i am freshly looking into the manual of my GX device under point 11 i see that my chosen option is lead acid, since that is closest to agm in my case, and in 11.2 it states agm in the list also :slight_smile:

And in that colum it states that svs, sts and scs all should be enabled
So i did that, except the sts since i don’t have a tempsensor for my batteries

To my understanding the BMV712smart is the chosen instrument to measure voltage and amps, as i set it up this way in my GX device

The readout of voltage according to bmv, cerbo, chargecontollers and my multimeter all seems to high 60.1 volt for instance while in absorption and suposed to be 58.8volts.

Setting the svs on or of and rebooting the system does not seem to influence it, also the limit charge voltage does not influence it, but as you explained before, the voltage limiter only works on batteries with a bms, so thats ok.

My bmv is measuring directly from the poles of the batteriebank, so its accurate, and displays correctly a to high voltage

I do understand a voltage drop occurs in the cables, but on my system it is very small, since the cables are short and of adequate size and krimps etc. Are good, also with measurements with a voltmeter it is very satisfying and way below the 1.1-1.3 volts that somehow gets added.

Side note: "old"150/100 chargecontroller only has ve direct port that we used on Cerbo GX and “new” 250/100 chargecontroller has ve can port that we used. As shown in 11.2 i checked my firmware and all is in order

In 11.3 i also see that the internal charge algorithm is disabled and controlled by the charge voltage setpoint of the inverter charger,
Is this perhaps a possible problem?
Sidenote, since we are off grid, my charger in the inverter/charger is disabled.
I believe ess does not apply to us?

11.4 indicates also for all batteries, this includes agm, and these functions are discribed to should work:
-11.4.1 limit charge current
-11.4.2 limit managed battery charge voltage
(Side note, this does not seem to work, even after rebooting)
-11.4.3 shared voltage sense
(Side note should work with both my chargecontollers and it will use BMV for sensing voltage)(BMV indicates 60.1 volts while limit is set at 58.8V)?
-11.4.4 shared temp sense
(Side note we don’t have a temp sensor)
-11.4.5 shared current sense
(Side note: it is on and conditions are met)
-11.4.6 controlling bms
Not applicable i believe

I hope that this message gives you more insight of our system and how i set it up, ill go check the settings in my inverter/charger, to make sure thats not the problem.

9

Charge voltages in Inverter/charger was correctly set, charger is disabled since we are off grid

10

Sounds like you have everything set up well both wiring and DVCC settings so I do not understand the overshoot as it is seen on the BMV also.

I answered as I did because most issues we see are poor wiring.

11

Thanks so much for your reply and thoughts you have put into this,
Temporarily solution for now that seems to work is i reduced few panels on the 150/100chargecontroller and setted its voltages 0.7volts lower, seems to work for now, so at least we don’t damnage our battery bank

Can it be a problem that old 150/100chargecontroller only has only ve direct and new 250/100 chargecontroller has ve can connections?

All have a beautiful day

12

The VE direct and VE CAN should be OK side by side. I have VE Direct MPPT and VE CAN alternator and the charge control works seamlessly on both devices. The VE CAN connection must have the terminators in to work.

13

Once again Thank you kindly sir,
To my knowledge i must agree with you and that is also what my supplier told me.
It comforts me to hear that it works good in your discribed situation,
Terminator plug is in.

At the moment voltage is still slightly high, but out of the dangerzone with few panels less and voltage settings on the suspected chargecontroller a bit lower.

14

Hello All,

Here is a little update,
I hooked up all the panels again and it currently is about 2800wattpeak on the 250/100chargecontroller with absorption voltage set at 58.25volt
And 4900watt on the 150/100chargecontroller with absorption voltage set at 58.15volt.

Now they seem to work together well achieving the absorption voltage of 58.8 volt as seen in cerbo, bmv712 and both chargecontrollers

I am still at a loss why the chargecontollers needs to be set at a lower voltage to regulate together the right voltage, but so far we had no overvoltage alarms anymore (>60volts)