Victron BMV 712 setup

[wareaglewalt]

I'm having difficulties with settings on my Victron. I have two 6 volt AGM Trojans and am unsure what to use for the full state of charge setting. I set the capacity to 117 amp hours, but when I get to a point of say 50 amp hours used, the voltage seems lower than it should be (like 12.2 or 12.1 volts) and the percentage of state of charge is really high like low 90s.

Should I just reset the monitor, fully charge the batteries and just put in the capacity only and let the monitor figure out the rest?

Thanks,

Joe

[uncle_bob]

Hi

1) Did you wire things correctly? Everything *except* the lower battery - terminal goes to one side of the shunt ( = low side). The *only* thing that goes to the other side of the shunt (= high side) is the battery. Charging cables, inverter cables, power to the rest of the trailer all to to the low side.

2) Does the shunt readout make sense? There are two possible shunts you could use. There are settings for both of them in the menus. If the shunt does not match the setting, the readings will be way off. Simple test is to turn on a Fantastic Fan and see if the current goes up by about 2 amps ( and not by 20 or 0.2).

3) If you have 6V AGM's, shouldn't the amp hours of each one be around 200 or more? If so, 200 ( not 110) would be what you put into the 712 as the "full" capacity.

4) The monitor power leads should go directly to the battery. The 712 should read the same thing that a multimeter does. If the multimeter says 12.1V, that's what you should see on the 712. If not, check the power wiring.

If your batteries are at 12.1V and the temperature is anywhere near normal, they are at the "stop using" point. That's true regardless of what the 712 thinks. The device will reset to "battery full" when it sees the charge current fall below a pre-set point. There is no need to do anything wacky to get it synchronized (assuming things are wired correctly).

Lots of fun !!!!

Bob

[SCOTTinNJ]

Do you have a load on the batteries at that point? Try taking all loads off and see what voltage you are at.

[fran&frank]

I'll echo Uncle Bob's comment-- I haven't seen and Trojan 6-volt AGMs with less that 200 amp hours, why did you set yours at 117?

[wareaglewalt]

Originally Posted by fran&frank

I'll echo Uncle Bob's comment-- I haven't seen and Trojan 6-volt AGMs with less that 200 amp hours, why did you set yours at 117?

My typo. I meant 217 for battery capacity. I do have a minimal load but it's normally just the fridge, propane detector. I'm just wondering if I just set the capacity to 217 and nothing else at default if the system will do the rest.

Also I read AGMs can discharge at or a bit lower than 12.0 volts with no real issue.

Thanks,

Joe

[AlinCal]

I had similar issues with mine I installed a few weeks ago but was more an issue with the solar charging reseting back to 100 before it was possible based on the AH used and charged via portable suitcase. Seems like it's closer to reality after raising the charged voltage setting. One of the things they tell you in the troubleshooting as I recall.

[Lgebhardt]

Something is off if your state of charge is showing 90% with 217Ah as the capacity and 50Ah used. You should be showing about 77%. Double check everything as Bob mentioned above, as well as the values you've entered into the monitor.

[uncle_bob]

Hi

Indeed there is no single magic voltage that instantly kills lead acid batteries. The issue is accelerated aging of the batteries. You get far fewer discharge cycles before they die when you go to lower voltages. Since the actual voltages are temperature dependent, things get even more complex. Go out in the full sun in the desert and your voltages may all be a half volt lower. Sit out in the freezing snow and the voltages are likely a half volt higher.

One of the cute things a full Victron setup will do is look at a temperature probe and adjust everything so it works out over temperature. No more massive over charging batteries in the summer. No more killing deep discharges in the winter. Yes, this involves a bit more than just putting in a 712...

Bob

[wareaglewalt]

Originally Posted by AlinCal

I had similar issues with mine I installed a few weeks ago but was more an issue with the solar charging reseting back to 100 before it was possible based on the AH used and charged via portable suitcase. Seems like it's closer to reality after raising the charged voltage setting. One of the things they tell you in the troubleshooting as I recall.

Yeah, that's what I was hoping to find out; what others might have put into the settings for their SOC for 2 6-volt AGMs. I currently have 13.3 volts but not sure if that's what I need in there. According to the manual, all I really need to put in there is that 100% SOC and the battery capacity.

Joe

[uncle_bob]

Hi

First some background:

A pretty typical charge profile for any lead acid is to run constant current up to some magic voltage in the 14.2 to 14.6V range. Once you get there, you dwell a bit and drop back to around 13.6 volts. If and when the current drops below some set point ( and possibly a timer expires) you fall down to around 13.2V.

The gotcha with most chargers in RV's is the current set point on the 13.6V stage. The charger does not know if current is going into the battery or a load. If the set point is something like a half amp and the RV pulls 1A all the time .... in never drops back. Putting a BMV 712 into the loop with the charger takes care of that.

Now your case:

Since you aren't playing with a charger and just working with the BMV, most of that really does not matter. Stand alone the monitor pretty much does not care what the charger does. It looks for a low current limit and declares the battery to be full. Since it *knows* about current into the battery independent of loads, it does a good job at this.

So ....

If everything is wired right and you only get to 13.3V, you have a problem with your charger / converter. If it's not getting to the right voltages, you are running with mostly empty batteries. The history log on the BMV will show you what's been going on.

Bob

[Lgebhardt]

Originally Posted by wareaglewalt

Yeah, that's what I was hoping to find out; what others might have put into the settings for their SOC for 2 6-volt AGMs. I currently have 13.3 volts but not sure if that's what I need in there. According to the manual, all I really need to put in there is that 100% SOC and the battery capacity.

Joe

I'm using two T105's (not AGM). I've got the following in my settings:
Battery capacity: 225Ah
Charged voltage: 13.2V
Tail current: 4.00%
Charged detection time: 3m
Peukert exponent: 1.25
Charge efficiency factor 94%
Current threshold: 0.10A
Time-to-go averaging period: 3m


I'm using a PD4655 as my charger. Yours may need different settings.

Note, my charger settles in at 13.31V so the 13.2V charged voltage is below this, but maybe I should set it a bit higher based on the manual (0.2V or 0.3V above the float voltage for the charger). It is however working well so I'm not adjusting it yet.

I also adjusted the charge efficiency factor to 94% based on info I found for the T105.

I don't have a midpoint monitor installed between my two batteries, but since you are having issues I'd check the voltage across each of them to ensure they are very close to equal both when charged and when partially drained. There may be a bad battery in the mix.

[kmerson]

I just finished installing a BMV 712 and have a setup question, so this seemed like the right thread. I've just got two standard Interstate batteries from Costco. Based on Interstate's website, I think they're SRM-24s, which seem to have a capacity of 81 Ah.

Other than setting the capacity to 162 Ah in the BMV 712 (and setting the aux. input to temp. since I did install the temp. sensor), are there other settings that folks recommended changing from their defaults?

Thanks!

[uncle_bob]

Originally Posted by kmerson

I just finished installing a BMV 712 and have a setup question, so this seemed like the right thread. I've just got two standard Interstate batteries from Costco. Based on Interstate's website, I think they're SRM-24s, which seem to have a capacity of 81 Ah.

Other than setting the capacity to 162 Ah in the BMV 712 (and setting the aux. input to temp. since I did install the temp. sensor), are there other settings that folks recommended changing from their defaults?

Thanks!

Hi

It's just a monitor so it's not very critical for setup. Whatever you put in for capacity will be used for the "you are at 81%" sort of calculations.

If you want to have lots of fun, there are some "ignore currents below this limit" sort of numbers. For lead acid's and normal installs, they should be ok. If it's a really cold day out and you have run out of things to read, you can dig into them

There are also some nonsense settings about the backlight and (?) an alarm. That also is in the "fun to read about" category.

Bob

[GSansoucie]

Originally Posted by kmerson

I just finished installing a BMV 712 and have a setup question, so this seemed like the right thread. I've just got two standard Interstate batteries from Costco. Based on Interstate's website, I think they're SRM-24s, which seem to have a capacity of 81 Ah.

Other than setting the capacity to 162 Ah in the BMV 712 (and setting the aux. input to temp. since I did install the temp. sensor), are there other settings that folks recommended changing from their defaults?

Thanks!

I have the same batteries, stock from AIrstream. I used 160 Ah to round down just a bit. I have charge voltage set to 13.2v, the default I think was 12.5v, the manual said to use 13.2.

I just finished the Victron install this afternoon. I tested some circuits, ran the Maxair fans, the inverter, lights, even the heater. I’m charging it right now with our new EU2200i setup, which is pretty much what we’d be doing when boondocking. I plan on disconnecting the power in a bit and letting the camper sit overnight with a load, probably a fan or two to see how it behaves overnight.

[ROBERT CROSS]

My SOC vs Time Remaining seemed way off....👎Doing a test now. 🤔

Bob
🇺🇸

[uncle_bob]

Originally Posted by ROBERT CROSS

My SOC vs Time Remaining seemed way off....👎Doing a test now. 🤔

Bob
🇺🇸

Hi

State of charge is based on 100% of the capacity you set the 712 up for. Time remaining is based on half the capacity number. The *assumption* is that it is a lead acid battery and you are only going to use half the capacity.

In addition time remaining averages the current used over some time period (which you set). If you have current "burps" (like from using the water pump) what's in the average might be a bit off from what you now are using.

Bob

[Kalashnikov]

This is what I used as well, ie. 225Ah for capacity. I have no idea why people are using 117, 162, 160, 170 etc for dual Trojans.

Originally Posted by Lgebhardt

I'm using two T105's (not AGM). I've got the following in my settings:
Battery capacity: 225Ah
Charged voltage: 13.2V
Tail current: 4.00%
Charged detection time: 3m
Peukert exponent: 1.25
Charge efficiency factor 94%
Current threshold: 0.10A
Time-to-go averaging period: 3m


I'm using a PD4655 as my charger. Yours may need different settings.

Note, my charger settles in at 13.31V so the 13.2V charged voltage is below this, but maybe I should set it a bit higher based on the manual (0.2V or 0.3V above the float voltage for the charger). It is however working well so I'm not adjusting it yet.

I also adjusted the charge efficiency factor to 94% based on info I found for the T105.

I don't have a midpoint monitor installed between my two batteries, but since you are having issues I'd check the voltage across each of them to ensure they are very close to equal both when charged and when partially drained. There may be a bad battery in the mix.

After I did the setup via Bluetooth the app seemed to 'work.'


However the external display still cycled through some kind of welcome message "B a t t e r y C a p a c i t y ....."



Is there any way to get rid of that?

[Kalashnikov]

Still don't have know if my BMV has the setup screen scrolling, haven't been back to look.

But anyway, found a definitive setting for the Trojans and BMV 712.

Courtesty of AM Solar:
https://amsolar.com/s/BMV-712-in-App...ooded-ntna.pdf

Summary:
- Connect the BT App (first download & install)

- Don't use BT pairing from OS, use the app only
- Select the BMV 712, update the firmware version if offered
- Select settings "gear icon"
- Battery
- Capacity: 225Ah for 2x Trojan T105
- Charged voltage: 14.2
- Tail current: 4%
- Peukert Exponent: 1.25
- Charge Efficiency: 94%
- Go back to settings, Misc, Relay
- Low SOC Relay: 50/50
- Aux Input: Temperature
- Temp Unit: Fahrenheit
- Exit - done!