Victron 700BMV

[sailaboutvic]

Fitted a new BMV700 and I am trying to Synchronised it to my batteries bank , ( batteries are 4 Trojan 6v T125 ) .

The setting I have used are AH 450 , charge voltages 14.5v, tail current 4.00% , charging time 3m , peukert 1.5, current threshold 0.10A, time to go 3m.

Has I use solar panels to charge I set the charging current to 14.5 Trojan give bulk at 14.8v .so it set to 0.3 lower.
Manuel says once the batteries are fully charge the BMV will sync itself .

Leaving the batteries on shore power over night ,
the SOC showed 100% .
since last full charge shows 0s .
But Synchronisation show 0.
What is it I am doing wrong ?

Also looking at my Victron MPPT it show its on bulk charge , surely if I am 100% SOC
14.2 voltages it show be on float and not bulk ?
Easy answers please

 

[pvb]

I think you have the charge voltage set too high; it would normally be set a little below the float voltage, and indeed the default setting is 13.2v.

I also think you have the Peukert coefficient set wrongly, for a T125 you should use 1.23 as the coefficient.

You may need to discharge the batteries by 20% or so and then re-charge them to get the synchronisation process working properly.

 

[sailaboutvic]

I think you have the charge voltage set too high; it would normally be set a little below the float voltage, and indeed the default setting is 13.2v.

I also think you have the Peukert coefficient set wrongly, for a T125 you should use 1.23 as the coefficient.

You may need to discharge the batteries by 20% or so and then re-charge them to get the synchronisation process working properly.

Thanks

Your right that it would be set at 13.2 but on they video it say , if your useing solar array it should be set 0.2/0.3 below Absorption voltage ,
looking at trojan spec sheet I can find an Absorption voltage but the bulk valve is 14.83v this is why it's set at 14.5v.
The batteries where discharge a bit before putting it on charge .

 

[pvb]

Maybe you could email your query to Victron, but do tell them exactly which charger and solar controller you have.

 

[GHA]

..... tail current 4.00% ,

Your right that it would be set at 13.2 but on they video it say , if your useing solar array it should be set 0.2/0.3 below Absorption voltage ,
looking at trojan spec sheet I can find an Absorption voltage but the bulk valve is 14.83v this is why it's set at 14.5v.
The batteries where discharge a bit before putting it on charge .

Not familiar with that unit but couple thoughts... tail current sounds very high, 1% is more often mentioned as a better figure.


Could your mains charger have switched to float too quickly so the monitor wasn't seeing 14.5v and 4% tail current at the same time? (Assuming that's what the figures mean)

As for when you go back on solar, I set float to the same as absorption (14.9V to allow for a little voltage drop) for my T105's & even then it's not a done deal that they really will get all the way to 100% charged even on a sunny day, takes a long time. From memory you can't change the switch to float time on the Victron?

Tail current is around 1.2v/0.5% for 225Ah when it stabilizes though seems it can be a lot lower if it's really cold, just checked the data from a light discharge a few days ago.

Check this out - guy who really knows his batteries >
https://marinehowto.com/programming-a-battery-monitor/

 

[sailaboutvic]

Hi GHA
Thanks for your input and link , need to take a good look at it . Maybe when I not had too much vino in me .
Any way I set the BMV as to Victron video , the only thin I altered was the charge voltage setting , and not sure I got that right , it say set .2/.3 below Absorption which I can't find for the T125 but I take it bulk and Absorption are about the same .
The only other think I change was the AH and that set a little lower .

https://m.youtube.com/watch?v=4Relj...fvcJLE6S5LmsQpbh2y4wl8Zyx7GmoZGg9_GP62H7bQc7Q

 

[GHA]

Hi GHA
Thanks for your input and link , need to take a good look at it . Maybe when I not had too much vino in me .
Any way I set the BMV as to Victron video , the only thin I altered was the charge voltage setting , and not sure I got that right , it say set .2/.3 below Absorption which I can't find for the T125 but I take it bulk and Absorption are about the same .
The only other think I change was the AH and that set a little lower .

https://m.youtube.com/watch?v=4Relj...fvcJLE6S5LmsQpbh2y4wl8Zyx7GmoZGg9_GP62H7bQc7Q

Well, much as I love Victron stuff don't agree with those settings, a batt at 13.5v taking Amps at 4% of capacity in Ah doesn't sound fully charged....

Always risky guessing from afar but looks like to reset your unit is looking to see 4% charge going in at 14.5V for 3 minutes - could your mains charger dropped down to it's float below 14.5V when there was still more charge going in? Maybe try the old favourite of turning off and on again if it does to set it back to absorption.
Most chargers/regulators seem to default to switching to float far too soon.

Enjoy the wine!

 

[pvb]

- could your mains charger dropped down to it's float below 14.5V when there was still more charge going in?

That was my thought also in post 2.

 

[sailaboutvic]

Well, much as I love Victron stuff don't agree with those settings, a batt at 13.5v taking Amps at 4% of capacity in Ah doesn't sound fully charged....

Always risky guessing from afar but looks like to reset your unit is looking to see 4% charge going in at 14.5V for 3 minutes - could your mains charger dropped down to it's float below 14.5V when there was still more charge going in? Maybe try the old favourite of turning off and on again if it does to set it back to absorption.
Most chargers/regulators seem to default to switching to float far too soon.

Enjoy the wine!

Battery charge is set @ Absorption is 14.5v float 13.5v or so the Manuel says .

{ looks like to reset your unit is looking to see 4% charge going in at 14.5V for 3 minutes }

Ok lost a bit here , are you saying that the charge as to stay at (4% of 14.5v) i.e. 13.93v for three mins before it can set it self?
If so I need to check on that .

 

[PaulRainbow]

Fitted a new BMV700 and I am trying to Synchronised it to my batteries bank , ( batteries are 4 Trojan 6v T125 ) .

The setting I have used are AH 450 , charge voltages 14.5v, tail current 4.00% , charging time 3m , peukert 1.5, current threshold 0.10A, time to go 3m.

Let me adjust those for you ;

AH 450 , charged voltage 0.3v less than float voltage, 13.2v, tail current 2.00% , charging time 10m , peukert 1.25, current threshold 0.10A, time to go 3m

Most importantly, don't get too hung up on the indicated SOC. Even if it's horrendously out, it won't effect the real SOC of the batteries.

 

[VicS]

Hi GHA
Thanks for your input and link , need to take a good look at it . Maybe when I not had too much vino in me .
Any way I set the BMV as to Victron video , the only thin I altered was the charge voltage setting , and not sure I got that right , it say set .2/.3 below Absorption which I can't find for the T125 but I take it bulk and Absorption are about the same .
The only other think I change was the AH and that set a little lower .

https://m.youtube.com/watch?v=4Relj...fvcJLE6S5LmsQpbh2y4wl8Zyx7GmoZGg9_GP62H7bQc7Q

The User's Guide for the for the Trojan batteries tells you that the absorption voltage is 2.45 volts per cell https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

See table 5 for flooded batteries for this and other para meters (As the lady calls parameters)

The video would be a million times better if you could shut the bloody music off!

 

[PaulRainbow]

Always risky guessing from afar but looks like to reset your unit is looking to see 4% charge going in at 14.5V for 3 minutes

Voltage would have to exceed 14.5v, and simulatneously the current would need to be less than 4% of 450ah, for 3 mins.

The settings are wrong. The voltage should be 0.3v lower than float voltage, not absorption. 4% is too high and 3 mins is not long enough.

- could your mains charger dropped down to it's float below 14.5V when there was still more charge going in? Maybe try the old favourite of turning off and on again if it does to set it back to absorption.
Most chargers/regulators seem to default to switching to float far too soon.

I don't see the point in tampering with the chargers, just because the BM is incorrectly calculation SOC.

 

[GHA]

Battery charge is set @ Absorption is 14.5v float 13.5v or so the Manuel says .

{ looks like to reset your unit is looking to see 4% charge going in at 14.5V for 3 minutes }

Ok lost a bit here , are you saying that the charge as to stay at (4% of 14.5v) i.e. 13.93v for three mins before it can set it self?
If so I need to check on that .

"4% of 14.5v" - no, 4% in Amps of 450Ah, so 18A going into the batteries at 14.5v buy the looks of it without pouring over the manual. Deffo not fully charged.
1% tail is the more accepted norm at absorption voltage so more like 4.5A tail in your case, if the charger trips to float too early and the victron does reset then sounds unlikely it will be fully charged either it the batteries are taking 1% current at float.
Mine take about 0.1/0.2A at float (13.8v) when fully charged. Much better IMHO that the charger/regulator stays at absorption long enough to actually get the batts charged so the current will drop down to about 1%.

From the link above - https://marinehowto.com/programming-a-battery-monitor/

The Known Full Reset:#1 Turn all DC loads OFF


#2 Fire up battery charger or engine & allow to run 4-5 minutes


#3 Voltage should be at ABSORPTION level or 14.4V+ (GEL 14.1V)


#4 Net accepted charge current should be less than 1.5% -2% of Ah capacity


#5 Okay to MANUALLY reset to 100% SOC

IMPORTANT: Battery voltage should be at absorption voltage not float voltage, unless it has been floating in excess of 24 hours.

 

[sailaboutvic]

Good morning guys , good to see everyone on the ball on a Monday morning .
Look like a good sunny day here in Tunisia so hoping with solar and shore power , I sort this out to day .
As vics so rightly pointed out Absorption 2.45v PC , miss that that's Vics .
Paul thanks for breaking the figures down , big help
GHA thanks for the link and your input .
Starting from scratch to day , hope I can get it sync.

 

[sailaboutvic]

Let me adjust those for you ;

AH 450 , charged voltage 0.3v less than float voltage, 13.2v, tail current 2.00% , charging time 10m , peukert 1.25, current threshold 0.10A, time to go 3m

Most importantly, don't get too hung up on the indicated SOC. Even if it's horrendously out, it won't effect the real SOC of the batteries.

question , in my case as I have solar panels I take it the the charge current to be set 0.3 below absorption 14.4v , set to 14.1v
In which case would the tail current still be 2%?

 

[GHA]

question , in my case as I have solar panels I take it the the charge current to be set 0.3 below absorption 14.4v , set to 14.1v
In which case would the tail current still be 2%?

Your trojans at 14.1v taking 2% tail current will *not* be fully charged. To guesstimate a full state of charge by looking for charge voltage below float and tail currentat 2% is garbage. No way will trojans showing those data be fully charged. I'll maybe have a play and a measure later to prove it. Can't believe everything you read on tbe web

 

[PaulRainbow]

Your trojans at 14.1v taking 2% tail current will *not* be fully charged. To guesstimate a full state of charge by looking for charge voltage below float and tail currentat 2% is garbage. No way will trojans showing those data be fully charged. I'll maybe have a play and a measure later to prove it. Can't believe everything you read on tbe web

You obviously know more than the people who make the battery monitor, crack on.

I'll leave this to GHA Vic, i don't want to tell you any more garbage.

 

[GHA]

OK, quick look. Mains charger on float, current sensor struggling to read such low current, usually reads around 0.1A/0.2A going in to fully charged batteries at 13.8v, clampmeter confirms it's next to nothing. The tiny change in voltage at the batttery is the fridge cycling. 2 x T105 so 225Ah when new, few years old now but still in good shape. (probably cos they get charged to actually 100% often, not 95% or 99% )

Next turn off the charger for a few minutes and turn on a few bits to take of a little of the surface charge >

Quickly tail current drops to just under 1A, confirmed by battery monitor, current sensor & clamp meter. Battery temperature 14.1C, current seems to be a bit higher when it's warmer, something like 1.4A but well under 1% in amps of 20H capacity in Ah. Will leave the charger off for while and check what goes in at float when discharged, but won't be much

 

[sailaboutvic]

Using the setting below I managed to get it to Synchronised.
Might need to play a bit more yet .

Still not 100% it's correct as I discharged a small amount then tried it a second time . mppt says it's on float but bmv hasn't synchronised a second time , maybe I need to discharge a lot more then just a few Amps

 

[PaulRainbow]

Using the setting below I managed to get it to Synchronised.
Might need to play a bit more yet .

Still not 100% it's correct as I discharged a small amount then tried it a second time . mppt says it's on float but bmv hasn't synchronised a second time , maybe I need to discharge a lot more then just a few Amps

It won't, it can't, because the voltage would have to exceed 14.1v, and simulatneously the current would need to be less than 2% of 450ah, for 3 mins.

Your voltage won't exceed 14.1v on float.