How to get victron battery monitor and JBD BMS to read same %

[Simi 60]

Have had the big EVE 280 bank running in the boat for 8 months now and still haven't been able to figure out myself how to get the Victron 702 reading the same as the JBD BMS app.

I get up in the morning, look at the Victron and it reads batts at 72% but reality is, according to JBD app 54%

I know it has something to do with the JBD BMS having reading a 280ah nominal but setting a 224ah cycle capacity (-20%) so the gauge on the app never reads higher than 80%.
(It seems I can change those numbers in the parameter setting but as yet, have not.)

But the Victron, when you put in battery capacity and then manually sync when batteries are accepting very limited charge reads as 100%
Things are never going to line up.

So here I am asking how to get them both the same or at least a lot closer.

Added bonus.....it'd be nice to get closer to 840ah nominal, say 750ah (-10%) than the current 672ah (-20%) cycle capacity that JBD has it throttled back to.

 

[sunshine_eggo]

"cycle capacity" is the actual tested capacity. The only reason it shouldn't be the nominal capacity is if you've actually capacity tested the battery and found it less than nominal. Set it to 280Ah.

Please screenshot your BMV settings settings.

It's going to take:

1) properly configuring your BMV
2) getting your battery charged to true 100% full charge.

 

[Simi 60]

Thanks for the reply
Set the cycle to 280ah
Fired up the Genset and started smashing in 160 amps
But it hit the wall at 80% and the ah sat at 224 and rising and back to 224
Voltage across 8 cells between 3.35 to 3.4v
Ran for another 30 minutes or more but never went higher..


Think it has to do with the 80% and full voltage setting
80% @ 3.4v and full @3.5v

Will go again tomorrow and let the 2500w of solar finish it off and see if it goes higher.

 

[sunshine_eggo]

BMV setup?

 

[sunshine_eggo]

Recommend the following changes to BMS config:

Balanced burn-on voltage 3.40
Balancing precision 0.02
charging over temperature 40
charging under temperature 3

 

[Bob B]

Thanks for the reply
Set the cycle to 280ah
Fired up the Genset and started smashing in 160 amps
But it hit the wall at 80% and the ah sat at 224 and rising and back to 224
Voltage across 8 cells between 3.35 to 3.4v
Ran for another 30 minutes or more but never went higher..


Think it has to do with the 80% and full voltage setting
80% @ 3.4v and full @3.5v

Will go again tomorrow and let the 2500w of solar finish it off and see if it goes higher.

I think you are right .... If you never get to 3.5V, the JBD BMS will never read 100% charged .... and will never switch over to tracking amps in and amps out for SOC calculations. It will continue to use the voltage guestimates for SOC calculations.
For the BMS to track SOC accurately, you need to occasionally reach 100% charge .... Oh, and any time you write any parameter change, the JBD BMS will revert back to reading the SOC as a guestimate based on voltage until you go thru a cycle and reach 100% charge again.

The Victron also resets it's SOC once you get to 100% and must reach that level occasionally to keep it in sync.

 

[Simi 60]

BMV setup?

Currently at 840ah capacity and will hit synch when the charger stops charging at, I think from memory, 28.4v

 

[Simi 60]

Recommend the following changes to BMS config:

Balanced burn-on voltage 3.40
Balancing precision 0.02
charging over temperature 40
charging under temperature 3

Care to explain why?
I have never seen them higher than 32c
But we are heading into summer and I do cruise in tropical waters.
So 40c may be possible

 

[sunshine_eggo]

Care to explain why?
I have never seen them higher than 32c
But we are heading into summer and I do cruise in tropical waters.
So 40c may be possible

Starting balancing at 3.20V is meaningless. Still in the flat portion of the curve. Even imbalanced cells appear near perfect at that level. Imbalance begins to manifest above 3.40V.

0.03V is too high. You want to start balancing the high cells sooner as 20mV above 3.40V is meaningful in terms of imbalance.

40°C is hot. It's above the desirable temperature for charging. If nothing else, it's a signal to you that you're operating in a suboptimal condition.

You had low temp charging protection effectively disabled. While you may never get anywhere near freezing, charging a LFP battery at or below freezing will destroy it.

 

[Simi 60]

Yeah I know freezing will kill it but a freezing day where we are is 18c

And I know 40c is hot and ideally I don't want to see it but I also don't want to shut the batteries and the boat down at what could be a critical time, think underway amongst reef and now no navigation as BMS has shut batts down.

The first two I'll look into, thanks.

 

[Simi 60]

I think you are right .... If you never get to 3.5V, the JBD BMS will never read 100% charged .... and will never switch over to tracking amps in and amps out for SOC calculations. It will continue to use the voltage guestimates for SOC calculations.
For the BMS to track SOC accurately, you need to occasionally reach 100% charge .... Oh, and any time you write any parameter change, the JBD BMS will revert back to reading the SOC as a guestimate based on voltage until you go thru a cycle and reach 100% charge again.

The Victron also resets it's SOC once you get to 100% and must reach that level occasionally to keep it in sync.

Looking at the eve 280 spec sheet it seems their charge % numbers don't quite align with the JBD numbers.

I think the charge % numbers are where the adjustments need to be made so going down that path now
I'll wait until the charger stops charging and adjust the voltage numbers as the new 100% and drop the rest back as per eve spec

 

[Simi 60]

I have taken note of the pre set BMS % numbers
Compared them to the EVE % numbers
And have hopefully got things a bit closer
Have chosen
100% undecided yet
80% 3.35v
60%. 3.3v
40%. 3.27v
20%. 3.22v

Batts are now reading 85%, never seen past 80% prior

 

[sunshine_eggo]

Yeah I know freezing will kill it but a freezing day where we are is 18c

And I know 40c is hot and ideally I don't want to see it but I also don't want to shut the batteries and the boat down at what could be a critical time, think underway amongst reef and now no navigation as BMS has shut batts down.

Doesn't shut the battery down. Just prevents charging.

Looking at the eve 280 spec sheet it seems their charge % numbers don't quite align with the JBD numbers.

I think the charge % numbers are where the adjustments need to be made so going down that path now
I'll wait until the charger stops charging and adjust the voltage numbers as the new 100% and drop the rest back as per eve spec

The Eve numbers are resting voltages. The JBD are more reasonable for a battery in operation.

The solution to your query is to charge the battery to 100% and allow BMV and BMS to sync to 100. Do that a couple times per month, or you'll be back here.

 

[Simi 60]

Doesn't shut the battery down. Just prevents charging.



The Eve numbers are resting voltages. The JBD are more reasonable for a battery in operation.

The solution to your query is to charge the battery to 100% and allow BMV and BMS to sync to 100. Do that a couple times per month, or you'll be back here.

The eve specs have both resting and under load numbers.

 

[sunshine_eggo]

The eve specs have both resting and under load numbers.

Charging isn't a load. When charging the target voltage should be HIGHER than resting.

 

[Bob B]

Looking at the eve 280 spec sheet it seems their charge % numbers don't quite align with the JBD numbers.

I think the charge % numbers are where the adjustments need to be made so going down that path now
I'll wait until the charger stops charging and adjust the voltage numbers as the new 100% and drop the rest back as per eve spec

Once the BMS reaches 100% charge it no longer uses those numbers ... except the full charge voltage.

When it reaches full charge, it starts tracking based on amps in vs amps out.

 

[Simi 60]

Charger throttled back amps considerably at 240ah and a "high" 3.4v/cell
Still only showing batteries at 84%
Resets the Victron to 720ah capacity and syncs
So no better than before, well 4% better on BMS gauge but still a big discrepancy between the Victron at 100% and the BMS at 84%

Grrrr

 

[Simi 60]

Charging isn't a load. When charging the target voltage should be HIGHER than resting.

Yep, I realise that but there is still is and always has been a discrepancy between the BMS and the Victron, gave it several months to try and sort itself out but it doesn't seem to be happening.
That's why I'm trying to "trick" it, but I fear this ekectrickery is smarter than me. (-;

 

[sunshine_eggo]

Charger throttled back amps considerably at 240ah and a "high" 3.4v/cell
Still only showing batteries at 84%
Resets the Victron to 720ah capacity and syncs
So no better than before, well 4% better on BMS gauge but still a big discrepancy between the Victron at 100% and the BMS at 84%

Grrrr

The solution to your query is to charge the battery to 100% and allow BMV and BMS to sync to 100. Do that a couple times per month, or you'll be back here.

Yep, I realise that but there is still is and always has been a discrepancy between the BMS and the Victron, gave it several months to try and sort itself out but it doesn't seem to be happening.
That's why I'm trying to "trick" it, but I fear this ekectrickery is smarter than me. (-;

The passage of time can only make it worse. Battery monitors need to periodically be set to a known SoC. Victron states "a couple times a month."

 

[Simi 60]

Charging isn't a load. When charging the target voltage should be HIGHER than resting.

Ah, got you
You are saying when charging I should be leaning towards the "at rest" numbers