Battery SOC minimum %

[leon.davibe]

The way I compute it in my head is the BMS is an (up to) 16S, so it can be a 4S if you want? Not so?

So for the 16S BMS to got to sleep and lose power and never wake up again because there of 6V will never happen with 16s, but a good chance to happen with 4s but thats not a problem because everyone has a 12v lying around.

Yea have not checked if it can do 4s

As far as i have it the big ones tend to be 8s to 16S just bought one too pictured

And different model tends to be 4-8s

my .jkvov is up and running
Just finished it

So only one left for repair the crappy cell one

 

[wingnut771]

Don't think you can compare then, JK focus is on the DIY market and cater for self made packs where PACE is commercially focused.

You can do a lot of damage with an active balancer if you dont know what you are doing.

Which is why I said if you have access to the BMS then "warranty" is void.

 

[wingnut771]

Yea have not checked if it can do 4s

As far as i have it the big ones tend to be 8s to 16S just bought one too pictured

And different model tends to be 4-8s

my .jkvov is up and running
Just finished it

So only one left for repair the crappy cell one

Okay, 8S then which = 2.5V x 8 = 20V, so if your 16s BMS dies at 40V, there is no snowball change in hell that you will have to jump it as the BMS works all the way down to 20V.

 

[leon.davibe]

Don't think you can compare then, JK focus is on the DIY market and cater for self made packs where PACE is commercially focused.

You can do a lot of damage with an active balancer if you dont know what you are doing.

Yes but active balancer cause problems if you do it always instead of above certain voltage

Must say i think jk focus is changing

Since this model fits all the pace holes and com ports etc

And as they get more exposure things may change

I simply wkn't take a bathery wigh a passive balancer

Chatted with a guy that build batteries comercially

And after they checked out all the options available they opted to design their own bms

This was many years ago though when passive balance was the only option

 

[Koosvanwyk]

Have you ever runnit down to 0%

Soh is a capacity % so thisnknky gets updated when the battery actually does a full cycle ie it resets the counter to zero if the battery hits 2.5v or whatever the manufacturer set as 0%

And then counts the kwh charges until it hits 100% soc

And then divides this capacity by the pack capacity this % is then SOH

So if a battery never hits 0%
Then the SOH is a meaningless metric

Indeed, the SOH readings on most BMS are useless, unless you often hit the UVP which is then used to determine remaing capacity which then feeds SOH until the next UVP event.

The exception here is pylontec which does some mathematical formula to guesstimate SOH

 

[Zuner]

Sounds like you need to do a test for humanity.

Hahaha added to list of projects.

 

[Zuner]

I'm sure it would. Who has that **** lying around?

I hade 1 in my box, went up to 45v then sparked and now it's dead lol.
Though i have Poe injectors which can do 50v

 

[Zuner]

There is always a risk the BMS safety kicks in and then you need to open the battery and charge individual cells, balance everything etc. Not something I feel like doing. I've seen the same on mine where the inverter draw over a couple of days on a flat battery is several percent.

Yup it's a very noticable % that it draws, which is why i never went below 15% in case i'm not home one day when it happens.
Though i have multiple automations to protect the system from accidental drain so I should be fine.

 

[leon.davibe]

Hahaha added to list of projects.

Yea no i wont do a low voltage shutdown test without having a plan for jump start

Cause i. Dread not bejng able to power it on

A few months ago the inverter did a low voltage shutdown and i slept through the auto restarts

For some reason if it powers up in a blend mode with battery missing it won't acknowledge the battery

So had to do a proper reboot killing all power eskom battery abd solar and get the battery up first

 

[Zuner]

Yea no i wont do a low voltage shutdown test without having a plan for jump start

Cause i. Dread not bejng able to power it on

A few months ago the inverter did a low voltage shutdown and i slept through the auto restarts

For some reason if it powers up in a blend mode with battery missing it won't acknowledge the battery

So had to do a proper reboot killing all power eskom battery abd solar and get the battery up first

I am at risk cause I run my system with the eskom breaker off and onlt turn it on if i need to, meaning if something happens my system will drain itself to 0.

I have too many projects on the go so this will go on the list for next year.

 

[ghaye]

Have you ever runnit down to 0%

Soh is a capacity % so thisnknky gets updated when the battery actually does a full cycle ie it resets the counter to zero if the battery hits 2.5v or whatever the manufacturer set as 0%

And then counts the kwh charges until it hits 100% soc

And then divides this capacity by the pack capacity this % is then SOH

So if a battery never hits 0%
Then the SOH is a meaningless metric

No, I've only gone down to 10%. I am very sceptical about that SOH reading. But the installer was there about a year ago and had a laptop plugged into the battery with the manufacturer's guys having a look at it.
The system was doing some funny things (I can't remember now what it was) after they added a second inverter. I'm pretty sure the installer had wrong settings somewhere. I never got an answer from them other than "it's all good now"!

 

[denmendez65]

No, I've only gone down to 10%. I am very sceptical about that SOH reading. But the installer was there about a year ago and had a laptop plugged into the battery with the manufacturer's guys having a look at it.
The system was doing some funny things (I can't remember now what it was) after they added a second inverter. I'm pretty sure the installer had wrong settings somewhere. I never got an answer from them other than "it's all good now"!

Isn’t SOH easy to check? Don’t you just check what is consumed and how much the battery supplied vs what your actual capacity is?

Just not sure about VARS. most energy meters, even the inverters only do active Power, not reactive. And then there is the inefficiency which could be factored in easily I would like to think.

 

[leon.davibe]

Isn’t SOH easy to check? Don’t you just check what is consumed and how much the battery supplied vs what your actual capacity is?

Just not sure about VARS. most energy meters, even the inverters only do active Power, not reactive. And then there is the inefficiency which could be factored in easily I would like to think.

From what i have seen The SOH only updates if the bathery hits 2.5v on a cell triggering 0% soc

If the amount of energy pushed into the battery from this point is less that stated capacity soh updates

So if it never hits 0% soc it will stay on whatever the last value was

The interesting thing is it can udjust up too
So if the balancing was out
If you sort it and the energy pushed nto battery is more than previously it will adjust up

Though someone stated that the pylontech does a bit of thumb sucking to compensate for not hitting 0

 

[leon.davibe]

Isn’t SOH easy to check? Don’t you just check what is consumed and how much the battery supplied vs what your actual capacity is?

Just not sure about VARS. most energy meters, even the inverters only do active Power, not reactive. And then there is the inefficiency which could be factored in easily I would like to think.

Yea simple capacity test
Run the system down to 0% normally the bms will coulomb count what energy goes in and upate

But yea you can get wrong readings and incorrect SOH

As some bms's don't count propperly at very low amps

Ie the shoto counts nothing under 1A

I have a small system so to best use all solar i try and balance the load to prevent the battery from chargjng
To have it available to accept the mid day peak so it spends quite a bit of time slow charging

Have seen a 5% drift a day

So if this happens while capacity testing the count may be out

So SOH must be taken with salt in some cases like mine