%SOC on/off under batrium

HughF

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Does anyone know if the watchmon + expansion supports %SOC charger/generator start/stop commands. I would like to consider moving my generator start control from my Outback vfx inverter/charger over to the BMS. My generator start/stop is controlled by a simple 12v active high signal, nothing fancy.
 

ChrisD5710

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I just recently asked this question to Batrium:

Quote:

"Here in the winter when the sun is absent I need to charge my battery bank from an external power source.

I have the Expansion Board and would like one of the relays to switch on the external power.

Ideal would be to switch the charger on when the SOC% reaches 20% and back off once the battery bank is back at 45% SOC%.

The closest settings I have found is this:

settings in Discharging:

Low cell cutout 3.30 v (CV3)
Low cell resume 3.50 v (CV4)

My idea is that the charger is switched on when any cell bank goes below 3.30 v and charger switches off once the lowest cell bank has reached 3.50 v.

However, None of the relay settings seem to match, but I know I must have overlooked something."

---

Here is the reply from Batrium:

We don't have a specific item for this option. See Expansion Output Functions

However possibly "Charging Limited" might be a possibility. It's normal purpose is to prevent fast charging if the battery is overdischarged and help it recover from this, in that circumstance the battery needs to be slow charged till it gets above a certain level CV5 and can then be charged as normal. Hence charging is limited between the Low Cell Voltage CV2 Understanding the WatchMon - Hardware configuration - CellMon settings. till it reaches CV5 and QV4 Understanding the WatchMon - Control Logic - Charging settings. Not sure if it fits your needs but worth a try and see if it works.

I tried to narrow it down a bit more and sent this to Batrium:

Thank You for Your reply.

I have verified that CV5 is located on Charging, item: Limited Power Cell Volt and can be adjusted.
OK to that, but then You loose me because CV2 is found on the page Voltview as CMU Alert Low. This value seems to be the same as CV2 and can not be adjusted.

Can You help me a bit more?

And the final reply, so far is:

I can't guarantee that it will work but thought it worth the try. The bottom number CV2 is the Low Cell Limit on the hardware area Understanding the WatchMon - Hardware configuration - CellMon It is charging limited all the way from the bottom allowable number till it reaches CV5. Below CV2 it won't charge at all

---------

Maybe someone in this forum can make something out of this help from Batrium?

Closest solution I have come up with is the relay setting:

Warning LVA discharge

When Low cell cutout volts goes below the setting the relay pulls and when lowest cell bank rises above the threshold, relay goes off.

This is verified OK, but there is no hysteresis so as soon as the charger starts the lowest cell bank voltage goes up, switching the charger off again..

Ideas anyone?

ChrisD
 

daromer

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I use an esp8266 and or Raspberry to do that controlling. :) Not answer to your question but you can have an esp8266 listen to the broadcasted values from watchmon and take Care of the generator start and stop
 

HughF

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Screw that then, I'll just leave it under outback control :)
 

hbpowerwall

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I used battery voltage and change the timer to 10min to it didn't flick on and off constantly wasn't perfect but worked perfectly for my mining rig back in the day
 

HughF

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hbpowerwall said:
I used battery voltage and change the timer to 10min to it didn't flick on and off constantly wasn't perfect but worked perfectly for my mining rig back in the day
I use LiFePo4, I prefer %SOC vs cell/pack voltage because of my discharge curve
 

hbpowerwall

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HughF said:
hbpowerwall said:
I used battery voltage and change the timer to 10min to it didn't flick on and off constantly wasn't perfect but worked perfectly for my mining rig back in the day
I use LiFePo4, I prefer %SOC vs cell/pack voltage because of my discharge curve


Does make sense thats for sure, I requested for it to be upgraded in the software when possible.
 

HughF

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hbpowerwall said:
HughF said:
hbpowerwall said:
I used battery voltage and change the timer to 10min to it didn't flick on and off constantly wasn't perfect but worked perfectly for my mining rig back in the day
I use LiFePo4, I prefer %SOC vs cell/pack voltage because of my discharge curve


Does make sense thats for sure, I requested for it to be upgraded in the software when possible.
I mean it's hardly a complicated logic function to add... Hopefully they will add it in a future release
 

Batrium

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Maybe the community should write the logic rules that you think would suit your requirement. After we have seen consensus from the group where others can also embrace the function it can be added to the options. Please assume that this will trigger the relay output which is wired accordingly to start the generator. Hence (Enable = true) when the generator is started will only be applied for a short period of time.
 

HughF

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Batrium said:
Maybe the community should write the logic rules that you think would suit your requirement. After we have seen consensus from the group where others can also embrace the function it can be added to the options. Please assume that this will trigger the relay output which is wired accordingly to start the generator. Hence (Enable = true) when the generator is started will only be applied for a short period of time.

Give us an output that is on at X% and off at Y%, with X and Y programmable, that will do us. We'll work around that with our genset start controls.
 

OffGridInTheCity

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To answer this question, I'd like to understand better how to to set SOC % to make it relevant. In my system I run in 80% SoC (float = x.xv) to 40% SoC (inverter cut-off = x.xv) but its based on voltage and I don't see how to set Batrim SoC or keep Batrium SoC aligned to real world voltage of the battery.

Setting SoC:
The https://support.batrium.com/article/229-soc-calibration says to go to Metrics tab and type in SOC % to indicate Full or Empty. So that's 100% or 0%? or I'm supposed to set 80% as Full? but what would that mean?

Maintiaining SoC on day basis:
On main Shunt page I see Re-Calibrate Low SoC and Re-Calibrate Hi SoC and the web site says..
Re-Calibrate Low SoC: ON/OFF to allow reset the State of Charge back to empty (0%) if it goes below this value. Only available in advanced mode.

But what does mean functionally? If I set it to 40% what does do / how does this keep things from getting out of wack over time.
 

HughF

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OffGridInTheCity said:
To answer this question, I'd like to understand better how to to set SOC % to make it relevant. In my system I run in 80% SoC (float = x.xv) to 40% SoC (inverter cut-off = x.xv) but its based on voltage and I don't see how to set Batrim SoC or keep Batrium SoC aligned to real world voltage of the battery.

Setting SoC:
The https://support.batrium.com/article/229-soc-calibration says to go to Metrics tab and type in SOC % to indicate Full or Empty. So that's 100% or 0%? or I'm supposed to set 80% as Full? but what would that mean?

Maintiaining SoC on day basis:
On main Shunt page I see Re-Calibrate Low SoC and Re-Calibrate Hi SoC and the web site says..
Re-Calibrate Low SoC: ON/OFF to allow reset the State of Charge back to empty (0%) if it goes below this value. Only available in advanced mode.

But what does mean functionally? If I set it to 40% what does do / how does this keep things from getting out of wack over time.
100% SOC is when all cells are in final bypass and your tail current drops below a certain value that you'll have to figure out.

Cycle charge efficiency (that's what outback call it anyway) tells the shunt to discount a certain % of power that goes to charge the batteries, because of charging efficiencies. Discharge aH are always counted at true value.
 

OffGridInTheCity

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HughF said:
100% SOC is when all cells are in final bypass and your tail current drops below a certain value that you'll have to figure out.

Cycle charge efficiency (that's what outback call it anyway) tells the shunt to discount a certain % of power that goes to charge the batteries, because of charging efficiencies. Discharge aH are always counted at true value.

>100% SOC when all cells....
Interesting, I never 'got that' anywhere. And if true, it doesn't sound good for a couple of reasons.
1) I don't use balance most of the time - why waste energy to heat when its not necessary. Last time I used bypass was 6 months ago when I added some new packs. The rest of the time, the packs stay in balance (within 70mv) all this time on their own - which is perfectly normal for healthy packs.

2) I've never charged my battery bank beyond 4.0v. Most of the time itnever reaches above 3.8v as I run in the middle of the discharge curve and maintain a low (<35%) DOD to try to extend the packs life. So under your comment - I cannot set 100% SoC because I would never get up to 4.15v + balance.

Seems to me this is too complicated. I should be able to set SoC at any time to be what I think is the % at that time of my battery bank. But I don't see any way to set a custom SoC value.

Bottome line - Batrium SoC is not useful for me so far. I don't say this to complain but rather my point is that an on/off feature is not useful if I can't more directly set/control SoC ... and I'm guessing I'm not the only one.

P.S. For the record - I'm a Batrium fan!!! :)
 

HughF

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I only picked that 'when all cells are in bypass = 100%' as what I would want batrium to use to recalculate 'full'. If you don't ever charge to those levels then you'd never hit 100%, which doesn't matter.

You can tell it you are at 100% at any time, it's in the metrics tab iirc. A better way would be how every other capacity meter I've used works, you have a >than voltage setpoint and a <tail current setting, combined sometimes with a parameters met timer.

You'd set your voltage to 14* 3.8, your current to whatever you charge at and your parameters met time to a short value. As your batteries charge up, when your pack reaches 14*3.8, it would reset full.

But I would much rather have that percentage value represent the true value of the pack and only ever be set to 100% when you fully charge to 4.2 or whatever, then cycle your daily cycles between 35-80% or whatever you prefer.
 

daromer

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You can set whatever SOC you want whenever you want BUT... You dont know what SOC you are at unless you are at top charge or bottom charge. at. 3.8V you can only guess it.. Thats why you need to go above 4.05 in generall to be sure. But with that said you can set it to recallibrate at lower too if you want.

recallibrate is needed because you have losses in the battery pack that the batrium dont know about. With the shunt the SOC dont need to be callibrated often at all. I would say many months between in best case and if your packs are in good shapre.

I use SOC to everything here. Its cruicial
SOC is user defined and you decide when its full and when its empty. Just calculate the capacity you have and reset soc whenever you want.

I for instance hardly run above 4.0V and reset my SOC and 4.0. I also have set to when the first pack reaches like 3V i know its empty and have then callibrated it to have that total capacity based on total discharge.

I dont see the problem you seem to have im afraid.
 

OffGridInTheCity

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daromer said:
You can set whatever SOC you want whenever you want BUT... You dont know what SOC you are at unless you are at top charge or bottom charge. at. 3.8V you can only guess it.. Thats why you need to go above 4.05 in generall to be sure. But with that said you can set it to recallibrate at lower too if you want.

recallibrate is needed because you have losses in the battery pack that the batrium dont know about. With the shunt the SOC dont need to be callibrated often at all. I would say many months between in best case and if your packs are in good shapre.

I use SOC to everything here. Its cruicial
SOC is user defined and you decide when its full and when its empty. Just calculate the capacity you have and reset soc whenever you want.

I for instance hardly run above 4.0V and reset my SOC and 4.0. I also have set to when the first pack reaches like 3V i know its empty and have then callibrated it to have that total capacity based on total discharge.

I dont see the problem you seem to have im afraid.
Let's say my 14s battery bank is currently at 3.9v/cell and I want Batrium to show 76% SoC. Where (in the interface) do I set it to 76%?

When I look at the Shunt->Metrics panel I see "Sate of Charge" that I can set - but the Full and Empty buttons confuse me. Is it as simple as setting it and ignoring the Full and Empty buttons? For example, I just now set it to 76% in this picture....

image_ljeust.jpg
 

daromer

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Yes you can set it just like that.
But if you only charge to 3.9V i would set that to 100%. Why would you set it to less than 100?
If you only go between 3.4-3.9 then 3.4 = 0% and 3.9 = 100% and the capacity between is your total capacity on the battery bank available.

Though you can of course set it to whatever but Batrium and all other BMS are made to reset only at a min and max SOC.

For instance mine is set to 4v = 100v and 3.0v 0%.

So to get it to auto callibrate properly this is how you should do it unless you know exactly what you got in the battery bank:

Set a guess number of AH.
Charge it to your top voltage
set SOC = 100%
Discharge it to empty
Look at SOC and how much AH is left
Reset SOC to % and AH to the new AH
Charge it back up and crosscheck if you ended up at 100% if not just change it some what.


Doing above will ensure that your autocallibrate will work going forward but it of course need you to run between 0 - 100 like most people do :) (Neither less voltage range)
 

OffGridInTheCity

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daromer said:
Yes you can set it just like that.
But if you only charge to 3.9V i would set that to 100%. Why would you set it to less than 100?
If you only go between 3.4-3.9 then 3.4 = 0% and 3.9 = 100% and the capacity between is your total capacity on the battery bank available.

Though you can of course set it to whatever but Batrium and all other BMS are made to reset only at a min and max SOC.

Ah ha. The actual battery has 780ah but I only need to use 36% of it on adaily basis to let meconsume all the PV array power I generate- and I've programmed hi (float)/ low (inverter off) to match this to help ensure long battery life.

So I kept trying to understand the Batrium interface in terms of showing 76% (hi) -> 40%(low) per actual battery... instead of thinking in terms of100% (hi) -> 0% (low) as a reflection of my operating parameters.

Thank you for helping me adjust my thinking!
 

daromer

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Glad to help.

I would use the parameters towards your actual voltage range. Because thats basically what you operate in. Whats in the battery left is irrelevant if you set stop charge and stop discharge before it.

Example: An EV today have a set range you can drive and use from the battery but in real life they actually have a reserve being able guarantee the longevity of the battery over time. they basically limit the use-range by setting the SOC more in middle than towards the ends :)
 
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