MPPT query

[GUMPY]

35 minutes ago, nicknorman said:

Tony does have a working BMS but it is rather opaque, not liking to communicate with the outside world much! That is the penalty of having that type of battery, they are good value in many ways but not in the context of the BMS, without the additional external switching module. And the BMS is "proprietory"

Battery here is lithium, comes as a complete system with the inverter, which does the majority of the control and works properly.  If the batteries people are cobbling together to work on boats don't have decent control systems then I would suggest they are not fit for purpose. 

[Tony1]

36 minutes ago, Loddon said:

Battery here is lithium, comes as a complete system with the inverter, which does the majority of the control and works properly.  If the batteries people are cobbling together to work on boats don't have decent control systems then I would suggest they are not fit for purpose. 

 

I cant speak for anyone else's setup of course, but I think my battery management arrangements are pretty decent. 

The batteries aren't perfect of course, and that's factored into the price you pay for them. You're working to a budget when you buy used cells that don't come with a built-in BMS.  But you do get proven high-quality cells manufactured for industrial vehicles. 

 

In terms of BMS components, my first safety measure is the BMV712 that will remotely switch off all of the chargers if the daily SoC limit of 85% is reached, and will switch them back on when the SoC falls to 50%. 

To be fair, that's more about prolonging battery life by avoiding very high SoC from happening, as its all to easy to forget about the charging for a while, and the batteries rise from a safe 85% to a less safe 95% very quickly when you're charging at 120 amps or more. 

 

And if the SoC measurement is not accurate for some reason, the chargers will go into float when the batteries reach 14.2v, so that's an extra safety measure. 

B2Bs are inefficient, but their charging voltage stays strictly within its set parameters of the charge profile, and as soon as the charge voltage is exceeded they go into float mode, which in my case is 13.1v, so effectively no charging at all. 

 

The third precaution is a BMV712 dedicated to monitoring the voltage and configured to disconnect the charging units if the battery voltage ever goes above 14.6v.

 

The final precaution is another BMV712 that monitors voltage and SoC, and if either parameter gets too low, it will disconnect all of the loads, but not the chargers. 

So on the plus side, my disconnects will allow the battery to recover from an extreme voltage event by leaving either the loads or the chargers connected to them, as appropriate. The built-in BMS units don't usually have that feature, as far as I know. They just disconnect the battery completely, which might leave it in an extreme-voltage state for days, if you're not around to take action.

 

All these bits and bobs cost a few bob to be fair, and it must be said that I cant monitor individual cell voltages without connecting a laptop to the batteries, so I don't know on a daily basis how individual cells are getting on, and I cant set monitors and disconnects to react automatically to individual cell voltages.

So its not perfect, but then the valuqes set for the BMS systems in many budget lithium batteries are so extreme that there is a risk the battery might be damaged before the BMS disconnect even kicks in. 

So although I had to pay extra and cobble together a battery and charging management system myself (with a lot of invaluable advice from the ever patient Nick), I believe I have some safety features and battery-health features that many off the shelf batteries dont have. 

Whether you really need those extra features that I have is another question.... 

 

 

Edited March 8, 2022 by Tony1

[TheBiscuits]

14 minutes ago, Tony1 said:

The built-in BMS units don't usually have that feature, as far as I know.

 

No. The Daly BMS I have disconnects either charging or discharging as appropriate depending on high/low total voltage/cell voltage/current/temperature. 

 

I don't need to do anything to make it do this, but obviously it's best not to be bouncing off the limits too often.

[Tony1]

3 minutes ago, TheBiscuits said:

 

No. The Daly BMS I have disconnects either charging or discharging as appropriate depending on high/low total voltage/cell voltage/current/temperature. 

 

I don't need to do anything to make it do this, but obviously it's best not to be bouncing off the limits too often.

 

Yes,

I referred to the BMS units that come installed in most budget end batteries, not to the more expensive models like Daly.

 

[TheBiscuits]

19 minutes ago, Tony1 said:

All these bits and bobs cost a few bob to be fair, and it must be said that I cant monitor individual cell voltages without connecting a laptop to the batteries, so I don't know on a daily basis how individual cells are getting on

 

I've watched the development of your system with interest, and I'm beginning to wonder if you should open the cases, disconnect the Valence BMS and wire in a Daly BMS ....

 

You could then flog some of the rest of your monitoring stuff on eBay.  

 

Alternatively I'd recommend that you set up an automated eBay search for the Valence Master BMS if you'd rather not dismantle your batteries.

[Tony1]

18 minutes ago, TheBiscuits said:

 

I've watched the development of your system with interest, and I'm beginning to wonder if you should open the cases, disconnect the Valence BMS and wire in a Daly BMS ....

 

You could then flog some of the rest of your monitoring stuff on eBay.  

 

Alternatively I'd recommend that you set up an automated eBay search for the Valence Master BMS if you'd rather not dismantle your batteries.

 

To be honest, I saw a video on how to break down the valence batteries and install a BMS, and I gave that some serious thought.

It wouldn't be all that difficult, and it would add the missing element of real time response to extreme voltages at the level of individual cells. 

As things are, I think my batteries are very safe as long as I keep the settings very conservative and check them with the laptop once a month or so, but I always have half an eye on potential upgrades I must say, and that is one that might just happen one of these days. 

 

Edited March 8, 2022 by Tony1

[MtB]

2 hours ago, nicknorman said:

Tony does have a working BMS but it is rather opaque, not liking to communicate with the outside world much! That is the penalty of having that type of battery, they are good value in many ways but not in the context of the BMS, without the additional external switching module. And the BMS is "proprietory"

 

I'm not sure we even know all the functions of the Valence internal MBS. We know it balances the cells but that it really. I'm not even sure how a user knows the cell balancing is working. 

 

Does it have any sort of high or low voltage disconnect Tony? Can you actually see what your cell voltages are or just the sum of them being battery voltage? 

 

[TheBiscuits]

1 minute ago, MtB said:

 

I'm not sure we even know all the functions of the Valence internal MBS. We know it balances the cells but that it really. I'm not even sure how a user knows the cell balancing is working. 

 

Does it have any sort of high or low voltage disconnect Tony? Can you actually see what your cell voltages are or just the sum of them being battery voltage? 

 

 

@peterboat posted a video or a screenshot of the software connected to the batteries a few years ago.

 

They monitor and balance cells, but if they go out of range all the internal BMS can do is tell the (missing) master BMS to disconnect.  

 

It's probably possible to reverse engineer the communications protocol but that's beyond most users.  It might even be a standard protocol but I don't know because I decided against the Valence batteries ages ago.

 

I'd rather have more access to my integrated BMS but I'm not cracking the case open until the 5 year warranty has expired!

[Tony1]

11 minutes ago, MtB said:

 

I'm not sure we even know all the functions of the Valence internal MBS. We know it balances the cells but that it really. I'm not even sure how a user knows the cell balancing is working. 

 

Does it have any sort of high or low voltage disconnect Tony? Can you actually see what your cell voltages are or just the sum of them being battery voltage? 

 

 

I can say that I checked my battery voltages individually and they are always identical to 2dp's, so I feel sure that it is keeping them in balance, but I havent yet looked at the individual cell voltages, I made up a laptop-to-battery cable after finding some instructions online, but I couldnt get the software to see my batteries after the first few tries, so I gave up like the petulant child that I am, and there the project rests, until motivation returns to my soul. 

When I get it working, I'm hopeful and optimistic that I'll see the individual cells in good balance, thanks to the internal BMS. 

 

So yes, you can definitely monitor individual cells, as Peter has pointed out a few times- you just need the software and a cable. 

 

What the internal BMS board wont do is disconnect the batteries, however. 

 

Edited March 8, 2022 by Tony1

[peterboat]

I think that after the number of years I have been using these batteries in both my boat and my electric truck, if a disaster was going to happen it would have by now! Maybe its because I top balanced properly? Or a don't over charge, or is it the fact that I use solar? Who knows and I don't care, disconnect is done by my solar controllers nothing else 

[peterboat]

1 hour ago, TheBiscuits said:

 

I've watched the development of your system with interest, and I'm beginning to wonder if you should open the cases, disconnect the Valence BMS and wire in a Daly BMS ....

 

You could then flog some of the rest of your monitoring stuff on eBay.  

 

Alternatively I'd recommend that you set up an automated eBay search for the Valence Master BMS if you'd rather not dismantle your batteries.

The master BMS are unobtainable and the software unavailable I knew the chap that worked for Smith's electric vans and had set up as independent for them, he couldn't help, if he needed a BMS he had to send the old one in to valence NI.

[Tony1]

18 hours ago, MtB said:

 

I'm not sure we even know all the functions of the Valence internal MBS. We know it balances the cells but that it really. I'm not even sure how a user knows the cell balancing is working. 

 

Does it have any sort of high or low voltage disconnect Tony? Can you actually see what your cell voltages are or just the sum of them being battery voltage? 

 

 

I had another poke around, and there is loads of stuff about Valence batteries in online solar/offgrid forums, as you would expect I guess.

I found a very helpful thread on a site called diysolarforum on page 9 of a thread called 'valence-xp-super-thread', where there seemed to be a general agreement (based on an interpretation of the manual) on the following points:

 

- The internal BMS boards only perform balancing between the cells within a battery, but not across batteries

- To balance between batteries, you need an external control, e.g. the Valence BMS unit

- The balancing between cells within a battery only takes place when there is 5V supply via the comms cable from a laptop or external BMS, so it look as if just leaving the laptop connected (and awake?) for a good few hours will allow the cells within each battery to balance

- normally the green LED on the battery case flashes every 20 secs, but when connected/balancing, it flashes every 5 secs

- there was a quote, apparently from the manual, that balancing will only happen when cell voltage is above 3.36v, so it seems you would have to be doing some sort of charging as well as have the cable connected

 

ETA: I cant get the link to paste in and work properly, so here is an extract from that forum page:

From "Valence XP Power System User Manual" Section 5.5 Functionality:
 

"The XP module is an intelligent battery. Each XP module has a printed circuit board assembly (PCBA) and associated components which carry out the following functions:

• Cell block voltage measurement
• Current shunt voltage measurement, i.e. each module keeps track of its current flow
• Temperature sensor monitoring; each module has 1 temperature sensor per cell bank and at least 1 SOC calculation for the module
  on PCBA (thermistor type)
• RS485 communications with the U-BMS; the following data is sent to the U-BMS

o Cell block voltages
o Current
o SOC
o Cell block balance on/off [?]

o PCBA temperature

o Cell block temperatures
o Model and Serial numbers (Rev 2 Only)
o Firmware Revision (Rev 2 Only)
o Balance Status
o Error Codes
o Event log with 23 event categories (Rev 2 Only)

• LED indicator for basic status of the module (see Section 7.)
• Cell block to cell block balancing, also known as intra module balancing. This compensates for slight capacity imbalances between the different cell blocks within the module. Each cell block has a shunt resistor which can be switched in or out of circuit. begins when the cell block voltage is >minimum threshold value and > 40mV higher than the lowest cell block voltage in the module. (see later section 8. for details of balancing technique)
• Non Volatile Memory with event logging capability and stored lifetime Watt Hour counter. (Rev 2 Only)

From Section 8 (Charging Profile & Methods):
 

"Cell block balancing is required to maintain the maximum available capacity of the battery system. This is performed by "passive balancing" and is carried out in 2 ways:

- Intra module balancing is controlled internally in each XP module. This is active on cells above 3.360V and > 40mV above the lowest cell.

- Inter module balancing is controlled by the U-BMS to compensate between different XP battery modules. This is active on modules with minimum cell block above 3.28V and >100mV above the module terminal voltage. This means in a system of N modules the maximum number possible with interbalance active is N-1 and this decreases as balancing continues.

 

Edited March 9, 2022 by Tony1

[TheBiscuits]

1 hour ago, Tony1 said:

The balancing between cells within a battery only takes place when there is 5V supply via the comms cable from a laptop or external BMS, so it look as if just leaving the laptop connected (and awake?) for a good few hours will allow the cells within each battery to balance

 

Maybe you should fix whatever is wrong with your laptop to battery cable then ...

 

If it only actually needs +5V power to activate the balancing, just a usb power feed to the appropriate connection might be enough, but fixing your lead and getting connected will allow you to see what is happening.

[peterboat]

58 minutes ago, TheBiscuits said:

 

Maybe you should fix whatever is wrong with your laptop to battery cable then ...

 

If it only actually needs +5V power to activate the balancing, just a usb power feed to the appropriate connection might be enough, but fixing your lead and getting connected will allow you to see what is happening.

I used to do it regularly and even posed a video on here showing me doing it  however after a while of finding that they were always balanced I gave up doing it! Over 2 years since I last plugged in the boat or the electric truck. I did top balance at 14.6 volts watching on the puter no problems encountered or expected 

[Tony1]

4 hours ago, TheBiscuits said:

 

Maybe you should fix whatever is wrong with your laptop to battery cable then ...

 

If it only actually needs +5V power to activate the balancing, just a usb power feed to the appropriate connection might be enough, but fixing your lead and getting connected will allow you to see what is happening.

 

I think the cable is ok, its the software that wont run properly- or at least it will open and show the main screen, but it keeps telling me that my COM port selected is incorrect.

I dont know how to identify or name COM ports, so I rather speculatively tried typing in COM1 to COM8, but it keeps saying 'incorrect COM port'. 

It could still be the cable not working, but on the diysolar forum I saw a few posts by a guy who had exactly the same message as me, and who resolved it by

installing a later version of the software.  

I tried the version he said worked but it still gives me that message. I even tried installing on my old laptop by get the same messages. 

There is also an 'access denied' message when the program tries to use a certain folder it needs, so I think I need to see if there is a more up to date version- I think this one is from 2019.  

 

I actually had another try this afternoon, and as part of that I tried plugging the USB end of the cable into a power bank, but the batteries still didnt respond. 

C'est la vie- at least for now....

 

 

[peterboat]

2 hours ago, Tony1 said:

 

I think the cable is ok, its the software that wont run properly- or at least it will open and show the main screen, but it keeps telling me that my COM port selected is incorrect.

I dont know how to identify or name COM ports, so I rather speculatively tried typing in COM1 to COM8, but it keeps saying 'incorrect COM port'. 

It could still be the cable not working, but on the diysolar forum I saw a few posts by a guy who had exactly the same message as me, and who resolved it by

installing a later version of the software.  

I tried the version he said worked but it still gives me that message. I even tried installing on my old laptop by get the same messages. 

There is also an 'access denied' message when the program tries to use a certain folder it needs, so I think I need to see if there is a more up to date version- I think this one is from 2019.  

 

I actually had another try this afternoon, and as part of that I tried plugging the USB end of the cable into a power bank, but the batteries still didnt respond. 

C'est la vie- at least for now....

 

 

Tony mine runs on an old windows system can't remember what it's called maybe that's the problem?

[nicknorman]

2 hours ago, Tony1 said:

 

I think the cable is ok, its the software that wont run properly- or at least it will open and show the main screen, but it keeps telling me that my COM port selected is incorrect.

I dont know how to identify or name COM ports, so I rather speculatively tried typing in COM1 to COM8, but it keeps saying 'incorrect COM port'. 

It could still be the cable not working, but on the diysolar forum I saw a few posts by a guy who had exactly the same message as me, and who resolved it by

installing a later version of the software.  

I tried the version he said worked but it still gives me that message. I even tried installing on my old laptop by get the same messages. 

There is also an 'access denied' message when the program tries to use a certain folder it needs, so I think I need to see if there is a more up to date version- I think this one is from 2019.  

 

I actually had another try this afternoon, and as part of that I tried plugging the USB end of the cable into a power bank, but the batteries still didnt respond. 

C'est la vie- at least for now....

 

Open “Device Manager” which shows all the hardware. Expand “Ports (Com & LPT)” to see the com port number.

 

As to the “access denied” problem, right click the programme icon and select “run as administrator”

Edited March 9, 2022 by nicknorman

[peterboat]

2 minutes ago, nicknorman said:

Open “Device Manager” which shows all the hardware. Expand “Com ports” to see the com port number.

 

As to the “access denied” problem, right click the programme icon and select “run as administrator”

I seem to remember it wouldn't run on windows 7 or 10, it was designed for a pro version?

[Slow and Steady]

 

42 minutes ago, peterboat said:

I seem to remember it wouldn't run on windows 7 or 10, it was designed for a pro version?

Do you mean windows pro version? It's just the same with all the cacky consumer stuff cut out. No need to even pay for it, Microsoft don't care, they just want the world to use windows.

[nicknorman]

On 08/03/2022 at 18:06, Tony1 said:

 

I can say that I checked my battery voltages individually and they are always identical to 2dp's, so I feel sure that it is keeping them in balance, but I havent yet looked at the individual cell voltages, I made up a laptop-to-battery cable after finding some instructions online, but I couldnt get the software to see my batteries after the first few tries, so I gave up like the petulant child that I am, and there the project rests, until motivation returns to my soul. 

When I get it working, I'm hopeful and optimistic that I'll see the individual cells in good balance, thanks to the internal BMS. 

 

So yes, you can definitely monitor individual cells, as Peter has pointed out a few times- you just need the software and a cable. 

 

What the internal BMS board wont do is disconnect the batteries, however. 

 

 

I think I spot a basic misconception. When you have 2 or more Valence batteries connected in parallel (ie a 12v system) then by basic physics there is no need to contemplate balancing between the batteries, this happens "automatically" because the terminal voltage of each battery connected in parallel must be identical (as you have found out!). Provided each battery's cells are balanced within themselves, all is fine and dandy.

Balancing between batteries is only necessary when the batteries are connected in series, eg a 24 or 48v system. For the same reason that cells in series within a battery have to be balanced.

[Tony1]

1 hour ago, nicknorman said:

Open “Device Manager” which shows all the hardware. Expand “Ports (Com & LPT)” to see the com port number.

 

As to the “access denied” problem, right click the programme icon and select “run as administrator”

 

Thanks very much Nick, I can see COM3 and COM4 on the ports list- I did try those two words earlier but maybe the access issue stopped it at the next step.

I'll have another crack at it tomorrow...

 

 

[nicknorman]

11 minutes ago, Tony1 said:

 

Thanks very much Nick, I can see COM3 and COM4 on the ports list- I did try those two words earlier but maybe the access issue stopped it at the next step.

I'll have another crack at it tomorrow...

 

Just checking ... you need to do this with the interface cable plugged into the PC...

[TheBiscuits]

Just now, nicknorman said:

Just checking ... you need to do this with the interface cable plugged into the PC...

 

I was about to post the same thing. 

 

My assorted USB-to-serial leads usually show up as COM 12 or so in windows.

[Tony1]

Thanks a lot guys, I'll be sure to check the ports list again when the cable is plugged in- fingers crossed

 

 

[Tony1]

1 hour ago, nicknorman said:

Just checking ... you need to do this with the interface cable plugged into the PC...

 

I ran it as admin and that seemed to get it working, thanks a lot for your help. 

 

The results were, I think, fairly decent.

The cells within each battery were all within 2mv of each other, so that seemed reassuring.

E.g. the cells in the first one were 3.299, 3.298, 3.299 and 3.300. 

The battery (module) voltages were 13.196, 13.187 and 13.194, so again not too bad considering I've not done anything to help them. 

I switched off the loads to try and get a level playing field instead of a steady drop in the charge, but all that did was to make the cells bounce back a bit, and increase in voltage slightly, so I'll need to repeat it when they have had some time to rest- but despite that, the initial values look reassuring, at least to my admittedly uninformed eye. 

 

There was one disconcerting thing though.

When I looked at the first battery, the SoC on the valence software showed as over 96% , which is not possible.

I fully charged them and synchronised the BMVs yesterday, and they've been running down since (with a bit of solar top up today), but its impossible they are at anything like 96% SoC. 

For one thing, the voltage was 13.19 (with a load of about 3 amps on them), and if they were at 96% SoC the voltage would be much higher. 

The BMV712s were all reading about 72% SoC, and interestingly, the second time I plugged the cable into that battery and read it, the reported SoC had gone down to 69%. 

I then rechecked the other two batteries, but they were still showing SoC of about 96%. 

So I'm not panicking about it, I'm assuming the method used by the software to calculate SoC must have a weak point in it, although its odd that one of the batteries did seem to correct itself to 69%, which roughly agreed with the BMV712s.

 

But apart from that anomaly, I'm actually amazed that the cells are so well balanced, after 18 months without a proper balance of any kind, and with my rather rough handling (and especially in the early few days of use, which included a brief excursion up to 15 volts). The valences do seem to have remarkable recovery powers.

 

Anyway, I've tucked them all in and read them a bedtime story, so they should be happy bunnies tomorrow. 

 

 

Edited March 9, 2022 by Tony1