Batrium Watchman CORE-Cellmate K9 feedback

[Zwy]

I've been looking at a BMS for my 48V system I'm installing in my house. I'm seriously considering the Watchman CORE with Cellmate K9. https://www.batrium.com/products/watchmon-core-k9

I'm looking at the CORE with 2 K9's as I have 32 280Ah LFP cells, 500a shunt. In research, I ran across this video.

and linked here in another thread. I'm starting to lean towards the Batrium but as this product is fairly new, I'm interested if anyone out there has used this unit and their experience with it.

I think this might be the way to go if I decide to expand my battery bank down the road, plus it gives complete monitoring of all cells. Price is really not a concern, from what I see this will be $900 plus shipping and then the contactor and some other parts. Anyone have a list of what they all used for install?

 

[Rocketman]

I have the Batrium Core + expansion board, but I have the blockmon’s. I really like the Batrium core as a bms. (The K9 was not available when I got the Batrium core.).

Batrium Watchmon Install

Hello everyone, I have a 2000 Monaco MotorHome, I will be installing eight 272ah Lishen LiFePo4 cells making a 2p4s 12v 500Ah (useable) battery. My two largest loads are a Victron MultiPlus 12/3000 inverter/charger and the engine "Boost" if my chassis battery gets low. For the BMS I chose a...

diysolarforum.com

This thread has what I used.

 

[OffGridInTheCity]

Yes sir - I'm in my 3rd year of using Batrium Watchmon 4 (WM4) + longmons. Watchmon Core is the
'new' Watchmon and can still do 'mons' even though they introduced k-9 units as an alternative. Mons (longmon, blockmon - e.g. cell monitors) are about twice as strong balancing as K-9.

I agree 100% that for large powerwalls and long term expansion - its been really good for me.

I'm currently up to 84 packs of 18650 cells with 260ah each = ~81kwh battery. They are arranged in 6 parallel batteries of 14s ... but Batrium doesn't care and shows all 84 packs... where each group of 14 blue lines is a 48v battery in the powerwall.

One thing I really like is multiple ways to balance.
1) Set a 'start balancing' voltage - which people tend to do so the packs will balance as they near full charge.

2) Use auto-level instead - which balances all thru the charge/discharge cycle to bring packs 'within' a max difference

3) Turn balancing OFF!! I find that with healthy packs, I only need to do touch-up balancing (a few days) once a year. The pic above shows 84 packs that were last balanced 8 months ago to within 30-40mv. They've drifted 10-20mv over the 8 months.

Another thing I really like is the flexibility to expand / contract - In 2022, my plan is to add 2 or 3 more batteries - e.g. recombine the 260ah packs into 520ah packs and have 1/2 as many blue lines as the longmons can balance this. Or I may do 3 more batteries and just add 42 more blue lines.

I like Batrium so much I bought a 2nd one for my trailer - which has a 14s88p 18650 in it. Some have commented that Batrium is made to withstand 'travel' as in bouncing trailers. These were balanced only once when commissioned (about 8 months ago) - but I don't go camping that much so I leave the packs idle at 3.77v and only charge up to 4.1v/cell just before going out camping.


Some negatives...
1) Its *expensive* and tech support is limited - seems like one should get better docs and support for the $.
2) It has wifi app (you see pics here) but you have to do custom code (there's a github source that @DIY Tech & Repairs worked out) to pull data out yourself. ***I wrote PHP to parse the data logs - you can dump the system data every 5 minutes or longer intervals.
3) I do have 'glitches' at least twice a year where I have to reboot the system. One was related to the longmon network (I've since fixed) and a couple related to weird shunt reading jumps that caused it to go 0% SoC.

If you go this way and I can help answer hands-on type questions to a limited extend - I'm happy to help.

 

[jtvt]

IIRC autolevel bypass extra isn't supposed to be used with LFP. I'll have to dig around and see if I can find that again.

I've had two mons flash 0 v while balancing which trips the breaker and I'm not sure if it's because of heat or there is a bug in the way the mon reports voltage while balancing. I've scoured the internet and have found both as possibilities. I've replaced them and cables and the problem goes away. I knocked back the temp limit on the balance and haven't had a new problem since then. I have 8 spare blockmons for future problems.

I've been thinking off turning balancing off too and doing it more on an as needed basis much as you would with equalizing for LA. The cells don't seem to really need it on a regular basis plus the above issue. And block mons have a decent balance capability(I would probably never switch to K9s for that reason). I find that I get more drift the more the battery discharges. So far my SoC has only hit 50%, but there seems to be more drift vs say 85%. I'm also wondering if I should drop my absorb V down a bit so I'm not quite so far toward the elbow. I'm using 56.4 absorb, 54.4 float. Balance starts at 3.51. So maybe knocking it back a bit would help drift between cells.

Anyway, sorry that doesn't help much for k9 questions.

 

[OffGridInTheCity]

>I've had two mons flash 0 v while balancing
This hasn't happened for me but I've read about this from others.
My issue was that I used junk wire to extend the longmon network chain to reach the Batrium - and had random faults. I finally wised up and used Cat6 twisted pair network wires - and the problems cleared up.

>And block mons have a decent balance capability(I would probably never switch to K9s for that reason)
Argeed....
BlockMon M8 has "Bypass current 0.00A to 2.20A (typically 1.00A)." - https://support.batrium.com/article/124-blockmonm8
Longmon has "Bypass current 0A to 2A (typically 1A)." - https://support.batrium.com/article/123-longmon
K9 has 0.5a "Auto-Level (balancing) function at 500mA with activity LED on each cell.: - https://support.batrium.com/article/351-cellmate-k9

For context, my longmons balance 260ah packs with a few days and I have them throttled to 1.7a and 55C max temps for longer life. They ccould easily balance 500ah packs within a week. The K9 at 0.5a would likely be 3x longer - e.g. 1.5weeks for 260ah and 3 weeks for 500ah - a bit too long for my level of patience.

> I've been thinking off turning balancing
Yes - I have 84 packs of 6 different cell types. Even if I were to top or bottom balance 'exactly' - the different cell type / chemistries cause the packs to diverge 40mv during the charge/discharge cycle... but they return each cycle to the original balance max difference.

The truth is that balance is not needed often on healthy packs. This seems counter-intuitive based on all the discussion on balancing - but cells/packs that won't stay in consistent, relative balance on their own could use attention / replacement.

I operate between 4.0v hi and 3.54v low. If I were to try to operate at shorter life / more capacity - say 4.17v hi - then tight balance would be more of an issue to avoid going over 4.2v. Lithium-ion has a wider voltage range to play with. LifePO4 is much tighter!

Bottom line - I just let it rip at 40mv to 90vm max differences each day thru the cycle and it's rinse/repeat each day and is stable with long stretches between touch-up balancing.

 

[Zwy]

IIRC autolevel bypass extra isn't supposed to be used with LFP. I'll have to dig around and see if I can find that again.

I've had two mons flash 0 v while balancing which trips the breaker and I'm not sure if it's because of heat or there is a bug in the way the mon reports voltage while balancing. I've scoured the internet and have found both as possibilities. I've replaced them and cables and the problem goes away. I knocked back the temp limit on the balance and haven't had a new problem since then. I have 8 spare blockmons for future problems.

I've been thinking off turning balancing off too and doing it more on an as needed basis much as you would with equalizing for LA. The cells don't seem to really need it on a regular basis plus the above issue. And block mons have a decent balance capability(I would probably never switch to K9s for that reason). I find that I get more drift the more the battery discharges. So far my SoC has only hit 50%, but there seems to be more drift vs say 85%. I'm also wondering if I should drop my absorb V down a bit so I'm not quite so far toward the elbow. I'm using 56.4 absorb, 54.4 float. Balance starts at 3.51. So maybe knocking it back a bit would help drift between cells.

Interesting that you would consider turning off balancing as you believe it isn't needed on a regular basis; but wouldn't switch to a K9 because it's balance current isn't as high. Isn't that contradicting yourself?

From my previous experience with building 24V packs and Daly BMS, I see the packs stay in balance until the pack gets either close to full charge (runners) or full discharge (again runners to the bottom). I don't operate packs outside of 20% to 90% SOC as a rule, packs always stay very close in balance. All were top balanced before assembly.

Anyway, sorry that doesn't help much for k9 questions.

That's OK, it hasn't been out that long and information on the K9 is sparse but any info concerning Batrium is always helpful.

I did order the CORE with 2 K9's the other day, 2 week backorder yet. The ABB shunt trip breaker arrived today. I'm well on my way to getting this put together.

 

[Zwy]

Yes sir - I'm in my 3rd year of using Batrium Watchmon 4 (WM4) + longmons. Watchmon Core is the
'new' Watchmon and can still do 'mons' even though they introduced k-9 units as an alternative. Mons (longmon, blockmon - e.g. cell monitors) are about twice as strong balancing as K-9.

I agree 100% that for large powerwalls and long term expansion - its been really good for me.

I'm currently up to 84 packs of 18650 cells with 260ah each = ~81kwh battery. They are arranged in 6 parallel batteries of 14s ... but Batrium doesn't care and shows all 84 packs... where each group of 14 blue lines is a 48v battery in the powerwall.
View attachment 74272
One thing I really like is multiple ways to balance.
1) Set a 'start balancing' voltage - which people tend to do so the packs will balance as they near full charge.
View attachment 74275
2) Use auto-level instead - which balances all thru the charge/discharge cycle to bring packs 'within' a max difference
View attachment 74276
3) Turn balancing OFF!! I find that with healthy packs, I only need to do touch-up balancing (a few days) once a year. The pic above shows 84 packs that were last balanced 8 months ago to within 30-40mv. They've drifted 10-20mv over the 8 months.

Another thing I really like is the flexibility to expand / contract - In 2022, my plan is to add 2 or 3 more batteries - e.g. recombine the 260ah packs into 520ah packs and have 1/2 as many blue lines as the longmons can balance this. Or I may do 3 more batteries and just add 42 more blue lines.

I like Batrium so much I bought a 2nd one for my trailer - which has a 14s88p 18650 in it. Some have commented that Batrium is made to withstand 'travel' as in bouncing trailers. These were balanced only once when commissioned (about 8 months ago) - but I don't go camping that much so I leave the packs idle at 3.77v and only charge up to 4.1v/cell just before going out camping.
View attachment 74273

Some negatives...
1) Its *expensive* and tech support is limited - seems like one should get better docs and support for the $.
2) It has wifi app (you see pics here) but you have to do custom code (there's a github source that @DIY Tech & Repairs worked out) to pull data out yourself. ***I wrote PHP to parse the data logs - you can dump the system data every 5 minutes or longer intervals.

This would be if you want to log data in an outside format? Not really my thing, I'm more along the lines of set it up once, monitor it now and then and correct any issues that come along. I'm not into having a pile of data and storing it. Too many irons in the fire I suppose.

3) I do have 'glitches' at least twice a year where I have to reboot the system. One was related to the longmon network (I've since fixed) and a couple related to weird shunt reading jumps that caused it to go 0% SoC.

If you go this way and I can help answer hands-on type questions to a limited extend - I'm happy to help.

I was pretty sold before I started this thread. This is my house system, I wanted something that would last a long time and be safe with effective monitoring. This really fit the ticket with 2 48V banks and the ability to expand if desired. Once a system has to handle large loads for extended periods, it changes the game considerably.

 

[OffGridInTheCity]

Interesting that you would consider turning off balancing as you believe it isn't needed on a regular basis; but wouldn't switch to a K9 because it's balance current isn't as high. Isn't that contradicting yourself?

For me, there are 2 purposes for balance.
1) Touch-up in auto-level as apposed to top or bottom balance. Auto-level can run day/night without having to hold the system at a particular voltage.
2) The other is when expanding / adding a new set of packs to the mix. In this case, the stronger balance greatly reduces the time needed to get things back on line.

Since you're going Batrium - you'll find its easy to experiment. You can turn off balance and see how goes.... and if not happy, turn it back on with a simple drop-down selection

 

[Zwy]

For me, there are 2 purposes for balance.
1) Touch-up in auto-level as apposed to top or bottom balance. Auto-level can run day/night without having to hold the system at a particular voltage.

I'm sure I'll have some questions about auto-level as you described it in your previous post.

With many BMS's, balance only occurs above a set voltage. My Daly is set at 3.5v to enable balance and set pretty tight around .2mv. I could see where auto-level would be advantageous.

2) The other is when expanding / adding a new set of packs to the mix. In this case, the stronger balance greatly reduces the time needed to get things back on line.

Understood.

Since you're going Batrium - you'll find its easy to experiment. You can turn off balance and see how goes.... and if not happy, turn it back on with a simple drop-down selection

I most certainly will. Thanks.

 

[jtvt]

Interesting that you would consider turning off balancing as you believe it isn't needed on a regular basis; but wouldn't switch to a K9 because it's balance current isn't as high. Isn't that contradicting yourself?

No, because when there is a need to balance, the higher current will allow balancing in shorter time. I'm not saying that I would turn off balancing for good. I'm only suggesting that balance be more of a manual activity rather than automated.

 

[jtvt]

BTW, the recommendation for auto level for LFP:

Batrium

support.batrium.com

 

[OffGridInTheCity]

No, because when there is a need to balance, the higher current will allow balancing in shorter time. I'm not saying that I would turn off balancing for good. I'm only suggesting that balance be more of a manual activity rather than automated.

And along these lines - I believe the Batrium balancing 'units' (that generate heat) last much longer when not in use most of the time. I currently have a 24.015yrs ROI - so when I say longer, I mean 20yrs vs 10yrs kind of thinking

 

[Gr00ldude48]

Interesting that you would consider turning off balancing as you believe it isn't needed on a regular basis; but wouldn't switch to a K9 because it's balance current isn't as high. Isn't that contradicting yourself?

From my previous experience with building 24V packs and Daly BMS, I see the packs stay in balance until the pack gets either close to full charge (runners) or full discharge (again runners to the bottom). I don't operate packs outside of 20% to 90% SOC as a rule, packs always stay very close in balance. All were top balanced before assembly.


That's OK, it hasn't been out that long and information on the K9 is sparse but any info concerning Batrium is always helpful.

I did order the CORE with 2 K9's the other day, 2 week backorder yet. The ABB shunt trip breaker arrived today. I'm well on my way to getting this put together.

Ah I could have sold you a few of mine I have tons of extra new K9's on hand from over engineering my setup haha. I have the listing in the for sale area of the site. I'm including Noctua 60mm fan and fuses n leads too

 

[Zwy]

Ah I could have sold you a few of mine I have tons of extra new K9's on hand from over engineering my setup haha. I have the listing in the for sale area of the site. I'm including Noctua 60mm fan and fuses n leads too

I saw the listing, I had already ordered. The fan was 12V, correct?

 

[Gr00ldude48]

Yes sir - I'm in my 3rd year of using Batrium Watchmon 4 (WM4) + longmons. Watchmon Core is the
'new' Watchmon and can still do 'mons' even though they introduced k-9 units as an alternative. Mons (longmon, blockmon - e.g. cell monitors) are about twice as strong balancing as K-9.

I agree 100% that for large powerwalls and long term expansion - its been really good for me.

I'm currently up to 84 packs of 18650 cells with 260ah each = ~81kwh battery. They are arranged in 6 parallel batteries of 14s ... but Batrium doesn't care and shows all 84 packs... where each group of 14 blue lines is a 48v battery in the powerwall.
View attachment 74272
One thing I really like is multiple ways to balance.
1) Set a 'start balancing' voltage - which people tend to do so the packs will balance as they near full charge.
View attachment 74275
2) Use auto-level instead - which balances all thru the charge/discharge cycle to bring packs 'within' a max difference
View attachment 74276
3) Turn balancing OFF!! I find that with healthy packs, I only need to do touch-up balancing (a few days) once a year. The pic above shows 84 packs that were last balanced 8 months ago to within 30-40mv. They've drifted 10-20mv over the 8 months.

Another thing I really like is the flexibility to expand / contract - In 2022, my plan is to add 2 or 3 more batteries - e.g. recombine the 260ah packs into 520ah packs and have 1/2 as many blue lines as the longmons can balance this. Or I may do 3 more batteries and just add 42 more blue lines.

I like Batrium so much I bought a 2nd one for my trailer - which has a 14s88p 18650 in it. Some have commented that Batrium is made to withstand 'travel' as in bouncing trailers. These were balanced only once when commissioned (about 8 months ago) - but I don't go camping that much so I leave the packs idle at 3.77v and only charge up to 4.1v/cell just before going out camping.
View attachment 74273

Some negatives...
1) Its *expensive* and tech support is limited - seems like one should get better docs and support for the $.
2) It has wifi app (you see pics here) but you have to do custom code (there's a github source that @DIY Tech & Repairs worked out) to pull data out yourself. ***I wrote PHP to parse the data logs - you can dump the system data every 5 minutes or longer intervals.
3) I do have 'glitches' at least twice a year where I have to reboot the system. One was related to the longmon network (I've since fixed) and a couple related to weird shunt reading jumps that caused it to go 0% SoC.

If you go this way and I can help answer hands-on type questions to a limited extend - I'm happy to help.

I need to figure out how to get everything squared up on my Batrium BMS now that I have the batteries online, I'm new to batrium settings and you seem to have them ironed out, I may give you a shout for some assistance.

I saw the listing, I had already ordered. The fan was 12V, correct?

Yes! I use the 12v with the sound quietner extension that comes with it. Has a few resistors in it. Fans run silent. The yellow wire is positive and black is negative.