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BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Tue Dec 20, 2022 10:25 pm
by RyanMorgan
If you don’t want the context nor a description of the issue (which may be helpful to some to diagnose the issue) then please skip and scroll to the solution below.

Context

There will be many who have invested in the Fox system over the past 2 years and the numbers continue to accelerate as time goes on.

Within the past 6 months, the news broke that chip shortages across the globe have resulted in a need for a new version of the HV2600 batteries (V2) which have now been released with a new chip to cope with the continued demand.

This has posed a somewhat significant compatibility issue with many choosing to add additional battery modules (the whole point of a modular system!) and ending up with a mixture of version 1 (V1) and version 2 (V2) batteries.

The consequence of this; the need for a new version (V2) of the Battery Management System (BMS) which would be reverse compatible with the V1 batteries that many people will already own.

Problem

There are initial signs that the so called ‘reverse compatibility’ has not gone smoothly. The mixture of V1 and V2 batteries along with the V2 BMS has resulted in a number of unwanted BMS & Battery Voltage alarms which interrupt the force charging of the batteries. Mainly the “BMS Hardware Protect” (211) and “Bat Voltage Low” (198) errors.

These seem to happen more commonly when the battery enters a “force charge” period (usually overnight for most with off-peak tariffs) and there seems to be a varying degree of results in terms of the alarms that occur and when.

I suffered with this for a couple of weeks and my issues varied from an alarm at the beginning of a charge period and never recovering (zero charge!), to a seemingly random alternating alarm every 5/10 mins but still managed to charge to roughly 60%(less annoying, but still annoying!) – examples of problematic charging profiles and the fixed one below.

Examples of problematic charging profiles.
Charging issue 1.jpg
Charging issue 2.jpg
Charging issue 3.jpg
Charging issue 4.jpg

How the charging profile should look (aside from a random point.. who knows what that was).
Charging fixed.jpg


Solution

I can’t take credit for this as someone else did the hard work in getting the info out of Fox UK and Fox China but the solution involved taking a spare ethernet cable and modifying it slightly – you will likely have a spare after taking delivery of the v2 BMS as you already have one for the v1 BMS.
See the image below for how this should look when finished.

Before beginning, shut down the system by firstly throwing the breaker on the BMS and turning the AC/EPS isolators to off. Lastly, turn the DC isolator off on the inverter itself. The screen will go blank and the lights on the BMS will all be off.

Step 1:
Peel/cut away about an inch of the sheathing of the spare ethernet cable – DO NOT CUT THE WIRES.

Step 2:
Of the 8 strands of wire inside the ethernet cable, identify 2 out of the 8 wires to cut - the solid green wire and white/brown striped wire.

It's not clear what these wires (number 6 & 7) do, or why they cause an issue - I'm sure this will become known in time but for now - it just works!
Pin legend crop.jpg

Step 3:
Isolate those wires and cut them carefully so as not to damage the others – you should have 6 wires inside the ethernet cable intact.

It would be best practice at this point to wrap a length of insulating tape around the exposed wires or any other fancy technique you may have up your sleeve!

Step 4:
Connect this modified ethernet cable to the RS485 port of the V2 BMS and to the RS485-1 port on the first battery in the series.

It has also been reported that connecting the modified cable between the COM port on the BMS and the BMS port on inverter also works - so take your pick!
It should be said though that, in my opinion, it is probably easier to connect the BMS to the first battery as this doesn't involve trying to fumble about under the inverter!

Please note: It’s not clear if this is important but it’s probably best that the V2 battery(ies) are first in the series.

Step 5:
When done, start up the inverter in the reverse order to that at the beginning of these steps.


The end result will look like this:
Inverter - Ethernet v2.jpg

If successful, and it certainly has been for me and two others on this forum that I know of so far, you should no longer experience any of the alarms described here and you can breathe a sigh of relief!

It’s not clear how this will evolve with Fox support – no doubt people experiencing this issue will be inundating Fox with requests for help. Anecdotally, it seems that they will probably be following this fix by either providing their own instructions or supplying modified ethernet cables.

Hope this helped. Any questions please post here or on the Facebook forum.

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Thu Dec 29, 2022 12:46 pm
by StealthChesnut
Thanks for posting this. I have now got a V2 BMS, some V2 and V1 batteries. I'm seeing exactly these faults/errors, i.e.:
  • Communication Fault Between battery and Device
    Bat Voltage low
    Bms Hardware Protect
Looking at the cables used for the RS485 ports, can you use a standard ethernet cable as a replacement? They don't look like they've been wired to the connectors as a standard, but if the pins are the same both ends it won't make any difference. I've tried making a new cable, leaving out pins 6 and 7, tried it between the BMS and battery #1 but it's not fixed my problems. Got a request in with Fox support to see what their thoughts are.


The manual screenshot you'd put in (google) translates as:
Negative power supply from the board
Isolated communications ground
CS CANL
CS CANH
Power Supply +12v from the board
Signal P+ (Output, needs detection)
Signal N- (Output, need to detect)
Isolated Communication +5V (output, need to detect)

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Mon Jan 02, 2023 11:48 pm
by Borehamwood
Yep having an issue with charging the mix of type C and v2 hv2600 batteries with a v2 BMS.
Just prepped a spare cable will try tomo see if it resolves this issue.
Fingers crossed will let you know in a day or so.

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Thu Jan 05, 2023 2:19 pm
by Borehamwood
It works lovely now.

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Mon Jan 16, 2023 3:07 pm
by Luke
I recentlly got my v2 BMS and experienced the exact same issues as yourself. I followed up with my contact in FoxESS who did my RMA and they are not only working on the issue but also preparing modified patch cables (such as the one you've posted) to send out.

They kindly send me one the same day I contacted them which has worked like a charm!

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Mon Jan 23, 2023 3:44 pm
by RyanMorgan
StealthChesnut wrote: Thu Dec 29, 2022 12:46 pm Thanks for posting this. I have now got a V2 BMS, some V2 and V1 batteries. I'm seeing exactly these faults/errors, i.e.:
  • Communication Fault Between battery and Device
    Bat Voltage low
    Bms Hardware Protect
Looking at the cables used for the RS485 ports, can you use a standard ethernet cable as a replacement? They don't look like they've been wired to the connectors as a standard, but if the pins are the same both ends it won't make any difference. I've tried making a new cable, leaving out pins 6 and 7, tried it between the BMS and battery #1 but it's not fixed my problems. Got a request in with Fox support to see what their thoughts are.


The manual screenshot you'd put in (google) translates as:
Negative power supply from the board
Isolated communications ground
CS CANL
CS CANH
Power Supply +12v from the board
Signal P+ (Output, needs detection)
Signal N- (Output, need to detect)
Isolated Communication +5V (output, need to detect)
I’m so sorry, I’ve only just seen this message as I don’t get any notifications from this site even though I’ve subscribed.

It’s a a good question and I’m not sure if you’ve had an answer already.

I believe the pins are the same in most if not all Ethernet cables. I have opened one up and found that rather than being a striped colour, it’s just white and bound to the corresponding solid colour.
I’m no expert in these cables…

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Mon Jan 23, 2023 3:45 pm
by RyanMorgan
Borehamwood and Luke - I’m so glad you’ve both had success in fixing this issue.

Good to hear that Fox have been quick to send out their own patched cables 👌

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Tue Jan 24, 2023 10:18 am
by StealthChesnut
No problem Ryan - I've made quite a few ethernet cables (100s!) in the past, but didn't have a tester with me now to check the pinouts. Thanks for posting the info!

Fox have sent a replacement cable which (along with firmware updates) seems to have stabilised my system. Now on a v2 BMS and 2x V2, 2x V1 batteries.

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Tue Feb 14, 2023 12:02 am
by Borehamwood
Top man Ryan.
Cannot thank you enough.
System working lovely with the modified data cable.
Had no issues since fitting it.
Long May it last.
Many thanks again.

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Sun Feb 26, 2023 12:50 pm
by Nredshaw
Thanks so much for this guide it’s working at the moment for us on 5 x v1 hv2600 and 3 v2 hv2600 batteries on bms 2 on a hybrid h1 5.0 inverter only had the v2 batteries fitted since Friday and noticed this problem on Saturday when the sun started shining the Soc got to 49% and had the problems described and after following the great easy to follow guide it starting working and 24 hours later it’s still working so big thumbs up 👍 now getting nice bit of sun and battery’s charging up nicely at 85% and added 10.5 kWh from 29% so hopefully with a bit of balancing it should be ok 👌, this guide was a life saver as it happened at the weekend and couldn’t get hold of anyone from installer and with high home energy user was not looking forward to importing it from the grid !

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Tue Mar 07, 2023 6:59 pm
by RyanMorgan
Nredshaw wrote: Sun Feb 26, 2023 12:50 pm Thanks so much for this guide it’s working at the moment for us on 5 x v1 hv2600 and 3 v2 hv2600 batteries on bms 2 on a hybrid h1 5.0 inverter only had the v2 batteries fitted since Friday and noticed this problem on Saturday when the sun started shining the Soc got to 49% and had the problems described and after following the great easy to follow guide it starting working and 24 hours later it’s still working so big thumbs up 👍 now getting nice bit of sun and battery’s charging up nicely at 85% and added 10.5 kWh from 29% so hopefully with a bit of balancing it should be ok 👌, this guide was a life saver as it happened at the weekend and couldn’t get hold of anyone from installer and with high home energy user was not looking forward to importing it from the grid !
Bloody lovely :) love hearing success stories. Glad it helped you!!

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Wed Mar 15, 2023 9:34 pm
by G4RNI
I haven't yet taken delivery of the V2 bats and BMS I want. I intend to install the V2 bats as an additional stack of 7 with my original stack of 7 V1 bats. I've installed switching for the data ( a simple manual ethernet switch £8 ebay) and heavy duty cabling for the extra run to the second stack (4AWG) and 125A double pole changeover switching for the battery leads. Sounds complex and it is quite a bit of work but hopefully will give me battery stacks A and B, both 7 batteries.

I made up a short RJ45 lead as described, tested it on my cable tester and all's ok. I installed it and caried out the following tests: App registering flows ok. Did a force charge, ok. Did an EPS test with mock grid failure (turned off my power at the mains), all ok.

Above all tested with my V1 BMS so, as changeover to the second battery stack involves powering down, throwing the changeover switches (bats and data) then powering up again, I'm hoping all will be hunky dory.

Thanks so much for the info about the cable! My mind feels much easier than it did a few hours ago when it seemed I was going to be up against insurmoutable odds.

Brilliant!

George G4RNI

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Thu Mar 16, 2023 11:53 am
by G4RNI
Just a quickie:

I emailed Foxess Customer Service ( service.uk@fox-ess.com ) yesterday afternoon to query a firmware update. They responded this morning, asking for my inverter serial number. By 11:15 they replied saying my firmware had been updated for me.

Master 1.54, Slave 1.02, Manager 1.57

Now that's what I call service! Great communications. No raggy ends left to tie up.

Excellent.

George G4RNI

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Wed Mar 29, 2023 4:40 pm
by philphluter
Exactly the same response for me today G4RNI. Thanks Martin Rimmer.

Phil

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Sat Nov 25, 2023 10:19 am
by marcus
I'd like to add another successful (and very grateful!) +1 to modifying the supplied RS485 cable solution!

I'd installed the BMS V2 with 2x new V2 batteries in front of the 2x Version C I had previously.

For 3 nights I saw forced charging working fine with no errors, then errors started before the next charge, 194 Battery over voltage ↑
194 Battery over voltage ↓ 211 Bms Hardware Protect ↑ 211 Bms Hardware Protect ↓ as others here seen.

I was reluctant at first to break into one of the cables supplied with the BMS/Batteries so made a patch cable with CAT5e/RG45 plugs with the 6 green/7 brown & white wires cut.. but then on powering up the BMS there was an audible alarm and flashing red LEDs.

Other than lots more shielding and maybe heavier gauge wires I can't see a difference, but modifying the supplied cable then worked fine, I've seen no more errors and now charging again over the last 2 nights.

My firmware versions (before and after) also:
Master 1.54, Slave 1.02, Manager 1.57

Re: BMS V2 with mixed v1/v2 batteries - Solution to persistent BMS alarms.

Posted: Fri Dec 22, 2023 6:24 pm
by Simon_Ashley
Many Thanks,

Had the same fault codes you mentioned after finally getting my V1 & V2 setup completed with V2 BMS.

Followed instructions and no more fault codes!

Thank you