question

jamie-robinson avatar image
jamie-robinson asked

Pylontech type A data cable causing alarm issues

Hello Everybody. I have installed 2 banks of US2000C Pylontech batteries on 2 seperate ESS systems. They are causing problems and are going into alarm mode with small high cell voltage spikes when the batteries are discharging.

The Tech guys at Pylontech say that it is the Victron type A BMS cable which is at fault and that Victron dont make it according t otheir specs. This seems far fetched as I have always found Victron research and support second to none. I was wondering if anyone else had heard this before?

I have installed many systems using Victron BMS cables and they all work so I am finding this a little difficult to believe. This from the Pylontech email. That's my point.

The one Victron make does not conform specifically for Pylontech. Pins 1-3 must be missing. This is due to a single function board in the C type battery. If these pins have cables in it injects unwanted DC (very small) but it's enough to crash the BMS. That's what it's likely to be.

The single most common support topic in a Pylontech C battery. I promise you.

BMS
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mattsmith avatar image mattsmith commented ·
Thank you so much for this post..! I swapped from BYD Box Pro 2.5 to Pylontech 3000C which has the same recommended cable to the inverter. After a very very frustrating morning I found your post and made a new cable with only the required pins. Restarted the whole system and bingo, it came straight up. I note it did need a full battery shutdown to come back. THANK YOU..!!!
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8 Answers
Alexandra avatar image
Alexandra answered ·

@Jamie Robinson

I had this recently with a set of UP5000. It refused to have comms with the GX at all. Was starting to question my own sanity.

Ended up making my own (a few actually because I tried connecting all the pins first thinking it was the cable) cable with only the 3 wires connected and it worked like a charm. It is early days still they have been up and running for about 4 days now, but does seem to be the issue.

It does seem stupid though.

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jamierobinson avatar image
jamierobinson answered ·

Thanks Alexandra.

Really helpful to see someone else has had issues here as well.

On the 2 systems I did, they communicated and worked fine except the batteries went into intermittent fault due to occasional high cell overvoltage.

Also have made some new cables which will get installed tomorrow. Let's keep everything crossed and see what happens.

Would anyone from Victron like to comment on this??

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Alexandra avatar image Alexandra ♦ commented ·

@Jamie Robinson

I lean toward a Pylontec thing as BYD and several other battery types that we install use the type A with no issues. So BMS comms design also have alot to do with it.

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No comment yet, but responding to say that I have seen it.

I've reached out to my contact at Pylontech with a link to this thread to ask for their opinion and they are looking into the claim.

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wkirby avatar image
wkirby answered ·

I've always made mine with just the three wires because I remember it written somewhere in the Pylontech documentation to leave the unused pins "empty".This does seem dumb though, the inputs shouldn't be so sensitive that an open wire causes enough of a problem. They should be pulled up or down inside the battery to prevent this very issue.

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jamie-robinson avatar image
jamie-robinson answered ·

Thanks for all the comments everyone.

I have used many sets of both BYD and Pylontech batteries in both off grid and grid parallel set ups and this is the first problem I have had with the victron cable. Have sent new 3 wire cables exactly as wkirby has mentioned and these will get fitted when they arrive on site. Will share the results once we have run it like this for a few days.

Wkirby is right I reckon. It is an over sensitive system which is affected in this way by induced voltages in an open cable. Will let everyone know if this fixes the issue.

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tristan-klatt avatar image
tristan-klatt answered ·

Hello together,

when i was installing my new ESS this week i found out, that for the Pylontech Type US 3000 (without "C") the type A-cable is required.

For my installation, the Pylontech US3000C(!) is the type B-cable required!

Hope that helps.

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tristan-klatt avatar image tristan-klatt commented ·

However, I also have the problem that (despite using the correct cable) a battery alarm is constantly displayed to me in the VRM, although the battery is 100% charged...

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nickdb avatar image nickdb ♦♦ tristan-klatt commented ·
Which battery alarm would this be?
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jamie-robinson avatar image
jamie-robinson answered ·

HI Tristan.

That is not what the Victron manual says.

It is quite clear that for a US3000 (No C) you need a B cable.https://www.victronenergy.com/live/battery_compatibility:can-bus_bms-cable

The data is transferred via the same 2 cables but it seems the issue is where to ground the system The C type batteries seem to have ungrounded BMS and the pins 1, 2 and 3 of the BMS must not be connected to anything.

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jamie-robinson avatar image
jamie-robinson answered ·

HI All.

Not surprisingly the new cables didn't work and I am still getting exactly the same faults as before. Looks like it is back to Pylontech for some more grief from the technical help guys!! This is my first issue like this but it makes me very wary of installing Pylontech in remote areas. All profit from this job and more has been used up in return visits.

NIGHTMARE......

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tristan-klatt avatar image
tristan-klatt answered ·

I had the same issues a week ago with my new (and first) ESS.

But i think, that was not a problem with the cables (B-type for US3000C).

The problem was solved for me, running the ESS-assistant again and reducing the voltage-currents, depending of the loads, in the last step of the assistant all to 48V.

Since that there were no more alarms in my system.

You can try this and i hope, thats helpful.

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