RS485 connection between LVTOPSUN and JK BMS produces Magic Smoke

[Norwasian]

In attempting to achieve communication between the inverter and the battery, I connected a standard Cat. 5e patch cord between the sole RS485 port on the 3KW LVTOPSUN inverter and one of the several ports of this same label on the JK BMS of the 48V, 280AH LiFePO4 battery. The magic smoke was instant, rendering the inverter useless. It will not even power on.

I had expected that I might need to play with the cable's pinout, and/or which battery port was connected, until I found a configuration which would be mutually intelligible to both the battery and the inverter. I had not expected to get only one chance to get it right. And I got it wrong.

It appears it will be an expensive lesson--to the tune of about $600.

 

[Norwasian]

I guess it's not as necessary as I had previously understood to have communication between the inverter and the battery. The seller of the battery had insisted, however, that there be such communication in order to provide me a one-year warranty on the battery. Presumably, the battery might not be properly charged and/or balanced without a connection between it and the inverter.

Once burned, twice shy. The inverter was already a quarter of the cost of the battery--I think I'll probably just forgo the warranty and get another inverter which I do NOT connect. Maybe I can even make a dummy cable to hook up to that RS485 port such that no one comes along and plugs anything else into it. Sigh. It seems odd to have such a dangerous option just dangling there like a carrot, with nary a word about it in any manual nor online. I had no intimation whatsoever that an incorrect RS485 hookup would do anything more than just prevent a proper communication of the parameters, etc. Certainly, I did not expect blue smoke / magic smoke.

But it's unlikely that I'll be able to either fix it or return it under warranty. I guess I did the wrong thing to plug anything to that RS485 port, and likely voided whatever warranty I might have had.

Wish I could have learned about this from someone else's mistake--but hopefully someone will learn from mine.

 

[wpns]

3KW LVTOPSUN inverter

Not familiar with that inverter, do they give a pinout of that port?

 

[Norwasian]

Not familiar with that inverter, do they give a pinout of that port?

The manual that came with it gives the pinouts for both RS485 and BMS.





However, the 3KW model has only one port, which is labeled "RS485" on the unit itself.

The 48-volt version of the 3KW LVTOPSUN seems uncommon. I don't find any in stock at the moment, and the manufacturer does not even list the model on their website.

 

[Norwasian]

Well, take this with a grain of salt. I'm in Thailand, and good information here is scarce. What's more, it is against the law here to post negative information online about anyone or any company, punishable by jail times, which exacerbates the information gap. But here is the information I have gathered so far.

1) The particular model of LVTOPSUN which I had bought, may have been a special OEM order, and is not among their usual lineup. LVTOPSUN inverters are manufactured by Deye, but may have different specifications.

2) Apparently, whereas "Deye" branded inverters should all use the RS485 ports for communication only, and not be a power source, these "special" models like my LVTOPSUN may inject power on that port, PoE-style. Twelve volts was mentioned as a possibility.

3) The battery seller confirmed that the battery itself should use its RS485 ports for communication only, and did not output any power.

I must necessarily be restrained about saying anything else which might be taken as critical, but will say that I have been unable, so far, to resolve this.

 

[Nobodybusiness]

What's more, it is against the law here to post negative information online about anyone or any company, punishable by jail times

Seriously?

They can make any kinda crap they want and nobody can even warn other people out it?

Talk about immunity.

 

[underdog5004]

I live in the US where I can say any damn thing I want. It sounds like your supplier is a big piece of garbage. Garbage selling garbage that won't stand behind the garbage. I hope you get this resolved generally honey catches more bees than vinegar but at the same time the truth has a right to be spoken.

 

[Norwasian]

Seriously?

They can make any kinda crap they want and nobody can even warn other people out it?

Talk about immunity.

Yes, seriously. If you really wish to look into this, you may download an English translation of the Thai "Commission of Computer Related Offences Act" from the United Nations server HERE. The law specifically applies to internet activities, including "defamation" (which still applies here even when the statements are true).

 

[marionw]

Do you have the pinout for the RJ45 jack on the battery?
You will most likely need to make a custom cable that only connects RS485A between the inverter and battery and RS485B between the inverter an battery. You may have inadvertently connected ground (or power) to an active pin.

As stated above, often times an RS485 port on an inverter has power on one pin which is used to power a Wifi dongle

 

[Norwasian]

As stated above, often times an RS485 port on an inverter has power on one pin which is used to power a Wifi dongle

Well, I would like to know how the inverter will communicate with the battery's BMS via WIFI. Because the manufacturer finally got back to me yesterday saying that the RS485 port was not designed to communicate with a battery, but rather to be used for WIFI. The problem with this explanation for me was that no mention was made of WIFI in the manual for the inverter, and I have seen nothing, as in NOTHING, in terms of any product listing for a WIFI dongle for the LVTOPSUN inverter.

I know I'm wet behind the ears with respect to this stuff, but it frustrated me to hear the manufacturer's representative telling me that the RS485 port was not for communication. Like, what??? The manual even says it is for communication! (See post above where the image is attached from the manual titling the port as "Communication Port.")

I was told they are offering to repair the unit for free--despite it supposedly being my fault that it was damaged--but that going forward I am not to attempt any connections to a BMS from that port. I might as well fill the port with hot glue so that nothing can be inserted into it again!

And now I have no idea how the balance routine is going to work properly in the BMS on a float charge. How will the inverter know when to switch from bulk charging mode?

Oh, and they claimed that the battery's BMS had power on that port--opposite to what the battery seller told me.

 

[Skypower]

You have a battery you purchased that has a JK bms in it? Was this a commercial project or a local builder? There are two types of JK bms’s, the flat book looking kind and the longer more exposed (“inverter”) type. Both are excellent. The latter has better communication for inverters. Nether version is absolutely necessary to communicate to an inverter if your inverter is set correctly and the BMS settings are correct.

 

[Norwasian]

You have a battery you purchased that has a JK bms in it? Was this a commercial project or a local builder? There are two types of JK bms’s, the flat book looking kind and the longer more exposed (“inverter”) type. Both are excellent. The latter has better communication for inverters. Nether version is absolutely necessary to communicate to an inverter if your inverter is set correctly and the BMS settings are correct.

Yes. I'm not sure exactly where or how the battery is produced, but it looks nice, both inside and out. I torqued the connections inside once it arrived and found only one of them loose. The cells are 280AH CALB cells, rated for 9000 cycles. The BMS is a JK 150-amp version. It has four RJ45 jacks, two labeled as RS485, and the other two as RS485 / BMS. Between these two sets of ports is a smaller one, the size of a telephone jack.

One like it is sold HERE, and if one scrolls down a little past the Thai, the English specifications are listed as well. It seems to be without a brand name, so it's possible the seller is piecing these together himself.