BMS with built-in relay?

spludgey

Solar Enthusiast
I just came across this BMS (I'm not affiliated) that seems to have a somewhat reasonable balancing current, as well as something that looks like a built-in relay. I don't have any experience with this type of BMS at all, but it looks like a pretty good solution to me. Has anyone used this one or one like it?

Unfortunately there's very little info in the listing.

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Samsonite801

Solar Addict
I finally received my shipment of 4x of this style (200a, 7s-20s) a couple days ago from China... I haven't wired them up yet, but unboxed, they seem to look of good quality superficially.

1632410621176.jpeg

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(The big black cable doesn't really go into the bottom of BMS, it was just poked up in there as it was packed, it has a ring terminal at the end of it)
 
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RichO

New Member
I finally received my shipment of 4x of this style (200a, 7s-20s) a couple days ago from China... I haven't wired them up yet, but unboxed, they seem to look of good quality superficially.

View attachment 65963

View attachment 65964
(The big black cable doesn't really go into the bottom of BMS, it was just poked up in there as it was packed, it has a ring terminal at the end of it)
Can you share some different views please (pins) ? Is there a relay function? Thing looks awesome.
 

Samsonite801

Solar Addict
Sure thing, they're at the storage unit right now, planning to run over after work, will grab some more views :geek:

Also, those round shaped things on the top end with the 2 fat terminals on them, are the relays. Must be like a twist switch (w/ stepper motor) type, so maybe wouldn't need power to hold it on or off, more like a latching relay would be where you can trigger the on or the off and it stays there, doesn't need constant primary field voltage to keep a relay closed or opened.
 
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RobertGreen

Solar Addict
. Must be like a twist switch (w/ stepper motor) type, so they don't need power to stay on or off,
Are you saying that you can see it is this type of relay based on it's appearance and construction, or are you just figuring that based on what would be a sensible design practice?

I ask because I'm currently waiting on the delivery of one of the JBD 300A relay based BMS and the supplier I used told me to expect a power draw from the relay, but said that it was a "dual coil" type with lower power use.
My understanding is that dual coil contactors usually have one higher powered coil which is activated to do the main switching, and then a smaller, lower powered coil which 'holds' the contactor closed after switching happens.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Are you saying that you can see it is this type of relay based on it's appearance and construction, or are you just figuring that based on what would be a sensible design practice?

I ask because I'm currently waiting on the delivery of one of the JBD 300A relay based BMS and the supplier I used told me to expect a power draw from the relay, but said that it was a "dual coil" type with lower power use.
My understanding is that dual coil contactors usually have one higher powered coil which is activated to do the main switching, and then a smaller, lower powered coil which 'holds' the contactor closed after switching happens.
If my memory serves, they use TE/Kilovac Energy Saver relays now, there was a previous model with a BYD relay but that did not work out so well. Keep in mind that Kilovac, like Gigavac are also made in China, as well as Mexico, USA and elsewhere. I've used similar relays from Dongya as well. The holding draw is not much for the energy savers.
 

Samsonite801

Solar Addict
Are you saying that you can see it is this type of relay based on it's appearance and construction, or are you just figuring that based on what would be a sensible design practice?

I ask because I'm currently waiting on the delivery of one of the JBD 300A relay based BMS and the supplier I used told me to expect a power draw from the relay, but said that it was a "dual coil" type with lower power use.
My understanding is that dual coil contactors usually have one higher powered coil which is activated to do the main switching, and then a smaller, lower powered coil which 'holds' the contactor closed after switching happens.

Yeah, my previous statement is pure speculation as I never dissected the relay. I haven't even powered it up to hear if it acts like it clicks and holds with some kind of spring release or something. I just noted the shape being round (perhaps resembling a stepper motor on the base of it) and unless it is some kind of relay resembling the old Ford style starter relays, then I suppose it could be a pull and hold contact plate relay with spring release. But my first inclination was that perhaps it is a rotary switch and just turns something in it like 1/4 turn to latch and other way to disconnect?

Sorry if it sounded like I was drawing too much assumption on my speculation, but I honestly couldn't say on how it works for real. I wrote that post kind of fast, and going back to read it, it does kind of seem like I may have pushed the possibility based on too much speculation...

I did go take some more closeup pictures, I'll post right now...
 

Samsonite801

Solar Addict
If my memory serves, they use TE/Kilovac Energy Saver relays now, there was a previous model with a BYD relay but that did not work out so well. Keep in mind that Kilovac, like Gigavac are also made in China, as well as Mexico, USA and elsewhere. I've used similar relays from Dongya as well. The holding draw is not much for the energy savers.

Does look like a Kilovac relay. Maybe can find the specs or exploded view somewhere on one. I didn't get a full picture of the label on it though...

It has 4 wires on it, perhaps just a pull and hold relay as you said...
 
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Samsonite801

Solar Addict
Cool I was able to scan the QR code on one of the above pictures showing the label on the relay:

Overview:

Datasheets:

 

RobertGreen

Solar Addict
Here's one of the contactor. Mine just arrived in the mail today even though the tracking says it's still 3000 miles away. It is indeed a Kilovac or TE contactor (at least according to the label 🙃)
edit: here's a spec sheet that seemed maybe a bit more useful.... It claims that (if these contactors are genuine) the power usage should be ~1.7watts https://www.te.com/commerce/Documen...200_Ser_Contactors&DocType=CS&DocLang=English
 

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Samsonite801

Solar Addict
The seller just sent me the pdf manual on this BMS (200a - 7s~20s)... In case anyone wants to review it.
 

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Samsonite801

Solar Addict
The app zip (maybe is an .exe for Windows, I never tried it yet)... Also looks like you can use Xiaoxiang BMS app for Android or iPhone...
 

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Prescient

New Member
A stupid question... I understand this BMS is a bit different to MOSFET BMSes in the way it cuts off. Normally there are two banks of MOSFETs so you can cut power to the load while still allowing the charger to recharge the battery, or vice versa. But on this one the contactor is bidirectional and SPST. How does it work?

So if you overdischarge the battery it will open the contactor to disconnect the load. But then how do you charge it again? On the QUCC relay BMS there's a 10ohm 10W resistor in parallel with the relay so presumably you can bleed a bit of charge back in, assuming the load isn't going to drain that away.

And likewise, if you are charging and reach what it decides is enough, will it switch off the contactor, meaning the load can't take any charge off?

In other words, is it just cutting off both load and charger in alarm states and leaving you to go in and fix it, or is there a way to recover without dismantling the pack?
 

Amitis

New Member
A stupid question... I understand this BMS is a bit different to MOSFET BMSes in the way it cuts off. Normally there are two banks of MOSFETs so you can cut power to the load while still allowing the charger to recharge the battery, or vice versa. But on this one the contactor is bidirectional and SPST. How does it work?

So if you overdischarge the battery it will open the contactor to disconnect the load. But then how do you charge it again? On the QUCC relay BMS there's a 10ohm 10W resistor in parallel with the relay so presumably you can bleed a bit of charge back in, assuming the load isn't going to drain that away.

And likewise, if you are charging and reach what it decides is enough, will it switch off the contactor, meaning the load can't take any charge off?

In other words, is it just cutting off both load and charger in alarm states and leaving you to go in and fix it, or is there a way to recover without dismantling the pack?
Please look at the photo again , there is an other wire connected to one ploarity of contactor so it can be detected any charger voltage available on your battery pack so that reconnect the contactor without you need to disassemble pack. also it is mentioned in user manual that after protection is activated it is required to disconnect the load and wait 60 seconds it might be need to re-activate in case of overload or short circuit.
 

Thomas55

New Member
Hello

My BMS is also the AP20S003S.
I have problems with recognizing the right number of cells. My system is for 36V with 12 cells. when i connect the 12 cells i find in the app that the BMS is listing 14 cells, with 0 V on cell 13 and 14 because there are only 12.
But the system goes in UVP because the voltage on these (not existing) cells is too low.

Has anyone solved this problem?

best regards

Thomas
 
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