Newbie alert! JK BMS with some hybrid vehicle batteries. Need advice on parallel setup with BMS.

[cyberfed]

The batteries:
I have 3 Audi Q5 hybrid batteries that are brand new. They are Li-ion (Lithium Coltbalt Magnesium, like your 18650's) chemistry. They are 13S for 48V.
I bought 3 JK BMS's: JK-BD6A17S6P
I want to use these three batteries in parallel. However I am unsure the the safest and best way to do this.

1. Should I wire them in parallel and give each battery its own BMS with its balance wires not shared with the other batteries/BMSs?
2. Should I use 1 BMS with the 3 batteries in parallel and the balance wires connected together?

3. Or should I just wire each battery independently of each other and then use the + - output's to go to a busbar that can be used to essentinally connect multiple batteries and be able to harness power from all of them, essentially in parallel.

Of course the batteries would be charged to the same voltage. Right now they are all sitting at 3V on the nose per the JK BMS (I connected one temporarly to the battery to make sure all is well, and indeed the batteries has a voltage deviation of .005v.

Thanks in advance!

 

[cyberfed]

I forgot to mention. I have a custom PCB installed under the plastic cover that connects all the balance wires via PCB and the exit point is a 30P IDC connector. So I can just plug in a 30p IDC cable and I get all my voltages from each of the 13 cells. To go from the IDC cable I used an adapter that allows me plug in the other end of the IDC cable and allows me to screw in the red balance wires from the BMS (so I can cut them real short). The IDC cable is only used on one row however in the PCB they are duplicated to both rows of the cable. That's the reason for the non red balance wires you see at the bottom they will tie in to the other row that'll have the balance wires so that both rows of the IDC cable will be identical and functional.

The PCB was designed by JAG35 and replaces the OEM proprietary BMS board. Making balance lead connections a breeze. The adapter was my own way of figuring out how to connect the IDC cable to the balance wires. Found these adapters that are perfect.

JAG35 sells a 10X tray "kit" to create a 7S 10P using 18650's, it uses the same type of PCB and IDC cable system.
However in that setup he connects each tray to each other daisy chaining the IDC cables (in that case they are 16p IDC cables) to one (Daly yuck) BMS). So I was wondering if that's the best approach for this, daisy chain the IDC cables connected to 1 BMS only. I've included a sample photo of what that looks like. The brass posts on the side carry the 24V. The pic doesn't show the Daly BMS but normally its sandwiched in the middle of the pack with an XT60 output/input cable. But you get the idea, should I do this type setup for the Audi's and just use 1 JK BMS?

 

[gotbeans]

typically we do the 3 separate batteries with 3 separate BMS and have a breaker and/or fuse for each of them.
then a wire and bring all 3 of those to a bus bar where they all connect. So they're safe behind a few safety mechanisms and their own BMS

However if you barely use any amps from them there isn't much a reason to have 3 separate BMS. You'd have to parallel 13 sets of 3 cells together and then BMS each of those "sets" to get your "13 cell series" single battery.. I wouldn't do it though
also 13 cells for 48 volt.. that's a new low. sad days ahead

 

[cyberfed]

@gotbeans First off, thank you for the advice! I appreciate you taking the time to respond with your advice. Since I already own the BMS's I might as well use them that way I can monitor each set of cells from each battery via bluetooth. I already have a beefy busbar and appropriate breakers ready. Right now I working on constructing the enclosure for the batteries. I think maybe you misunderstood why I'm using 13S.

I'm not taking a bunch of cells and combining them to create 13S. The hybrid car battery is already built as 13S in its own enclosure. All I need to do is hook up + - and the BMS. I have plenty of other 48V systems that I actually built with individual cells those are all 16S so hopefully whatever is going on in your life to make you feel "sad days ahead" over something as insignificant as a set of batteries impacts your emotions, you can "feel better" knowing normally any 48V system I build is 16S.

Everything that will be powered by my packs are low amperage usage, just common household items, not even the big items like the fridge or microwave, just lights, fans, other things. The batteries can push between 100-150A continous (of course they drain super fast). But in my case I'll be lucky to pull more than 100-300watts. So 3 paralleled each approxmiately at 1.8kWh hrs gives me almost 6kWh to play with. That goes a long way when a set of lights is 30 watts..

Once I finish this build, and about 4 other packs I have to build with LEV60 LifePo4 batteries. A mix of 24v and 48v. I plan to build a pack that can sustain the fridge at least during the night. I'll probably use 200Ah 24v Lifepo4 batteries for that until I reach a storage of engery in the neighborhood of 20-30kWh. I rent so I just build mini packs to power random stuff. For example I work from home and I have 2 packs in parallel with 16S LifePo4 batteries at 48V. I can power my office for a little over a week and allows me to replenish the other 2 packs I have that are identical so I can charge those up via solar and swap em out when the others are low. My office as you may guess doesn't pull that much wattage.

I've even got some super compact baby portable packs at 24v that are in a small pelican case that have USB chargers (and battery terminals if I wanted to connect an inverter) that hold 1kWh of engery. Not much but great for charging phones, laptops, ect, on the go, at the beach, while camping ect...they recharge with just 2 100W panels in just a few hours. Here in Florida, sun is almost never a problem! I see you are in Colorado so I know you have no problem with sun since Colorado gets the most sun than any other state! I used to live there for 5 years. I moved outta Florida for a change of scenery. I ended up missing my family so I moved back. Honestly I want to be back in Colorado, its heaven there for an outdoor enthusist such as myself. I could see myself taking my truck one of those really rought 4x4 trails in the mountains to a nice spot in the middle of nowhere where I will never see another human and have epic views, setup starlink, and work from there as I camp! Here in Florida, camping isn't that fun, there's no offroading, or mountains. I suppose I could work from the beach, but I don't wanna be around people. I should hunt around for a spot...hmmm..

You may be asking "why is he asking for advice if he has built other packs", well the answer is simple I wanted to ensure I was doing things safely and following kinda the most common safety measure other people with way more expirence than myself do. I'm still very much a newbie. Having a degree in Computer Engineering which is essentially Electrical Engineering but with more programming classes, the concepts are not foreign to me.

If others have ideas for configurations and safety I'm all ears. Safety is at the top of mind.

Anyone do Peltier cooling on their BMSs? If so have you had condensation issues? My BMSs don't get hot due to the low amperage they have to deal with, but if I move up to say the fridge I imagine that it would get warmer. I know BMSs like to be cold. I have a view Peltiers with 120mm fans laying around that I could use. But condensation has kept me from using them. Just curious...I guess I'm trying to find a use for the Peltier's I bought. I was going to use them on my Raspberry Pi's but the size of the heatsink made it impractical. Thinking I might sit my Pi5 that has an NVME drive attached on the bottom to it to keep the SSD cold but again I worry about condensation building up inside the enclosure. I support that rant is for another forum all together! I have some MG chemical I forget exactly the model of it but its like a laquer you can put on any electronic component that makes it non-conductive and waterproof. I've tested it and it works. Maybe I could coat the inside of the BMS with it. This is what happens in my brain, it goes all over the place with ideas. Ok shutup now.

Cheers mates from Flori-duh!