Prepping for Lishen 272ah cells - busbars

[Boondock Saint]

Howdy, I ordered 32 of the Lishen 272AH cells from Michael this week. They should arrive with HW but I didn't ask for addditional busbars. I want to fully prep for their arrival and for testing, assembly etc.

The Lishen spec sheet says there is 89mm from center to center of the holes / studs.

My current plan is to make a 48v system with 16S2P pack assembly.

Has anyone done exactly this with the 272 and if so, what busbar product did you use? Except for combing the 48v packs, are there any other HW considerations I should know about? I haven't decided on a BMS or what to do about that yet either.

Thanks in advance.

 

[Sanwizard]

Howdy, I ordered 32 of the Lishen 272AH cells from Michael this week. They should arrive with HW but I didn't ask for addditional busbars. I want to fully prep for their arrival and for testing, assembly etc.

The Lishen spec sheet says there is 89mm from center to center of the holes / studs.

My current plan is to make a 48v system with 16S2P pack assembly.

Has anyone done exactly this with the 272 and if so, what busbar product did you use? Except for combing the 48v packs, are there any other HW considerations I should know about? I haven't decided on a BMS or what to do about that yet either.

Thanks in advance.

I believe I measured 70mm center to center for the cells. I have the lishen 272ah. I will need to double check.

 

[DThames]

2 cells parallel, then 8 series (2p8s)? Or 8 series, then parallel those 2 strings (8s2p)?

 

[Boondock Saint]

I believe I measured 70mm center to center for the cells. I have the lishen 272ah. I will need to double check.

Thanks for that.

2 cells parallel, then 8 series (2p8s)? Or 8 series, then parallel those 2 strings (8s2p)?

That's the rub, I just don't know yet. This is a 48v system at the end, so whether it's 2x24v in series then those in parallel, or just 16 cells in series and 2 in parallel . . . I don't know the efficient layout yet and I guess that does determine the length of the busbars doesn't it?

I was going to plan that in a separate thread but what the hells, let's go for it here.

Considering adding BMS and total HW, what would be the most expedient way to put together this 48v system with 32 cells?

 

[Sanwizard]

Thanks for that.



That's the rub, I just don't know yet. This is a 48v system at the end, so whether it's 2x24v in series then those in parallel, or just 16 cells in series and 2 in parallel . . . I don't know the efficient layout yet and I guess that does determine the length of the busbars doesn't it?

I was going to plan that in a separate thread but what the hells, let's go for it here.

Considering adding BMS and total HW, what would be the most expedient way to put together this 48v system with 32 cells?

I get 72mm when they are side by side. My buss bars are 70mm center to center.

 

[Boondock Saint]

Much appreciated. I didn't realize that busbars had oblong holes, this allows for a little wiggle room.

Didn't I read somewhere that some mfr indicates the cells must face upwards? Can they lay sideways if there are only a few deep?

 

[DThames]

Sorry, I didn't write what I was thinking. Rather than writing "2 cells parallel, then 8 series (2p8s)? Or 8 series, then parallel those 2 strings (8s2p)?
I should have said, "2 cells parallel, then 16 series (2p16s)? Or 16 series, then parallel those 2 strings (16s2p)?

I don't think that question changes the bus bars size. You can make 2, 48v batteries, with one BMS each, then parallel them or you can make 1, 48v battery (twice the size) with only one BMS. I think most people would make one battery, using 2 cells in parallel, 16 times (in series). I was just curious what your plan was.

 

[Boondock Saint]

Hey I'm curious what my plan is too! :D

I agree with your two possibilities, and this might be determined by my available space in the storage are and how I can fit/configure them.

I suppose using a single BMS with 2 cells in parallel x 16 = 48v would be beneficial, if there isn't any glaring downsides to doing so.

 

[flgboy]

Ask Michael to order more bars for you. they are super cheap when included in with the order. Get some extra based on your worse case scenario config...

 

[jtvt]

Howdy, I ordered 32 of the Lishen 272AH cells from Michael this week. They should arrive with HW but I didn't ask for addditional busbars. I want to fully prep for their arrival and for testing, assembly etc.

The Lishen spec sheet says there is 89mm from center to center of the holes / studs.

My current plan is to make a 48v system with 16S2P pack assembly.

Has anyone done exactly this with the 272 and if so, what busbar product did you use? Except for combing the 48v packs, are there any other HW considerations I should know about? I haven't decided on a BMS or what to do about that yet either.

Thanks in advance.

Just order some more busbars. You have time.

I currently have 2 16 280ah (not sure there is much difference 272 vs 280) cell strings in parallel. Each string is fused. I'm adding two more strings once I get my second battery order in a couple months. I use double bus bars. I asked for extras when I ordered. $1 per bar extra.

Get yourself a torque wrench. I'm don't know if you are getting welded studs, but don't guess on how tight is tight enough. IMO, serrated lock nuts are junk. I think that has led people to over torque them and strip the threads. When I get my next set of batteries, I will experiment with lock washers.

There are different opinions on parallel strings versus parallel cells. Look in resources. I think there is a doc that lays out the differences. What it boiled down to me was it's hard to troubleshoot a bad cell and the bms balance mechanism is weaker per cell with parallel cells. Some say it's possible for cells in parallel strings to diverge. I have not observed that yet. My plan was to make parallel strings and if it didn't work out, I would just reconfigure the battery into parallel cells. So far no reason to do so. I use a single Batrium BMS for all the cells. This is more money than the other brands, but you will need a bms per string with other brands. With Batrium I can just add 32 more blockmons to the bms system for my other cells. I don't have to add another bms.

I used a cheapo bms with a contactor for the first part of the top balance procedure and a 60 amp power supply to finish. You will need a power supply. There is a top balance sticky post that has info.

 

[Just John]

Much appreciated. I didn't realize that busbars had oblong holes, this allows for a little wiggle room.

Didn't I read somewhere that some mfr indicates the cells must face upwards? Can they lay sideways if there are only a few deep?

I would not recommend you face the over pressure vents anyway except up. If you over charge, you can start to boil the (very nasty) hydrocarbon electrolyte. The small window on the cells is the vent that is supposed to break and prevent the pressure from building up and rupturing the aluminum housing. When placed on the side, you wouldn't just vent toxic (and flammable) gas, but also liquid electrolyte. See what happened with Will and the big battery review. Even though the manufacturer says it is OK to do so, I wouldn't. But that is my opinion, last I heard manufacturer was saying it is not a problem.

 

[Boondock Saint]

Roger that - order more busbars at once!

I can add another BMS. Last night I was contemplating 2 x 250A BMS . . . but it seems my 48v resources are currently (no pun intended) somewhat limited. I'm open to suggestions and in favor of already having at least one and a PSU on hand when the cells arive.

 

[DThames]

Roger that - order more busbars at once!

I can add another BMS. Last night I was contemplating 2 x 250A BMS . . . but it seems my 48v resources are currently (no pun intended) somewhat limited. I'm open to suggestions and in favor of already having at least one and a PSU on hand when the cells arive.

I purchased 2 used BYD 24v batteries. Being used, the cells were somewhat out of balance due to capacity differences. The cell connections are welded, so not easy to try to rearrange and match cells. I put the two batteries in parallel but then added some 18gauge balance wires between like numbered cells. So it is wired like 8s2p from a power standpoint but uses only one BMS. I would consider a similar build an option for you. If you want to removed the balance jumpers and add a second BMS at a later date, that would be easy.

 

[Sanwizard]

Ask Michael to order more bars for you. they are super cheap when included in with the order. Get some extra based on your worse case scenario config...

Great idea. I just purchased seperate for $61.00! Not cheap.

 

[Just John]

Roger that - order more busbars at once!

I can add another BMS. Last night I was contemplating 2 x 250A BMS . . . but it seems my 48v resources are currently (no pun intended) somewhat limited. I'm open to suggestions and in favor of already having at least one and a PSU on hand when the cells arive.

I have a used power supply I was planning to offer in the for sale section here. If you are interested, let me know.

Thread 'Cheap power supply for top balancing (tested and works well).' https://diysolarforum.com/threads/cheap-power-supply-for-top-balancing-tested-and-works-well.19846/

The second one I linked in there. I don't have the box anymore (recycled) but can make some high quality cables to go with it (10 gauge with ring terminals). Take my advice, don't use the alligator clips included with any cheap supply.

 

[Boondock Saint]

I put the two batteries in parallel but then added some 18gauge balance wires between like numbered cells. So it is wired like 8s2p from a power standpoint but uses only one BMS.

V e r y Interestink

One&One pos
One&One neg
Two&Two pos
Two&two neg

and so on down the row? Does this limit the BMS ability to really manage the cells or does this just average things out for the two cells at a time?

Great idea. I just purchased seperate for $61.00! Not cheap.

Oh man that's just two decent happy hours :D

 

[Just John]

V e r y Interestink

One&One pos
One&One neg
Two&Two pos
Two&two neg

and so on down the row? Does this limit the BMS ability to really manage the cells or does this just average things out for the two cells at a time?




Oh man that's just two decent happy hours :D

18 gauge is way undersized for that application.
If you are going to parallel the cells and use a single BMS (should work fine) then you need current carrying cables. I assume he was just talking about balancing, not actually using them like that.

 

[Boondock Saint]

@ JJ - I had already thoroughly scoured your PSU thread and bookmarked some. I looked at some limiting factors like NO HOUSING offered etc.

I was thinking the cheaper offering should suffice since this will be a one and done use of the supply, and I live in an RV and fight for space for any material objects, and women that weigh over 105lbs.

Ya, I interpreted this as a balancing act, since the current is pulled through the busbars in series.

 

[Just John]

@ JJ - I had already thoroughly scoured your PSU thread and bookmarked some. I looked at some limiting factors like NO HOUSING offered etc.

I was thinking the cheaper offering should suffice since this will be a one and done use of the supply, and I live in an RV and fight for space for any material objects, and women that weigh over 105lbs.

Ya, I interpreted this as a balancing act, since the current is pulled through the busbars in series.

Yes, for top balancing you just need cheap and reliable. For charging packs, something more expensive is usually what you want. Most good chargers for packs won't work for top balancing, so people get stuck with a used supply that at most they might use every year or two if their cells get out of balance.

Once installed "permanently", use a good quality connection (I like Anderson connectors) for a "charging port". Some supplies and chargers can actually drain your batteries if you leave them connected while off. I like the Anderson connectors because they are polarized and won't be easily shorted out. You do pay a premium, but you also get a premium product (including silver plated copper connecting pins).

 

[Boondock Saint]

Yup, I use the Anderson plugs for my winching etc etc. I make my own 2/0 cables with tinned lugs.

I just read where someone here doesn't use a BMS, they have active balancing from their LV426 or some such AIO solution.

Which one is it that you still have? The one on Amazon for $66.99? It does/doesn't have a case/cover? Sorry I'm a little confused but interested.