DIY Electric Car Forums banner

1 - 20 of 26 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter #1 (Edited)
Hey everyone, I'm currently working on converting a VW Vanagon to Electric.

48 Nissan Leaf Modules (Arranged to 120V)
KDH14650B Series motor controller (Shouldn't need to pull any more than 300A)

Are their any BMS's on the market that can manage 16s and are a bit cheaper than Orions price tag of nearly 1000$?

Thanks
 

·
Registered
Joined
·
4,058 Posts
So each Leaf Module is 4 cells. You said you're doing 48 of those, so that's 96 lithium cells. Correct?

How are you arranging them? 24s2p? That's about 100V max. 120V nominal is 32s. Not sure you can really do a ton to split the actual modules into their respective cells.

I like Zeva, they have a modular 12s system and you can add batches of 12s at a time, so with 24s.
 

·
Registered
Joined
·
184 Posts
ive seen a system called TinyBMS.

They do a 16s system, relatively cheap too, alot of good fedback on them at endless sphere forum

Anthony.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #4
Each Nissan Leaf Module consists of 4 cells ( 2 in series and 2 in parallel) so each module has a average voltage of 7.4V and 66.2Ah. Im arranging them 16s3p to get a total voltage of 118.4V
 

·
Registered
Joined
·
184 Posts
Hi,

although you say you have 16 cells, in fact you have 32.
Each leaf module inside has effectively 2 cells, if you put a voltage meter across the 2 end you will see approx 8 volts.

You would need a bms that`ll monitor and protect 32 cells in your case, either 2 x tinyBMS or a Zeva BMS from australia, or others.
But, you will need a 32s bms.

Anthony.



Each Nissan Leaf Module consists of 4 cells ( 2 in series and 2 in parallel) so each module has a average voltage of 7.4V and 66.2Ah. Im arranging them 16s3p to get a total voltage of 118.4V
 

·
Registered
Joined
·
4,058 Posts
Each Nissan Leaf Module consists of 4 cells ( 2 in series and 2 in parallel) so each module has a average voltage of 7.4V and 66.2Ah. Im arranging them 16s3p to get a total voltage of 118.4V
I corrected, sorry. I meant each module has 4 cells, but they're 2s2p as you state.

Your pack is still not 16s3p, that is a terminology used to define the number of cells in series/parallel, not to be used to define the number of modules like a Leaf cell, hence me asking for your clarification. 16s seemed really low for a vehicle. 32s seems more reasonable.

So if you're doing 16 modules in series, with 3 in parallel, you've actually got a 32s6p battery pack.This would be about 3.7V per cell nominal, and 4.2V max. That'd equate to a pack voltage of 118.4V nominal and ~134.4 V if you wanted to take it all the way to 4.2V.

Long and short, you need a 32s BMS, not a 16s. Each cell needs to be monitored. You could do two 16s BMS, or three 12-cell BMS. Most BMS out there will allow you to have some unused channels. 12s multiples on a BMS might be easier to find.

Take a peak at the Zeva BMS:
http://www.zeva.com.au/
 

·
Registered
Joined
·
28 Posts
Discussion Starter #9
Hey guys thank you all the help you have been giving me I definitely wouldn't be able to get this done right without this community.

So attached to this post I have 2 images. One of them is the inner workings of a single Leaf Module showing how the 4 batteries are arranged in the module. The other picture is a little diagram I made on how I believe I need to wire it to get 120V with the 48 modules. Im not too sure as to how I would wire a 32s BMS to this unit I have considering I don't want to physically break into each cell and potentially compromise it. Thank you guys for all the help so far if you guys can help me with understanding how to go about wiring a BMS to this and check to make sure my configuration is correct I'd really appreciate it.

FYI-In the picture the copperish paint strokes represent the bus bars.
 

Attachments

·
Registered
Joined
·
78 Posts
Does anyone have any experience or general input on the Batrium system, which does have a monitor designed for the Leaf cell terminal layout ?

These aren't standalone monitors, they need to be connected to the supervisor.

https://www.batrium.com/collections/cell-monitor/products/leafmon-8w
Batrium is pretty much the goto solution of the https://secondlifestorage.com/ forum, lots of information there. In short, Batrium has no real limit on the cells it can manage, and will scale to 32s easily, and even has Leaf-specific cell monitors. It works by connecting monitors together via a serial link before connecting to the supervisor, hence there is no practical number to the maximum number of cells.

Zeva 16S may work too, with two of them being linked.
 

·
Registered
Joined
·
5,056 Posts
So attached to this post I have 2 images. One of them is the inner workings of a single Leaf Module showing how the 4 batteries are arranged in the module. The other picture is a little diagram I made on how I believe I need to wire it to get 120V with the 48 modules.
The configuration works fine: groups of three modules are wired in parallel, then all of those groups are in series (and the 48 modules are physically arranged in four groups).

Im not too sure as to how I would wire a 32s BMS to this unit I have considering I don't want to physically break into each cell and potentially compromise it.
You don't need to break into the modules. They have three terminals, making the cell-level connections available. From the centre terminal to one main terminal is one pair of parallel cells; from the centre terminal to the other main terminal is the other pair of parallel cells. When you have the modules in parallel this way, these two connections to a paralleled set of modules will give you two cell levels of the 32 levels of BMS connections, each BMS connection monitoring a set of 6 cells in parallel. There is no way to connect a BMS separately to each cell of a parallel set.
 

·
Registered
Joined
·
28 Posts
Batrium is pretty much the goto solution of the https://secondlifestorage.com/ forum, lots of information there. In short, Batrium has no real limit on the cells it can manage, and will scale to 32s easily, and even has Leaf-specific cell monitors. It works by connecting monitors together via a serial link before connecting to the supervisor, hence there is no practical number to the maximum number of cells.

Zeva 16S may work too, with two of them being linked.
Thanks, I was wondering if anywhere else, other than that forum, had anyone using that BMS.
 

·
Registered
Joined
·
4,058 Posts
Batrium is pretty much the goto solution of the https://secondlifestorage.com/ forum, lots of information there. In short, Batrium has no real limit on the cells it can manage, and will scale to 32s easily, and even has Leaf-specific cell monitors. It works by connecting monitors together via a serial link before connecting to the supervisor, hence there is no practical number to the maximum number of cells.

Zeva 16S may work too, with two of them being linked.
The 16s units are standalone, and wouldn't neccessarily work together. They'd work independantly.

I'd use 3 12s units with master and go for 36 total channels and not use 4 channels.
 

·
Registered
Joined
·
4,058 Posts
Thanks, I was wondering if anywhere else, other than that forum, had anyone using that BMS.
They're popular on the DIY Powerwall groups, but haven't seen anyone use one in an EV yet. They seem to improve their offerings quickly, so it wouldn't be a surprise someone uses one in an EV.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #15
Thank you to everyone who responded. You guys are totally right the system I'm proposing is in fact a 32s system. I didn't quite understand the functionality of that middle terminal but I get now that terminal allows you to measure the voltage of each of the 2 parallel batteries in the module. Thank you frodus, glyndwr1998, brian_ for helping me make sense of it. So I think I'm going to go with buying 2 "Tiny BMS s516 - 150A/750A" thank you glyndwr1998 for the recommendation. Attached to this is a diagram of how I believe each wire needs to be connected to the 2 BMSs'. I do have a question though; does each BMS run independently of one another or do they both need to be in communication with eachother?

Sorry for the barrage of questions I'm just trying to understand as much as I possibly can before I go about making this thing.
 

Attachments

·
Registered
Joined
·
78 Posts
So I think I'm going to go with buying 2 "Tiny BMS s516 - 150A/750A" thank you glyndwr1998 for the recommendation. Attached to this is a diagram of how I believe each wire needs to be connected to the 2 BMSs'. I do have a question though; does each BMS run independently of one another or do they both need to be in communication with eachother?
TinyBMS doesn't have support for communicating between multiple units. While theoretically it could work, each unit will require separate contactor, and they may be stomping on each other when balancing the 8th module (16th cell pair). The company is out of Lithuania, and some people reported unreliable customer service.
 

·
Registered
Joined
·
184 Posts
hi daltonguitar,

sadly a cheap reliable simple bms is a holy grail when expanding beyond 16 cells.
I cannot comment on the relaibility of the tinybms system, only that i have had some comms with them in a home storage system im going to build in the near future.
There are cheap bluetooth smart bms systems available via aliexpress china, some good videos on youtube on them, search smart bms.

The zeva bms looks good, the new one uses an automotive grade cpu, and is modular, so you could use 3 slaves and 1 master, not sure what the cost is of those though.
Good luck with your search, report back with which way forward you went with.
Thanks.
 

·
Registered
Joined
·
217 Posts
I've been using a Chargery BMS 24 on my CozE for a couple years now - it seems to work great. I don't remember even paying $325 for it so if you shop around you could probably find a better deal. They make units that are for more than 24 series I believe as well. I plan on trying out the ZEVA system for my next build. Here is an example:

https://www.ebay.com/i/223066773456?chn=ps
 

·
Registered
Joined
·
78 Posts
I've been using a Chargery BMS 24 on my CozE for a couple years now - it seems to work great. I don't remember even paying $325 for it so if you shop around you could probably find a better deal. They make units that are for more than 24 series I believe as well. I plan on trying out the ZEVA system for my next build. Here is an example:

https://www.ebay.com/i/223066773456?chn=ps
Before considering Chargery, I'd recommend reading this thread :

https://endless-sphere.com/forums/viewtopic.php?f=14&t=95330
 
1 - 20 of 26 Posts
Top