[OR-Carl]

I might be way off but 72v x4 parallel for charging, bms, dc/dc and then series over to the controller.

I might be a little lost here, but are you suggesting a way of re-wiring the pack on the fly to switch between 4x 18s modules of 72v (74v?) to a configuration of 72s and 295v? It would be a strange approach if you are trying to simplify the wiring.

As for lumping a bunch of other stuff into the BMS, I am not sure how that would make things simpler for you. The BMSes only real job is to monitor the cell level voltages, balance them if they are drifting, and raise alerts over CAN bus to shut down any process that threatens to over or under-discharge a cell. The BMS pulls tiny amounts of power from the pack, so if it included a DC-DC converter, for example, you would have to wire it separately anyway.

Since DIY EV cars are so diverse, there will probably never be just one integrated system like you are describing - there are just too many variable for something like that to make sense. If you want to integrate a bunch of information into a single display, including GPS navigation, you would probably have to look into getting a tablet that communicates with the BMS over CAN. You can get CAN-USB interface units, but programming something like that, and making your own GUI for the tablet is going to be a big project.

 

[OR-Carl]

Yes, its closer to 74v. How I see it in my head is bus bar with 4packs paralleled for charging and for (4)BMS.. I was trying to keep within the confines of some of the China made systems with GPS/Bluetooth and a simple gauge app for the phone/tablet. Then out to the controller/ V/Amp monitor in series.

So if you have 4 modules with all the positive terminals ganged together (and all the negatives as well) then in order to connect them in series you have to break all those connections or else you are going to short the whole pack when you go and try and put them in series. So to do this would need 3(6x?) contactors to break the parallel arrangement, and 3 more to switch them into series. Make sure you fuse them all up too, or a single failure would be a problem. A BMS does not really care what the overall pack voltage is, it just looks at cells - often in groups of 12, so the only advantage here would be that you could charge with a 72 volt charger?

Am I right to assume that you are thinking of using prismatic LFP cells, or perhaps lead acids? Based on the fact that you are leaning towards getting a warp 9, I assume you are building a "classic" style EV like was all the rage about 20 years ago?

 

[OR-Carl]

Sorry for the snarky reply, I was amused at the thought of there someday being vintage EV enthusiasts who restore old lead-acid geo metros There are of course still plenty of good things to be said for reusing a DC motor.

As for BMS options, I believe there are a few others out there. I used a thunderstruck Dilithium on my project. It is modular, with support of up to 24 cells per module. So you would need 3 (one BMSC and 2 BMSS) to handle 72 cells, but it can be expanded with up to 384 cells in a single system.

Battery Management System

EV BMS (Battery Management System)

www.thunderstruck-ev.com

I suspect the Orion would also let you combine several BMSes together if you wanted to add more cells later. It has been a while since I researched BMSes, but I seem to recall there was at least one other option i looked at, by the makers of the Zilla line of controllers, maybe?

There are CAN enabled displays out there, but they are really just a BMS interface, so they would not be suitable to run other programs like you are envisioning. I got an Engage, which just shows me a handful of stats on the dash. If I really want to dig into all the statistics, a laptop can pull up a text-line interface for both BMS and Charger. Anyway, I have been really happy with that system, but I think most of the options out there are pretty solid.

Battery Management Systems :: Dilithium Design EV Display

This touch-screen EV Display is extremely handy for showing pack voltage and current cell voltages state of charge and battery temperature Packed full of information right at your fingertips For use with the Dilithium Design Battery Management Controller BMSC or the brand new Dilithium Master

www.thunderstruck-ev.com

Battery Management System :: EnGage II Display (SOC meter)

This EnGage II Display is a State of Charge Meter that is for use with the Thunderstruck Battery Management System and now is also usable with TSM Curtis drive systems limited features Select from Voltage highest or lowest cell voltage or standard deviation Also has a backlight button and warning

www.thunderstruck-ev.com