Battery Help!

[4r3st3r]

Hi all,
After seeing all of your amazing builds, I have been inspired to build my own E-conversion. However, I know almost nothing about lithium batteries, BMSs or charging technologies and so I would love your advice before I blunder in and spend too much money on the wrong thing!

I will be using:
QS Motor 3Kw 48V hub motor
Kelly Controller KLS7254N

As far as I understand: the battery uses 50A continuous and 100A peak, so I need a 48v battery that can provide those Amps. Is that right?
Some questions:
The BMS is attached to the battery (?) so would a battery that I buy come with a BMS pre installed. Do I need to program or edit the BMS to ensure that it keeps the cells in the battery balanced and with enough voltage? Or can I leave it to it, and use / charge the battery as I would with a lead-acid battery?
Is it better to get a battery custom built with the correct voltage / amperage output with a BMS that can handle that?
I think I have two mounting places for batteries, is it better to buy two 48v batteries (each with a BMS) and mount them in parallel, or two 24V batteries and mount them in series (with a BMS each, or one for both?)

Apologies if these questions have been answered elsewhere! I worry most things on this forum go straight over my head!
Thanks in advance for any and all help / advice!!

[Electric Cowboy]

A lot of these answers depend on your build. You might want to consider one of the Boom Motos. They are not as polished as Zeros or Energicas, but they are 10kW hub motors with 6-9kwh batteries. and they cost $6500 to $7500 they are reasonable quality for the cost, and EASILY hackable. Way better to start with one of these and modify than to build from scratch if you are new. It will also help you learn a lot.

They aren't perfect, but they are good enough for their price.

[Stevo]

Hi all,
Some questions:
The BMS is attached to the battery (?) so would a battery that I buy come with a BMS pre installed. Do I need to program or edit the BMS to ensure that it keeps the cells in the battery balanced and with enough voltage? Or can I leave it to it, and use / charge the battery as I would with a lead-acid battery?
Is it better to get a battery custom built with the correct voltage / amperage output with a BMS that can handle that?
I think I have two mounting places for batteries, is it better to buy two 48v batteries (each with a BMS) and mount them in parallel, or two 24V batteries and mount them in series (with a BMS each, or one for both?)

If you buy from a salvage yard to get a good deal on Nissan Leaf modules or Chevy Bolt modules you will need to learn how to cut them apart.
Same with a Tesla pack, but all of those flashlight batteries will be a challenge to incorporate a BMS. The pouch cell modules are easier to deal with.
If you are building your own pack, like I did, you can arrange them anyway you want or need to. since this is your first build, try to go with one stack in series and figure out how to mount them on your frame space. They can be divided into groups. I have 3 groups of battery pouches all wired in series. There are a few BMS options available,,,, you'll have to do some research. I went with the Thunderstruck BMS.
ElectricCowboy has some good advice for you, But if you want to do your own from scratch, AND if you have the ability to weld and fabricate your own mounts and stuff, you can build your own for 1/2 the cost of a Boom Moto

[EVcycle]

Chevy Volt batteries come in a 48 volt single pack. Ready to roll for around $500.
I have used them in several projects. You can purchase 50.4V Lithium chargers for about $250.
Use the Controller as a BMS and have fun!

Ed

[4r3st3r]

First off, thanks everyone for their advice and help!

EVcycle: Do you know where I might find some for sale? That sounds pretty perfect?

Electric Cowboy: That is a good idea - but I wish I had thought of that before I bought all the other components! I am also planning on trying to make my conversion as inconspicuous as possible, so I think probably better to go more custom parts than what I would salvage from the boom! Thanks for the tip though, next time I will almost certainly do that!

Stevo: Thanks - I've never really played around with batteries and I am worried about ruining some expensive bits of kit! I think for peace of mind I will try and find someone else to build a pack for me as it will save me a whole load of trouble!

The other idea I have had was that perhaps I could buy, say, 3 20ah 48V packs and wire them in parallel. If I am trying to get 100A continuous then getting 3 packs that can provide 40A continuous would mean that it was 120A total. Does that work? Or have i missed something monumental?
If I were to do this, would I have to get another BMS to protect them all, will the BMS on each individual pack do that for me?

Thanks again!

[Stevo]

Don't fear the elMoto!
Nissan Leaf modules are super easy to work with. I've not worked with the Chevy batts but the videos don't look too difficult.
Wiring 3 48v packs in parallel will increase your amphours but not your amp output...that's still limited at the cell level. And there
is debate of whether you should parallel at the cell level versus the pack level, if that makes sense to you. Instead of 3 x 48v packs,
you should have 1 x 48v pack with 3 parallel cell stacks

[4r3st3r]

Wiring 3 48v packs in parallel will increase your amphours but not your amp output...that's still limited at the cell level.

Ah ok, thanks for clearing that up. My "genius" plan is, as usual, not going to work at all.
Having been looking at the numbers, it seems that my controller is demanding way too many amps? Its a 48V system so 100A continuous is 4800W of power (yes?!). I am only running a 3Kw motor, so it sounds like its demeaning far too many amps. The motor specs say that it only needs 45A continuous and 100A peak - which seems much more achievable. Which of these should I be following? Do I need to spend way more cash on trying to provide it 100A CC when its only ever going to be drawing 45A?!

[Stevo]

Like Ed said, just go with Chevy Bolt or Nissan Leaf modules and call it a day. The automotive grade batteries will do fine for what you plan...
https://www.ebay.com/itm/Nissan-Leaf...ry!95540!US!-1

You will only need 6 to make your 48volt pack. They weigh about 8 1/2 lbs each so only about 50 lbs total weight.

Here is a youtube I found on a 48volt Chevy Bolt pack ...WOW! Much smaller than a 48v Nissan Leaf pack:
https://youtu.be/pxSm9Zk2_1s