She wants to buy me a battery for 79th B'day..

For my bike she wants to buy me a battery, her trike has much more range, as I discovered yesterday when I had to peddle up the hill to the house. It gets a bit complicated.

Heavy old Bike has a 36 volt brushed non programmable rear hub motor, I have added a Bafang 350 watt jump bike motor on the front.
Bike as I bought it has 3 SLA 12V batteries in a case that is approx 3.5 by 3.75 by 17 inches long.
There is no provision on the bike for a BMS, and therein lies my dilemma.
Have installed a BMS on my Etractor, so do understand the basics of how they work.
I do not know how to wire a battery that comes with its own bms, the batteries am looking at have a twisted pair for running the bike and then some kind of connector for BMS, Can this just be wired to the main output wires or????
My Etractor and Etrike both use Nissan Leaf modules and the BMS for them just installs on the negative terminal and controls the charging and output etc no problem,
Really like my bike, it suits me, but yesterday the wife, son in law and grand daughter out distanced me, would love a pointer.

Buy a 48v battery no lead and a motor kit with three phase motor. In USA we have them shipped $225.00.
Good you have battery skills. Just make one or.
Battery Hookup
2/4/6 PACK - PANASONIC 48V POWER MODULE 13S 6.4A 299.99WH
Regular price$180.00
These people have other batteries but not now
Plus they are only 1,500 mah but 25amp cells

BCH has a bunch of 36v packs, those will work fine as is,

I have the same uber/jump front hub, I think 15 to 20 amp is the max I was told,
So if you put 4 of those packs in parallel, you are good to go.

I am making a pack using 6 of those packs in parallel, 30 amp max at 40v and 1.5kw, I can literally ebike to canada, lol.

ynot said:

There is no provision on the bike for a BMS, and therein lies my dilemma.

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Most ebike batteries come with a BMS preinstalled in them, if you go that route. You'd need a battery that is of the same voltage range as your existing setup, so any typical 36v (10s) lithium battery would work, as long as it:

--has sufficient Ah / Wh capacity to achieve the range you need.

--has sufficient current (A) delivery capability to supply the systems on your bike with the max power they will ever need for your usage.


I do not know how to wire a battery that comes with its own bms,
An ebike type battery with it's own BMS will typically just have a charge port that you connect to the supplied charger, and discharge port + and - wires you connect to the controller battery input + and - wires. You don't need to worry about the BMS or any internal wiring; it's already there.

If you're looking at some other type of battery, you'll need to give us the link to it for us to help you with it.

the batteries am looking at have a twisted pair for running the bike

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Twisted pair? Those are typically pretty small gauge for data lines only. Not tyipcally intended to carry sufficient current to run one motor, much less two.

and then some kind of connector for BMS, Can this just be wired to the main output wires or????

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You'd have to post a link ot the specific battery you're referring to for us to tell. (assuming the link has sufficient information itself).

@ Amberwolf, I was expecting to use my existing charger for the new battery and it has no BMS port, just the power output wires.
So will have to buy charger and battery to keep the BMS happy? The BMS that I use for my Leaf modules simply connects to battery negative and all charging and discharging is done using the BMS for the negative terminal.

BTW, thank you for the tip about connecting a second controller to the throttle, I was happily going to solder all three wires for the slave controller, you saved me.
Is it possible to do the same for the brake lever? One brake lever to shut off both controllers, I was simply going to install the brake lever far enough away from the thumb throttle that it would be difficult to keep power on while braking. Would prefer to be legal, as the trike will get a lot of looks.

You need a good battery
Every single thing centers around the battery

Then comes the controller, choose wisely

Thristly, Motor, again choose wisely

How fast does one have to go and for how long, at what slopes. Do you want to cheap out on wimpy battery for your system only wanting to step up a bit in power later on.

You need a lithium ion battery that fits your bike.
48v 40a and whatever Ah/Wh you want.
Get a 48v 40a generic controller
Ride the current motor until no longer
Get a better motor.
Get a better bike.
Upgrade
Rinse Repeat

ynot said:

@ Amberwolf, I was expecting to use my existing charger for the new battery and it has no BMS port, just the power output wires.

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If it helps, think of it like this:

Chargers don't have BMS ports.

BMSs have charge ports.

You plug the charger into the charge port of the battery, which is wired to the BMS internally (assuming there is a BMS).

If the battery has a BMS, that's automatically dealing with passing current from charge port to battery. The BMS is "invisible" to you as far as the difference between a battery with one and without one.




Assuming the voltage of the charger is correct for the new battery:

If your existing charger is low enough current output to be safe for the new battery, then you can use the existing charger. That is dependent on the max charge rate of the new battery (whether or not it has a BMS).

For instance, if your charger is a 36v 10A charger, but the new battery can only take a maximum of 2A charge, then you will need a new 2A charger, unless the one you have has a user-accessible current limit adjustment to drop it from 10A to 2A.

If your charger is a 36v 2A charger, and the new battery can take up to 5A charging current, then your existing charger will work fine, it just wont' charge it as fast as it could be charged at (which is fine).


Regarding charger voltage: If your charger is for a 36v battery (10s) then typically that has a 42v final voltage (sometimes a few tenths above that). If that's what it is, it should work for any other typical 10s 36v pack. Just check that the max charge voltage of the new battery matches that of the charger.

If the charger is too high a voltage by far enough, then if the battery has no BMS it could be overcharged (or if the BMS ever fails). If the charger is too low a voltage by far enough, the BMS (if the battery has one) may not be able to fully balance cells if they get far enough out of balance.

The BMS that I use for my Leaf modules simply connects to battery negative and all charging and discharging is done using the BMS for the negative terminal.

Click to expand...

That is what most BMSs do.

BTW, thank you for the tip about connecting a second controller to the throttle, I was happily going to solder all three wires for the slave controller, you saved me.

Click to expand...

Sure. I got the tip from Teklektik years ago to only connect the signal wires between the two controllers.

Is it possible to do the same for the brake lever? One brake lever to shut off both controllers,

Click to expand...

Unlike the throttle signal, which is variable, the brake signal is just on and off for most controllers. So it is not sensitive to small variations in voltage caused by ground loops.

But to prevent ground loops between teh controlers that could affect throttle and any other variable signals, you can still connect just the signal wire between the two for that, as well. Grounding the signal (assuming "Low brake" is used, if your controller also has "high brake") at either controller (via the brake lever) would then turn both of them off or engage braking mode, depnding on how they're designed.

I can not speak from personal experience but I know that there are LiFePO4 batteries advertised as drop-in replacements for SLA batteries ... same size, shape and capacity. They weigh a bit less, have built-in BMS, use the old SLA chargers and have a much longer service life (not to mention a much flatter discharge curve).

I think the light just went on
https://www.amazon.com/HAILONG-Battery-Electric-Scooter-Lithium/dp/B09JNVQ19B/ref=sr_1_5?crid=39PGI2LCT5DH1&keywords=ebike%2Bbattery&qid=1650965286&sprefix=ebike%2Bbattery%2Caps%2C201&sr=8-5&th=1

In this example the pair of large wires is the output for motor, the small wires are for charging.
Sorry for being so dense.
Will have to take it on faith that the bms will protect from over discharging when the charger is unplugged. I could charge through the output wires but that would bypass the BMS.