Hello I'm trying to figure out what battery I'll need for this

Posted by definitlynottheone@reddit | ebikes | View on Reddit | 13 comments

So as the title says but I'm wondering what battery will work for this motor controller the original went kaput and I threw it out without checking but I'm mainly confused because on one part of the controller it says voltage dc 52v and another part says off voltage 42v and will I need to match the amps its probably a silly question but any help would be appreciated thanks.

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Informal_Arachnid_84@reddit

A 52v lithium battery has a low voltage cutoff of around 40~45 depending on the BMS. A 52v (14s) would be ideal.

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definitlynottheone@reddit (OP)

Okay thank you very much 👍

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JG-at-Prime@reddit

Hold up there.

That might not be the correct battery for your bike.

Batteries operate within a voltage range. A 36V battery (what you linked) charges to a maximum voltage of 42V. Its safety cutoff “empty” is 30V.

A 48V battery is “full” at 54.6v and “empty” at 40v.

A 52V battery is full at 58.(something)V and “empty” at around 42V.

The various batteries are named for their nominal voltage. Not the maximum voltage.

You want a battery that is the same voltage range as your old battery. Look on your old charger. The output voltage will be listed.

What is the old chargers output voltage?

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definitlynottheone@reddit (OP)

So would a 52v work on it theoretically idm about how far it goes I jus need to know what voltage battery to make it run.

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JG-at-Prime@reddit

If the controller is rated for a 52v battery, then yes. That’s what you want.

Think of voltage like pressure. It’s how fast energy is flowing.

Think of amps like flow. It’s how much energy is flowing at that pressure.

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definitlynottheone@reddit (OP)

Oh ok sweet as thanks you've been very helpful I was just confused on what the off voltage and voltage rc differences were and how about the amps does it matter if I have less/more?

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JG-at-Prime@reddit

Yes, it does matter.

Volts multiplied by Amps = watts.

If you have a 48v battery and a 20 Amp controller then it’s easy to work out that the motor is being run at: 48x15.65=751.2 watts.

It works all 3 ways. If you have a 750 watt motor running on 48 volts, we can work out that 750/48=15.625 amps.

Batteries are rated in 4 ways.

Nominal voltage: 48v (this will tell you the maximum (54.6v) and minimum charge voltage (40v).

Amp Hours: This tells us how long the battery is capable of running a 1 amp load. (Let’s say 15)

Amps: this metric tells us how many amps the batteries BMS can put out on a sustained basis. (30 amps)

Watt hours: 48x15=720 watt hours.

Controller have both a sustained amp rating and a peak amp rating.

Motors are rated as how much volts and amps that they can handle without overheating.

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definitlynottheone@reddit (OP)

Okay thank you that's way more in depth so something like this would work?

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JG-at-Prime@reddit

It seems like it should work. You might need to splice some wires, but that’s normal.

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definitlynottheone@reddit (OP)

Yea I bought the one that had the xt60 socket so no splicing needed but thank you you've been helpful I really appreciate it a lot have a good day 👍

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definitlynottheone@reddit (OP)

No clue I've thrown it all away I jus pulled out the motor control and hub recently cause I got a bit of motivation but I'm very new to this I do know amps is the range and voltage is the power that's about it.

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Significant-Pen-6049@reddit

Holy crap I was seeing things at first

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definitlynottheone@reddit (OP)

So as long as I get a 52v it should be fine do I need to match the amps (probably another silly question tbh but Google said that amps is just how far it would go but when I went to uni we learnt amps is current and current is how fast the energy moves so yeah) to sum it will a 52v battery be fine and does it matter if the amps is less.