What are my options?

I have a 250W rear hub motor. 36V 13.8 Ah battery. I am going to install a KT15A controller and KT LCD8 display. Im not sure of the gear ratio of the motor I think its a Shengyi SY73627.5VE0592S6

Could someone help with parameter settings to set this all up?

Also what are my options for squeezing the most out of this motor?
Am I right in thinking I can get a bigger controller and adjust the settings to limit the output? What are the advantages and disadvantages of this? Is it worth it with 250w motor?

I'm not expecting much but just want to optimise as best I can. Any advice will be gratefully received! Im a newb but I can spin a spanner and I'm keen! Should probably mention that I'm an electrician so I'm pretty happy tearing things apart and pretending I know how to put them back together. Thanks in advance! Sorry if this is a repeated topic but i'm finding the search function a bit clunky.

Battery specs below..
Cell Type : 18650 – 2.6A / 2.9A / 3.45A
Max Cell Space : 18650 * 40pc
Max Capacity : 36V / 13.8Ah ; 48V / 10.35Ah ; 496Wh
Dimension : 431.3mm * 105.2mm * 64.3mm ( PRO Type )
Housing: Aluminum
Waterproof : IPX-5
communication: UART / CANBUS
Capacity LED Display : YES.
BMS EN13849 certificated : YES

Thanks again!

KT controllers with most KT displays can be turned down by increments to as low as 50% of their maximum amps. So you can use a bigger controller than 15A, though even a 22A controller will be in a physically larger package.

The specs on that battery don't include max or continuous amps for cells, terminals, or BMS. So there's not enough data there to guess how much you can boost your bike's power before the battery becomes a problem. Most likely your motor (which I'm not familiar with) can take quite a bit more power than nominally 250W, which is how 36V x 15A would be categorized by most manufacturers.

jimmyjimmyjayjay said:

I have a 250W rear hub motor. 36V 13.8 Ah battery. I am going to install a KT15A controller and KT LCD8 display. Im not sure of the gear ratio of the motor I think its a Shengyi SY73627.5VE0592S6

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A few of the parameters like gear ratio are used to determine the speed (calibrate the speedo), however, on geared motor, a lot will have a built in speed sensor. If you motor connector is a single connector with 3 large pins and several small ones, then count the number of small pins. For the hall sensors, there's typically 5 conductors (+5V, GND, and the 3 hall phases), but for motors with a built in speed sensor, there will be 6 conductors.
If your motor connectors are separate, with 3 large conductors and a separate Molex connector for the halls, then check to see if it has 5 wires, or a 6th white wire.

E-HP said:

A few of the parameters like gear ratio are used to determine the speed (calibrate the speedo), however, on geared motor, a lot will have a built in speed sensor. If you motor connector is a single connector with 3 large pins and several small ones, then count the number of small pins. For the hall sensors, there's typically 5 conductors (+5V, GND, and the 3 hall phases), but for motors with a built in speed sensor, there will be 6 conductors.
If your motor connectors are separate, with 3 large conductors and a separate Molex connector for the halls, then check to see if it has 5 wires, or a 6th white wire.

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Thanks for your reply. It's 9 pin with the white wire.

Start with P1 = 40 and adjust up/down till the display shows the right speed. However, the KT LCD's use the wheel sensor and the wheel diameter set in the display to determine mileage on the trip odometer, so that's usually off,

Buy a 36v/48 KT controller, maybe the 20A model. You can always turn the amps down. There's a 6FET 25A version that is slightly larger which is hard to find.

Chalo said:

KT controllers with most KT displays can be turned down by increments to as low as 50% of their maximum amps. So you can use a bigger controller than 15A, though even a 22A controller will be in a physically larger package.

The specs on that battery don't include max or continuous amps for cells, terminals, or BMS. So there's not enough data there to guess how much you can boost your bike's power before the battery becomes a problem. Most likely your motor (which I'm not familiar with) can take quite a bit more power than nominally 250W, which is how 36V x 15A would be categorized by most manufacturers.

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Thanks I really appreciate the reply!

How would I go about finding out the rating of the battery? Pull it apart and have a look? It has "REENTION" imprinted on it. Battery code is 10ICR19/66-4. If any of that means anything?

docw009 said:

Start with P1 = 40 and adjust up/down till the display shows the right speed. However, the KT LCD's use the wheel sensor and the wheel diameter set in the display to determine mileage on the trip odometer, so that's usually off,

Buy a 36v/48 KT controller, maybe the 20A model. You can always turn the amps down. There's a 6FET 25A version that is slightly larger which is hard to find.

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I found the KT22A which is rated at 11amps. Only issue is the size I want to keep it in the downtube ideally. If i set the amps to max will I get the max amps or the rated amps? For example the KT15A will I get 15A(Max) or 7A (Rated). Its quite hilly where I am so just want a bit extra up the bigger hills. Thanks for the info!

jimmyjimmyjayjay said:

Only issue is the size I want to keep it in the downtube ideally.

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Do you already have a frame that accepts the battery, or are you fabricating something custom?

jimmyjimmyjayjay said:

Thanks I really appreciate the reply!

How would I go about finding out the rating of the battery? Pull it apart and have a look? It has "REENTION" imprinted on it. Battery code is 10ICR19/66-4. If any of that means anything?

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You could look for online support from Reention and ask them.

jimmyjimmyjayjay said:

I found the KT22A which is rated at 11amps. Only issue is the size I want to keep it in the downtube ideally. If i set the amps to max will I get the max amps or the rated amps? For example the KT15A will I get 15A(Max) or 7A (Rated). Its quite hilly where I am so just want a bit extra up the bigger hills. Thanks for the info!

Click to expand...

Max amps is the number that matters.

E-HP said:

Do you already have a frame that accepts the battery, or are you fabricating something custom?

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Just upgrading what I've got (photo attached) It's my first e-bike which I got cheap second hand. Keen to learn as much as I can and hopefully build something bigger and better at a later date. Waiting for the new e-bike laws to be decided here in the UK so I can see how far I can bend them I have found a 48V 14Ah battery that should fit. What would that do to the equation? I'm used to working with ohms law, not sure how to incorporate torque, mph, range etc. into that. Is there a simple way of thinking about it? Or some useful equations I can think about? I know I could probably just google it but having all the info here in one place is really helpful and google always brings me back here anyway Thanks for all the input and helping me learn! This is an awesome forum!

Chalo said:

You could look for online support from Reention and ask them.

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I just checked their website. It seems they just make the battery case. So its anyone's guess as to what's inside.

jimmyjimmyjayjay said:

I have found a 48V 14Ah battery that should fit.

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where did you find the battery. Do you have a link?

E-HP said:

where did you find the battery. Do you have a link?

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Do I dare believe that my battery numbers are the same? What will melt first?

Going by that chart for the battery BMS rating, my max 15 Amp is about right?? Is it better to run a 20/30amp controller at 75/50%?? Or just max out the 15Amp?

If the chart and the battery pack descriptions and footnotes are correct, then the pack contains 13S4P of Samsung or LG cells (the case holds 52 cells, so 52/13 = 4 parallel groups. For 4P and 14Ah, each cell would have a capacity of 3500mAh, so the common cells used by Samsung and LG are the 35E and MJ1 respectively. The 35E has an 8A discharge rate and the MJ1 is 10A. So, the cells in the pack when new, should be able to provide either 32A or 40A. I would limit current through the controller to 25A to be conservative, if you trust the ad. If on the other hand, the cells are generic Chinese cells (not likely because I haven't seen a high capacity, 3500mAh, generic cell), then 15A-20A is probably the most you'd want to discharge at.

jimmyjimmyjayjay said:

Going by that chart for the battery BMS rating, my max 15 Amp is about right?? Is it better to run a 20/30amp controller at 75/50%?? Or just max out the 15Amp?

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What is the battery amps max continuous rating? That is what is important here.

E-HP said:

If the chart and the battery pack descriptions and footnotes are correct, then the pack contains 13S4P of Samsung or LG cells (the case holds 52 cells, so 52/13 = 4 parallel groups. For 4P and 14Ah, each cell would have a capacity of 3500mAh, so the common cells used by Samsung and LG are the 35E and MJ1 respectively. The 35E has an 8A discharge rate and the MJ1 is 10A. So, the cells in the pack when new, should be able to provide either 32A or 40A. I would limit current through the controller to 25A to be conservative, if you trust the ad. If on the other hand, the cells are generic Chinese cells (not likely because I haven't seen a high capacity, 3500mAh, generic cell), then 15A-20A is probably the most you'd want to discharge at.

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Ok so my brain melted first! The above is the calculation for the 48V 14Ah?
My 36V 13.8Ah battery has Max 40 cells in the larger case, according to data in my first post from the manufacturer. Where did you get the 52 cells from?

On my battery label it says
36V
Rated 13.2Ah. 475.2WH
Typical 13.8Ah. 496.8WH
I took one end of the battery cover off and I can see 8 batteries in a triangular shape so i'm guessing 5 rows of 8?

I've somehow managed to come up with this for my 36v 13.8Ah using samsung 35E cells. Is that right? I really am just guessing.
So we multiply the discharge current by the parallel groups? I need a maths lesson.

Total Number of Cells in the Pack: 40.00
Battery Configuration: 10S4P
Pack Capacity: 14.00 Ah
Pack Energy: 504.00 Wh
Pack Max. Voltage: 42.00 V
Pack Nominal Voltage: 36.00 V
Pack Cutoff Voltage: 26.50 V
Max. Discharge Current: 7.00 A

Battery Pack Calculator | Good Calculators
© 2015-2024 goodcalculators.com

Thanks again!

jimmyjimmyjayjay said:

Ok so my brain melted first! The above is the calculation for the 48V 14Ah?
My 36V 13.8Ah battery has Max 40 cells in the larger case, according to data in my first post from the manufacturer. Where did you get the 52 cells from?

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Yes. I searched "how many cells in a Reention EEL Pro case?" So at 48V, that's 4P. At 36V, the case could hold 5P (50 cells), with 2 unused spots.

Sorry, I wasn't referring to your first post. I looked at the link you provided for the 14 Ah battery you found.

Anyway, just get a controller that has the ability to set the max output current, buy a battery and look inside once you get it to see what you got, and how much current it can provide.