Battery continuous discharge amp and controller amp need to match?

I have a 2000-4000 watt cyclone motor that runs on a 40a controller with a 60v20ah battery that has a continuous discharge current of 50a. Does the amp of the controller have to match the continuous discharge amp of the batteries? Or is it better to have one higher or lower than the other? Please keep in mind this is on my pedal cab.

Also, after a good days use (about 6hrs), whenever I full throttle the motor, the power cuts out, until I have to re-throttle it again, and it does the same thing over and over, it’s very annoying. This only happens when I gun it. Prior to the 6hr mark, it’s fine. Weird thing is, the battery never went dead, just keeps cutting out the power. I’ve had this setup for 9 months. Any info helps, thank you.

I have a 2000-4000 watt cyclone motor that runs on a 40a controller with a 60v20ah battery that has a continuous discharge current of 50a. Does the amp of the controller have to match the continuous discharge amp of the batteries? Or is it better to have one higher or lower than the other? Please keep in mind this is on my pedal cab.

Also, after a good days use (about 6hrs), whenever I full throttle the motor, the power cuts out, until I have to re-throttle it again, and it does the same thing over and over, it’s very annoying. This only happens when I gun it. Prior to the 6hr mark, it’s fine. Weird thing is, the battery never went dead, just keeps cutting out the power. I’ve had this setup for 9 months. Any info helps, thank you.


Sent from my iPhone using Tapatalk

You're stomping your battery into the ground. Do not run it until it cuts off, if you can help it. When it does that, it's because the voltage has dropped low enough under load that either the controller or the BMS is intervening to keep you from destroying the battery by overdischarge. Neither of those things will keep you from discharging it deeply enough to reduce the battery's lifespan and performance, though. The fact that your battery recovers some voltage after the load is removed does not make it any less empty.

At full 50A load, your battery contains nominally 24 minutes worth of power, full to empty. Six hours is a lot of use in that context.

Maybe get a watt meter for your trike so you can keep track of voltage and amp-hour usage, and recharge before you damage your battery.

The BMS discharge capacity and max cell discharge rate should both exceed the controller's current rating. So your system is good in that regard.

What would happen if I swapped out the 40a controller for a 60a, 80a, or 150a controller?

When the motor and controller amps exceed the amps of the batteries bms setting, the bms will shut off the battery. This is what is happening at the end of your ride, when the battery volts drops below what the bms is set to cut off at. The BMS will cut off for too much amps, or for too low voltage, or both.

And yes, you are beating your battery into the ground. Bear in mind, when they rate cells, its what the cell can in fact dish out. But that spec is far more than the battery can dish out repeatedly without damage.

Basic rule of thumb here, is if they say the battery handles 40 amps, best to make it do that very seldom, and for very short durations. I'm not saying you need a 20 amps controller, but that you need to back off the power as soon as possible, and do the bulk of your riding using 20 amps.

A watt meter on your handlebars is essential, so you can start backing down on the throttle asap, when you see it pulling 40 amps.

In addition to the battery bms cut off, there is also a low voltage cut off built into the controller. When you gun it at the end of the day, you are having the controller cut off. Unlike bms, a controller lvc will reset as soon as the battery voltage rebounds with no load on it. But its still bad for your battery, to use full throttle at the end. Watching the watt meter and using less early in the day is the only way to make your battery last longer into the afternoon. Once the controller lvc starts kicking on, you really need to stop using the battery, except to slowly limp home.

The battery and BMS need to be able handle **lots** more energy usage than the maximum the controller will allow.

The maximum specs are for bursts of just a few seconds

continuous ratings for minutes at a time are often 50-80% lower.

Most people need electronic limiting, the self-discipline involved in developing your intuition and not pushing up to the rig's limitations is very rare.

If you want long range, cruising for hours, then you will need a very large and heavy battery, or provide 80+% of the energy required yourself by pedaling.

pongyboy1 said:

Weird thing is, the battery never went dead, just keeps cutting out the power.

Click to expand...

It's cutting the power *because* it's "dead". It's trying to save itself from you. The details were explained well enough by other posters above, but that's the essential thing--when it starts cutting out, it's time to recharge it rather than beating it to death a little at a time.

pongyboy1 said:

What would happen if I swapped out the 40a controller for a 60a, 80a, or 150a controller?

Click to expand...

Then you destroy the battery faster, by exceeding it's designed capabilities.

This will also make your other problem worse, because it will cutout sooner, and more often. Then the damage caused by doing this over and over will degrade the battery, and it will happen even sooner and even more often.

It's also possible for the BMS of the battery to be damaged by the higher current in a way that prevents you from using the battery at all, until it is replaced.

Also, the higher current controller has the potential to overheat your motor, if you use the higher power a lot, depending on the loading it already sees.

If you need more range, get a bigger battery to replace this one or a second similar battery to add in parallel.

If you need more power, get a bigger battery *that can also handle the power needed* to replace this one, and *then* get a bigger controller (and possibly motor).

Thank you all for the helpful info!

I have a 40a controller and 45a 2-4K motor. Does wattage increase if I had a 50a bms and upgraded to a 100a bms? Let’s say running on 72v. My main concern is, if I upgraded to a higher rated bms, will the wattage far exceed that of the motor? Don’t want my motor to be fried.

pongyboy1 said:

I have a 40a controller and 45a 2-4K motor. Does wattage increase if I had a 50a bms and upgraded to a 100a bms? Let’s say running on 72v. My main concern is, if I upgraded to a higher rated bms, will the wattage far exceed that of the motor? Don’t want my motor to be fried.

Click to expand...

Your controller will only deliver as much power as it's designed to. The battery/BMS does not make any difference unless it struggles to provide that much power. Several people have already told you to use more BMS capacity and cell capacity than the minimum your system needs.

On the other hand, if your 50A BMS is working, and you only have a 40A controller, it's a waste of money and effort to upgrade the BMS. It won't make your system perform any differently.

pongyboy1 said:

I have a 40a controller and 45a 2-4K motor. Does wattage increase if I had a 50a bms and upgraded to a 100a bms?

Click to expand...

If the BMS isn't tripping, then no.

Thank you for the info!

Think of battery capacity and BMS capacity as a reservoir. The juice is there if you call on it, but you only use as much as you use. The problem arises if you demand more juice than your reservoir can supply. Having more capacity than you need is not a problem.

Chalo said:

Think of battery capacity and BMS capacity as a reservoir. The juice is there if you call on it, but you only use as much as you use. The problem arises if you demand more juice than your reservoir can supply. Having more capacity than you need is not a problem.

Click to expand...

Would getting a larger capacity battery, with a bms of 80a or 100a, giving me more overhead, help solve my issue?

pongyboy1 said:

Would getting a larger capacity battery, with a bms of 80a or 100a, giving me more overhead, help solve my issue?

Click to expand...

Having more amp-hours in the battery will let you run it longer before it is exhausted. It also weighs more and costs more, like for like. You don't need a bigger BMS, but there's no harm in having one.

You might as well buy the appropriate controller for your new 100A BMS Battery, one thats programmable, has regen, FOC
24fet is quite a big controller - Size: 275x121x62mm - Net Weight: 2.05 kgs

https://hallomotor.com/products/hallomotor-high-power-sine-wave-48v-60v-72v-3000w-5000w-100a-ebike-programmable-intelligent-controller-tft750c-colorful-display

pongyboy1 said:

Would getting a larger capacity battery, with a bms of 80a or 100a, giving me more overhead, help solve my issue?

Click to expand...

That' depends on exactly what you consider to be your issue. As I posted previously:
https://endless-sphere.com/forums/viewtopic.php?p=1613279#p1612887

amberwolf said:

If you need more range, get a bigger battery to replace this one or a second similar battery to add in parallel.

If you need more power, get a bigger battery *that can also handle the power needed* to replace this one, and *then* get a bigger controller (and possibly motor).

Click to expand...

A bigger BMS on the battery doesn't do anything for you unless:
--the controller needs that power
--the cells in the battery can handle that power

Also, your usage of the system would also have to put a high enough load on the motor to make the controller pull more power from the battery, or else a bigger BMS and controller woudln't do anything for you.


So...what *exactly* do you want to change about your system's performance and behavior?

Do you want it to go faster?

Do you want it to go farther?

Do you want it to accelerate quicker?

Do you want it to haul heavier loads?

What are the conditions you ride in? (hills? flat? wind? stops and starts? continuous riding? etc)

Etc.

You have to decide what you want it to do, and then post that here, in as much detail as you can possibly write, and then we can try to help you figure out which parts of the system must be changed to accomplish your goal.

WOW! Awesome info here! I just learned so much. Thanks for for the clear info for building a system correctly, and actually informing me that I built mine wrong : (
I'm pretty sure my battery/BMS will not last too long the way I drive. Live and learn. I will be sure to upgrade on next purchase.
Hats off to Chalo, Dogman, Amberwolf and others!
Thank you

amberwolf said:

pongyboy1 said:

Would getting a larger capacity battery, with a bms of 80a or 100a, giving me more overhead, help solve my issue?

Click to expand...

That' depends on exactly what you consider to be your issue. As I posted previously:
https://endless-sphere.com/forums/viewtopic.php?p=1613279#p1612887

amberwolf said:

If you need more range, get a bigger battery to replace this one or a second similar battery to add in parallel.

If you need more power, get a bigger battery *that can also handle the power needed* to replace this one, and *then* get a bigger controller (and possibly motor).

Click to expand...

A bigger BMS on the battery doesn't do anything for you unless:
--the controller needs that power
--the cells in the battery can handle that power

Also, your usage of the system would also have to put a high enough load on the motor to make the controller pull more power from the battery, or else a bigger BMS and controller woudln't do anything for you.


So...what *exactly* do you want to change about your system's performance and behavior?

Do you want it to go faster?

Do you want it to go farther?

Do you want it to accelerate quicker?

Do you want it to haul heavier loads?

What are the conditions you ride in? (hills? flat? wind? stops and starts? continuous riding? etc)

Etc.

You have to decide what you want it to do, and then post that here, in as much detail as you can possibly write, and then we can try to help you figure out which parts of the system must be changed to accomplish your goal.

Click to expand...

Okay so I’m based out of Denver. It’s not really hilly in the main area that I work. In downtown we have a main strip that stretches for a mile from one end to the other. One end is the bottom of the hill, the other end is the top of the hill. But the hill is not a straight climb like San Francisco, but it gradually inclines throughout the entire strip. Definitely less than a 45 degree angle, about 5-15 degree angle over a course of 1 block. Each block was different ever so slightly. Some parts of downtown the hills are at a 35 degree angle. Weather wise, I also ride in the snow and rain as well. The main thing is trying to take heavy loads without having the bms bottoming out below the amperage point because the motor I’m assuming is trying to pull as much as it can from the battery with all that weight I’m carrying in my pedicab, say 4 big people up a hill for 10 blocks. Yes, I would like it to go faster and farther, and be able to haul heavy loads, quick acceleration not so much, customers don’t really like that jolt when I gun it, slow/moderate climb to top speed is best.

What changes do I need with my setup

2-4K 45a cyclone motor
48-72v 40a sine wave Bluetooth motor controller
60v20ah batteries (Btr Power, 50/100a bms, 1 parallel 20 series)

pongyboy1 said:

In downtown we have a main strip that stretches for a mile from one end to the other. One end is the bottom of the hill, the other end is the top of the hill. But the hill is not a straight climb like San Francisco, but it gradually inclines throughout the entire strip. Definitely less than a 45 degree angle, about 5-15 degree angle over a course of 1 block. Each block was different ever so slightly. Some parts of downtown the hills are at a 35 degree angle.

Click to expand...

Nope.

The steepest paved streets anywhere in the world are about 35% grade. That's about 19 degrees, and impassable to many motor vehicles.

One of the more notorious and difficult steep streets in Seattle where I lived for a while is called the Counterbalance, after a cable tram that climbed the hill back in days of yore. It peaks at about 20% grade, a little over 11 degrees.



I'd be very surprised if the steepest grades in central Denver are even half that steep, which would be 10% grade or 5.7°. The steepest paved road in the whole Denver metro area that I could find mentioned is Magnolia Road, a few miles up Boulder Canyon. It purportedly has maximum 13% grade, or 7.4°.

Baldwin Street, Dunedin, NZ. There is a warning at the bottom not to try and drive campervans up the street.

These guys made headlines on drift trikes

https://youtu.be/xUvW7kcKFQM?t=78

Chalo said:

The steepest paved streets anywhere in the world are about 35% grade. That's about 19 degrees, and impassable to many motor vehicles.

One of the more notorious and difficult steep streets in Seattle where I lived for a while is called the Counterbalance, after a cable tram that climbed the hill back in days of yore. It peaks at about 20% grade, a little over 11 degrees.

Click to expand...

I wonder what the folks that determine what steepest is, use as the qualifying criteria. There are definitely very short sections of paved road that are well above 30 percent, but I don't think that qualifies. I don't think they should either, otherwise people will be claiming their driveway is the steepest street in the world. There must be a minimum distance. This is supposedly the second steepest "street" in SF, 37.5%. You can see, it only runs the distance of the building, and climbs about 20 feet in that distance (just eyeballing it). At least the pic provides some sort of reference. I'm sure my ebike could climb it no sweat, since it would take less than a minute, so no time to overheat.
https://www.google.com/maps/@37.7985585,-122.4063984,3a,75y,353.43h,98.94t/data=!3m6!1e1!3m4!1s3wHOTGBjKg25qjtMOlUbQQ!2e0!7i16384!8i8192

I was thinking of trying to ride up each of these streets, but some would take a lot of riding to get to, even using the train or ferry to cross the bay. Most are pretty short climbs, so just something fun to do:
https://www.onlyinyourstate.com/northern-california/san-francisco/steepest-streets-san-francisco/

I've ridden up all the ones on my side of the bay, except one, from the "climbs" listed here. Moeser, that's mentioned as a side note, is the hill I use to test regen on.
https://bayareabikerides.net/the-berkeley-hills-death-ride/

Precisely why you need a few thousand watts of power to get up that hill quickly.

Seattle-PS-QAnne.jpg

Click to expand...

Chalo said:

pongyboy1 said:

In downtown we have a main strip that stretches for a mile from one end to the other. One end is the bottom of the hill, the other end is the top of the hill. But the hill is not a straight climb like San Francisco, but it gradually inclines throughout the entire strip. Definitely less than a 45 degree angle, about 5-15 degree angle over a course of 1 block. Each block was different ever so slightly. Some parts of downtown the hills are at a 35 degree angle.

Click to expand...

Nope.

The steepest paved streets anywhere in the world are about 35% grade. That's about 19 degrees, and impassable to many motor vehicles.

One of the more notorious and difficult steep streets in Seattle where I lived for a while is called the Counterbalance, after a cable tram that climbed the hill back in days of yore. It peaks at about 20% grade, a little over 11 degrees.
View attachment 1


I'd be very surprised if the steepest grades in central Denver are even half that steep, which would be 10% grade or 5.7°. The steepest paved road in the whole Denver metro area that I could find mentioned is Magnolia Road, a few miles up Boulder Canyon. It purportedly has maximum 13% grade, or 7.4°.

Click to expand...

I might’ve over exaggerated, but you are right


Sent from my iPhone using Tapatalk

Nice thing about a pedicab is, you can just add a "virtual extra passenger" worth of weight in the form of a multi-kW bank.

Since you are looking for several hours' run-time per day you need that anyway right?

So your burst peak draws are still relatively low C-rate compared to the pack as a whole

no need to pay the extra for high **power** cells

and lots of room under the seats and even the floor

means high **energy** density is not even "that critical"

I'd focus on cycle lifespan, good longevity drastically reducing your wear-cost per month per year.

Consider LFP or maybe even LTO, even in a propulsion use case, properly cared for may get a decade or more!