Rad Power bike cutting out with Bolton controller

[uberbike]

I am helping a friend with his Rad Power bike and Bolton controller upgrade. After install if I go up a significant hill with full 1500w of power for like 2-3 minutes the bike cuts out. Screen goes blank and bike stops. When I check the power meter on the battery it won't respond with any lights. If I unseat the battery and re-seat the battery indicates full and the bike will work again.

I tried this on two identical fully charged batteries and I get the same symptom.

Is it possible this stock battery just can't handle being asked to put out twice the power as stock and the BMS is cutting out?

I tried the same hill, same battery, same controller but pedaled more and was easier on the throttle and it made it ok.

I don't know model number of bike but attached are pics of the bike and battery.

Thanks in Advance!

 

[harryS]

I don't think any BMS actually measure current and take steps to constrain it.at the rated value. I believe they are designed to recognize a dead short and shut off, but it's too expensive to shut off if you are pushing say 28-30 A on a "25A" BMS. In my opinion, the current rating applies more to the ability of the BMS pass transistor to handle a steady current.

What is likely happening is voltage sag in the cells is shutting off your battery. That means the cell voltage is dropping below 2.8- 3.0 volts under a heavy load, and the BMS shuts off the battery. Sometimes switching the battery on/off switch will reset the BMS. Other times, you may have to unseat the pack. Sometimes, if you wait a few minutes, it may restart on it own.

You're talking about a significantly heavy load too, two minutes under heavy throttle? That's going to deplete the voltage reserves in the cells and contribute to sag.

 

[harryS]

We're talking about the battery and BMS though. My point is even though it may be a 25A BMS, that doesn't limit the current. It's the characteristics of the cells that determines how much current is provided when the controller demands it, And the OP doesn't have enough battery,

 

[uberbike]

Thanks for the feedback everyone!

I heard back from Bolton that I just can't go that hard on this motor. The stock motor is 500w and peak at 750w and i am putting 1500w thru it. Chances are it is overheating and turning the system off. It was recommended by Bolton that I just turn the max power of the controller down to something more reasonable and don't go so hard on it, and so far that strategy has worked. They should warn people about this when they buy it but they did not.

As far as BMS: most have multiple reasons they can shut the pack down. Could be one cell (or cell group) is below the threshold or output is over max amps, but its a black box and no way to tell. Funny part is it shuts down in almost exactly the same spot every time, and it is past the really steep part of the hill.

 

[Kyogiro]

I don't think any BMS actually measure current and take steps to constrain it.at the rated value. I believe they are designed to recognize a dead short and shut off, but it's too expensive to shut off if you are pushing say 28-30 A on a "25A" BMS. In my opinion, the current rating applies more to the ability of the BMS pass transistor to handle a steady current.

What is likely happening is voltage sag in the cells is shutting off your battery. That means the cell voltage is dropping below 2.8- 3.0 volts under a heavy load, and the BMS shuts off the battery. Sometimes switching the battery on/off switch will reset the BMS. Other times, you may have to unseat the pack. Sometimes, if you wait a few minutes, it may restart on it own.

You're talking about a significantly heavy load too, two minutes under heavy throttle? That's going to deplete the voltage reserves in the cells and contribute to sag.

I agree. When I'm in the low end of my battery life, I have to ride at lower PAS because there's just not enough voltage left in the cells to sustain a higher load.

The exact same phenomenon happened as OP described.

I wouldn't bet everything on being able to go 1500W on a sustain manner with the new motor either.

 

[harryS]

I thought the battery pack's max current was governed by BMS though?

As you can see the 35E has 8A continuous, 13A max discharge rate. (per cell)
The Rad pack is 4 in parallel, therefore, in theory the cell itself has 32A continuous, 52A max.
However, BMS limits it to 25A (if it has 25A BMS), instead of 52A.

That's how I understood..

I agree. They use a 4P configuration, so you'd expect 32A easily. OP wrote that he is seeing 1500W which is 32A on 48V, He's using a KT meter which give an instant watt reading,. If we believe the display. he's not being restricted to 25A. I just don't think the inexpensive BMS we see on ebike batteries are intended to limit current in the normal operating range. .

It's a long time to be pulling that kind of power and is something I've never done. No hills here. Cells get hot and that further lowers the current, Motor gets hot too, which means increases resistance of the windings, and that's why Bolton is able to sell those 750W motors. .

 

[rich c]

Thanks for the feedback everyone!

I heard back from Bolton that I just can't go that hard on this motor. The stock motor is 500w and peak at 750w and i am putting 1500w thru it. Chances are it is overheating and turning the system off. It was recommended by Bolton that I just turn the max power of the controller down to something more reasonable and don't go so hard on it, and so far that strategy has worked. They should warn people about this when they buy it but they did not.

As far as BMS: most have multiple reasons they can shut the pack down. Could be one cell (or cell group) is below the threshold or output is over max amps, but its a black box and no way to tell. Funny part is it shuts down in almost exactly the same spot every time, and it is past the really steep part of the hill.

It didn't occur to you that putting 1500w through a 500w motor would generate a ton of heat? Rad used to say in the owner's manual not to go up long hills on level 5 PAS. That was in full stock setup. Did they take that warning out?

 

[JTK77]

I thought the battery pack's max current was governed by BMS though?

Rad has Samsung 35E cells, 13 Series, 4 Parallel.
Here's the spec sheet for Samsung 35E.

https://www.orbtronic.com/content/samsung-35e-datasheet-inr18650-35e.pdf

As you can see the 35E has 8A continuous, 13A max discharge rate. (per cell)

The Rad pack is 4 in parallel, therefore, in theory the cell itself has 32A continuous, 52A max.
However, BMS limits it to 25A (if it has 25A BMS), instead of 52A.

That's how I understood..

You are correct. BMS has cut off limit. Its not always super accurate. Typically BMS allows some peak/burst etc higher than constant current for a moment before cutting the load.

 

[AHicks]

Holding wide open throttle with full available battery amperage for more than just a few seconds is asking for trouble. Even with a 750w motor installed, it's going to be getting pretty hot. The big amperage is avialable for crossing a busy road, catching up with a riding buddy, or climbing a short hill. You're going to need to use a little discretion here, or you're going to be replacing burnt parts frequently.....

If there's any doubt here, look at the size of the wires in use. You think wire that size is going to be OK handling 20 plus amps, or 30? NOT EVEN A LITTLE CHANCE!

I've been running a 1000w geared hub motor (MAC 12t) w/35a KT controller and stock RAD battery in a RAD City for several years now. It's a rock solid setup that has never had a single issue. The controller is set to limit power to no more than 1100w as observed using the display. This was done for fear of the size of the wire used internally within the battery - it's 14 or 16ga I don't remember which. Running over 20 amps through wire this size for a second, fine. Extended times, and heat is going to build very quickly.

The fact this bike is shutting down after 2-3 minutes is the only reason it didn't turn itself into a smoking pile of ruble that smells REALLY bad!

 

[JTK77]

Vented G062.1000 is what you need for higher power. Good quality 60v battery with 8kw continous capability and low IR feed the 48A controller for little over 3kw Max.

 

[m@Robertson]

Actually the fat Bafang "true 750" G060 can handle 2000w continuous no problem - that was on a custom Lyen controller. You can also get a 35a controller specifically meant for a 60v system and the G060.750 will take that in stride as well.

I also know of someone who did that same Lyen controller (available via E-S) with the 500w G060 motor that Rad sells and represents as a 750. It too took the power without complaint. But once the owner found out he didn't really have a 750w G060 inside the case he was *pissed* and the result was another long and bitter thread on Facebook that the Rad Power Bikes owner ended up getting into.

Given that both motors can handle this power - and I haven't heard this complaint elsewhere on the Bolton setup - I think its possible @harryS was correct and this is a low voltage cutoff issue inside the controller and not a battery shutoff thanks to exceeding amperage limit. Usually when a BMS pops, it stays shut off by design until the pack is plugged into a charger. Thats the only thing that will wake it up. Which means you walk the bike home.

A low voltage cutoff on the other hand resets itself when you cycle the power on the controller/display. I've been nursing a bike home on an almost drained pack and had a shutoff. I've been able to stop, cycle the power, get the battery back and then just creep home on a lower power level to avoid the sag that shut me down. I've also popped my BMS on a big 2wd bike where the BMS peak setting was only a tad over what my motor controllers (plural) wanted while going up a hill. I had to pedal old school back home to a charger. Lesson learned: spec a battery with a BMS whose 'continuous' rating matches my 'peak' controller output.

 

[AHicks]

Actually the fat Bafang "true 750" G060 can handle 2000w continuous no problem - that was on a custom Lyen controller. You can also get a 35a controller specifically meant for a 60v system and the G060.750 will take that in stride as well.

I also know of someone who did that same Lyen controller (available via E-S) with the 500w G060 motor that Rad sells and represents as a 750. It too took the power without complaint. But once the owner found out he didn't really have a 750w G060 inside the case he was *pissed* and the result was another long and bitter thread on Facebook that the Rad Power Bikes owner ended up getting into.

Given that both motors can handle this power - and I haven't heard this complaint elsewhere on the Bolton setup - I think its possible @harryS was correct and this is a low voltage cutoff issue inside the controller and not a battery shutoff thanks to exceeding amperage limit. Usually when a BMS pops, it stays shut off by design until the pack is plugged into a charger. Thats the only thing that will wake it up. Which means you walk the bike home.

A low voltage cutoff on the other hand resets itself when you cycle the power on the controller/display. I've been nursing a bike home on an almost drained pack and had a shutoff. I've been able to stop, cycle the power, get the battery back and then just creep home on a lower power level to avoid the sag that shut me down. I've also popped my BMS on a big 2wd bike where the BMS peak setting was only a tad over what my motor controllers (plural) wanted while going up a hill. I had to pedal old school back home to a charger. Lesson learned: spec a battery with a BMS whose 'continuous' rating matches my 'peak' controller output.

Struggling a bit with the bold....

It's not a question of whether or not the motors will handle the power for a few seconds, it's the "continuous" where I'm pretty sure you can expect you're going to have issues. I would really like to see documentation showing where 500-750w motors will handle 2000w "continuous". It would lead to the question regarding why the motors are rated for 500-750w when they will handle 2000w continuous?

I know the answer. They can't possibly be run at that power level "continuously"......

2000w is roughly 40a. Not going to happen. Not continuous. Suggest that saying otherwise might be a bit misleading to the uninitiated....

 

[JTK77]

Struggling a bit with the bold....

It's not a question of whether or not the motors will handle the power for a few seconds, it's the "continuous" where I'm pretty sure you can expect you're going to have issues. I would really like to see documentation showing where 500-750w motors will handle 2000w "continuous". It would lead to the question regarding why the motors are rated for 500-750w when they will handle 2000w continuous?

I know the answer. They can't possibly be run at that power level "continuously"......

2000w is roughly 40a. Not going to happen. Not continuous. Suggest that saying otherwise might be a bit misleading to the uninitiated....

Correct. The G060.750 can handle little over 1000w continous if not run at slow rpm. Even My vented G062.1000 motor would struggle 2000w continous although 3000w is ok for a moment. I'm running this motor with 60v controller at 48A max.

 

[mjeds]

trim the C5 setting from 10 down to 7-8 that will stop the motor from peaking at 100%, it will curve it to 70-80% of max power.

personally have mine set to 5 50% of max power. so mine never goes above 750watts. no need for 1500 watts on my commute, plus it makes sure I can get 30+ miles out of a17ah battery, on 10 was barely getting 15 miles.

 

[JTK77]

I'm not too familiar with that motor. I doubt it would be any better but can't say for sure.

 

[ExPatBrit]

The KT LCD has a voltage display option, once your battery is under 45 volts avoid PAS 5 and throttle.

You can also set the cut-off a couple of volts lower don't run the battery down that low but it will prevent instantaneous current surges (throttle drops the voltage about 4 volts) tripping the controller.

A real 750W motor won't help this, I had the upgrade and big motor . The big motor doesn't have the heat-soak issues where power drops off.

It definitely worth turning it down a bit, my upgraded Rover was set to max out at 1300W .

 

[m@Robertson]

Struggling a bit with the bold....

It's not a question of whether or not the motors will handle the power for a few seconds, it's the "continuous" where I'm pretty sure you can expect you're going to have issues. I would really like to see documentation showing where 500-750w motors will handle 2000w "continuous". It would lead to the question regarding why the motors are rated for 500-750w when they will handle 2000w continuous?

I know the answer. They can't possibly be run at that power level "continuously"......

2000w is roughly 40a. Not going to happen. Not continuous. Suggest that saying otherwise might be a bit misleading to the uninitiated....

The bike with the Lyen controller was running 60v. Thats a one-off as those controllers are individually built and sold personally to a buyers' specs as I understand it. You talk to the guy on Endless Sphere and the two of you work out what you want and he makes one for you.

Your math is wrong on 2000w. A 52v bike at peak charge with a 35a controller is 58.8v*35a=2030w. Thats top of every peak but I didn't say a 52v bike did that. I will touch 1950-2000w on mine but not for long. A 60v bike the math works out to 67.2v * 35a = 2352w. Again all peaks but there's enough fudge there to say thats a bike that can realistically be said to be running in the 2000w ballpark up a hill for more than a short time. What makes this much more than a single guy telling tales about his unique build is lots of the Sondors fat bikes have been upgraded like this and the kits to do it are readily available on Electrobikeworld. The push to upgrade to 52v bikes melted away once the 60v stuff became more or less mainstream in their DIY community.

Is 'continuous' forever? Of course not. But are the 60v-powered bikes durable enough to have effectively never engendered a report of frying the motor? I've never heard of one. You'd think a bike like that - that is also capable of exceeding 40 mph - would have trouble reports (and accident reports and funerals) but it never has.

I can say from my own experience that if I run up a long, steep hill with my 52v system with twin 35a KTs I will hit and hold about 1500w-1800w on the back motor as the bike labors up a hill with peaks at 1950-2000. The regulars here all have heard me say over and over I went to mids because I didn't like how the hub motors stressed in hills. Wellllll... This is what I was talking about. This is exactly why I went to mid-drive backed 2wd.

 

[AHicks]

The bike with the Lyen controller was running 60v. Thats a one-off as those controllers are individually built and sold personally to a buyers' specs as I understand it. You talk to the guy on Endless Sphere and the two of you work out what you want and he makes one for you.

Your math is wrong on 2000w. A 52v bike at peak charge with a 35a controller is 58.8v*35a=2030w. Thats top of every peak but I didn't say a 52v bike did that. I will touch 1950-2000w on mine but not for long. A 60v bike the math works out to 67.2v * 35a = 2352w. Again all peaks but there's enough fudge there to say thats a bike that can realistically be said to be running in the 2000w ballpark up a hill for more than a short time. What makes this much more than a single guy telling tales about his unique build is lots of the Sondors fat bikes have been upgraded like this and the kits to do it are readily available on Electrobikeworld. The push to upgrade to 52v bikes melted away once the 60v stuff became more or less mainstream in their DIY community.

Is 'continuous' forever? Of course not. But are the 60v-powered bikes durable enough to have effectively never engendered a report of frying the motor? I've never heard of one. You'd think a bike like that - that is also capable of exceeding 40 mph - would have trouble reports (and accident reports and funerals) but it never has.

I can say from my own experience that if I run up a long, steep hill with my 52v system with twin 35a KTs I will hit and hold about 1500w-1800w on the back motor as the bike labors up a hill with peaks at 1950-2000. The regulars here all have heard me say over and over I went to mids because I didn't like how the hub motors stressed in hills. Wellllll... This is what I was talking about. This is exactly why I went to mid-drive backed 2wd.

Math is fine. I thought we were talking about a more conventional bike using a single 500-750w 48v motor/battery and a (single) 35a KT controller.

You start talking about a bike with an extensive list of mods like you are talking about and I quickly loose interest.

 

[uberbike]

Thanks for all the feedback everyone. I now see the errors in my ways. I was just installing this for a friend based on the info I had. When doing the real math and seeing the info here I can see this controller can overpower the motor and battery and you don't get something for nothing. I toned down the settings on the controller and I think it will be fine with some monitoring of the power output while riding.