QS6kW hub Suzuki gsxr with Kelly issues

Now I need some help. I have built a Suzuki gsxr 600 to a QS hub motor "Café racerish" bike.
I am running a 72v 50 Ah 3600W lithium battery. The setting on the Kelly controller said battery low volt setting was suggested at 60V. Then the problem is that I can not drive uphill at full power the battery drops below 60 and the controller cuts out. That means that the bike is dead. I can not switch off and back on. I can only get power back by plugging in to a wall socket and then it may read 68v or so. It would be great to get it to light back up by just flicker the key in the switch on and off! I have had to beg for power twice in the last few days.
Should I reduce the low volt limit of the battery? Or is there any other setting I could fiddle with so it can handle short power boosts without "killing the vibe"

I have had some issues with the battery in the past so I reduced battery limit current to 90%.

I used the bike last weekend for 30 km not the range I was hoping for but today the range is far worse. Is my battery ruined? Or can I tweak some settings that are holding me back.

I could post all my settings here in case a friendly guru would be willing to look it over. Most settings are default.
Looking forward to some practical advice . Thanks

You could add capacitors
If Ri is low enouth the voltage of your Li cells should not drop that hard.
https://geothunder.com/capacitor-powered-electricbike/

If the battery is dropping from 4.2V to 3V per cell under load then it is either undersized or not healthy. The BMS and controller is shutting off to protect the battery correctly.

Suggest checking each cell bank under load to see if you have a faulty one

60V on 20s or 72V is 3V per cell. I would consider that 0% SOC.

Do not try to lower your cut off you are to low now. I don't know what type of cells you have so most of it would be a guess.

Find out what type of cells or battery you have.

If your pack/battery has been run down to 60V there is a good chance that some of the cells have been discharged to 0V. Your BMS will not charge from there because it's not safe and could catch fire.

Need to have your battery check out it to see if it's bad. If it is not then it's some thing else

I'm no guru, maybe one will come on soon. Just seen this post

by k10e3r » Sep 06 2021 4:57pm

You could add capacitors
If Ri is low enouth the voltage of your Li cells should not drop that hard.
https://geothunder.com/capacitor-powered-electricbike/

Click to expand...

and read "For anyone who would like to run their electric bike off of capacitors let me save you some time.

Simple Answer:
With current technology capacitors are not a viable option for powering an electric bike."

I'm thinking what is this?

HolmarS said:

Now I need some help. I have built a Suzuki gsxr 600 to a QS hub motor "Café racerish" bike.
I am running a 72v 50 Ah 3600W lithium battery.

Click to expand...

This sounds pretty close to what I have ordered (but not yet received) from China for my build...

Would you mind telling the manufacturer/brand name and place and way of purchase?

The one I ordered was promoted on "Alibaba" with this picture and specs:

Checking your celles is probabbly the best way to go. I wouldn't change voltage cut of neither.

@ ZeroEm
Adding capacitors can be interresting to handle current peaks. Not to power the hole bike.
I put small capacitors with low ESR over each mosfet of the esc to protect them from voltage peaks and a larger pack with more capacity at the entrance of the esc to reduce voltage drop.

Well this looks really similar to mine.
After 3km it burned over. The connectors between the poles where so thin that they burned. During this the BMS boards got damaged as well.


The box is similar and the meter is the same.
I hope that they have improved the quality of the battery since I got it.

This seems to be a running theme for many newer builds.

more motor/controller kw draw than the battery can maintain.

its important to match the battery's capabilities to the max pulse power demands of the controller/motor combination.

battery cost has risen dramatically as controller/motor prices have stayed about the same.

I would say a simple rule of thumb would be to purchase a battery based on the max pulse it can attain safely and repeatedly rather than its kwh rating.

If the builder would share the kelly controller's amp limits it would help in suggesting a solution/compromise.

if you can fit another battery pack that would be a good plan of action.

for now simply lowering the max amp draw of the controller to what the bms allows (90% is clearly not even in the neighborhood) would solve the shutdown problem.

its a compromise that solves your problem until your battery budget can meet your fun quota.

The battery would not charge and had no range. Just don't understand how capacitors would fix his issue? Looked like spam.

by k10e3r » Sep 07 2021 1:06pm

Checking your celles is probabbly the best way to go. I wouldn't change voltage cut of neither.

@ ZeroEm
Adding capacitors can be interresting to handle current peaks. Not to power the hole bike.
I put small capacitors with low ESR over each mosfet of the esc to protect them from voltage peaks and a larger pack with more capacity at the entrance of the esc to reduce voltage drop.

Click to expand...

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I this your current battery? It would be worth seeing how many cells are good and bad. May be able to salvage some or most of it.

y HolmarS » Sep 07 2021 3:30pm

Well this looks really similar to mine.
After 3km it burned over. The connectors between the poles where so thin that they burned. During this the BMS boards got damaged as well.

Click to expand...

IMO the battery should start out brand new as capable of handling more than the max power and amps that

**the owner will ever allow** the controller to draw.

Ideally by double or triple.

Then the key is setting the controller (or CAv3) up so that it will indeed never pull more that what the user intends.

If the controller is pushing the max capacity of the pack to a stressful point, aka voltage drop, when the pack is new

then after 50 cycles, then 100 cycles,

the pack's natural wear process will no longer deliver the desired performance, accelerating declining SoH in a death spiral wearing out ever faster.

"Looked like spam" Nice to read that ZeroEm.

Let me explane.
First thing is to repare your power pack and check cells.

Reparing is one thing. But I suppose you don't want to have the same issue twice.

It looks like your power pack is not adapted to the curent you are pulling.

I see two solutions. Put larger tabs bewean each cell. But "C" rating of the cells might be critical and pulling high curent will end in litle cycle life of the cells.

If you add Capacitors with low Ri in parallel to your pack it will help to reduce the curent peaks wich are harming your power pack.
A lot of curent will come from the capacitors and less from the pack.
This is only valid for a short period (a few seconds) but it is the period where the curent is highest.

For example you take a 18650 cell with +/- 30 mOhm
https://www.onexbattery.com/product/nd-18650-lithium-battery-3-7v-2500-mah-3c/
Lets put 20 cells in // so we get Ri=1.5 mOhm

This Super Capacitor for example have 0.28 mOhm and 2.85V max
https://www.ebay.fr/itm/284404539991?hash=item4237d4e257:g:aF0AAOSwEVVhEzs8
If you put 30 of these in serie you get 85,5V and 0.28 mOhm

Lets go less extreame with 30 of these you can have 100A for 3seconds
https://www.ebay.fr/itm/265167504570?_trkparms=amclksrc%3DITM%26aid%3D1110013%26algo%3DHOMESPLICE.SIMRXI%26ao%3D1%26asc%3D20210125103646%26meid%3Dff00e2b60eae43d9ba69a95384dada4a%26pid%3D101112%26rk%3D4%26rkt%3D24%26sd%3D264382046751%26itm%3D265167504570%26pmt%3D1%26noa%3D0%26pg%3D2563228%26algv%3DSIMRVIMLRV5WebV1_0%26brand%3DUnbranded&_trksid=p2563228.c101112.m1982&amdata=cksum%3A265167504570ff00e2b60eae43d9ba69a95384dada4a%7Cenc%3AAQAGAAACEBsWsb747MHg%252FgZTRO%252FG%252FSDbnlalo6L8bW2EIK9%252Bu5wEOJrUmhBq3ALoi2fPp4JmFIF94RdwqrOm7bmP82eD%252B3EKfPMH0ERdxvV4G4RrjeUJ5pN1AGI5yxmiJt7tbf6I6CuuLAfuJN%252B8bqedFwVHYdffT4teM%252BwNDAD9yHZI6yDm8cACFM7NcD8NItii%252By43X1TWGYg3hyzQD3VqK2z1FaE41FSt3aEJMSkIh2sCnNhl1rIg35JRN0Xf9HyhQx0fIhCxQXdUDQ0qYS6VQ%252B5smTK5jdiDWHo8cqqLEU%252BvBrm7rBDb3EzC9iAPWSWI2Vh%252FRqU0oTsQLSj%252FtK37EfwIWGvov8KpCmOMDHINmuqBt4rAEmmKG6nk8rg%252F6Gq4f9eBEU7M9Icca0g6u8bb18b%252BQKzsIJAPD2wNd8spFvKBKe%252FapwPhL4J7RnlOte%252FsZAAz7sq2bSbVqUONtTnly16%252FOp0aKtxnKE23N%252BerS28wd3YcLJ%252FJkVx%252F6J6hZmhMBUNrz72GzIjMHCKNcD7aTFUdZt%252BAScl23mUEYuRpKmL%252FRLErI4kuMfGEq%252B6SEa1GCXu3cr30thGMMy9LGu6lMmR7AdDfGyMIOFoUzX7y7DTOW63c2X7hUiEXBHYaCu5FJII8R9THzZidttOSj%252FddhppgbafXm8nyjP8raxwJwpKfop%252B0SFN4zauvda9JV%252B3TbfN1Vg%253D%253D%7Campid%3APL_CLK%7Cclp%3A2563228

Sorry third solution.
Gear down your transmition ratio.

by k10e3r » Sep 09 2021 10:54am

"Looked like spam" Nice to read that ZeroEm.

Click to expand...

Was not personal to you. More of a reaction to all the spam on ES. Understand were Capacitors have there place and would have extended the life of his battery when new.

Here are my settings.
I dont have a transmission so no change there, unless I am misunderstanding something.
I may have been looking at the wrong specs when buying batteries. I was focused on V Ah and watts but not really on the current capacity compared to the capacity of the controller. FOr example my controller should be able to handle constant 200A and up to 500A for 30 seconds. That is not the performance of this battery.

But please take a look at my setting and if we can make adjustments.

Really appreciate your help here E-heads (as someone referred to us )

HolmarS said:

Well this looks really similar to mine.
After 3km it burned over. The connectors between the poles where so thin that they burned. During this the BMS boards got damaged as well.
The box is similar and the meter is the same.
I hope that they have improved the quality of the battery since I got it.

Click to expand...

Those tabs are probably thin for a good reason, which might be to serve as fuses in case of current being too high, to avoid catastrophic failure of the cells themselves. I don't think this is a quality problem (but I might be wrong). My battery has similar features (but it has been build to be able to supply way more amps though, because the cells themselves are capable of delivery very high currents).

So I think unfortunately here you will always be limited by your battery maximum current draw. So if you choose to repair this battery, which you probably should at least to be able to ride for a while, the only safe option is to lower the max current in your Kelly settings. To be more precise, you need to lower the "current percent " parameter by a lot, probably the "battery limit" too (but kellys are really bad at monitoring battery current consumption unfortunately), until you reach acceptable current levels for your battery. You need a current sensor to do that, do you have one installed on your bike already? You also need to know what is the maximum current your battery is rated for, so in case you don't know it you might want to contact the manufacturer. Then try to match both by trial and error. Obviously start with very low values and gradually increase instead of the other way around.
Unfortunately that ultimately means lowering the power of your bike by quite a lot, there will be a big decrease in performance no matter what.

You should always keep in mind that all builds have their limit, it's either the battery, the controller or the motor (or in extreme cases the driver himself :lol: ). Generally it is preferable to be limited by the controller or the motor, but in practice the limit is often the battery. You just don't want it to be too far away from the two others, try to have a somewhat balanced setup.

In your case, the long term solution is to find a more powerful battery. You should check at automotive grade cells, try to avoid the random chinese battery makers. Maybe some of them are good, they do have great tech sometimes, but it's really a big gamble on a very pricey device.... If you go for well known automotive stuff youre almost guaranteed it will last and be close to the advertised specs.
Sorry to bring bad news, I know it's a bummer.

Nice build otherwise, don't be greedy on the pictures I'd like to see more!

IMO the limit should be the controller always.

And through its control settings, ideally also with heat sensor failsafe overrides

so that your actual peak usage is well below

what the controller is capable of,

what your pack can handle

and what the motor could do.