How to know how much battery volts the ebike controller can take?

E-driver_

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How do I know how much battery volts the ebike controller can take?

I mean how much above the voltage I could go on the battery above the controller's stated voltage?

When I open the controller those battery kind of looking things has text on them saying something about 63volt.

The text outside on the controller says 48volt as seen on the pictures.

How do I know how high I can go on a battery without frying the controller to death?

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Truthfully, you won't know until it fails for how high a voltage it will take. ;)

Keep in mind that you want to leave a margin, somewhere around 20%, for "random" voltage spikes during operation. If you push it to the edge, then one of those can just take it out at any time (usually blowing FETs, which usualy fail shorted, which then try to brake the motor suddenly--if it's a non-geared hubmotor in your front wheel, that could crash you pretty hard under the wrong conditions). :/

The voltage on the largest can-style capacitors is one limit. 63v in your case.

The voltage rating of the FETs (the black things on the metal bar) is another limit. You'd have to look up the specs sheet for the FETs in your controller, for the Vds max limit, usualy right at the top of the spec sheet.

The voltage rating on smaller caps that are usually near the FETs is another limit; sometimes they are not all on the battery rail, so those won't matter, but if they are on the battery rail they'll see battery voltage and must be able to handle it.

The tough one is the LVPS, or the low-voltage power supply, which is the stuff electrically after that big resistor near the edge of the board (gray with orange/white/brown/gold stripes on it). The circuitry there takes the battery voltage and downconverts it to the 12v(or 15v) and 5v that the brains of the ocntroller use. Most of these LVPS cant' even directly handle the battery voltage that the controlelr itself is rated for, so they use that big resistor to waste power as heat to lower it to what the LVPS can handle. So if you raise the battery voltage, you may also have to change that resistor to keep the LVPS safe.


For more detailed info, there's a number of threads about this sort of thing, often labelled as "overclocking" or "overvolting" the controller, sometimes just "how high a voltage can I use", or something like that. Or "can I use a 72v (or whatever) battery on my 48v (etc) controller". I think I've covered things like figuring out the LVPS resistor in a few of those.
 
E-driver_ said:
How do I know how high I can go on a battery without frying the controller to death?


Most 48V KT controllers will work at 52V. Often the MOSFETs and capacitors are limiting factors. The cap in your pic is rated at 63V, so you wouldn't want to exceed that, and fully charged 52V battery is 58.8V.
 
E-HP said:
E-driver_ said:
How do I know how high I can go on a battery without frying the controller to death?


Most 48V KT controllers will work at 52V. Often the MOSFETs and capacitors are limiting factors. The cap in your pic is rated at 63V, so you wouldn't want to exceed that, and fully charged 52V battery is 58.8V.

Aha ok.
How can you see that it is 63 volts by the way?
 
If the shunt is soldered with tin, that is going to draw more amps from the battery to the motor correct?

But does this modification also draw more voltage to the motor from the battery? Or does it only affect amperege?

Also, if I have a controller of 36 volts stated, which is then modified with shunt-soldering, is that controller going to wear out the battery faster?

For example if the controller originally is stated at 36volts and 350watt and I am using it with a battery of 36volts and 420 watt.. And then I solder the shunt. Would that also wear out the battery faster?

And if so, would it be a better idea to use a 36volt battery with higher wattage before riding on the bike again, after the shunt modification?
 
Also, there's no 420 watt batteries.
You might confusing that with watt hours.
But typically, a higher watt hour battery of the same voltage can sustain more amp output without damage because there's more cells in parallel sharing the load, but it's not a direct correlation.
Different cells that the battery might be made from all have their maximum amp draw they're rated for, so there's a lot of variability.
But with my first battery, when I soldered my controller shunt the extra amp draw got one of the connector tabs between groups so hot it melted thru the cell shrinkwrap and shorted out against the can, killing the battery.
 
Voltron said:
Also, there's no 420 watt batteries.
You might confusing that with watt hours.
But typically, a higher watt hour battery of the same voltage can sustain more amp output without damage because there's more cells in parallel sharing the load, but it's not a direct correlation.
Different cells that the battery might be made from all have their maximum amp draw they're rated for, so there's a lot of variability.
But with my first battery, when I soldered my controller shunt the extra amp draw got one of the connector tabs between groups so hot it melted thru the cell shrinkwrap and shorted out against the can, killing the battery.

Aha ok. So perhaps when soldering the shunt it would be great to use a wattmeter and just solder little by little? Seeing if the solder will increase the amps somewhat?

Do you know if this extra amp-draw makes the bike faster? Or does it only get stronger up slopes, because of extra torque(if done correct that is)?

How do I know if the extra amp-draw might hurt the battery? Can I look at the watts(watt hours?) stated on the battery or something to get a clue if I might do damage to it?
 
It should make it faster much, but def accelerate better.

There's a few posts on here about controlled shunt modification, and yes, a ammeter or wattmeter will be a good idea.

Does your battery have a fuse?
 
Voltron said:
It should make it faster much, but def accelerate better.

There's a few posts on here about controlled shunt modification, and yes, a ammeter or wattmeter will be a good idea.

Does your battery have a fuse?

Yes I think so. It looks like this:
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And that battery looks like it maybe uses springy metal contacts, they're known for getting less springy with heat, getting looser, then the bad connection heating up more etc, until it melts the plastic housing around the contacts.
 
Hmm ok.

Well the bike kind of sucks right now anyway :) Too slow. So maybe I could take my chances with this battery anyway :)

Did you guys say the shunt modifications makes the bike accelerate more? Or does it also make it stronger going uphill in slopes?
 
E-driver_ said:
Well the bike kind of sucks right now anyway :) Too slow.

What bike? You have about 500W nominal/1000W peak to play with, which for a normal size person on a normal bike, should be pretty perky. But if the bike is a dumb slow design, like the godawful fat tire turds that are hot sellers these days, it will get in its own way.

It's so easy to get a more powerful KT controller than the one you have, that it seems like a mistake to modify that one and make it run too hot. Just get one with more beef, if your battery will support it.

Note that increasing your battery voltage to the maximum your controller will tolerate (14S instead of 13S) will only increase gross power by 7.7%, so not at all a big deal.
 
E-driver_ said:
Hmm ok.

Well the bike kind of sucks right now anyway :) Too slow. So maybe I could take my chances with this battery anyway :)

Did you guys say the shunt modifications makes the bike accelerate more? Or does it also make it stronger going uphill in slopes?
That was pretty much my approach too 😆
They're basically the same thing... Better accelerating on the flats is pretty much the same load as steady up a hill.
But, hills heat stuff up way more!
Usually there's way less airflow cooling things, and the amp peaks last longer. On the flats, there's a huge amp surge, but when you hit top speed and keep going, the amps drop, and airflow is high. And usually, you can only keep it pegged but for so long. But lots of city grid, pulling away hard from stop sign to stop sign for a lot of blocks heats thing up just fine too! Lol
Hills usually hold you below the motor rpm where's there's good back emf, so amp flow stays crazy high at the same time there's less air cooling.

Be careful though once you get going.. I started out with a first battery about like this
s-l500.jpg

and wasn't satisfied until I had one like this. Lol
KIMG0054-640x360.JPG
 
Seems like Voltron and A.W. are cousins are something, if you judge the book by the looks of ones ebike.

All very cool in my books :thumb:

Controllers have capacitors, capacitors have voltage ratings, dont touch it. My 36v controller has 60v caps, the 36v charges to 40.40v all its life (not 42v). I use my 52v battery on the 36v controller as well, thats every single day. The 52v is 58.80v, caps are 60. Only issue, the e-abs does not engage when the 52v is fresh (at 58.80v). The routine has always been use the 52v first, get your kicks first, then when the 52v's bms kicks in, switch to the 36v which isnt as peppy if you know what I mean. My setup aint much, I find I dont go much over 20mph, though sometimes I peg it. 36v 35a generic, its held up for yrs now. Just wire mods and a hack job or two. Actually I fixed it all a couple weeks ago. Cleaned it up, was on a non-lazy roll that day.
 
calab said:
Seems like Voltron and A.W. are cousins are something, if you judge the book by the looks of ones ebike.

All very cool in my books :thumb:

Controllers have capacitors, capacitors have voltage ratings, dont touch it. My 36v controller has 60v caps, the 36v charges to 40.40v all its life (not 42v). I use my 52v battery on the 36v controller as well, thats every single day. The 52v is 58.80v, caps are 60. Only issue, the e-abs does not engage when the 52v is fresh (at 58.80v). The routine has always been use the 52v first, get your kicks first, then when the 52v's bms kicks in, switch to the 36v which isnt as peppy if you know what I mean. My setup aint much, I find I dont go much over 20mph, though sometimes I peg it. 36v 35a generic, its held up for yrs now. Just wire mods and a hack job or two. Actually I fixed it all a couple weeks ago. Cleaned it up, was on a non-lazy roll that day.

Aha ok.

I am going to try this on a controller looking like this.

ATTACH]


What do you guys think? In relation to the battery and so on I mean.
 
Voltron said:
E-driver_ said:
Hmm ok.

Well the bike kind of sucks right now anyway :) Too slow. So maybe I could take my chances with this battery anyway :)

Did you guys say the shunt modifications makes the bike accelerate more? Or does it also make it stronger going uphill in slopes?
That was pretty much my approach too 😆
They're basically the same thing... Better accelerating on the flats is pretty much the same load as steady up a hill.
But, hills heat stuff up way more!
Usually there's way less airflow cooling things, and the amp peaks last longer. On the flats, there's a huge amp surge, but when you hit top speed and keep going, the amps drop, and airflow is high. And usually, you can only keep it pegged but for so long. But lots of city grid, pulling away hard from stop sign to stop sign for a lot of blocks heats thing up just fine too! Lol
Hills usually hold you below the motor rpm where's there's good back emf, so amp flow stays crazy high at the same time there's less air cooling.

Be careful though once you get going.. I started out with a first battery about like this
s-l500.jpg

and wasn't satisfied until I had one like this. Lol
KIMG0054-640x360.JPG

Aa I see. Do you know if there are some way to cool down the controller if needed? I know they use statorade for motors. But perhaps there is some method for the controllers as well? Some type of paste or something?

Cool bike haha :)
 
From my experience, as long as it's not in an enclosed no airflow box, the battery or the motor will melt first.

And thanks... Now you see these tips are from first hand experience lol.
 
I think I perhaps messed something up. It did not start. Or perhaps too much current went through the controller/motor or something.

Does not seem to start. What is the most probable fuckup? The controller itself or the motor? :)
 
If the case of the controller is getting too hot then you need to have air flow over it while you ride, or you might want to upgrade your controller to more fets. Then you can start aluminum blocking the fet backing plate for extra heat sink, you could go as fancy as you want. Fins, mass, sq-inches, you name it.
 
I think I blew something in the battery. Because when I put the XT60 from that battery into a wattmeter nothing happens, even when I push the on-button on the battery. But the same wattmeter started blinking when used on another battery that I have.

So.. I am probably not going to screw around more with this shunt-stuff. I think I will buy another controller instead, with more amps. But. Does anyone know if I could salvage the battery somehow? Perhaps I just blew a fuse or something? Or what could be the issue there?

Would you recommen me to open it and try to reconnect some cables or something? To make it work again I mean. It seems to be charging when I charge it with the wall-cable. Any idea on what might be wrong with it and how it could be saved?
 
E-driver_ said:
I think I blew something in the battery. Because when I put the XT60 from that battery into a wattmeter nothing happens, even when I push the on-button on the battery. But the same wattmeter started blinking when used on another battery that I have.

Fuse? That's the likely (and easy) thing if your battery pack has one. They're usually tucked inside on an inline holder, and secured with a wrap of tape.

But... if your battery fuse burned, it's a good sign your battery doesn't want to play this game. Don't let the battery be the weakest component of your system.
 
Chalo said:
E-driver_ said:
I think I blew something in the battery. Because when I put the XT60 from that battery into a wattmeter nothing happens, even when I push the on-button on the battery. But the same wattmeter started blinking when used on another battery that I have.

Fuse? That's the likely (and easy) thing if your battery pack has one. They're usually tucked inside on an inline holder, and secured with a wrap of tape.

But... if your battery fuse burned, it's a good sign your battery doesn't want to play this game. Don't let the battery be the weakest component of your system.

I opened the battery. I did not understand what the fuse was in this battery. But... Looks like I blew the circuit card straight out of the park :)

From the picture it seems like it was burnt on the stake:
 

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Well, it looks like you found the problem.

If there's a fuse, it will probably be on the big red wire between the BMS and the main power connector on the battery case. Not all battery packs have one.
 
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