Can someone explain this to me?

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ebike11   100 kW

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Can someone explain this to me?

Post by ebike11 » Nov 23 2019 3:00am

Hi guys
Im very grateful for all of the help Ive received on here. I have learned a lot. After experimenting with multiple motors, im now running the qs205 and sabvoton 72200. I recently bought a used 72V pack and didnt realize that the continous amps for that battery pack was only only around 30A. I found out the hard way after giving full throttle up a hill, the battery cut out and could smell burned connections. Ill open up the pack and see what I can salvage. I guess the battery was rated way too low for that set up. My question is..even if a battery is rated less power than the motor/controller needs, shouldnt the motor just make less power with less power going through the controller? The battery is the power source so why would that part of the ebike system get damaged rather than just the motor underperforming because its not getting enough power.
Hope you understand what I mean. Thanks!

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st35326   100 W

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Re: Can someone explain this to me?

Post by st35326 » Nov 23 2019 4:00am

ebike11 wrote:
Nov 23 2019 3:00am
Hi guys
Im very grateful for all of the help Ive received on here. I have learned a lot. After experimenting with multiple motors, im now running the qs205 and sabvoton 72200. I recently bought a used 72V pack and didnt realize that the continous amps for that battery pack was only only around 30A. I found out the hard way after giving full throttle up a hill, the battery cut out and could smell burned connections. Ill open up the pack and see what I can salvage. I guess the battery was rated way too low for that set up. My question is..even if a battery is rated less power than the motor/controller needs, shouldnt the motor just make less power with less power going through the controller? The battery is the power source so why would that part of the ebike system get damaged rather than just the motor underperforming because its not getting enough power.
Hope you understand what I mean. Thanks!
Because the cells and likely connection points couldn't handle the current that controller wanted to flow. If you wanted to run that you should have turned the current way down in the programer but what fun is it having a high amp motor/ controller and a low amp battery.

leffex   100 W

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Re: Can someone explain this to me?

Post by leffex » Nov 23 2019 4:07am

Check all wires and connectors. Try check the fuse in the battery. Most batteries have a bms that monitor power outtake and charging so that may be why it shut off after over-current protection set in in your full throttle up a hill episode. Usually this function will reset itself after a few seconds or after turning the battery on/off with its power button if it has any.

If else it may be the smell that burnt some important component. Then if you dare you can open the battery up to se what has happened.
Salestech in an ebike store

ebike11   100 kW

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Re: Can someone explain this to me?

Post by ebike11 » Nov 23 2019 5:43am

st35326 wrote:
Nov 23 2019 4:00am
ebike11 wrote:
Nov 23 2019 3:00am
Hi guys
Im very grateful for all of the help Ive received on here. I have learned a lot. After experimenting with multiple motors, im now running the qs205 and sabvoton 72200. I recently bought a used 72V pack and didnt realize that the continous amps for that battery pack was only only around 30A. I found out the hard way after giving full throttle up a hill, the battery cut out and could smell burned connections. Ill open up the pack and see what I can salvage. I guess the battery was rated way too low for that set up. My question is..even if a battery is rated less power than the motor/controller needs, shouldnt the motor just make less power with less power going through the controller? The battery is the power source so why would that part of the ebike system get damaged rather than just the motor underperforming because its not getting enough power.
Hope you understand what I mean. Thanks!
Because the cells and likely connection points couldn't handle the current that controller wanted to flow. If you wanted to run that you should have turned the current way down in the programer but what fun is it having a high amp motor/ controller and a low amp battery.
Yes I see..but since the battery is the main power source, why wouldnt the controller be limit itself to whatever the battery could put out?
I can understand if I put a high power battery onto a small controller and fry the controller, but its the reverse in this case it seems

Balmorhea   10 kW

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Re: Can someone explain this to me?

Post by Balmorhea » Nov 23 2019 5:56am

ebike11 wrote:
Nov 23 2019 5:43am
Yes I see..but since the battery is the main power source, why wouldnt the controller be limit itself to whatever the battery could put out?
How is a controller supposed to know the limits of the battery supplying it? It's just electricity. The controller only has its own limits to restrict it.
I can understand if I put a high power battery onto a small controller and fry the controller, but its the reverse in this case it seems
You've got it all wrong. The controller will only draw as much power as it's capable of handling. What you're saying here is like saying that you can drink out of a cup, but if you drink out of a bucket you'll drown. The size of the vessel has no effect on your own capabilities. The size of the battery has no effect on how much maximum power the controller can transmit.

AHicks   100 W

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Re: Can someone explain this to me?

Post by AHicks » Nov 23 2019 9:10am

The controller has no idea of what is upstream from it. Doesn't even care. If the controller is able to flow 100a for instance, and has a 100a load to feed, it's going to do it's level best to try and supply that 100a load with 100a - with predictable results when supplied by a battery capable of just 30a.

The answer, as mentioned, is to set the controller up so it can't pass any more power than the battery can supply. In this case, 30a.

Voltron   10 MW

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Re: Can someone explain this to me?

Post by Voltron » Nov 23 2019 6:38pm

The more and more powerful your controller becomes, the closer and closer it gets to being like just hooking the two battery leads together in a short circuit... Hundreds of amps can flow at peak if it's a big enough load. But the controller has no way of knowing what is supplying the power, or if it's melting down while it's doing it, unless it has a temperature sensor on the battery that rolls the power back on the controller.

HK12K   10 kW

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Re: Can someone explain this to me?

Post by HK12K » Nov 24 2019 12:20pm

Are you certain the smell is coming from the battery pack? I ask because Sabvoton went out of business years ago and most all of the controllers currently being sold under the Sabvoton label have a reputation for going up in smoke.

Have you tried metering the battery pack to see if it's putting out any voltage?

ebike11   100 kW

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Re: Can someone explain this to me?

Post by ebike11 » Nov 27 2019 7:30am

HK12K wrote:
Nov 24 2019 12:20pm
Are you certain the smell is coming from the battery pack? I ask because Sabvoton went out of business years ago and most all of the controllers currently being sold under the Sabvoton label have a reputation for going up in smoke.

Have you tried metering the battery pack to see if it's putting out any voltage?
Yeah its the battery. It was only rated for 30amp continuous but i noticed that after it happened. I guess ill need to look for a new pack

HK12K   10 kW

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Re: Can someone explain this to me?

Post by HK12K » Nov 27 2019 10:00am

Ugh. Yeah, sounds like new pack time.

That said, if that pack was equipped with a bms it may have been what smoked. It's possible the cells inside may have escaped unscathed, but you won't know until you open it up and investigate.

Fwiw I'd store it somewhere safe in the meantime, especially if you're unsure of what's going on under the wrapper. Just to be on the safe side.

ebike11   100 kW

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Re: Can someone explain this to me?

Post by ebike11 » Nov 27 2019 4:50pm

HK12K wrote:
Nov 27 2019 10:00am
Ugh. Yeah, sounds like new pack time.

That said, if that pack was equipped with a bms it may have been what smoked. It's possible the cells inside may have escaped unscathed, but you won't know until you open it up and investigate.

Fwiw I'd store it somewhere safe in the meantime, especially if you're unsure of what's going on under the wrapper. Just to be on the safe side.
Thanks a lot for the advice! Ill surely follow it

d8veh   100 GW

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Re: Can someone explain this to me?

Post by d8veh » Dec 03 2019 5:52am

It'll be the BMS that smoked or the power wires. The cell-pack will probably be OK. BMSs normally have over-current protection, so it could be just the internal power wires that melted - easy repair.

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E-HP   100 kW

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Re: Can someone explain this to me?

Post by E-HP » Dec 03 2019 9:52am

ebike11 wrote:
Nov 23 2019 3:00am
im now running the qs205 and sabvoton 72200
bought a used 72V pack and the continous amps for that battery pack was only only around 30A
I guess the battery was rated way too low for that set up
What's the configuration of your pack (20S ?P)?

ebike11   100 kW

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Re: Can someone explain this to me?

Post by ebike11 » Dec 03 2019 8:29pm

E-HP wrote:
Dec 03 2019 9:52am
ebike11 wrote:
Nov 23 2019 3:00am
im now running the qs205 and sabvoton 72200
bought a used 72V pack and the continous amps for that battery pack was only only around 30A
I guess the battery was rated way too low for that set up
What's the configuration of your pack (20S ?P)?
Hi..i just bit the bullet and bought a new 72v 20s10p with 25R cells. Im expecting much better performance i hope

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DogDipstick   10 kW

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Re: Can someone explain this to me?

Post by DogDipstick » Dec 03 2019 9:01pm

My 20s EV lipo can burst 95 amps through the shunt without blinking. ~80v. Its fun. I feel so bad for people with 30-40A max packs.
83.1v of Ironhorse XC.. :) :bolt: by Chevy :bolt: :D Broke 10 horsies :twisted: (..about 80% healed..).. :? Anybody.. what equals √3 times the line to neutral voltage? Asking for a friend.. :| (gottenymoem4115thangs?Yall?) :confused: Fabricator @ BSECo. Inc.

Balmorhea   10 kW

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Re: Can someone explain this to me?

Post by Balmorhea » Dec 04 2019 12:08am

DogDipstick wrote:
Dec 03 2019 9:01pm
My 20s EV lipo can burst 95 amps through the shunt without blinking. ~80v. Its fun. I feel so bad for people with 30-40A max packs.
My pack made of car cells is supposed to be good for 300A continuous, 500A burst. I use a 35A controller, so I use a 35A rated BMS. I haven't measured actual peak amps. My display shows a maximum ~1800W on a fresh charge. It feels about the same as when I used a 35A rated pack.

I don't feel sorry about having used the lighter weight pack before.

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