Any advantage of 40A BMS for a 30A controller?

Obsessed biker

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Sep 14, 2019
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Same thing with the battery peak and continuous,the controller is 30a continuous and probably 40-45 peak momentary or whatever the fet's are rated for.Most ebikes don't draw more than 30a unless it's a hot rod and the average constant draw is only 6-7 amps,any higher and your run time would be pathetic.
Here is a pic of my controller. It's max limit says 30. But is that really just it's continuous?
91055
 


Frogslayer

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It's hard to know if they don't state without testing. Your label on your controller looks like the label on my 36v controller.
15723245487936919181094698557735.jpg
 

Street Ryderz

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Ok, that helps. And accounting for what frogslayer said, it sounds like it would draw higher amps under load like going uphill. What I don't get is that the controller determines power usage and theoretically won't go over 30a unless its short bursts. So unless I regularly hit the peak draw and the controller allows it to go over how would the extra 10 available amps be utilized? Would it actually give me more torque or speed uphill? Hope I'm not frustrating you or anything. It just has to have really solid advantages for me to not see it as redundant. Lol
Yes it would give more torque when required.
 

Street Ryderz

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Here is a pic of my controller. It's max limit says 30. But is that really just it's continuous?View attachment 91055
Yes that's continuous,it's peak/momentary is not listed.It's probably 40-45a peak or whatever the fet's are rated for,you can open the controller and see the fet's whether or not you will see the markings on the fet's idk no offence but that looks like a cheap controller so it may just use cheap low grade fet's(unmarked).
 

Obsessed biker

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Yes that's continuous,it's peak/momentary is not listed.It's probably 40-45a peak or whatever the fet's are rated for,you can open the controller and see the fet's whether or not you will see the markings on the fet's idk no offence but that looks like a cheap controller so it may just use cheap low grade fet's(unmarked).
Ok, i went ahead and got the 40a bms. Although the battery pack is sealed with no labels confirming it's actually the 40 instead of the 30, but i suppose I'll find out at some point. Unfortunately, the day after I received the battery, my bike got stolen! Ugh! Fortunately, i hadn't installed the wheel or even charged the battery yet, so i still have those. But the bike was a good cromo steel frame and the basis for me to go electric and feel safer that it had steel dropouts. I have another bike, but it's got a suspension fork with alloy lowers. Even with 2 torque arms, I've seen pics of busted alloy or mag dropouts that make me worry about installing on alloy. Thanks for your help though, Street!

Oh yeah, btw, yeah it's a cheap controller that came with the kit. I wanted to get the bike going first before upgrading controllers, but looks like all that's gonna have to wait now. I'm about to post about an alternate project you may have some knowledge about though. If i can get that going id at least have some transportation.
 
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Street Ryderz

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Oct 14, 2016
Messages
3,171
Ok, i went ahead and got the 40a bms. Although the battery pack is sealed with no labels confirming it's actually the 40 instead of the 30, but i suppose I'll find out at some point. Unfortunately, the day after I received the battery, my bike got stolen! Ugh! Fortunately, i hadn't installed the wheel or even charged the battery yet, so i still have those. But the bike was a good cromo steel frame and the basis for me to go electric and feel safer that it had steel dropouts. I have another bike, but it's got a suspension fork with alloy lowers. Even with 2 torque arms, I've seen pics of busted alloy or mag dropouts that make me worry about installing on alloy. Thanks for your help though, Street!

Oh yeah, btw, yeah it's a cheap controller that came with the kit. I wanted to get the bike going first before upgrading controllers, but looks like all that's gonna have to wait now. I'm about to post about an alternate project you may have some knowledge about though. If i can get that going id at least have some transportation.
That suck's sorry for your loss but at least you still have the main components.
 
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