Im building an eskate board for a school project and looking to prebuy a battery pack around 10s2p or 6s2p with a bms already installed. What websites should I look at? I am aware of mboards, evolve, etc but wondering if other options exist. I heard that the meepo battery replacements may have BMS but I dont see any documentation on the website to confirm this.
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Any off the shelf esk8 battery will have a BMS
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First you need to understand that a diy supplier built battery, like from Skyart Power or Mboards, is going to bypass the discharge bms which is safer for the rider if you are using a vesc since discharge current is limited by the settings entered into the vesc. If you buy a pack from an esk8 manufacturer, like Meepo, then it will likely have discharge limited by the bms. This can be risky if the vesc or esc is set to draw higher amounts of current than the discharge bms allows resulting in a hard cutoff where you are ripping up a hill and the board suddenly dies and you faceplant due to the sudden loss of momentum. If you do buy a pack from an esk8 manufacturer and don’t want to physically alter the bms yourself then it’s best to pair it with the esc that it’s designed to go with.
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IMHO you shouldn’t suggest to use a bypassed battery and listing the benefits, without also saying that leaving the skate turned on by accident will permanently destroy the battery.
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A low voltage alarm would help
This is actually a key feature of a BMS
Let me know if I’m mistaken, but this is only true if you have something else besides the vesc connected to the battery and switched on… Otherwise, the low voltage cutoff setting in the vesc will switch off the vesc to protect the battery. Of course you have to program the low cutoff, so yes the OP needs to be aware of that too…
The low voltage cutoff in the vesc will only make sure that the motor doesn’t get power if the voltage is too low. The vesc itself will not power off, and it will draw a small amount of current all the time - until either you disconnect it or the battery gets completely depleted. A friend of mine just drained his 12S battery to 6.5V total this way a few weeks ago. He let the vesc plugged in for a few weeks, and that vesc didn’t have any turn off features.
Some vescs (mostly the newest gen makerx stuff I think) have the feature to automatically turn off after a set amount of time that you can setup in vesc tool, this is usually setup to be 30 minutes. Even this ignores the low voltage cutoff, however it turns off quickly enough that it cannot deplete the battery below safe levels.
However OP didn’t specify whether a vesc will be used in the project, or a generic ESC. And with looking for a 10s2p or 6s2p config there’s a good chance it will be a generic ESC. Whether a generic chinesium ESC has an auto turnoff feature and how it is implemented exactly can vary. In that case it might be better to run a discharge BMS to make sure the parasitic loads from the ESC cannot deplete the battery pack to unsafe levels.
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This is not true. The ESC itself will destroy the battery.
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True, I have been using spintend and makerx esc the last few years and got those settings confused, since they both allow have the timed auto-off…
I have a 10s3p that is collecting dust. It’s not charging at the moment because it probably has a cell or 2 that need to be replaced. If you’re willing to get into the guts of batteries and can use a multimeter you’ll do fine. Send me a message and we can work out a $ number.
Instead, if you want to pickup something without thinking about all that - grab something from Batteries – SkyartPowerSystems contact them, Artem is super nice and will talk to you about a custom solution.
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