Bumblebee Battery Wholesale (EV battery modules and more!)

Vendor Corner (SERIOUS)
103

You’re correct, our sales target is higher than our competitors (and you are spot on, our sales target is generally around $0.22/Wh).

There’s a few reasons for this:

  • We offer free shipping (US lower 48 only), and eating the cost of shipping these very heavy modules is expensive
  • eBay fees are crazy high (we are working on getting our own eCommerce platform with lower fees)
  • We dont have the sales volume of those larger companies (yet!) so we pay more for each module, pay more for shipping, etc.

However, we also get a lot of batteries that BHU and BCH rarely (if ever) get. We have a strong focus on automotive (HEV, PHEV, BEV) batteries, and lots of these cells cant be found anywhere else other than digging them out of the belly of a car (which we do for you)! While those competitors tend to traffic in a lot of round cells (18650’s mostly) and packs for cell recovery, we are selling complete battery modules ready to be put to use in all kinds of DIY applications.

I do agree though, lower prices are better for everyone! We are working to grow and expand as we build out this new side of the business, get our own eCommerce platform, cut out middle men in our supply chains, get more efficient with our workflow, etc. As we are able to achieve those goals, we will hopefully be able to lower our sales target :slight_smile:

Any tests performed/testing data is listed on each module’s product page :slight_smile:

For the time being, we usually dont test each module other than just a cursory inspection and voltage check (to make sure it’s not at too low of a voltage). This may change as we expand this side of the business, depending on customer interest.

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104

Do you test one of the modules in the lot, or are these tested before they get to Bumblebee? How do you know these still have reasonable capacity left and aren’t mostly spent batteries?

105

We check each and every module for voltage (and AC IR, but we dont publish that since it’s a very technical spec and not super useful without a lot of context). We have not capacity tested any of the modules we have listed. If we do, the tests performed and the test results will be listed in the product description on each listing :slight_smile:

No, pretty much all of the EV batteries we receive arrive to us in complete battery packs (think: massive metal enclosure that bolts to the bottom of the car), and we usually dont have any data or history for each pack.

All our EV modules are sold AS-IS, and until we add testing to our workflow we unfortunately cant guarantee the capacity or other manufacturer specs. I’ve been advocating for adding testing for at least one module from each pack, but it’s still early days for our EV battery division (AKA, just me).

We do, however, have a 30 day return policy. If there’s something wrong with the module and it’s our fault (not as described, 0V on arrival, damaged in shipping, etc.) then we will pay for return shipping and refund you. If there’s something wrong that’s not guaranteed (low capacity, high DC-IR, etc.) and you really dont want the module anymore, you can pay for return shipping and we will refund the cost of the module.

I understand that might not be the most satisfying answer, but it’s the honest one. I hope it answers your questions! :slight_smile:

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106

Great info, thanks!

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107

Sure thing, thanks for your questions! I’m all about honesty and transparency, I have seen way too many vendors in this community flop because they thought they could pull a fast one on a bunch of skaters :joy:

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108

I have fallen down a very deep research rabbit hole today, and I stumbled across something that made me laugh:

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I thought y’all might get a kick out of it too. The next page has instructions for where to drill holes in the battery to drain out the water :joy:

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109

W…T…F…:scream:
Does it say how to dispose of the water?

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110

It sure doesnt :rofl:

It does discuss the dangers of hydrogen gas… briefly :joy:

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Apparently this is an industry standard method for discharging an EV battery, because I keep finding the same delightfully funny/horrifying diagram in the emergency response documents from different manufacturers.

And yep @Battery_Mooch, you’re right. Just “drain the water,” no mention of how much toxic sludge that water might contain. Should be safe for your neighbor’s flower beds, right? :joy:

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112

I guess once the pack is mostly discharged they use salt to reduce the resistance to make it easier to fully discharge the pack? But since it’s mostly discharged before this happens there isn’t a lot of the cell-destroying electrolysis going on (hinted at by the lack of hydrogen warnings).

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113

It might be okay though as they only use salt at the end so there isn’t nearly as much corrosion of the metal going on and the cells aren’t getting opened up.

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114

That assumes that the cells arent already opened up. These are instructions for “Storage of damaged vehicle with the damaged battery” after all. But I see what you mean.

115

Whoa…never thought about that. These can be packs from an accident. Very good point!

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116

Ok, story time.

I got a message from someone on eBay asking if the Mitsubishi i-MiEV modules that we have listed come with a BMS or not. I was told that they do not, and the listing that I made says they dont, so I was about to tell him no. But then I figured “what the hell, I’ll check.” I popped one open, and what do you know:

IMG_6916
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Now when it comes to PCBs, I know just enough to get me into trouble, but not enough to know on sight exactly what I am looking at. So while this PCB looks very BMS-y to me, I figured I should look into it more in case it’s just a voltage-sensing-and-reporting-to-the-mothership type deal.

I cleaned the conformal coating off the square IC in the center, and this is what was written on it:

F3612M2
1232KE401
(A1)
SGP

Searching any of those codes brings up a plethora of generic component-sourcing websites, none of which have an actual datasheet (that I could find). However, searching that first code did bring me to this ARPA-e report about several EV’s and their BMS/BMU systems, which was incredibly interesting (if you’re a nerd like me):

In that report (page 16) it lists the NEC F3612M2 as the “BMS Primary CPU,” so that answers that question (if that report is to be trusted). On page 15 it also correctly identifies the “Voltage & Balance ASICs” as “Linear LTC6802G-2” which matches the skinny rectangular chip on the PCB. Searching that chip brings up this datasheet:

https://www.analog.com/en/products/ltc6802-2.html#product-overview

That seems to confirm that the PCB is, in fact, a BMS. The ARPA-e report also says that the BMS system for the complete i-MiEV pack consists of a master unit that talks to the charger and ECU of the car, and slave units on each module which monitor the cells, passively balance them, and report cell data back to the master unit.

My BMS questions seem to have been answered at that point, so I let the eBay customer know.

Reading through the rest of the report, I noticed that a lot of the cars they inspected used a similar master/slave BMS architecture. This matched my anecdotal data from the modules I have opened up and inspected.

That got me thinking. When an EV pack comes into the shop, it’s usually complete with all it’s parts. A lot of them still have the master BMS unit, hooked up to all the slave units in the modules. Is there a possibility that I could jack into the master BMS unit and read pack data before tearing it down?

There’s potentially a lot of really useful info about the packs, if there were a way to access it. That said, I have no idea how to access it. I dont even know if the master BMS unit has any kind of data storage, all the data it gathers might be lost when it powers off. Still, it seems like a really interesting idea to me.

I did a bit of digging, and I just barely scratched the surface of “Vehicle Communication Interfaces” (VCIs) and “factory scan tools,” which are used by dealerships and shops to read/write to the various electronic systems in a car. Most of those seem to assume you are working on a complete car though, not a disembodied battery pack.

I know it’s a long shot, but does anyone know anything about any of this? I find it endlessly fascinating.

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117

Not enough to help you with anything other than identifying chips but good luck! Very cool stuff IMO.

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118

That one hit a bit too close to home

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119

I did several tests on all of the various companies before selecting to choose bumblebee Battery to see how much expertise they have around their product. Bumblebee Battery was fast to respond to my queries, and they’re also on time, ensuring that I appreciated everything. Even though.

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120

Wow, ok that Mitsubishi pack looks like it can be broken down to individual cells :eyes::eyes: what do those cells measure out to? I wonder if possible to deconstruct and make some esk8 packs :sunglasses:

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121

Roughly 185mm x 120mm x 50mm, probably a bit smaller. I can get better measurements when I’m back at work next week. They are still fuckin’ huge cells, not sure how they would work out for an esk8. Maybe a big eMTB pack?

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122

Are they round cells or spicy pillows? Gonna parrot someone earlier and ask how well they’d fare outside their corset

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