Atkam said:Some additional information of my integration:
...
Ales
It looks to me that all you would have to do is drive a pair of contactors as soon as that single main contactor signal is closed. Basically both packs would close their main contactors simultaneously.jkenny23 said:collink or Atkam, where did you tap into the contactor power lines to determine the state?
It seems like you need to switch out your pack within 200ms before any errors could occur based on some DTCs I found in the service manual.
IssacZachary said:Of course the more sensible thing to do is patiently wait until Tesla 3's, Chevy Bolts and Gen 2 Leafs can be bought as cheap used cars.
Man!goldbrick said:I paid about $10k for my new model S after all the rebates and tax credits...
IssacZachary said:How in the world did you pay only $10,000 on a NEW TESLA MODEL S? :shock:
Please feel free to tell me your secrets!
mux said:European new Leaf owner chiming in here - I'm planning to do basically exactly the same mod that ATKAM and Collink did. It really seems to be as simple as hooking up contactors on the RLY V signals on the main battery connector, however, I would like to be extra super sure if there are no other issues to take into account.
I'm an electronics design engineer by trade and would be able to make this mod decently professionally. If ATKAM/Collink are willing to share their notes, I can formalize them and make them into a proper tutorial. I'm also interested to know if it isn't possible to tap off the battery wiring going to the on-board charger, as that is extremely easy to access without the need for a bridge or lift.
The real interesting thing about this is the ability to get additional capacity economically. I can get new 2900mAh (10Wh) 18650s for $2.04/pc, meaning a 96s20p pack would be $3916, doubling the range of the car. At 46g per cell, it's only 88kg or 200lbs of extra weight. Of course, the contactors, wiring, additional firewall, secondary BMS and so on will cost a bit extra on top, but it's significantly less than the price premium of a new 40kWh car.
mux said:I should have probably specified as well: I specialize in power electronics and lithium ion batteries (people around me are starting to recognize me as 'that guy that eats 18650s for breakfast') so I'm planning on using a BMS of my own design. A BMS does not have to be expensive, they just are because they're usually specialized and low-volume.
lorenfb said:mux said:I should have probably specified as well: I specialize in power electronics and lithium ion batteries (people around me are starting to recognize me as 'that guy that eats 18650s for breakfast') so I'm planning on using a BMS of my own design. A BMS does not have to be expensive, they just are because they're usually specialized and low-volume.
That's the difficult part versus just using another Leaf battery with it's BMS, i.e. a custom BMS with all the balancing circuitry and processor
for the 18650 cells.
Agreed.EVDRIVER said:I'd be interested to see the safety strategy for packaging these additional "packs" How they are safely contained, deigned for weight distribution and accidents, isolated, etc. To date I have yet to see one project completed with a safe design. There is a reason the traction pack enclosure is so heavy. What many people think it costs to do such work vs what it actually costs to do properly is usually a surprise in the end, at least for those honest enough to admit it. Anyone that has built a quality EV conversion and accurately documented the costs can relate to this. To safely design a pack in a car is no small feat and people with extensive experience with small hobby packs on the internet are now attempting to work with lethal high voltage. I've seen some scary comments posted that reveal a complete lack of knowledge of HV traction systems and safety. Years back an "experienced" person was killed tinkering with a LEAF pack so please be careful or buy a used longer range EV.
mux said:The real interesting thing about this is the ability to get additional capacity economically. I can get new 2900mAh (10Wh) 18650s for $2.04/pc, meaning a 96s20p pack would be $3916, doubling the range of the car. At 46g per cell, it's only 88kg or 200lbs of extra weight. Of course, the contactors, wiring, additional firewall, secondary BMS and so on will cost a bit extra on top, but it's significantly less than the price premium of a new 40kWh car.
IssacZachary said:Anyhow, there's a recent flood of cheap LiFePo4 batteries on eBay and Amazon at a stellar price, close to $100 per kWh! So a 30kWh pack would cost around $3,000. The main reason I'm attracted to the LiFePo's is that they are not flammable. So that eliminates one danger.
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