Extra Battery, How to Integrate with 24kWh Traction Battery?

[IssacZachary]

I got $5000 off from CO when I bought my 2017 Leaf. I doubt any of that would apply to a lease. A quick google search shows this same rebate ($5k) is extended to 2021 in CO. I never saw the money as it went straight from CO to the dealer and they just took it off the purchase price.

Ah. I see that the bill has changed on EV tax credits in Colorado. So it looks like yes, on a new EV one could get $5,000. I got about $4,000 on a used EV, but the bill no longer covers used EV's.

[IssacZachary]

Getting back on topic, I wonder how this guy managed to get a Leaf to switch between two BMS's.

https://www.youtube.com/watch?v=Y9agY5Vbv8U

This would be ideal for a battery trailer. You could leave the battery trailer at a charging station, or put roughly 6kW (20' x 20') of fold out solar panels on it and leave it in some parking lot or something, and then come back to a fully charged battery trailer. You wouldn't need the two batteries to have the same voltage like has been done with some of these other experiments, hence they could be charged separately.

[jkenny23]

Getting back on topic, I wonder how this guy managed to get a Leaf to switch between two BMS's.

https://www.youtube.com/watch?v=Y9agY5Vbv8U

This would be ideal for a battery trailer. You could leave the battery trailer at a charging station, or put roughly 6kW (20' x 20') of fold out solar panels on it and leave it in some parking lot or something, and then come back to a fully charged battery trailer. You wouldn't need the two batteries to have the same voltage like has been done with some of these other experiments, hence they could be charged separately.

I saw that a while back, it seemed pretty sparse on details. There's strangely an update as of 4 days ago, saying they can add 6 and 12 kWH also. I shot them an email asking for more details. It might be worth it to do one of the smaller range extensions just to see how they do it and see how scalable it is...

[davewill]

Getting back on topic, I wonder how this guy managed to get a Leaf to switch between two BMS's.

https://www.youtube.com/watch?v=Y9agY5Vbv8U

This would be ideal for a battery trailer. You could leave the battery trailer at a charging station, or put roughly 6kW (20' x 20') of fold out solar panels on it and leave it in some parking lot or something, and then come back to a fully charged battery trailer. You wouldn't need the two batteries to have the same voltage like has been done with some of these other experiments, hence they could be charged separately.

Looks completely and utterly fake to me.

[jkenny23]

I'm quite skeptical of the smaller range extending options but for a full pack swap it seems pretty simple to me, just swap out the full BMS/contactor connector which he could have done manually when he put the camera down, and the 2 packs could be left in parallel since only one set of contactors would be active at any time.

[IssacZachary]

I'm quite skeptical of the smaller range extending options but for a full pack swap it seems pretty simple to me, just swap out the full BMS/contactor connector which he could have done manually when he put the camera down, and the 2 packs could be left in parallel since only one set of contactors would be active at any time.

I think you could leave both batteries in parallel and just use their contactors for changing between batteries. You could also possibly close both batteries' contactors and run both at the same time, provided both had the exact same level of charge and therefore voltage.

It would still be risky doing it that way though as seen here:

https://www.youtube.com/watch?v=6Zivzvh9Bx0&t=49s
[youtube]https://www.youtube.com/watch?v=6Zivzvh9Bx0&t=49s[/youtube]

But it looks like the problem resistor is in the inverter, not the battery itself. If you keep the contactors open in one traction battery there shouldn't be anything in there that could get fried that I know of. But there is a risk that there could be. It would be nice to find a diagram of how the traction batteries are wired just to make sure. Switching low voltage signals between batteries would be cheap and easy. But it would be nice to keep both connected to the main bus without any costly high power switching device. At most, a second set of contactors would be used to isolate the bus going to the second battery, especially if that battery were on a trailer.

Here's a video on the 12V signals:

https://www.youtube.com/watch?v=d0IozEyeGSk

[mux]

Giant kick for this topic. I've finished up all the required wiring for the extender battery. This turned out to honestly be much easier than I expected, and considering the vague and scattered hints I had to work on so far I think I'll make a step-by-step walkthrough for the entire process of building an extender battery for the Leaf. Anyway, it's all in this video:

[youtube]https://www.youtube.com/watch?v=k3jaGtkyxvA[/youtube]

Next up, I will be putting a whole shitton of batteries in my trunk and drive around with it for a while to see how the installation holds up, how the contactors fare, if anything becomes hot, if fast charging works correctly, all that stuff. A company in the Netherlands has provided me with some VW GTE/eGolf battery modules to do my tests with, which makes my life a whole lot easier than having to weld a pack just for this test.

Then if everything is well and I got my custom BMS and control electronics in, I'll be making a permanent battery pack in a fireproof box underneath the car. This has already been designed in CAD, but building it is going to be a pretty labor-intensive process (considering I'm laminating it from fiberglass inside a big wooden laminating mold). So I don't expect that part of the story to come anytime soon.

But yeah, at the moment, it seems like I'll be driving around in a very long range Leaf in a week or so, maybe two!

[IssacZachary]

Giant kick for this topic. I've finished up all the required wiring for the extender battery. This turned out to honestly be much easier than I expected, and considering the vague and scattered hints I had to work on so far I think I'll make a step-by-step walkthrough for the entire process of building an extender battery for the Leaf. Anyway, it's all in this video:

https://www.youtube.com/watch?v=k3jaGtkyxvA

Next up, I will be putting a whole shitton of batteries in my trunk and drive around with it for a while to see how the installation holds up, how the contactors fare, if anything becomes hot, if fast charging works correctly, all that stuff. A company in the Netherlands has provided me with some VW GTE/eGolf battery modules to do my tests with, which makes my life a whole lot easier than having to weld a pack just for this test.

Then if everything is well and I got my custom BMS and control electronics in, I'll be making a permanent battery pack in a fireproof box underneath the car. This has already been designed in CAD, but building it is going to be a pretty labor-intensive process (considering I'm laminating it from fiberglass inside a big wooden laminating mold). So I don't expect that part of the story to come anytime soon.

But yeah, at the moment, it seems like I'll be driving around in a very long range Leaf in a week or so, maybe two!

Many thanks!!!

Keep us posted!!!

EDIT: And great video!!! You wired it exactly how I imagined I would do it.

[mmmike]

Go mux! Go mux! Great work and video! I plan to do a similar extender although I was thinking I will make my battery pack not permanent and charged off-board in my shop. I want to have the pack in a suitcase (or two) and only connect up in the trunk in the infrequent event when I need the extra range. But if your permanent install looks good maybe I will change my mind.

[mux]

Go mux! Go mux! Great work and video! I plan to do a similar extender although I was thinking I will make my battery pack not permanent and charged off-board in my shop. I want to have the pack in a suitcase (or two) and only connect up in the trunk in the infrequent event when I need the extra range. But if your permanent install looks good maybe I will change my mind.

I'm seriously considering doing both. The permanent battery will increase my total useable capacity to around 35kWh, which is probably just a couple kWh shy of what we need to go on holiday and get there in one go. So for long trips, I think I'm going to try and package up these VW GTE batteries in some kind of easily removable container, cook up some safe high-current contacts behind one of the unexplained removable covers in the trunk and make a removable trunk battery. Those GTE batteries are 1.086kWh each at 12 series, so I need 8 of them to get to 96S, which is about 8.7kWh, a nice increment to the main battery.

Another option is to ALSO do a main battery swap with more modern cells. On a volume (85L) and weight (155kg) basis, you can fit about 40kWh inside the main battery shell if you use modern 18650s, or about 45kWh of 2170s. Well, a bit more because you can forego the compression stacks and use that volume for batteries. This, combined with the permanent extender, would make the 2011 Leaf a 60kWh car, without sacrificing trunk space. Certainly interesting, although I do NOT look forward to the labor involved in that. I think I'd only do that if I had a salvage pack available to me that I can just take my time swapping out the cells over the course of many weeks.

Regardless, the plans for everything will be published here, free of charge, for anyone to try out. If it all works out, I am pretty sure this is the way to go with Leaf extender batteries.