mux
Posts: 94
Joined: Sat Jan 13, 2018 3:52 am
Delivery Date: 13 Oct 2011
Leaf Number: 6177

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Sun Feb 11, 2018 2:31 pm

That voltage spiking to 100V and then down is probably a combination of the Leaf RLY N/P and precharge relay switching in a certain order every time the pack is connected/disconnected. This guy has the sequences on video:

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

So that is nominal, nothing particularly wrong I don't think.

Be very careful when opening (and more importantly: closing) the main battery. It's gasket sealed all around for a good reason. At least one person had his Leaf flame out due to water getting into the main pack. Caulking is not enough, you need a compliant gasket around the pack to properly weatherseal it.

andrewtbennett
Posts: 6
Joined: Sat Feb 03, 2018 9:15 am
Delivery Date: 15 Feb 2014

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Fri Apr 27, 2018 2:00 pm

Finally had a few days to have another go at integrating the extra pack. Mux thanks for your input, I saw your recent videos and had actually came to the same conclusion that mosfets were the only way to safely integrate new relays without the leaf realising - so thank you for proving that it works first :) - my circuits are slightly different but do the same job. Now need to properly balance the packs and see exactly how much extra range I can get. I think possibly making the pack up to 100s 10p might allow the 18650s to start helping the leaf earlier in the range as at present (due to different chemistry) they only really make a difference beyond about 35% residual. It would also stress the new 18650s less - especially as some of them must be over 10 years old. No temperature issues at the moment. All staying nice and cool without any active thermal management. As for the persistent error code (negative contactor stuck closed) I have concluded that this is a sensor issue as the signals from the vcm are as expected and I can hear the leaf's relays working as they should too - so for the time being we're just resetting the codes each time and it's become part of the routine and at least it makes the car unstealable. There have been no new error codes since install. When I get chance I'll upload some photos and some real world range figures but for now thanks for all the help to everyone who replied to the above and to anyone who is wondering "can it be done" the answer is YES, absolutely.

mux
Posts: 94
Joined: Sat Jan 13, 2018 3:52 am
Delivery Date: 13 Oct 2011
Leaf Number: 6177

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Sun Apr 29, 2018 2:58 am

I've done some spreadsheeting on changing the amount of series cells, and it doesn't matter. I've gone through all combinations of NCA and NMC cells with 94-102S, and you can never get more than approx. 40% of nominal capacity out of the extender pack before VLBW. There is basically still well over half of the extender pack left after the car already says it's empty. In practice, it's even more pronounced; I get my VLBW at about 130km these days, and can drive it down to about 250km. I mean, for now it makes estimating range very simple: just multiply whatever the car says it can do by 2.

So don't even bother. Just keep the same series amount of cells, it will be best for cycle life anyway. I'm currently working on the electronics that will fix the displayed range, this will be done and tested before the summer holidays.

Edit: also, it's probably informative to tell you that I have had the contactor failure DTC once as well, when replacing my MOSFET driver solution with a new custom board (as shown in my last video). A firmware bug caused the contactors to not close at the correct time. I was really ragequitty at the time but persisted, reflashed corrected firmware, cleared DTCs and waited a bit, and it all went away. I don't think I actually damaged anything, there must be some sensor that actually does the contactor-welded-closed-measurement that is sensitive to something else causing stray DTCs. Same goes for the isolation DTC, it intermittently shows even though I've gone through the entire service manual procedure of narrowing down where it could come from. Some of these sensors are just a little bit too sensitive it seems.

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