South Carolina Powerwall

silverse2m6

Member
Joined
Jun 16, 2017
Messages
93
Hi Y'all (some say All Y'all for plural)

I have been tinkering with alt-energy for the last decade. Did my own biodiesel, installed PV system for my golf cart, then my RV (660W/208Ah 12V system). I want the house to be off grid one day.

In 2012 we leased a LEAF for 2 years and since we returned it, been looking at a Tesla. I would like to be able to recharge it with solar.

This year I caught wing of Pete's project and bought me about 1k x 18650 cells from eBay recycled laptop batteries.
I have been harvesting, testing, sorting for the last 2 months.

The next project is the following:
I have a cabin which is off grid but running off a genset for the last 3 years. Looking to equip the cabin with PV panels and a powerwall before moving on to the House.
image_ykkjtq.jpgimage_gspwxq.jpgimage_huhyuw.jpgimage_vwftkk.jpg
 
Glad you found us :) I would love a cabin in the wooods, on a hill, with no kids, Kickass internet & unlimited hot water - be bliss lol
 
Before starting with the large battery built, I have decided to train myself using about 180 cells < 2200 mAh that I was not planning on using anyway. I took 160 of these to attempt to make a 71Ah 14.8V (1777mAh average) battery for my RV.
After testing and charging/discharging them, I compiled each cells capacity in an XL file.


By using some basic maths each of the arrays is pretty capacity balanced to each other. [emoji41]
image_pnohji.jpgimage_swixye.jpg
 
Nice test bank.
 
Yes just dont use pluming flux
 
I dont want to ruin anything but you need to resolder those cells. They need to flow out better. The soldering station you have seem to have very little mass on that tip/iron. And perhaps to low power too. They should flow out a bit better.

Look at my video i did and at 7 minutes in and you see how it should look.

Because your joints look like cold joints and adding fuse wire on those can cause contact issues and heat or just no contact at all.
 
daromer said:
I dont want to ruin anything but you need to resolder those cells. They need to flow out better. The soldering station you have seem to have very little mass on that tip/iron. And perhaps to low power too. They should flow out a bit better.

Look at my video i did and at 7 minutes in and you see how it should look.

Because your joints look like cold joints and adding fuse wire on those can cause contact issues and heat or just no contact at all.
Will do ! Thanks daromer. The reason I put this here is for exactly this kind of feedback. Better now than having to take everything appart. Soldering station goes up to 480F, how hot do you solder? (Maybe the answer is in the video!)
 
Good that you take it right :) We are all here to learn.

The heat of the soldering iron as such is not the big thing. Ie F/C. As long as it can melt the solder thats hot enough.
Its about having enough mass/energy so you can heat up the object so the solder actually flows out. When you then add copper busbar you need even more energy/heat.
In general its about picking a soldering iron with alot of mass in the tip and also in the rest of it. Atleast 50W but i generally state that 75-100 or even 150w is better. We do not want to heat the cells more than needed and to do that it need to go fast.


Regarding soldering irons I also made this video earlier:
 
daromer said:
Good that you take it right :) We are all here to learn.

The heat of the soldering iron as such is not the big thing. Ie F/C. As long as it can melt the solder thats hot enough.
Its about having enough mass/energy so you can heat up the object so the solder actually flows out. When you then add copper busbar you need even more energy/heat.
In general its about picking a soldering iron with alot of mass in the tip and also in the rest of it. Atleast 50W but i generally state that 75-100 or even 150w is better. We do not want to heat the cells more than needed and to do that it need to go fast.


Regarding soldering irons I also made this video earlier:
Thank you for the tutorial videos ! Subscribed !
I now understand better what you mean, solder needs to be more of a puddle and less of a ball. I redid the welds, only took 10 minutes or so but saved me hours of headaches later for sure. Thank you dagomer !
 
Quick update on my project. I now have 4 x 80P modules (4x20) soldered and tested. No shorts and they have been resting for 5 days now and still show 4.13V (I charged them at 4.14V). Pictures to follow.

In the process of testing I noticed an offset with the 4 Opus chargers i have (of +0.02 V to 0.05V) so they may have been overcharging my cells since they stop at 4.2V but may actually be above that.
 
i would say that you are lucky if the opus chargers are within 0.05V :) Thats pretty good for that price. Mine differ alot more.
 
I did not realize that ! Is there anyway to prevent them from charging to 4.2V (they actually seem to go over in my case by minimum of 0.02V) ?
 
no you cannot change that.

And its not that of a big deal i must say. That little 0.02 does not make any significant difference for 1 test.
 
There is no such thing as at xx it is totally damaged. The higher you go the less cycles you get kind of. For normal use the manufacturer have set it to 4.2V.
 
Thank you Daniel. What kind of pack holder do you recommend. I like the ones I see on HBPOWERWALL but I since I'm using the 4x5 plastic cell holders they pack holders need to he either 4 or 5 cell deep. I think they come in 7 deep...
 
every dischargerI've used has been different some by 100's of mah not so much of a problem if your testing for good v bad cells. How every if your using rePackr to build balanced packs it won't work very well for you.

NB: I've used plumbers solder 50/50 on every one of my cells ..lol
 
Back
Top