Well, I’m not upgrading the battery pack. I’m donating the 914 to Formula Slug instead (https://www.formulaslug.com/). They are the local University EV enthusiasts, and they are totally interested in working on Sparky. I’m donating the car and a lot of extra parts. They get the joy of finding a battery for it, and spiffing up the car.
This is a bittersweet moment for me.
Not proud to admit this, but my battery pack is not just dead, but very dead.
I now have to recycle 102 CALB60AH batteries. They were not doing well before I moved, and were neglected during the moving. A friend stopped by to help with removing the batteries, and they were so swollen that it has been very difficult to get them out of the boxes.
I was able to save 3 from the entire pack.
On the plus side, she did bring two large boxes filled with CALB100AH, so now I have to go hunting for the rest to fill my pack.
I’ve been wondering why the BMS light will partially light up for the last few months. I’ve been busy, so I didn’t follow up on it. However, when driving home last week, the BMS alarm went off just before I was about to get on the freeway. I pulled off to a side-street, and called for a tow truck. While I was waiting, I started checking batteries, and sure enough – one was sitting at 2.94v, when the others were almost all a 3.3v.
Over the weekend I replaced the battery and now I don’t have the partial warning from the BMS. (The partial warning is where the BMS warning light just barely glows – it is a standard incandescent bulb. The full warning is when the light is full on and the audible alarm goes off).
Hmmm, so I got the new 12v battery installed with no trouble. Plugged it in, and it is now fully charged.
Time to charge the main pack. I plug in the pack, turn on the charger, and now it is making an odd hissing noise. I’ve contacted the factory to see what they want me to do. Meanwhile, the car is not a daily driver at all. *sigh*
The BMS was complaining about a battery for some time now, but when it got to the point where the complaint was EVERY morning, it was time to find out which one was bad. This is difficult when there are 108 of them. However, there is a method to finding the bad one:
Quite likely you will have identified the bad battery in step 3, but steps 5 and 6 will clearly confirm this.
What makes a battery go bad? If the battery is new, then it will fail within a month or less. If the battery has been in the pack for a while, then it has received some form of trauma (such as a connector flopping on and off or been hit or something like that).
In my case, the battery had a loose connector, which caused one of the bars to bounce on and off the battery. This is a Bad Thing ™. To see why, check out this photo:
The controller is still working – the problem was in the potbox. Apparently, the cheaper potboxes can have the rheostat inside slip. Who knew?
I’ve replaced the old potbox with an all-in-one pedal and potbox from Curtis. Nice solid construction, but I’ll need to work on the position of the box – the cable from the box is currently under my foot – not good.
Well, I had to get the car towed home yesterday. Symptoms: gradual decrease in power until the motor was no longer spinning. Fortunately, I was in the right-hand lane of the freeway and was able to pull off on an offramp.
Lessons learned:
1) Check the batteries of your test equipment on a regular basis. My portable voltmeter’s battery was dead.
2) Keep your towing service – you never know when your car is gonna stop working. AAA was excellent and only took 15 minutes to arrive.
I REALLY hope the controller isn’t dead, as I didn’t want to buy a different controller just yet. At least I’ve got a lead on a (hopefully) more reliable one. Nothing solid yet.