Hey everyone, TL;DR: I replaced my VESC, added a charge port fuse, and my charger’s red and green light are both on during charging (before only the red light was on during charging). The charger continued charging for 5 minutes after the remote showed the board at 100%. Should I be worried/what would you do?
Long version:
After replacing an Eovan VESC (original problem thread here, link to board-in-question here), one thing I’ve noticed is that the charger’s red and green light are both on during charging. I don’t think this is normal so I kept a close eye on the charging process today (first full charge after new VESC). When the board reached 100% on the remote, I noticed the charger wasn’t stopping (here is a video of the charging lights and board readout). I let the board charge for about 10 minutes after I originally saw 100% and it still didn’t stop, so I pulled the plug. Do you guys think there’s any cause for concern?
Here is some relevant info:
My problems started when I shorted my charge port by dropping a micro USB exactly in the open charge port (yes, actually). There was a spark and a couple second flame from the port melting. No visible internal damage or heat exposure.
The board worked for a couple miles after the short, but then one of the motors began twitching and provided a huge amount of drag when riding.
I switched the motor wires and ran motor detection (to see if the problem was VESC or motor-related) but the VESC started smoking during the detection. I immediately powered off, disconnected, and the VESC was shitcanned and replaced.
The new VESC took 2 months to arrive, so the board was sitting on 95% charge with no way of discharging, not sure how problematic that was.
When the VESC arrived, I installed it, and then enlisted my dad (retired aircraft mechanic) to help me fuse the new charge port (we fused the red wire per his advice). The charger is a 5A charger and based on that he said to start with a 5A fuse and see.
Questions:
Could I have a problem with my BMS due to the short?
Could adding a fuse on the charge port have caused an issue with the charging?
Is it the charger or BMS that determines when charging is complete?
Could it just be that I’m being overly worried and my BMS is just balancing the cells or something after long-term storage and maybe that’s why the charger is still on?
The replaced Eovan ESC (third party VESC compatible) should not have anything to do with your issue.
To avoid the long wait, you should probably have replaced it with a VESC or another available third party VESC compatible unit. 2 month is really frustrating…
The BMS should have a mosfet switch on the charge port side and should decouple the charger from the battery once the cells are full. It should also decouple the charger if one cell group is in an overcharged state. A short can easily damage the BMS and the all sorts of funny things can happen. The charger should also sense the pack voltage and stop charging when the total pack is full. However, one cell group can be overcharged while others are not yet full. In combination they look like nearly fully charged cells. The charger would still continue to charge and the overcharged cell would be pushed into the danger zone. This is where the BMS would react and decouple the charger. If that function is damaged, you should replace the BMS or the entire battery. I guess the BMS is integrated into the battery.
A fuse has no impact on the charge. You can drop a 10A fuse there.
Could it just be that I’m being overly worried and my BMS is just balancing the cells or something after long-term storage and maybe that’s why the charger is still on?
The company Eovan should really answer that question for you. They have to know… A balanced pack should actually not go aout of balance within 2 months time…
You’re probably right, but I was hesitant to select and program a 3rd party VESC without proper component specs for the battery and motors, especially as a beginner. I’ve asked for component specs from Eovan before and they tend to give incomplete answers or dodge my questions, especially for the battery. I remember asking them about the continuous discharge rating for their “Panasonic 21700” cells and they would just refer me to the website with the advertised “96A discharge”. Other people have commented that 24a discharge per cell is unreasonable and they’re either quoting the specs for actively cooled Tesla cells or it’s a burst discharge rating. I guess I could just find a VESC with overkill specs and pretty much copypaste the Eovan settings.
Thanks for taking the time to give your explanation.
I will explain the situation to Eovan and see what their response is. While their customer service has been above average so far (minus my package getting delayed) I have heard things from them that I know to be wrong. I find that if I gather advice here it prepare me for my conversation with customer service and get to the bottom of things faster.