Sulfur smell when charging

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tsimpson1

New member
Joined
Mar 23, 2021
Messages
2
Hello
I wanted to share a fix.
My 2015 i3 rex was producing a strong sulfur smell intermittently during charging. I knew from past experience it was battery related from the smell.
I could not find anything about lithium batteries odor on google, I knew the car had a separate lead acid battery for the lights, fans, heat, etc.
I removed the left cover under the frunk after charging the car. The battery was extremely hot.
The connections were very loose.

the fix - please be aware that this is a risky repair, battery gas is explosive. I witnessed a battery explode. Its very loud, powerful, and acid, lead and plastic are blown everywhere. If it happens close to you, you will be covered in acid, and some of the battery will probably go under your skin.

In a very well vented area, I disconnected the safety switch for the car on the right side, removed the lead acid battery bracket, you can slide the battery slightly forward and access the positive terminal. make sure the 10 mm wrench does not touch anything, wrap the handle in tape to protect it. After pulling the pos terminal off, you can move it further forward and undo the neg terminal, pull it out and clean the posts, my neg had pitting and corrosion, do the same for the terminals, you want them shiny. I used some battery grease to prevent future corrosion. Reverse the steps, again, being careful with connecting the positive side. re connect the reconnect the safety switch, re set the clock,
 
It's easy to remove the negative battery cable first. This can be done without sliding the battery forward. Then one wouldn't risk electrical arcing should the wrench removing the positive cable touch ground.

Also, there's no liquid sulfuric acid in the i3's AGM battery. Unlike in a typical flooded-cell battery, the sulfuric acid is absorbed into glass fiber mats between the lead battery plates which would greatly reduce the risk of acid burns should an explosion occur. However, each cell in the i3's battery has a pressure relief valve that should prevent internal pressure from increasing enough to explode the battery, so the explosion risk should be minimal.

Loose battery terminals shouldn't result in a hot battery and sulfur odors. These symptoms suggest an internal short circuit or another internal battery problem that resulted in one or more cell pressure relief valves opening due to high internal pressure. This can't be fixed. A replacement battery is almost certainly needed.
 
So.... what was the "fix"?
Did you install a new battery?
I don't see that listed anywhere. All I see is that you removed the old one and then cleaned the posts.
 
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