Battery dangers?

AJ5258

New Member
I finally pulled the trigger and bought an Ebike. I bought a Giant LaFree+1. I picked it up yesterday and after getting everything finalized, and as we were loading it into my car, the guy tells me to never leave the battery charging overnight because it could catch on fire. With everything I’ve read about Ebikes I have to admit that I’d never seen anything even close to this advice. Is he way off base or is this a concern?
 

MarkF

Active Member
Battery fires are very rare and I have yet to hear of one that was started by a charger on this forum. It would take a faulty charger to over charge a battery. If you had one, it would over charge the first time you used it. I will say it's not a bad practice to unplug your battery when it's done though. I charge mine over night when I forget to charge my battery earlier in the day before a ride because I'm not worried about me charger.
 

Ken M

Well-Known Member
I believe most battery fires are from serious shorts from damage to a cell that results in the electrolyte catching fire. I do agree with the earlier comment that it would take a seriously defecting charger to cause a battery to catch fire.

That said just keep your ebike away from major flammables wherever you park or store it. I think there are few videos on the internet of ebike fires and you can get an idea of how much clearance is needed to ensure they don't ignite a home fire.
 

Solom01

Active Member
You know I've never had a house fire that burned down my house...but I still have fire insurance because the consequences of not having insurance would be so horrific. Regardless of the brand of bike lithium battery fires are scary and not leaving any large lithium battery plugged in all night is just a commonsense thing to do. People do that with EVs but those are more complex and expensive and have quality BMSs that shut down the charger when it's full. If you can't remember to charge your bike any other way spend a few bucks on a timer that will turn the charger off after a set number of hours. Besides the safety issues, charging lithium batteries to full capacity is bad for the battery's life span, so you'll also extend the life of your battery by not keeping it plugged in overnight.
 

Timpo

Well-Known Member
Battery fires are very rare and I have yet to hear of one that was started by a charger on this forum. It would take a faulty charger to over charge a battery. If you had one, it would over charge the first time you used it. I will say it's not a bad practice to unplug your battery when it's done though. I charge mine over night when I forget to charge my battery earlier in the day before a ride because I'm not worried about me charger.
Even if you had a faulty charger, wouldn't BMS shut it down?
 

Mr. Coffee

Well-Known Member
My $0.02

It has been years since any of the major e-bike manufacturers has had a safety recall due to a battery defect (please correct me if I am wrong, but the last one was in 2015 with respect to some Pedego batteries). In the meantime quite literally millions of e-bikes have been sold.

My own opinion (and you can and should take it with a grain of salt) is that the risk of a battery fire is tiny unless the battery has been damaged (which usually means it has been dropped), someone has made unauthorized modifications to the battery or the charging apparatus, or it is stored in an extremely hot location. I'd personally be more stressed about leaving batteries in a hot car on a sunny day than by charging it overnight.

Worldwide, I'd guess in that last three years hundreds of e-bike riders have had fatal accidents. I doubt there have been more than a few dozen battery fires, and probably no more than a handful that have involved name-brand bikes or batteries. So if you want to focus on risk consider what is happening when you ride, not what happens to your bike when it is parked in your garage.
 

AJ5258

New Member
Great replies. Thanks to everyone. I live in the Phoenix area and have no plans to leave the battery in my garage which routinely gets over 120-130 degrees in the summer. I keep the batteries for my leaf blower and hedge trimmer inside until I use them. That said, I really never planned on leaving the battery hooked up to the charger inside indefinitely either. I was just taken aback when the LBS told me that I should never charge it overnight. It sounds as if there’s no real known dangers and charging the battery for 6 hours or so isn’t an issue. It’s just better to do it when I’m awake......just in case.
Thanks everyone!
 

rich c

Well-Known Member
They said on the news tonight that investigators are looking at lithium batteries and chargers as a possible cause of the fire on the dive boat in California.
 

AHicks

Well-Known Member
It's not really "bad" for it... it's just that charging to 80% every time or most times will extend the life of the battery.
I see this thought, and it's not that I disagree totally, it's just that concept needs to be tempered a bit, with the idea of balancing the cells. The balancing is done on the tail end of the charge, probably starting around 90% if i were guessing. If the charge is cut off at 80% on a regular basis, that battery is not being balanced, which could actually shorten it's life.....

Do as you like, but keep the need for balancing frequently in mind......
 

AlanDB

Well-Known Member
I don't know the answers, but for convenience and maximum range, I top off my batteries every time I charge during the active riding seasons. In the winter, I store them with a partial charge (60% to 80%), keep them inside (65 to 70 degrees) and check them monthly to make sure there isn't a drainage problem. Last winter I did not need to put them on the charger at all as they didn't lose much of the charge while stored for 4 or 5 months. This spring I just topped them off before the first ride.