Charging non ballanced 3S Li-Ion packs

[Razvan]

I know it's a silly question and I already know the answer but I've been laughed in my face for stating that is wrong and dangerous. I've been banned from groups for raising awareness and threaten by this so called battery specialists.

Long story short:

There is a company in UK that sells RC Boats - more precisely bait boats.
They come with 3s Li-Ion packs with no BMS (they can't use a bms on them cause the cut off can leave the boat stranded on the water when battery low voltage cut off)
I know there is a simple solution for this to just use a BMS for charging and leave the discharge unprotected.

Now the problem is they are selling non balanced chargers with the batteries, I just bin mine and I'm using a proper iSDT charger but most majority of their customers are using those mains non balanced chargers.

On top of all this there is a person who is selling solar panels for these batteries with Chinese charge controller that he set up for 12.6v but again no balancing option.
I had a very strong dispute with him recently where I stated to stop providing those solar panel setups because he could hurt someone or in the best case scenario damage those packs prematurely.

I'm posting this here so I have some proper professional views on this, officially.

I am a mechanical-electrical engineer and I work for AWS dealing with industrial UPS/Power solutions ( mostly data centers) and I know exactly how a battery string works and how is managed but for some reason I can't make my point serious and I really think sooner or later someone will get hurt.


I attach here the pics with the battery packs and the chargers they provide also the solar panel setup this guy is selling. (he is saying he is an electrician but I think he has no idea what he is selling and how lithium packs are working)

Thanks for your time.

 

[sunshine_eggo]

Balance chargers have been used ever since 2S and larger Lithium batteries were used on RC items. Balance chargers are quite prolific and are the accepted way of safely charging these unmanaged batteries - just like you do.

Non-balance charging can be done safely if the cells are top balanced, but without monitoring, you can't know for sure. When balance chargers are used routinely, a top balance is generally well maintained and balance charging it's necessarily required each time.

I recently had to charge three 5S DeWalt 20V MAX batteries without the stock charger that monitors cells. I took a risk and charged to 4.1V/cell (20.5V total). Fortunately, the cells were sufficiently balanced and showed very little deviation when I checked them after the charge.

Those products you linked could potentially be excellent sources for a battery fire if one is not aware of the risks and over-volts cells within a 3S battery that is not top balanced.

 

[Razvan]

So far I did not hear about any fires but I know for sure lots of packs are failing. I had some packs over from some anglers and I notice one string completely failed and those cells completely drained/damaged. Almost everyone who is using those non ballancing chargers report the packs are very hot when on charge.
Most of the people who are using these products are fisherman and they don't understand how balancing or top balancing works. They also have no clue how dangeros a 18650 pack can be especially in a tent or a car/van where these are usually charged.

My guess is later on when they start cycling the packs more and they become unballanced they will be fires.

 

[sunshine_eggo]

So far I did not hear about any fires but I know for sure lots of packs are failing. I had some packs over from some anglers and I notice one string completely failed and those cells completely drained/damaged. Almost everyone who is using those non ballancing chargers report the packs are very hot when on charge.
Most of the people who are using these products are fisherman and they don't understand how balancing or top balancing works. They also have no clue how dangeros a 18650 pack can be especially in a tent or a car/van where these are usually charged.

My guess is later on when they start cycling the packs more and they become unballanced they will be fires.

Agree.

 

[740GLE]

You can’t prevent stupid.

I also fear the increase in e-bike fires will continue to rise and making headlines.

 

[sunshine_eggo]

So far I did not hear about any fires but I know for sure lots of packs are failing. I had some packs over from some anglers and I notice one string completely failed and those cells completely drained/damaged. Almost everyone who is using those non ballancing chargers report the packs are very hot when on charge.
Most of the people who are using these products are fisherman and they don't understand how balancing or top balancing works. They also have no clue how dangeros a 18650 pack can be especially in a tent or a car/van where these are usually charged.

My guess is later on when they start cycling the packs more and they become unballanced they will be fires.

Sounds like an educational opportunity. There are some really cheap balance chargers, like the imax B6 clone. Probably cheaper than new batteries.

 

[Razvan]

I agree, there are plenty on the market. All my friends are using them but majority are using the provided charger or those solar panels. I guess they have to find out the hard way. Just today one person on the group was complaining that his battery is not charging anymore and he put a picture with the solar panel and the charge controller directly connected to the battery. I pointed out to him that what he is doing is wrong and probably that's why the battery failed in the first place, immediately I was attacked by the person who is selling those solar panels telling me to mind my own business because nothing is wrong with the setup. At the end the admin deleted the post.

 

[Razvan]

here we go another post just now on the group:

X-Boat owners club | Are my batteries charging while the red light is flashing

Are my batteries charging while the red light is flashing. I’m sure it use to stay solid when I charged them last time

www.facebook.com

I hope it's ok to post here the public link, if not please let me know and I'll remove it but it's a great example on how to burn down a house.

 

[sunshine_eggo]

Am I seeing batteries being offered without balance leads?

 

[Razvan]

Am I seeing batteries being offered without balance leads?

They do have balance leads but some of them are in the plastic case. So the battery manufacturer know what they are building.