Ebike battery charger (li ion)

Hey all,

I want to build an ebike battery charger (made from li ion cells). The battery would be approximately in the 14S3P configuration. What I'm currently thinking is using a AC to DC module who's output connects to a CC CV buck converter, which connects to the battery. This is done for every series stage of the battery. The parallel cells won't short together as the AC to DC converters provide DC isolation.

The charger in this video uses the same method:

What do you think of my approach and is there a better way to do this?

ningaman151:
What do you think of my approach and is there a better way to do this?

Yes, buy a charger, and cell balancer.
Pack voltage AND cell voltage needs to be precise, and current must be reduced when cells are below ~10% and above~90%, to prevent the pack from bursting into flames. A Li-ion charger is not a task for a beginner.
Leo..

Wawa:
Yes, buy a charger, and cell balancer.
Pack voltage AND cell voltage needs to be precise, and current must be reduced when cells are below ~10% and above~90%, to prevent the pack from bursting into flames. A Li-ion charger is not a task for a beginner.
Leo..

What? I'm making my own charger. I'll be using the same charger concept as the one in this video:

But obviously having 14 series stages opposed to 3. (Also 3 parallel instead of 2, but that is irrelevant)

A 14S 58.8volt/2Amp (double the charging current) e-bike charger is ~US$20 on ebay,
and a proper balancer is another ~US$10.
You decide if a cobweb of 14 supplies and 14 charger modules is a 'better' option.
Leo..

An EBike Li-Ion battery will have a lot of energy and cause a really big fire if it is mistreated. Buy a charger from someone reputable whom you can sue for damages if it goes wrong and burns your house down.

...R

Wawa:
A 14S 58.8volt/2Amp (double the charging current) e-bike charger is ~US$20 on ebay,
and a proper balancer is another ~US$10.
You decide if a cobweb of 14 supplies and 14 charger modules is a 'better' option.
Leo..

From what I've seen, it has been advised to not use Chinese battery charging or balancing electronics.

Robin2:
An EBike Li-Ion battery will have a lot of energy and cause a really big fire if it is mistreated. Buy a charger from someone reputable whom you can sue for damages if it goes wrong and burns your house down.

...R

I'm a complete newb when it comes to knowing reputable sources of battery charging kit. Can you point me in the right direction please?

ningaman151:
From what I've seen, it has been advised to not use Chinese battery charging or balancing electronics.

And using a bare 'Chinese' power supply board and 'Chinese' charge controller board is ok?

ningaman151:
Can you point me in the right direction please?

I have no knowledge of suitable chargers for large Li Ion batteries. I have some tools with Li Ion batteries and I use the charger that came with them. Also I NEVER leave the batteries on charge when I am not present, or when I am asleep.

...R

Wawa:
And using a bare 'Chinese' power supply board and 'Chinese' charge controller board is ok?

You are right on that one, there's the risk regardless. But I think (correct me if I'm wrong) changing each stage separately (4.2v) is safer than having a Chinese bulk charger (58.8v).