The battery builders club

How-Tos & Esk8 mechanics
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#18967

are you sure its still charging? what are the p-group voltages?

#18968

Maybe you did fry those 3 cell packs

#18969

Heard quite a few stories of it fraying and breaking.

I love braid. But not for connections like that.

One of these packs will have some braid connections

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1 Like
#18970

I replaced the 3rd to last and the other 2 still test properly

#18971

Charging light is on at the charger. P-groups are between 3.7v and 4.2v

#18972

Its not charging because you have groups at 4.2.

Its either trying to balance, or probably just doing nothing.

When you assemble a pack, all the voltages of each individual group should be as close as possible

3 Likes
#18973

Really? Hmm will take it under advisement but I don’t see why a braided connection done properly would wear anymore than a silicone wire. Being done properly is probably the real kicker here though.

#18974

Search here and builders. You’ll find photos that back up my fears.

1 Like
#18975

I have set up that test rig to run continuously so I will put it to the test tomorrow.

#18976

Why wouldn’t it just not charge the group’s at 4.2 and only deliver power to the lower packs? isn’t that the point of a BMS?

#18977

No. It doesn’t work like that.

Your charger is outputting the voltage equal to the voltage of all series summed.

What BMS does is to try to balance p groups by slowly draining voltage from some of the groups. So it i balansing by draining not charging.

4 Likes
#18978

Nope, most don’t work like that

2 Likes
#18979

Not really how it works

#18980

So do I just hook up the low packs to a charger and bring them all up to 4.2v individually?

#18981

That test rig isn’t testing what i believe to be the true causeof connections like that breaking.

Lemme make you a video

2 Likes
#18982

You can and then discharge the pack and then recharge the pack and watch how it charges

#18983

Ohhhh I love videos.

1 Like
#18984

Do I have to ride the board or can I use another way to discharge the pack? I believe I saw a “discharge” button in metr or VESCTool somewhere

#18985

You can discharge it however you want… but doing a real world discharge will also let you know of other problems with the pack. If there are any.

#18986

Far too wet and rainy here for riding. I’ guess I’ll discharge the indoors way. I need to invest in a treadmill.