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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 17th Dec 2018, 2:56 pm   #1
ITAM805
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Default What could go wrong?

I wonder how many people have tried fitting 2 fully charged 18650's as described by the indents?
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Old 17th Dec 2018, 4:08 pm   #2
G8HQP Dave
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Default Re: What could go wrong?

Two things to say about this:

Why is there not a standard for multi-cell holders? I.e. all the same way round, or alternating. Annoying that you have to check every time, or assume that the spring end indicates negative.

Why do they expect us to be able to see black-on-black indents at the bottom of a piece of plastic which stays mostly in the shade wherever you put the light source?

Actually, make it three things to say:
How is the end-user supposed to know what to do if the near-invisible indents seem to disagree with where the springs are?
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Old 17th Dec 2018, 4:47 pm   #3
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Default Re: What could go wrong?

At least the holder shown appears to have an insulated guard round the non-spring positive terminal, which should prevent it from operating in reversed polarity.
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Old 17th Dec 2018, 5:07 pm   #4
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Default Re: What could go wrong?

No isulation Dave, it's a bonfire just waiting to happen
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Old 17th Dec 2018, 5:35 pm   #5
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Default Re: What could go wrong?

Are Li cells meant to be used in parallel anyway?
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Old 17th Dec 2018, 5:43 pm   #6
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Default Re: What could go wrong?

Quote:
Are Li cells meant to be used in parallel anyway?
Yes, and it works well. there is a common terminology for RC (radio control) packs, 3S2P means 3 in series 2 parallel, the cells are paralleled first so the balancing circuit can work. All intermediate stages are taken out to a small connector for cell balancing.
 
Old 17th Dec 2018, 6:02 pm   #7
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Default Re: What could go wrong?

Well, I never knew that, thanks.

That holder's still an idiotic thing to release into the wild though!
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Old 17th Dec 2018, 6:39 pm   #8
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Default Re: What could go wrong?

Also Nick I think most laptop battery packs are 3S2P
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Old 17th Dec 2018, 6:48 pm   #9
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Default Re: What could go wrong?

Parallel 18650s are common in mobile phone external battery packs (the sort that have a 5V USB socket).

That holder is indeed a fire waiting to happen. I wonder if it could be a production line assembly error?
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Old 17th Dec 2018, 7:08 pm   #10
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Default Re: What could go wrong?

Looks like an assembly/picking mistake to me. Plenty of the workers are producing things that they don't necessarily understand, and before you know it 1,000 units have gone out of the door before online feedback suggests something is wrong.

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Old 17th Dec 2018, 7:25 pm   #11
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Default Re: What could go wrong?

Yes i agree...it looks like a friday afternoon product rather than deliberate design. The iffy side has a black wire from the spring, which is right...or wrong. I think its a duff unit

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Old 17th Dec 2018, 7:40 pm   #12
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Default Re: What could go wrong?

Forum rules forbid naming and shaming but I ordered a pair of the usual series type and they were depicted as such on the page, but they're both constructed this (wrong) way, so one wonders how many have escaped into the wild?!
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Old 17th Dec 2018, 8:02 pm   #13
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Default Re: What could go wrong?

It looks like a conventional series holder with an incorrectly fitted link. Easy enough to fix, but obviously dangerous if somebody didn't notice it. The only positive thing I can think of is that the heat from the short circuit would probably melt the plastic and break the circuit before a real fire started.
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