Passthrough charging-simple but impossible to achieve?

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I have seen parties at a park with a loud sound system powered from a car's lead-acid battery carried in a wagon.
I have seen dead-battery cars started with a small portable Lithium battery. The small Lithium battery can do both.
 
Spartacus1917 said:
I'm also assuming that commercially produced bluetooth speakers that operate from mains DC adapter or internal Li batteries have been rigorously engineered and tested for safety reasons
Click to expand...
As the old saying goes, 'assume' makes an ass of of you and me.

I would imagine every bluetooth speaker is made in China (or at least the Far East), and there's certainly no rigorous engineering or safety testing over there.

I knew the head of the UK branch of a big multi-national electronics company, and they started having TV's made in China/Taiwan/Korea - so they approached the factories to ask how much it would cost per unit for CE certification. The answer was about a penny - just the cost of the sticker - no tests would be done, just fitting a sticker on it.
 
Nigel Goodwin said:
(some text removed for clarity)
I would imagine every bluetooth speaker is made in China (or at least the Far East), and there's certainly no rigorous engineering or safety testing over there.
Click to expand...

Would you believe that some manufacturers over there don't bother with formal safety tests and some even use the safety marks though not authorized to do so?

I had an MP3 player that had an internal lithium battery and it could charge and play at the same time. After reading the instructions and warning, I realized that there was probably no "real" charging circuit in it beyond a resistor. Unhappy with the lack of overcharge protection, I scrapped it for a few parts.
 
You're right - only the cost of affixing the sticker.

As we neared the product release date an engineer tested a CRT display made in Korea by one of the leading manufacturers of such products and found that it did not meet the U.S. DHHS requirements for X-Ray Safety. How could that be? That test can be done by anybody anywhere, but somebody has to sign the submission which apparently included phony test results. That resulted in a Saturday meeting with a lawyer in which we regrettably decided to delay the product introduction until the product passed the tests. As one member of the team said "I would not trust them any further than I can throw them."
 

There was a member on here (can't remember who?), who worked for an American company having toys made in China - the first shipment was fine, luckily they checked the second shipment as the Chinese had used leaded paint on that batch. It wasn't that long ago either.
 
No, sorry.
It needs a charge controller as well as the balance/protection board.

The charge circuit has to exactly set the voltage applied to the battery, and limit the current to a safe level when the battery is not at full voltage.

It's only fully charged when at the correct voltage and the current has dropped right down.
 
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