Battery Pack Pwr supply

[HVAC Controls]

Hello, I have a very humbling question about a battery pack for which my daughter lost the charging supply. Just a wall mart 2400 MAH battery pack for phone/laptop charging. I use this thing consrtantly. It uses a 16.8v 2a charger, which I'm waiting for the mailman to deliver but which is taking forever.

So- in wanting to just cobble something up for short term use I grabbed an old 12v (2.5a) power supply from a ROKU and a 5VDC (2A) supply from....a drawer...and ran them in series for 17 VDC @ 2A. Unfortunately it doesnt work, it appears to start and then generate an LED flash code (which I cannot seem to decipher, no mention of codes in manual). Thought maybe it was floating away from something with a ground reference so I tried grounding the neg to earth and chassis, nothing there.

Polarity is correct for the standard (outter barrel on plug is neg). Wife just showed me how shes been using an 18v (.2A) that fits the plug but takes all day (I thought maybe the .2 was triggering a sensitive overvoltage, nope)

Any advise Anyone could offer, more for me to learn at this point, would be greatly appreciated. Thank you.

 

[barry]

Have you actually measured 17V?

 

[betwixt]

Two possibilities come to mind:
1. if a ground is connected and one side of the outputs is internally connected to it, you are shorting out one of the supplies.
2. (more likely) the supplies are not both able to maintain output voltage, the weaker one may be 'back driven' by the current of the dominant one.

Brian.

 

[Audioguru]

You did not say the battery chemistry. It might be a 4 cells Lithium or a 12 cells Ni-MH or old Ni-Cad.

A lithium battery usually has a 5-wires balanced charger so that each cell is never overcharged. The current must be limited and when it drops to a low amount the charger should disconnect. 16.8V is the absolute maximum voltage to prevent an over-voltage explosion and fire. You are lucky that the charger detected that your 17V or its current is too high.

A Ni-MH or No-Cad battery also needs its charging current current limited to avoid a damaged battery.

 

[HVAC Controls]

Have you actually measured 17V?

Yes sir.

--- Updated Nov 27, 2021 ---

Two possibilities come to mind:
1. if a ground is connected and one side of the outputs is internally connected to it, you are shorting out one of the supplies.
2. (more likely) the supplies are not both able to maintain output voltage, the weaker one may be 'back driven' by the current of the dominant one.

Brian.

Thank you Brian. It occurs to me now that ive never seen these exposed to full load because the fault condition they interlock to- that condition only demands enough to run the blinky alarm. Certainly a dip could have proceeded my measurement and lead to lockout.

 

[MSPWebstore]

A battery is an electrical device that stores energy and converts it into electricity as needed. It supplies power to devices such as laptops, mobile phones, and tablets. There are many types of batteries but the most regular ones are lead-acid, nickel-cadmium, nickel-metal hydride, and lithium-ion.

Battery life is determined by a number of elements like the size and type of the battery. The performance of a battery will also depend on how much it has been used and how much strain was put on it.