faking a full battery for charging circuit

[kolonelkadat]

I recently got a bts-06 bluetooth speaker on ebay with the in tention of repurposing it. I absolutely do not want the battery as part of the new device. With battery removed and powered from 5v in, it runs for a spell and then shuts off.

I know Li ion batteries are like 3v6 - 4v1 or there abouts. But is it safe to connect my ~5v supply to the battery pinouts or is there some other trickery i should employ?

Ive tried looking up datasheets to no avail.

[DavidMenting]

The battery charging circuit most probably measures the voltage of the battery to determine a fully charged state. A fully charged Li-ion battery will never reach 5V, so the circuitry might not be able to withstand that.

To drop the 5V down to 4. something Volts, you could connect one or two diodes in series or hook up an LDO regulator set at 4.4V or thereabouts.

[Delta]

Replace the battery with a biggish cacapacitor, then power the device as normal (via usb?).   The cap should keep the charging circuit happy by giving it something to squirt current into and watch the voltage rise...

[kolonelkadat]

Replace the battery with a biggish cacapacitor,

very clever. this seems to have done the business. I wish i had bigger than 4700uF caps laying around though.