Did I do something wrong? Battery test

I wanted to "test" whether or not a Magic Shine bicycle light had some type of "cut out" to protect a battery prior to the Li Ion battery pack's own circuit shutting off. My results were perplexing......

The light was set in front of a fan and set to medium - at which time with a fresh battery it began drawing .62A at 8.1V.

Hours later, I discovered the light to be drawing .80A at 6.4V I had expected that the light would be shut off by the battery at any minute.

I went to get another cup of coffee and returned about 10 minutes later to discover that the light was "blinking " and the voltage had dropped out to 5.5V.

Does this mean that the 4x18650 Li Ion battery pack failed to protect itself from low voltage overload? After disconnecting the light I watched the unloaded battery terminal voltage climb to about 6V after fifteen minutes.

What's the deal? What did I ruin now?

Go to the following and search on Magic Shine. There is a wealth of information there.

CandlePowerForums > Beyond Flashlights > Transportation Lighting > Bicycle

Burpee - you ignorant slut -you don't deserve any answers on the Candlepower forums.

Your questions are ignorant and aren't deserving answers. Go away stupid!

And don't PM veteran thread writers with your lame comments either.

Take your dumb requests and go!

:huh2:

(unless this is a SNL reference)

burpee said:

I wanted to "test" whether or not a Magic Shine bicycle light had some type of "cut out" to protect a battery prior to the Li Ion battery pack's own circuit shutting off. My results were perplexing......

The light was set in front of a fan and set to medium - at which time with a fresh battery it began drawing .62A at 8.1V.

Hours later, I discovered the light to be drawing .80A at 6.4V I had expected that the light would be shut off by the battery at any minute.

I went to get another cup of coffee and returned about 10 minutes later to discover that the light was "blinking " and the voltage had dropped out to 5.5V.

Does this mean that the 4x18650 Li Ion battery pack failed to protect itself from low voltage overload? After disconnecting the light I watched the unloaded battery terminal voltage climb to about 6V after fifteen minutes.

What's the deal? What did I ruin now?

Click to expand...

If you had 4 x 18650 starting at 8.1 Volts, then these were in a 2s2p configuration to give double the capacity. Then not knowing what kind of protection circuit they added to the pack, I'm assuming the typical discharge protection triggers and breaks the circuit at 2.5V/cell (or 5.0V for your pack--but their protection circuit may monitor each parallel pair for 2.5V separately).

I'm not sure if they put in a "low voltage" warning to explain the blinking, but when low voltage protection breaks the circuit, as the battery voltage recovers back up to 2.8V, the low voltage protection circuit break will reset. So continued draining after it resets will drop the voltage down to 2.5 and trigger another protection break, and so on. That may have caused your blinking if it was at a slower rate. Faster blinking would likely be a low voltage intentional signal.

Also, if you keep Li-Ion batteries below 2.7V, they will sustain damage in proportion to how low, and for how long they go below 2.7V, so you want to stop using them either when you see your light dim, or the first protection shutdown occurs. That would allow the cells to only be at the 2.5V damage level for a brief time, before rebounding back above 3.1V and avoiding any damage.

burpee said:

Burpee - you ignorant slut -you don't deserve any answers on the Candlepower forums.

Your questions are ignorant and aren't deserving answers. Go away stupid!

And don't PM veteran thread writers with your lame comments either.

Take your dumb requests and go!

Click to expand...

I'm not sure if they put in a "low voltage" warning to explain the blinking, but when low voltage protection breaks the circuit, as the battery voltage recovers back up to 2.8V, the low voltage protection circuit break will reset. So continued draining after it resets will drop the voltage down to 2.5 and trigger another protection break, and so on.

Click to expand...

Thanks, for some reason I thought most individual cells had a cut out at 3.0V. This I thought would result in the battery "cut out" at somewhere near 6V.

The reason for the testing is these lights have seem to have very little conformity or QC. I've had the same model light produce its "low battery" button red light at 7.5V, but the first one I had went down to 7.2V before coming on.

I was using the light on an all night ride and had the low battery light come on at 4AM when in fact the lights still had nearly 50 per cent capacity. Hence the "testing." Other high quality batteries I use "lock out" at 6V and won't come back on until they receive a charge or sit for many hours.

Now I'll take all my stupid questions and get out of here so all you cool flash light guys can talk about your "bucks" and "flux". AH -boo-hah......