LEDs pulsing

letschat7

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I have some lithium AAA batteries that are rechargable and I'm running them in a Coast flashlight. I understand the Coast can handle lithiums running at 1.7v. Yet this pulses or lightly strobes when turned on. Shouldn't the batteries be regulation and provide nice consistant light that doesn't slowly get dimmer and dimmer?
 

Dave_H

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Specifically what type of rechargeable Lithium AA's are you using? I don't have any, but are they not supposed to output 1.5v (not 1.7v you mention)? Which Coast flashlight? Not enough info.

What is output capacity of the AAA's versus what the light needs? Sounds like cells may not be able to supply enough current.

Dave
 

letschat7

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Don't know the model, XTAR batteries.
 

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Macgravy

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From you attachments, the batteries seem to be a regulated (to 1.5v dc) lithium ion batteries. AAA batteries of this type have safety things in them for over current and such. If you flashlight draws more than the over current safety on the the battery it will shut down. For this type of battery about 1.5 amps is over current. I believe from your attachments that there are 3 batteries (Just guessing) are in series, making 4.5v dc. That would seem correct for lighting an LED. I'm going to guess that you flashlight is pulling to much current out of the AAA batteries.

Now, the lithium 1.7v dc batteries that you refer to are known as Lithium Iron Sulfide (ie, Energizer type). They are relatively safe and come without any protection circuits. But they too have an over current of about 1.5 amps. They won't go into shutdown, all these do is drop their voltage due to their internal resistance.

I do have a hard time believing that this flashlight will draw all that much current from AAA batteries. Maybe try this flashlight with alkalines to see if they work at all. Alkalines should be ok too, but will not last long if this flashlight draws a lot of current. If you put in a set of fresh alkalines and it doesn't light, then there is a very high current draw. The next step is to try the Energizer type lithiums. These are pretty expensive today after covid for some reason. (Maybe supply chain stuff).

If there is another regulator inside the flashlight (or a driver circuit), that may have developed a problem. Of simply, you may have the strobe turned on....maybe a reset to that driver circuit needs to be done. Try tapping the button multiple times to clear out of the strobe.

I know, I'm long winded. Sorry about that.
 

Macgravy

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OK...So it's 6 volts....Be that what it may, those rechargeable(?) batteries that you show are still limited to like 1.5 amps...they are still in series...

Now, after going to the Coast website...This seems like something of what they call a Pollysteel Flashlight. There are a number of them. Currently there are the 200, 400, 600, 1000 series....they seem to come in all sorts of colors...the 200 series are not rechargeable and take 3 Alkaline cells only...the 400 series seem to be closer to the one shown..the 600 series has an entirely different battery carrier from what you show...the 1000 series is a 9 AAA type carrier, so the 400 series might be yours....and takes 4 Alkaline cells or 1 special rechargeable cell in a special carrier.

What you are showing are 1.5vdc rechargeable(?) regulated cells...I guess...It would be nice to see another picture or 2 of the battery types that you are using outside of the carrier. I'm guessing that your not using the rechargeable type that Coast recommends...and you just inserted the rechargeable cells into the Alkaline carrier....and hoped it would work....I'm guessing that doesn't work...and that is what brought you here.

Once again, I would try the Alkaline batteries in that carrier and check to see if that works...Have you tried that?
 
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