Panasonic "supermarket" lights do not allow NiCd/NiMH?

[smootik]

I was near a flashlight shelf in supermarket, so I took a look at what is sold there.

A 2xAA Panasonic incandescent drew my attention because its package showed crossed out NiCd and NiMH signs. AFAIK this means Panasonic recommends not to use rechargeables (presumably only their own primaries). I can take photo on the next visit there.

Did you notice similar official restriction on other flashlights?

 

[LEDninja]

The M@gLED also has restrictions.

Many low end flashlight designers use the high internal resistance of alkaline cells as part of the circuit. Removing the resistance by using NiMH, NiCD or lithium batteries results in the lights functioning outside specs causing possible damage.

 

[Aussie Cheese]

but this is an incan, so it is direct drive. which these bulbs are rated for 1.2v per cell anyways, so rechargeable batteries are fine, the only problem they are referring to is the initial current surge which is much greater than a primary battery.

 

[Mr Happy]

I think one issue with rechargeable NiMH in lights, historically, is the high self-discharge rate. Most people put a light in a drawer, leave it for months, and expect it to work in emergencies. Prior to the new LSD cells, if they put NiMH in it they would most likely be flat when called upon. Another issue is the probability of people running the light down until it is dim. The average consumer will have no idea this is a bad thing and will damage the batteries, causing the batteries to deliver unsatisfactory performance.

Given that consumers expect a light to "just work" when called upon, it is easiest for the manufacturers to steer them away from rechargeable batteries (or else to make dedicated rechargeable lights with a built-in charger and charging cradle).

 

[Darkpower]

The M@gLED also has restrictions.

Many low end flashlight designers use the high internal resistance of alkaline cells as part of the circuit. Removing the resistance by using NiMH, NiCD or lithium batteries results in the lights functioning outside specs causing possible damage.

I noticed that warning with the mag-LED dropins as well. I have been using both NiMh and NiCd with the mag-lite LED and not had a single problem.

 

[Aluminous]

Another issue is the probability of people running the light down until it is dim. The average consumer will have no idea this is a bad thing and will damage the batteries, causing the batteries to deliver unsatisfactory performance.

How do you determine when to stop on NiMH usage in flashlights, if not by the light dimming? Or is this only an issue with the low-end supermarket-type flashlights, and not the better ones?

Perhaps there is some difference because of the applications, but when using NiMHs in my digital camera, I have often run them until the camera shuts itself off because of the batteries' lowness, and so far haven't seen any negative effects.

 

[Mr Happy]

The problem, when it exists, is with multi-cell devices. If the batteries are run down too low then one of them is in danger of being reverse charged by the others, and this is what causes the damage. Single cell lights do not have the same problem and you can run them until they are dim without worry.

The key question is how low is too low? In digital cameras there is a circuit that gives a low battery warning and automatically shuts the camera off before the batteries are discharged too much. In a flashlight there is usually no such circuit and they can drain the batteries right down to nothing (often they are designed to do so in order to extract every drop of power from alkaline cells).

The answer is to stop and recharge as soon as you see any noticeable drop in brightness. If the bulb in an incandescent light is starting to look yellow instead of white, then stop. If the bulb gets to orange or dim red you have gone way too far.

 

[snakebite]

i set up a neighbor with some 8ah panasonic high rate d nimh for their flashlights.
all was well till they dropped a cheap plastic eveready $.99 cheapie with a set of these in it.
the drop crushed the glass in the base of the bulb causing a short.
the strip along the barrel instantly turned bright orange hot,burned through the side,and caught fire.
no more lights with the battery in direct contact with the tip of the bulb base!
probaby a cya on panasonic's part.
those evereadys are a sorry excuse for a flashlight anyway!

 

[Aluminous]

The problem, when it exists, is with multi-cell devices. If the batteries are run down too low then one of them is in danger of being reverse charged by the others, and this is what causes the damage. Single cell lights do not have the same problem and you can run them until they are dim without worry.

The key question is how low is too low? In digital cameras there is a circuit that gives a low battery warning and automatically shuts the camera off before the batteries are discharged too much. In a flashlight there is usually no such circuit and they can drain the batteries right down to nothing (often they are designed to do so in order to extract every drop of power from alkaline cells).

The answer is to stop and recharge as soon as you see any noticeable drop in brightness. If the bulb in an incandescent light is starting to look yellow instead of white, then stop. If the bulb gets to orange or dim red you have gone way too far.

Thanks. Is there a reliable way (such as with a multimeter) to test NiMH levels to see if they're getting too low (and what point would that be) or too uneven?

 

[bfg9000]

Yes, NiMH cells should not normally be drained under 1.0v no-load or 0.9v when under load.

It's not just the MagLED that recommends against rechargeables. Even before the MagLED came out, the instruction manual for the Mag incans specifically stated, under WARNINGS:

• To reduce the risk of personal injury or harm to your flashlight, take the following precautions:
• Use only alkaline batteries from a reputable manufacturer.
• Do not use rechargeable or reusable alkaline batteries.

Why? Perhaps since rechargeables won't leak and ruin your flashlight, they worry you'll never buy another flashlight (a laughable idea around here). It's more obvious why a battery company's flashlights, like Duracell, Eveready or Panasonic, would come with such a warning.

 

[Mr Happy]

Yes, NiMH cells should not normally be drained under 1.0v no-load or 0.9v when under load.

I would give slightly different numbers than this. A fully drained NiMH in good condition will show 1.2 V no load or not much less, after resting. If you find a NiMH cell reading 1.1 V or lower, the chances are that it is old or damaged.

If you are checking a cell with a meter to see how close to empty it is, I'd say you should apply a small load and then make sure it reads above 1.0 V or so under load. It does no harm to recharge sooner rather than later.

 

[Lynx_Arc]

with the low internal resistance of rechargables a cheap flashlight that shorted causing a fire and/or melted light and harming people or destroying property the liability would be limited by saying don't use them in this light.