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Why are dynamo radios and torches a bad idea?

We strongly recommend NOT using dynamo operated products in emergency kits.

8 years experience tells us:
Dynamo torches and radios, including wind up, shake or squeeze types should never be relied upon in an emergency, emergency and survival kits should not contain these devices.

Dynamo products have an internal battery which is charged by winding, shaking or squeezing a handle. If these products are left for a long period of time without charging, the internal battery may become completely discharged and then become very hard to recharge. This means that in an emergency these dynamo products may not work at all, or will take several minutes to recharge but may then quickly go flat. Due to the variable quality of these products we no longer consider them appropriate for emergency kits, unless used as a back up to battery operated devices.

The only exception to this is if the dynamo product also has a battery compartment which operates separately to the internal battery; this means that if the dynamo component fails you can use batteries instead.

We would recommend that all of your existing dynamo products be checked and then regularly maintained to test their functionality (at least every 6 months). We recommend using high quality LED torches with long life alkaline batteries as these are a much more reliable product. LED bulbs are very reliable and alkaline batteries (NOT carbon Zinc batteries) have a 5 year shelf life and do not have a tendency to leak like the old carbon batteries.

TEST CHALLENGE

Do you have a dynamo torch or radio? Then try this.

  1. Switch on the torch and/or radio, leave it switched on until it goes flat (could take a while with a new one, may not take long for an old one).
  2. When it is completely flat now charge it up by winding or shaking/squeezing etc.
    • How long does it take to charge?
    • How easy is it to charge?
    • Can you charge it while doing the type of job you will be doing in an emergency?
    • Now turn on the torch/radio, how long does it last?
  3. Imagine you are in an emergency, with the battery flat trying to wind or shake this equipment when in a stressful emergency situation. Apart from the fact that it may no longer work due to age or malfunction, it is also a real pain to try and operate when you are trying to undertake jobs during an emergency. Did you ever see anyone in a real emergency winding one of these?

Don't forget - Modern alkaline batteries have a 5 year (or more shelf life). LED torch "bulbs" are renowned for working for thousands of hours before they fail (ordinary incandescent bulbs are unreliable and short lived). Why would you use an unreliable electro mechanical device in your emergency kit if you could have a very reliable (and probably brighter) battery operated piece of equipment?

Survive-it used to sell these as everyone believes they are great and there is a high demand for them. However we now no longer supply them as we believe that an emergency kit should "work reliably when you need it most".

The following comments where found on the net/forums which support our experience that dynamo products are not suitable for emergency kits

ConsumerSearch product-review
The main drawback to windup or crank flashlights is that they're not built for durability, and warranties are short or even unspecified -- which lessens their value for emergency use. It would be wise to keep a more durable "lifetime" flashlight on hand as well.

CRANKLIGHTS: Most of these $10-$20 crank powered lights are, frankly, utter junk. They accumulate the energy from cranking in a small 2032 lithium-ion rechargeable coin cell. That's fine, but they are not regulated to prevent the coin cell from being over charged or over discharged, which is exceptionally easy to do. Either of these actions permanently damages the lithium-ion cell to the point where it will hold almost no charge or a very brief charge. In order to say, you will likely get one good use out of any of them and the're through.

Re: Dynamo ('wind-up') flashlights
I had a few of these and they all were great at first but once they go dead they never really held a charge again.

I don't know if they have a battery in them or a capacitor but either way it came fully charged. And yea you could open the box and turn it on and it'd go for 30 minutes without even touching the crank. Soon as you lost that charge you would wind for 5 minutes and light would only last for 30 seconds before becoming uselessly dim.

They were all fun on xmas day but since then they just add to the clutter in the house-- no actual use.

Re: Dynamo ('wind-up') flashlights
With 200+ hour run-times being commonplace among ordinary battery-powered LED flashlights, there's not much point in messing with crank-powered lights. The extra mechanical complexity more than offsets any perceived advantage in not needing batteries. They aren't any more reliable than battery-powered lights - In fact, their plastic crank, gears, springs, dynamos, etc. make them considerably LESS reliable than ordinary flashlights. Under protracted use, most of them WILL fail - often, when you need them the most.

Re: Dynamo ('wind-up') flashlights
That's pretty much the problem with the majority of crank lights out there. A lot of them use not even NiMH cells, but a tiny button cell or three, not really meant to be recharged. They throw some tiny new cells into the lights so that when people in the store click the power switch on, they are greeted with a blast of decent light. "Oooh wow, cool. This is pretty bright." And they buy it. When the tiny cells peter out, you are left with the scenario bexamous experienced above.

I have mixed feelings about rechargeable torches. The biggest problem is that if the batteries happen to be not charged then the torch is useless- you can't charge it and wait, because you want the torch *right now*. Batteries now have a long shelf life, and with an LED torch they have a long working life too.

Above sourced from the internet September 2013
Survive-it Limited