looking for an alternative...

[Caligvla]

I am looking for a suggestion...

I have a 4D mag running a TERRALUX TLE-300M, I wanted to keep this in my car's trunk/boot as an emergency light, however I am concerned that the alkalines will lose power over time and my light wont be ready when I need it. Can you guys recommend and alternative power source... please let me know the pros and cons as well...

thanks!!!

 

[TigerhawkT3]

The easiest solution is to test and/or replace them approximately once a year. Pros of this are low cost and ease-of-use, and the con is that you'll have to remember the yearly maintenance. You could also look for those 3AA>D adapters that put the cells in parallel (or the easier-to-find but lower-capacity 1AA>D adapters), and load them up with Energizer L91s (lithium AAs). Pros would be much longer shelf life and no fear of them leaking, while cons would be that it's a bit expensive.

 

[Caligvla]

The easiest solution is to test and/or replace them approximately once a year. Pros of this are low cost and ease-of-use, and the con is that you'll have to remember the yearly maintenance. You could also look for those 3AA>D adapters that put the cells in parallel (or the easier-to-find but lower-capacity 1AA>D adapters), and load them up with Energizer L91s (lithium AAs). Pros would be much longer shelf life and no fear of them leaking, while cons would be that it's a bit expensive.

What about 3AAs to 1D in series, using Eneloops? That should give me 18v and I believe the Terralux can take up to 24v... They have a ton of Eneloops at my local Costco right now and I read they stay charged for a long time... Would they have a similar shelf life to the Energizer L91s?

Would the Terralux be a little brighter since I was running 18v through it instead of 6v with D alkalies? What do you think I would sacrifice in run time?

Where do you get 3AA>D parallel adapters??? I could use those for another project...

Thanks for your help!

 

[TigerhawkT3]

Oh, well, if the TLE-300M says it can take up to 24V, then sure, use the series adapters. Parallel adapters have occasionally been available, possibly from online dealers or CPFM, but I didn't find them with a quick perusal. Fortunately, they're easy enough to make, as they're much simpler than series adapters. All you really need is a top and bottom plate. A nice insulative holder is icing on the cake.

In terms of shelf life, lithiums will work better than the Eneloops, although the latter do have a decent shelf life (especially compared to ordinary NiMHs). If you use lithiums, you could probably forget about it for 3-5 years at a time, while with Eneloops, I'd recommend topping them up every year or two. The benefit to the Eneloops is that if you have some sort of fancy charger or analyzer, you can test the cells to make sure they're still strong, then recharge them and replace them in the light. With primaries, you can't do that, for obvious reasons. The funny part is that Eneloops and L91s are about the same price.

For runtime of 4D alks vs. 12AA Eneloop or L91, you'd have to know the efficiency of the TLE-300M's converter, as converter efficiency can vary with input voltage. If we assumed that 1) the chemistries are the same (I know they're not; bear with me), and 2) the difference between low and high input voltages is negligible, then 4D will give greater runtime than 12AA, simply because of the fact that 4D occupies more volume (less space wasted by air), not to mention cell construction (some components inside cells have a pretty much fixed size - this usually makes it more volume-efficient to use a single cell of capacity 2x rather than two cells, each having capacity x). Now, since the 4D is alk, that means they'll have reduced capacities at high loads. The TLE-300M should (if it's a decent buck or boost-buck) draw significantly less current from an 18V (or so) batt than from a 6V batt. The question is whether the load from a 6V batt is high enough for D alks to take a significant hit, especially as the cells are depleted and their voltage drops, making the TLE-300M draw more current.

Bottom line: you should be fine getting the 3AA>1D series adapters and 12 Eneloops. Just remember to inspect and charge them every year or two.

 

[Caligvla]

Oh, well, if the TLE-300M says it can take up to 24V, then sure, use the series adapters. Parallel adapters have occasionally been available, possibly from online dealers or CPFM, but I didn't find them with a quick perusal. Fortunately, they're easy enough to make, as they're much simpler than series adapters. All you really need is a top and bottom plate. A nice insulative holder is icing on the cake.

In terms of shelf life, lithiums will work better than the Eneloops, although the latter do have a decent shelf life (especially compared to ordinary NiMHs). If you use lithiums, you could probably forget about it for 3-5 years at a time, while with Eneloops, I'd recommend topping them up every year or two. The benefit to the Eneloops is that if you have some sort of fancy charger or analyzer, you can test the cells to make sure they're still strong, then recharge them and replace them in the light. With primaries, you can't do that, for obvious reasons. The funny part is that Eneloops and L91s are about the same price.

For runtime of 4D alks vs. 12AA Eneloop or L91, you'd have to know the efficiency of the TLE-300M's converter, as converter efficiency can vary with input voltage. If we assumed that 1) the chemistries are the same (I know they're not; bear with me), and 2) the difference between low and high input voltages is negligible, then 4D will give greater runtime than 12AA, simply because of the fact that 4D occupies more volume (less space wasted by air), not to mention cell construction (some components inside cells have a pretty much fixed size - this usually makes it more volume-efficient to use a single cell of capacity 2x rather than two cells, each having capacity x). Now, since the 4D is alk, that means they'll have reduced capacities at high loads. The TLE-300M should (if it's a decent buck or boost-buck) draw significantly less current from an 18V (or so) batt than from a 6V batt. The question is whether the load from a 6V batt is high enough for D alks to take a significant hit, especially as the cells are depleted and their voltage drops, making the TLE-300M draw more current.

Bottom line: you should be fine getting the 3AA>1D series adapters and 12 Eneloops. Just remember to inspect and charge them every year or two.

Thanks so much... Right now you can get a pack of 6AA + 2AAA Eneloops at Costco for $17.00

I can deal with a once a year check / top off the batts...

 

[SilverFox]

Hello Caligvia,

Remember that the self discharge rate for NiMh cells (including Eneloop cells) increases a lot for every 10 F increase in storage temperature.

With the temperatures you can see inside a vehicle, you may have to top your batteries up every month during the summer, but they would last longer during the winter.

Another thing you could consider is placing the light inside a small cooler to buffer it against the heat.

Tom

 

[Caligvla]

Hello Caligvia,

Remember that the self discharge rate for NiMh cells (including Eneloop cells) increases a lot for every 10 F increase in storage temperature.

With the temperatures you can see inside a vehicle, you may have to top your batteries up every month during the summer, but they would last longer during the winter.

Another thing you could consider is placing the light inside a small cooler to buffer it against the heat.

Tom

Wow I didn't know that... What about filling up the 4D mag with CR123a Primaries? Is there a CR123a -> D adapter out there?