Good high-capacity 12V rerchargeable battery pack for LEDs?

[percussivepaul]

Hi,

I'm planning a wearable LED project that needs 12V batteries. Current draw may be in the range of 0.1 to 1.0 Amps, based on specs I'm seeing. (More likely on the lower end, I would guess). Since I want it to last a while I want a high capacity battery pack.

I'm seeing this stuff on ebay and other places: http://www.ebay.com/itm/Portable-12V-Li ... 0937990572
This is really attractive due to the high capacity and integrated charger and power switch -- much easier to work with. And at that price it seems great. But indications here that the actual capacity on such battery packs might be much lower than advertised: http://ve2zaz.net/blog/index.php?/archi ... -pack.html

Just curious if anyone has any experience or recommendations.

[nixiebunny]

I have some experience wearing an LED thing... http://www.cathodecorner.com/videocoat/

I would agree that the item in question is likely to be 2500 mAH, based on the weight of the pack. An 8000 mAH LiPo pack should weigh about 1.5 lbs.

I use Turnigy 11.1V 5000 mAH LiPo packs from HobbyKing. The cost the same $25, but provide an honest 5000 mAH of energy. They also sell a charger that runs from 12V, so you can go generator-less.

If you get these, replace the connectors with something better. These ones have hermaphroditic connectors that can inadvertently be plugged into each other, causing sparks, fire etc.

[anthroprose]

I'm using a similar model for various 12v things... just make sure to test thing with plenty of time to potentially order a more upscale model if things do not work out (It has a digital circuit breaker inside that limits the output amperage)... One of these will not power my spark gap igniter and a 12V solenoid.. it just shuts off... I used a 10xAA battery cage and NiMH to get my 12V instead.

Also for an option are those little 5V USB lipstick chargers... I get them in bulk for around $5 and they can run an arduino+megabrights all night long with 2800Mah (its a 3.6V LiPO with up/down regulater on top of it..).

[melodiousdirge]

I am planning on building 18.5v litium packs with a step down power supply ($5 on ebay) to run my LEDs this year. Some things I have tried before include:

8x AA's in a holder gives you 12v with about 2 amp hours. So, if you're running them at 1A constant it will be less than that due to the heating and you'll get about an hour out of the pack. If you're only pulling like 100mA it would probably last all night. Downside is that it's not a very green way to power your things, and the cost of replacing them all will add up.

12v NiCd battery; I bout several of these advertised as 3600mAh off ebay for last year and they worked OK, but you need a proper NiCd charger to charge them, and the ebay packs tend to be crappy quality and fail.

12v Li-Ion off ebay; as others have said these have nowhere near the capacity they advertise, and I have had one die on me after 1 use. If you want lithium, get a 4 cell "18650" holder and buy protected cells. ($8 each new, $1-2 each used). These are great cells, but you'll need a proper charger, and you should probably do some reading to make sure you know what you're doing, as lithium cells can catch fire if mistreated.

12v Lead acid cell: Amazon, Ebay, and sciplus.com all have little lead acid cells for pretty cheap. These are heavy, and the blocky shape is kind of a pain to find a pocket for, but they give you a great bang for your buck, and can be recharged off a solar cell, or a running car's power system.