20ah laptop battery for HID system
I have been considering building a few lights using small HID foglamps.
They are prewired with ballasts and draw about 40w
i am considering these 20ah external laptop batteries:
my question is, has anyone ever built a light using a similar battery?
i am concerned about putting too much load on the battery and overheating/exploding/or just wrecking it and wasting $100
some kind of hero...
Sorry, I've never built a system using Li-polymer batteries or with 40W of HID lighting - but here are some things to think about...
Originally Posted by alxbrsk
The packaging of the battery you are looking at is a bit clumsy for use on a bike - but I'm sure you could make it work... The capacity of the battery is a bit misleading. When you look at the WH rating, it will get you less than 2 hours of burn time with your 40W light.
40W of light from an HID is bright enough to ride the Baja 1000 at serious speed ... Along with that comes the heat generated from the lamp and ballast - do you have some way to manage that in the package for a bike or is this for something else?
You are justified in wondering about the discharge rate for these batteries... They are likely intended for a much lower discharge for electronic equipment. I would look for something with better packaging and closer to what you need for this application. If you were hoping for something that can work double duty for your laptop - you should get more info from the battery manufacturer...
Even if discharge rates are a measley 1C on that pack, it would more than sufficient for 40W HID hot restrikes. Curious though, what kind of 40W HID ballasts are there? 35W Bosch overdriven a small amount?
Anyway, I would be more focused on safetying the charging process rather than the discharging process with LiPo's though.
some kind of hero...
All good points mudmojo, but I lived through the complications of Li-ion protection circuits and 10W HIDs . There was a series of problems with the combination that is documented on another thread in the forum. I still have random problems with the protection circuits in the battery packs and I only use a 10W HID.
Originally Posted by mudmojo
when i first saw that battery, i was really impressed by the 20ah claim and thought they ment that that was the current at 12 volts
i did not notice that it also claimed that the battery was 74wh
this would mean that the battery is only good for 6 amps hours at 12 volts
i think i am going to stick with cheap and easy leds