Battery help

Post by **Skyone** » Wed Dec 07, 2005 8:50 pm

Can you take a sharper image of that small green board with the black chip (6 legged) on it? Looks like a charger...

calvary3a1 · Post by **calvary3a1** » Wed Dec 07, 2005 9:02 pm

Thats the best i can do, im using a scanner. Hopefully its good enough

Post by **Skyone** » Wed Dec 07, 2005 9:03 pm

Can't make it bigger?

timmeh87 · Post by **timmeh87** » Wed Dec 07, 2005 9:11 pm

alright. the lithium charger wont work on the ni-mh pack and vice -versa. different end-of charge conditions.

a step-up dc-dc is any dc-dc that ouputs a higher votlage than the input voltage. if you wanted to get 7.2v off this pack to, say, run a portable, then you would need something that takes in 3.6 (obviously) and gives out 7.2 or whatever you want.

can you type in all the numbers and letters on that chip in the order they appear?

...and then in alphabetical order just for fun

calvary3a1 · Post by **calvary3a1** » Wed Dec 07, 2005 9:20 pm

DS2502
9920C2
207AG

Wow that was hard.. this thing is tiny

just for fun
000222225799ACDGS

Post by **Skyone** » Wed Dec 07, 2005 9:23 pm

What the heck is that? A Battery Monitor? Like the one you're making tim? Haha!

timmeh87 · Post by **timmeh87** » Wed Dec 07, 2005 9:24 pm

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2924

so it seems like its just a chip to give the battery a uniquie ID, for whatever purpose they wanted to do that for...

i was right about the 1-wire communication though.

anyhow. thats sort of disapointing

Post by **Skyone** » Wed Dec 07, 2005 9:27 pm

Hm, no chance of that being a charger...

timmeh87 · Post by **timmeh87** » Wed Dec 07, 2005 9:28 pm

yeah i actually misinterpereted the datasheet. it dosent even read voltage... you are just able to read the data off of it over a wide voltage range. heres the line:

"Reads over a wide voltage range of 2.8V to 6.0V from -40Â°C to +85Â°C"

you can udnerstand why i thought that.

Post by **Skyone** » Wed Dec 07, 2005 9:30 pm

Ya, misleading. Would just a normal diy/buying a NiMH charger work anyways?

calvary3a1 · Post by **calvary3a1** » Wed Dec 07, 2005 9:33 pm

Funny story,

I was testing the lithium battery to see if it had any charge in it. I was using a small 3v motor from a vibrating massage thingy to test it. I didnt know which side was positive and negative for the motor or the battery so i went through several combinations to see if it worked. Well i had been through all the possible combinations twice and it didnt work so i was about to give up when "Bzzzzt" the thing came to life! It scared the crap out of me! I threw the motor and battery off the wall when i jumped. My heart about shot out of my chest! It took a few seconds for my heart to slow back down. I guess the battery works!

timmeh87 · Post by **timmeh87** » Wed Dec 07, 2005 9:34 pm

i depends how they work. you cant just hook batteries directly to a power source, as you will pump current into the battery so fast that it will explode.

so you can either limit the current, or the voltage.

limiting the current lets the voltage go as high as it needs to go to get the current inside the battery.

limiting the voltage allows as much current can get into the battery at that voltage. the ad vantage to this is if you set the voltage to just higher than the fully charged voltage, it will just stop on its own when it gets fully charged. its also easier, which is why im going to assume that most battery chargers work this way. the problem with that is that if you have a charger designed for 1.25 volts, then it will not charge a 3.6v pack.

but if you make your own charger like that guy did, which is both voltage AND current limited, then you should be cool. as long as you use the right value of reg.

Post by **Skyone** » Wed Dec 07, 2005 9:34 pm

Haha, that's happened to me, accept with a whiner buzzer. OW!

calvary3a1 · Post by **calvary3a1** » Wed Dec 07, 2005 9:42 pm

Haha, I dont know why it scared me so bad since i was waiting for it to happen but sure enough it did.

Thanks to all of you for spending the time to try and help me. Im new to this stuff so thanks for being patient with me. Ill probably try to build that charger you showed me just for fun. I dont really need the batteries but it'll be good practice for me since im trying to build an atari portable. Thanks again for all the help!

Post by **Skyone** » Wed Dec 07, 2005 9:46 pm

Sure thing man! Always welcome her on the benheck forums!