battery indicator

Post by **Skyone** » Tue Dec 06, 2005 3:20 pm

Wait how much volts will it be able to rate?

Harshboy · Post by **Harshboy** » Tue Dec 06, 2005 3:29 pm

rawls, how much did you pay to make that, and could you use that for a 6 to 7.2 battery? Can you PM me about maybe making a few for me and pricing, if your willing to do it.....

timmeh87 · Post by **timmeh87** » Tue Dec 06, 2005 3:55 pm

what rawls has is similar to what im making, its based on the same concept (chip that does everythign for you

)

of course i still want everyone to hold out for mine (moneymoneymoneymoney). it will be better. i promise

Harshboy · Post by **Harshboy** » Tue Dec 06, 2005 5:40 pm

i will buy yours once it is done, if you want i can test it too.......or not, thats fine too. Don't worry, i'm sure many people will buy yours

Keep us updated

timmeh87 · Post by **timmeh87** » Tue Dec 06, 2005 5:54 pm

well heres an update - i got my chips today! i heart TI. in 36 hours flat they did ship them.

i was starting to assemble the prototype, it looks like this right now:

https://muss.cis.mcmaster.ca/~bernast/i ... yboard.jpg

tiny eh? the baord is very basic, its mostly to allow me to solder things to the miniscule pins than to serve as an actual functional board. it will be way different in the final version.

the way these chips work is somewhat peculiar... i need a way that the user can pull pins 2-7 up or down (or even leave them floating!), to change some pack-dependant settings. i dont want to use dpdt DIP's, because that would bring up costs, so i was thining mabe id just set it up so there was a row of pads that you could short with a bead of solder... unfortunately this would lead to a double-sided pcb... which will also bring up costs. lol.

i need a few MOSFETs to complete this, and i have two exams in the next two days. im hoping to go to the local electronics store (NOT radioshack, damn them) friday or saturdayish. i also need to buy a 7.2v Ni-Mh pack to test it with! im just going to get some cheap no-name batteries from the surplus store ($15 for six, 2200mAh claimed, but theryre prob. closer to 1900) and make my own pack.

sniper_spike · Post by **sniper_spike** » Tue Dec 06, 2005 5:55 pm

Oooo.. Very small=very nice.
Good work mate!
Now lets just hope it works with enough accuracy to acutaly be usefull

Turbo Tax 1.0 · Post by **Turbo Tax 1.0** » Tue Dec 06, 2005 5:59 pm

hmmm will this work for li-poly batteries im asking because dont they usually have a pretty constant voltage?

Harshboy · Post by **Harshboy** » Tue Dec 06, 2005 5:59 pm

idk if you have Wal-mart in Canada but they have 2500 mAh batteries in 4 packs for only 6 bucks! Atleast at my Wal-mart they do....but then again, since its expensive in Canada, the prices are probally equivalent. Good job too......i can see this being very succesful

sniper_spike · Post by **sniper_spike** » Tue Dec 06, 2005 6:01 pm

I gotta check that out!

timmeh87 · Post by **timmeh87** » Tue Dec 06, 2005 6:15 pm

this wont work for li-poly, its designed only for nickel chemistries (nicd as well as nimh)

BUT

im making a personal one for my portable, which will use li-poly. i probably wont make it for a while though. but when i do i can sell it.

Turbo Tax 1.0 · Post by **Turbo Tax 1.0** » Tue Dec 06, 2005 8:13 pm

cool count me in for a li-poly one...... eventually when its built

Post by **Skyone** » Tue Dec 06, 2005 8:48 pm

I'll need a Nickel (NiMH). Anyway:
That looks really nice! Where are the LED's going to go?

timmeh87 · Post by **timmeh87** » Tue Dec 06, 2005 9:24 pm

the pin header is for the LED's. a ribbon cable will go onto the pin header, and the leds will go on the other end of the ribbon cable

or you can just solder them directly to the pins like i did on mine

this thing works by measuring how much current it takes to charge it, then counting backwards during discharge to accurately light up the LED's. every time you charge or discharge it, it remembers how much capacity it had, and updates its internal memory. there is a limit though. it had a "programmed full count", and a "capactiy error". PFC - error = capacity. but when the error register hits max, it just stops counting. i belive you can get around this by changing the PFC (the PFC is determined by sensing which of pins 2-7 are high, float, or low), and resetting it.

also the datasheet dosent specify how many cells this can be used for, but i think its only limited by the breakdown voltage of your MOSFETs, since the chip itself uses a voltage regulator to get its power (not a reg like youre used to, but some sort of weird DMOS thingy that i dont fully understand yet). im going to design it like its going to be used for a 7.2v pack, but by changing like two resistors you could set it up for almost any voltage. (ill probably also offer a separate 3/4 cell model, since it dosent need the whole reg thing to run off 3 or 4 cells, and thus would be like 4 dollars cheaper)

Post by **Skyone** » Tue Dec 06, 2005 9:28 pm

Wow this is awesome!
When will it be ready for testing?

timmeh87 · Post by **timmeh87** » Tue Dec 06, 2005 9:35 pm

well it depends on how smoothly it goes. if it works on the first try, perhaps i will have a christmas present for you.

if it dosent, who knows...

as far as when i go into production, probably mid january or something. i need to find a reliable way to produce circuit boards.