I am making a clock, and using the DS1307 clock chip. I plan to use a self charging LiPo system to power the chip itself.
What mAh battery would eb suited for this chip? The battery should be able to sustain the chip for around 48 hours on battery power. I also want to make an automatic charging system that keeps the battery at 100% when power is avalible. I also think I need a booster chip to keep the voltage at the required 5 volts.
I would like to get all of the parts from SparkFun.
And ideas? I am thinking the following:
Battery: Lithium Ion Battery - 110mAh - PRT-13853 - SparkFun Electronics
Booster: NCP1400-5V Step-Up Breakout - PRT-08999 - SparkFun Electronics
Charger: SparkFun USB LiPoly Charger - Single Cell - PRT-12711 - SparkFun Electronics
Will this work? Also, do you know of a place that has the same or compatible parts for less?
What else is this clock going to have?
As a backup battery for the DS1307, it is common to use a 3v coin cell and this will easily last over a year.
If the battery is not powering anything else then you would be better off with a coin cell. If it is going to be powering something else then we would need to know what the other components are.
Mowcius
The battery is only for keeping the hip running in a power outage. I just want to do something different than everyone else. I also want it to be automatically maintaining. With the LiPo battery, it will always be charged. Also, with that battery, this could last on a shelf for like 4 years... I just want that sort of redundancy, because this will not be easy to set. If I got the next level, it ould last approximately 20 years!
Well in that case, I recommend this battery:
LiPo coin cell ;D Best of both worlds. Easy to fit in a project then and mount to a citcuit board.
Regarding the charger and breakout board, it all looks good. I think that should all work fine.
Mowcius
So I could get that coin cell at first, and then if I so choose, I could get a small LiPo battery pack?
Well the coin cell is at 3.7v and so is the pack.
The coin cell is also 90mAh higher capacity than the pack you linked and also cheaper.
I would recommend you use this and add two connections next to it so if you want to use a larger capacity pack in the future you can take out the lipo coin cell and attach the new pack to a JST plug on the connections you left.
Mowcius
It's actually 90mAh more. I dont know... I guess I knwo my options, and I will decide when the time comes.
Thanks for your suggestions and knowledge Mowcius!
It's actually 90mAh more
Who said differently? ;D
Thanks for your suggestions and knowledge Mowcius!
No problem,
Mowcius
Who said differently? ;D
LOL ;D :
A CR1220 on the DS1337 will last for about 20000 hours (ignoring self-discharge)
if you diode-or it with the main power source. The current draw is less than 2uA
when you are not doing I2C communication. When you are doing I2C communication
the current is supplied by the main power source.
The schematic and parts list for the circuit I use is in the PICO1TRC datasheet
at Loading...
(* jcl *)
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Thanks, but I am not looking to buy kits, sorry.
Alright, I need a littl more help. Afer reading some more, the chip runs on 5V and the battery backup is supposed to be 3.3V. There is no ground conenction for the battery backup. do I just tie the ground of the battery to the grounds for the chip power?
Thanks, but I am not looking to buy kits, sorry.
The schematic showing the battery connection and the battery
life calculations are in the datasheet. No purchase is necessary
to read the datasheet. The information in the datasheet also
answers your second question 
(* jcl *)
Ok, thanks.
You wouldn't happen to know on which of the 42 pages it's on?
You wouldn't happen to know on which of the 42 pages it's on?
That's left as an exercise for the reader
There is a table of contents. Take a look at the RTC section and the schematics.
The DS1337 datasheet is the bulk of the pages.
(* jcl *)
Is the DS1337 compatible with the DS1307? 
Is the DS1337 compatible with the DS1307?
I thought they were closer until I just looked at the DS1307 datasheet 
The DS1307 has two power pins -- one for battery and one for Vcc.
The DS1337 only has one power pin. For the DS1337 you can diode-or
multiple voltage sources. The DS1337 uses the extra pin as an output.
Sorry for the mixup. I hadn't looked at the datasheets in a while. I chose
the DS1337 because I wanted two outputs.
(* jcl *)
Ok, so do I conenct the grounds as mentioned above? As in the 5 volt and 3.3 volt grounds connect?