MAh - Battery question

[kevj]

Hmmm... well that's not good news.

Can anyone recomend other batteries I may consider that are very small?

Also, is there an easy way to jump up voltage without loosing a lot of power in the process? There are other 1.5v and 3v solutions, but I need 5 volts.

I'd be really surprised if in the current advancement of really small electronics that the most I can draw out of something this small is 3 mA.

Suggestions?

[mackrackit]

I do not have a battery suggestion other than using button cells series / parallel to get the voltage and amps needed.

But why 5 volts? If this is PIC based there are many chips that will run at 3 volts and less if a 4 mhz osc is used. The current consumption is lower too at the lower voltages. Supporting circuitry may have a low voltage solution also.

[ronsimpson]

I use boost up converters like the ZXSC100 in high volume. We boost 3 volt batteries up to 5 volts. There are many different types of boost up ICs Some of them work down to 0.8 volts input.
http://www.zetex.com/3.0/pdf/ZXSC100.pdf
http://www.zetex.com/3.0/pdf/zxsc410-420.pdf

[tenaja]

I use boost converters from www.maximic.com . They have some that are pretty small with minimal external parts. (That means less board space.) The one I use is about 87% efficient going from 1.2v to 3v.

When adding batteries, if you combine them in series, you add the voltages. When combining them in parallel, you add the capacity. If you want to add both the voltages and the capacity, then you have to add a set in parallel and a set in series.

You should look at your data sheet for answers to your particular questions. Most batteries are rated at a mimimal discharge current, and increasing the discharge current will decrease the capacity.

Note that if you can figure out a way to run at 3v instead of 5, your batteries will last up to 40% longer--which might allow you to eliminate that second battery. The reason is that your current draw will drop significantly--just look at the PIC data sheet in the Electrical section for current draw at various voltages. When working with small packages, it could be worth the effort. At the worst, you might be able to run the PIC at 3v, and your other peripheral at 5.