ESP8266 Community Forum

- Tue Jan 05, 2016 9:56 am #37966 Hi,

I want to power my ESP12 project with cells.

My project is running OK with nodeMCU, and for all the developpment I've used a USB battery pack with a MCP1702 regulator.

Now, I've bought some power managers :

One simple MCP1702
One Pololu step down (https://www.pololu.com/product/2097)
One Pololu boost with NCP1402 (https://www.pololu.com/product/2114)
One Pololu boost with U1V11F3 (https://www.pololu.com/product/2561)
One Sparkfun boost with NCP1402 (https://www.sparkfun.com/products/10967)

I can say that the Sparkfun boost was ok with my ESP and 2 AAA alkaline cells. But I've burned it down in an accident, so I have to wait for a new one to perform some tests.

Regarding the other options, my test is very simple : be able to perform a node.heap() via Esplorer. When everything is OK, test is OK. When a problem occurs, mostly Esplorer don't receive a proper signal and keep printing random chars, test is KO.

I've tried many cell options :

9V cell
AA lithium cells
CR2032 cells, mounted in serie and/or parallel

As you can see in the result table, most of my solutions are KO.

Somebody could give my some advice to enable my ESP with one or two cell?

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- Thu Jan 07, 2016 4:40 pm #38162 If you want to use coin cells, you may want to add a fairly large capacitor to buffer power spikes.

The module could draw over 200mA at times, and coin cell is not able to deliver that much of current.
By fairly large, I mean, really large, at least 20mF. You probably want to consider supercap to reduce package size, like, for example 0.1F 5.5v supercap.

But probably you want to avoid any additional components, like LDO or buck boost. Since each component need to use some power, and there is only so little juice in the coin cell.

With very good power scheduling (deep sleep is a must), you may be able to power the module for a week.

- Thu Jan 07, 2016 5:21 pm #38168

By fairly large, I mean, really large, at least 20mF. You probably want to consider supercap to reduce package size, like, for example 0.1F 5.5v supercap.

When selecting a cap for this purpose (ultra low power) it is important to consider the self discharge of the cap. I assume you already consider the self discharge of the battery.

BTW, the MCP1700 has a much lower voltage drop, and the 200mA spec should be OK if the esp is active for very short periods (it runs at about 70mA but spikes up to 400mA for a ms or two when WiFi is busy).

- Fri Jan 08, 2016 5:17 am #38192 You probably need to say more about what sorts of thing you want to achieve - how long you want the batteries to last, how much sleeping, how many Wifi requests etc.

ESPs run fine on a couple of AA batteries though. You don't need a regulator or booster or anything just the 2 AA's in series should be fine. There is a long discussion thread about battery powered ESPs here. Following on from the AA test that links to i've another 2xAA test running at the moment where i've fine tuned the connection time with static IPs etc and its so far done over 17000 wakeUp - HTTP request - backToSleep cycles.