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LRAT
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Joined: 15/06/2021
Location: Australia
Posts: 4

Posted: 04:53am 15 Jun 2021

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Hi,

I've got a home made weather station (Arduino based).
This station runs 24/7 and has 12 sensors attached to it.
It currently runs on sealed lead acid batteries (12V 12Ah), charged by a 12V, 20 Watt PV-panel.
Between the solar panel and the battery sits a Kemo #MO83 charging regulator.
However, lead batteries are not ideal to be deep cycled and I end up replacing my batteries twice a year.

I am now looking to have the batteries replaced by a 12V power bank (Lithium ion or LiFePO4).

Can anybody recommend such power banks?

They will need to match following criteria:
-12V output
-Needs to be able to be charged by solar
-Needs to be able to deep cycle
-Has an inbuild BMS
-Will need to deliver about 50 mA continuously
-Sturdy and rugged, a high IP factor rating would be great but not essential
-No gimmicks, just plain power

In the summer there will be days on end of full charge but in the depth of winter there could be many days in a row of overcast conditions.

Most of these battery banks come with USB connectors. That could work for my Arduino board but I also need a voltage between 12V and 24V for my anemometer (At the moment I use a buck converter to achieve 18V).
Many thanks for your help and recommendations in advance.
Cheers,

Luke

Davo99
Guru

Joined: 03/06/2019
Location: Australia
Posts: 1578

Posted: 06:16am 15 Jun 2021

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Pretty easy Solution, use a bigger panel like a house hold type that will supply enough power to charge the battery even when it is overcast and use a bigger battery or double or Triple up on them. That will lower the DOD and greatly prolong battery life. With the current draw you have the battery should be completely full and the weather station running off the panel without touching the battery in daylight hours.
Everything I have seen despite the Lipo bandwagon hype says LA is still MUCH cheaper. I bought 5x 9ah SLA a couple of months back for $10 ea

The other alternative is to go to a scrap yard and test their batteries for one that is holding some charge. Even if the things are not generating the amperage to start a car, they may well have plenty of capacity for what you need. Anything that is showing 12V or more is likely to fit the bill. You'll probably buy it for a few bucks over scrap price and when it does die, you'll get the majority of the price back if not more due to the price of the scrap going up.

I have a couple around the place just like this. One I have had for about 3 years now. ATM it's charging off 2x 175 Panels and providing power to my Diesel heater which draws anything from .6A to about 3a Continuously. Only run it down to 11V once and that was after 3 days of cloud where I had the thing running non stop. Pretty cloudy today but with the heater off it's charged right up again.

If the 20W panel is not sufficiently charging the LA battery, A lipo will run out of power under the same conditions. If your panel is big enough it should be providing 8-9 Hours of power a day even when overcast. 250W household panels or even 190s are cheap as Chips and would provide all the power you could need under any conditions.

olNick
Newbie

Joined: 11/03/2020
Location: Greece
Posts: 14

Posted: 02:05pm 11 Aug 2021

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Hi,

This might be of interest to you. AN environmental, very low power consumption data logging system I was part of, designed to run un-attended in the wild

https://github.com/jcw/jcw.github.io/blob/main/zips/zelkova-2019-04-01.zip

Quite a few low power trcks there...

anyway,
nick

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