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Forum Index : Microcontroller and PC projects : Solar Supply for MM with HC-12
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| Andrew_G Guru  Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Hi, I'm still struggling to get the power consumed by a MM170 with HC-12 down so I can get decent life out of 2x AA batteries. Does anyone have a simple circuit and parts list for a solar charger, or a "garden light" that can be "adapted"? I'm sure it would be useful for other projects too? Bunnings, Jaycar and RS are nearby. Thanks, Andrew |
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palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
Hi Andrew, I have a small solar panel on the roof of my golf cart charging some Ni-Mh cells to run a Micromite based GPS that tells me how far it is to the green. It works very well, has been there for about 3 years. I recently bought some of these Solar Cells I siliconed them to a solid backing and made my own panel, fairly cheaply, to charge a couple of Li-Ion cells. Paul. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2171 |
what range do you need from the HC-12? There is a mode that uses tiny current but obviously the range gets hit. Is the radio coms 2-way? consider putting the HC-12 to sleep when not needed (FET on the power pin). Try using dynamic setting of the MM clock where you can, e.g. run everything at 5MHz and only switch up (to the bare minimum speed required to do the job) when you have something to do. There is also sleep and the WAKEUP pin but I have never played with them. Also consider the AA's you are using. They are really variant - Big Clive did a really insightful vid here. "Simply Duracell" are to be avoided like the plague. I know they are re-chargers but just to illustrate all cells are not created equal. |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
Aldi are flogging a solar charging "shed light" which might work, 900mah lithium, 3.7v, amorphous solar cell, PIR motion sensor. I don't think the solar cell has much output, but the combo looks like set-and-forget which could be a useful hack |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1667 |
Garden light would be my choice. Actually checked outa few at Bunnings yesterday. Was checking them out for suitability to run a 24 hour fan on a weather station. It needs 2.4V at about 100mA. One had 2x2000mAh 18650's & the other a single 1000mAh 18550 Li-Ion. Both had the battery & charging circuit in the enclosure under the Solar panel so easily tapped int. Add a simple Buck/Boost reg module from eBay & the job's done. Phil. Edit, Will try & add a couple of Bunnings & eBay links in the morning. About to turn to stone.... |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Hi Phil, you wouldn't have the brand or model or price? I'll need to send my wife as I am on crutches for 4+ more weeks and she'll need to identify it. Andrew |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Hi all this is my third attempt to reply via my iPad - I keep losing text. I'll explain and reply via my PC tomorrow. Thanks Andrew |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1667 |
This is the one with the two 18650's. $44.00. The other one is a Duracell, but can't find it on their site. It has a single 1000mAh, & the solar panel flips open to remove or change the battery. Phil. |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1667 |
All the electronics are under the panel & it's easy to tap off the batteries with a reg. Just need to disconnect the wires to the LED's. No other electronics in the reflector part. |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Phil, thanks. I'll ask my wife to get one for me when she is up to it (she is not 100% mobile and I am recovering from an Achilles tear - crutches for another 4+ weeks then months of rehab). Chronic, thanks but I think we have missed the Aldi one by a week as we can't get to the shops for a few days. CaptainBoing, thanks. I started this topic a few weeks back but had only partially tested it before I tore my tendon. I think I had slowed the MM down (to 20), configured the HC-12 to low power and put them both to sleep in between transmissions but still had a decent drain of 0.5mA (to be confirmed). I'll post my code back at the original thread in case anyone is still interested. I'm pursuing the solar charge option for this and other projects, including a weather station to help manage my new Smart-house systems (if I can get it all working) see this topic. Thanks again for your help, Andrew |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Hi Phil, I finally pulled the unit apart and, as usual, I'm trying to understand how it works before I rip into it . . . (I don't care about the LED lamp - for now). I am confused as to how it charges the cells (2x 18650). It appears to me that the unit has to be switched "On" before it can? (unless it is there is no connection to the battery +ve from the solar panel??). If this is the case I can happily move on and do as you say - ie keep the 2x 3.8V LiFes in parallel, use the 3V8 for the HC-12 and regulate down to 3V3 for the MM and BMP180 - easy. Thanks, Andrew |
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| kg4pid Regular Member  Joined: 08/03/2015 Location: United StatesPosts: 50 |
Will your location be subject to freezing temps? I read where lithium batteries are ruined when they are charged below freezing. Max |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Hi Max, I'm in sunny Melbourne and while overnight frost is possible it will always get above freezing during the day. But it is a good warning so I'll keep it near a warmish wall etc. These units are sold as "garden lights" but they do suggest changing the batteries every year (in the fine print) . . . It only took a few minutes to separate the solar panel and battery from the light and connect it to a MCP1700 (3V86 in 3V24 to 3V3 out). Should work nicely (OK for MM, BMP180 and the rain/wind sensors, with the full 3V86 for the HC-12 GPS and DH22). Andrew |
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