Solar power + LiPo

[bobdabiulder]

Hi guys.  I was thinking: I use way too many batteries for things because I don't have a benchtop power supply.  I use lots of things that need 3.3v, 5v, etc.  I'm trying to find a very inexpensive solution to this, and I think I may have it.

 

If I set up a few small solar panels outside, each outputting ~6v 1w, I could use these with some charging circuitry to charge up a decent capacity (1000+ mAh) during the daytime, so whenever I need to use it, it's ready.  I've read about mppt chips, but they may be too expensive.  

 

My goal for this is to have sustainable and cheap in the long term power at the ready.  I would like to have it be low maintenance, meaning that the battery will always be connected, and charging a bit.  What solutions would you recommend?  

[Canada EH]

LiPo should be used for very high discharge applications, it needs to be babysat and protected. It is meant for RC stuff, but ebikers use LiPo. I would suggest using a safer battery, like LiFePO4, or build your own pack(s). I wouldn't even bother with pouches, just stick to cans. You could even just use laptop batteries, they are low discharge batteries, and available very cheap. Charging could be done with a cheap 12V 65A server PSU, or Meanwell PSU with CC/CV. Then figure out a way for solar pannels and any other electronic gadgets required, which is beyond me.

Quote

Solar power + LiPo

 

[Enderman]

You should NEVER trickle charge a lipo especially for long periods of time or unattended.

That's just asking for a house fire.

[mariushm]

You can probably charge a regular AA battery 300-500 times using just 1 kWh, which is probably less than 50 cents on your bill. So it's not like you're saving a lot of money.

Just buy rechargeable batteries and a very good charger.

Phone chargers and whatnot also use very little power... basically the money you'd spend on solar panels and the circuits to fill a battery during the day and then use the battery to output various voltages would be more expensive than the money you'd save in a few years on your power bill.

 

[Canada EH]

Solar panels are very expensive. And if you are going that route, you should go all the way.

I would suggest flying to China for vacation and buying panels over there, and ship them back via ship. You'd save so much money.

[W-L]

18 minutes ago, bobdabiulder said:

Hi guys.  I was thinking: I use way too many batteries for things because I don't have a benchtop power supply.  I use lots of things that need 3.3v, 5v, etc.  I'm trying to find a very inexpensive solution to this, and I think I may have it.

 

If I set up a few small solar panels outside, each outputting ~6v 1w, I could use these with some charging circuitry to charge up a decent capacity (1000+ mAh) during the daytime, so whenever I need to use it, it's ready.  I've read about mppt chips, but they may be too expensive.  

 

My goal for this is to have sustainable and cheap in the long term power at the ready.  I would like to have it be low maintenance, meaning that the battery will always be connected, and charging a bit.  What solutions would you recommend?  

As mentioned Li-po is not best suited for that kind of application you may be better off just getting a deep cycle lead acid battery, with that you can get 12V and easily step down the voltage for other applications. You'll still need a charge controller but those are quite inexpensive theses days . 

[Canada EH]

You can get 12V L.A.'s in very high Ah capacities, 20Ah, 50Ah, 100Ah and more!

 

[r4tch3t]

Go for an arduino with a mppt  library for control.  the dedicated chips are for much larger power installations where a percentage or two can be hundreds of watts or more.

If you go for lithium batteries there are plenty of low cost charge controllers.  same for lead acid.

You won't save money but you can have fun building it.

I'm doing something similar but for lighting in my garage, 20W  panel, bunch of lithium 18650s, led strips and a little bit of control circuitry

[bobdabiulder]

Ok, thanks guys.  I'm changing my plan, it will be like @r4tch3t's idea, except maybe fir the solar part - i might scrap that now.  This new plan will use a lithium ion 18650 batterie, and cheap, easily availible boards from china.  It will be a portable charger for my phone, and have a couple buck/boost converters for low power things like testing LEDs.  I will have it be chargeable using either usb or a bigger, new solar panel.  By my estimates, with everything but the enclosure and the optional solar panel included, it will be about $15.  

[r4tch3t]

Make sure you get the better version of the lithium charger as it includes the protection circuitry for the battery,  useful if your battery doesn't have one inbuilt.

[SwagiYo]

On 13/11/2016 at 5:24 AM, bobdabiulder said:

Hi guys.  I was thinking: I use way too many batteries for things because I don't have a benchtop power supply.  I use lots of things that need 3.3v, 5v, etc.  I'm trying to find a very inexpensive solution to this, and I think I may have it.

 

If I set up a few small solar panels outside, each outputting ~6v 1w, I could use these with some charging circuitry to charge up a decent capacity (1000+ mAh) during the daytime, so whenever I need to use it, it's ready.  I've read about mppt chips, but they may be too expensive.  

 

My goal for this is to have sustainable and cheap in the long term power at the ready.  I would like to have it be low maintenance, meaning that the battery will always be connected, and charging a bit.  What solutions would you recommend?  

i would recomend NiMH batteries they are easier and safer to use. 

 

[Huntsman]

If your aim is to get 3.3V and 5V, why not just modify a cheap ATX PSU for it? Safe and reliable.

[bobdabiulder]

Nothing about a cheap off-brand atx psu screams safety and reliability.  Besides the fact that it won't go boom like a li-ion battery, it does have high power components like transformers and capacitors which I'd rather have behind a fully enclosed plastic wall like in a phone charger than in a solid metal hole ridden box.  I will consider the use of nickel metal hydride batteries as an alternative.  I don't remember, do they have issues with "memory" or always being charged?  Thanks guys.  Is it at all possible for an 18650 battery to be 5800mAh or even 9600mAh?  I see some unbelievable prices with those unbelievable claims on ebay from china.  Any suggestions for cheap batteries that live up to expectations?

[klh2000]

On 11/15/2016 at 9:54 PM, bobdabiulder said:

Nothing about a cheap off-brand atx psu screams safety and reliability.  Besides the fact that it won't go boom like a li-ion battery, it does have high power components like transformers and capacitors which I'd rather have behind a fully enclosed plastic wall like in a phone charger than in a solid metal hole ridden box.  I will consider the use of nickel metal hydride batteries as an alternative.  I don't remember, do they have issues with "memory" or always being charged?  Thanks guys.  Is it at all possible for an 18650 battery to be 5800mAh or even 9600mAh?  I see some unbelievable prices with those unbelievable claims on ebay from china.  Any suggestions for cheap batteries that live up to expectations?

Never buy lithium batteries form china, they will NOT meet their rated capacity. I think the largest 18650 is 3400mAh. Only buy from reputable sellers and from brands like Sony, Samsung, LG, or Sanyo.