Here's is what I have; What do I need?

[AquaMoose]

I am wanting to build a solar panel charging station for our mobile devices drawing off one (or two) 12v 9A batteries.

I am a very, very experienced DIYer. I have a liberal budget for this, but, I'm not wanting to go all-out, as it will only be used occasionally (every couple to few weeks). I could just go out and buy the $150 kit and be done - but where's the fun in that???

I'm up-cycling some batteries. I have two Panasonic UP-PW1245P1 - 12V 9A SLA batteries. Whether I use one or both of them at once - really does not matter. I looked up the tech-specs on these and it says 12V 270W - however they are advertised (all internet sources) as 12V 9A (thus only 108W). I don't know where the confusion is, so I'm just using the lower value to be safe (108W). Tech Spec: http://industrial.panasonic.com/lecs...CJ4000CE19.pdf - if you want to look.

I need a solar panel (and what ever else is required) that will charge these batteries in a couple/few hours - and keep them topped off.

These batteries will be powering 4 to 6 (maybe 10) USB chargers (5V 1A output) for cell phones and such. Draw on battery will very greatly depending on how many chargers/phones are plugged in at once and how long they will need to be plugged in to charge.

The usage will likely be along the lines of: Set the solar rig up at camp. Go out swimming / hiking / fishing for an hour to two. Come back to camp and top off our phones & relax for an hour or so. Go on another adventure for an hour to two and come back for an hour or two.

Overnight the batteries will be expected to completely charge my wife and my phone - and maybe one or two of the kids phones. My home charger for my phone output is 5.3V 2A and charges my phone in about an hour.

This is not expected to be life support My truck is setup as a Search & Rescue Vehicle, so I've got dual 1000A batteries in my truck along with 2 1000W inverters - so I am more than capable of charging a device from my truck. This solar panel charging station is just a fun and functional project.

[sensij]

Others on the forum may have other thoughts, but here is what I see:

With that battery fully charged, you can get 270 W for 10 min, 108 W for ~30 min, or 4.7 W for 20 hours. In terms of conventional Ah ratings (20 hour basis), it is about a 7.8 Ah battery.

It looks like it will only accept a charge current of 1.2 A or less. That would probably limit you to a 20 W panel, and you would need many hours of good sun to put a charge into it. This does not look like a battery that is meant to be rapidly charged.

[Sunking]

I'm up-cycling some batteries. I have two Panasonic UP-PW1245P1 - 12V 9A SLA batteries. Whether I use one or both of them at once - really does not matter. I looked up the tech-specs on these and it says 12V 270W - however they are advertised (all internet sources) as 12V 9A (thus only 108W). I don't know where the confusion is, so I'm just using the lower value to be safe (108W). Tech Spec: http://industrial.panasonic.com/lecs...CJ4000CE19.pdf - if you want to look.

I need a solar panel (and what ever else is required) that will charge these batteries in a couple/few hours - and keep them topped off.

Those are a UPS batteries. However they are not made to be cycled. If cycled you get 100 cycles and they are pretty much done. You do not want them, they are chit.

A 12 volt 9 AH battery if discharged at a very slow 20 hour rate of 5 watts have 50 watt hours usable. Discharged at the 10 hour rate of 10 watts only 30 watt hours usable. However any USB charger you buy today is a Serial device meaning if it uses 2 amps or 10 watts @ 5 volts, it draws 24 watts or more from the battery. Or about 2 hours till dead on a 12 volt 9 AH battery. That is one or two cell phones. Good luck with your plan.

Your whole idea is badly flawed based on bad information and assumptions. If your truck has a two heavy duty batteries and electrical system like you claim, you do not need anything. If anything just a simple 20 to 100 watt panel connected directly the truck battery so you fell better by spending money. Or run the truck engine for 10 minutes which will do more will do more than a 100 watt panel in a week. Your truck battery and alternator has more than what you need to do what you want by a magnitude of 10.

But if money is burning a hole in your pocket at least do it right. A 100 Watt Panel panel, 10 amp Controller, and an Optima Blue Top D31M, or Odyssey 31-800. Should not cost you a penny more than $500. That ought to cool your pockets off.

If it were me just use the truck.

[SunEagle]

Those are a UPS batteries. However they are not made to be cycled. If cycled you get 100 cycles and they are pretty much done. You do not want them, they are chit.

A 12 volt 9 AH battery if discharged at a very slow 20 hour rate of 5 watts have 50 watt hours usable. Discharged at the 10 hour rate of 10 watts only 30 watt hours usable. However any USB charger you buy today is a Serial device meaning if it uses 2 amps or 10 watts @ 5 volts, it draws 24 watts or more from the battery. Or about 2 hours till dead on a 12 volt 9 AH battery. That is one or two cell phones. Good luck with your plan.

Your whole idea is badly flawed based on bad information and assumptions. If your truck has a two heavy duty batteries and electrical system like you claim, you do not need anything. If anything just a simple 20 to 100 watt panel connected directly the truck battery so you fell better by spending money. Or run the truck engine for 10 minutes which will do more will do more than a 100 watt panel in a week. Your truck battery and alternator has more than what you need to do what you want by a magnitude of 10.

But if money is burning a hole in your pocket at least do it right. A 100 Watt Panel panel, 10 amp Controller, and an Optima Blue Top D31M, or Odyssey 31-800. Should not cost you a penny more than $500. That ought to cool your pockets off.

If it were me just use the truck.

I guess what is bothering me is why those cell phones would discharge so fast if they are swimming, hiking and fishing in the country. My cell will last more than a day with minimal use so I really don't have to recharge it every day. And for the cost of that solar charging system I could purchase 10 of those 20000mAh USB 5V Battery packs.

[AquaMoose]

@sensij - Good Info. I guess I will look for different batteries.



@Sunking
Yeah, I can use my truck, that was never a question. I could also shove a Faraday rod up a kangaroos arse and let my dog chase it around the camp site but, I wouldn't be in a solar panel forum if I wanted to pursue any of my other options. Plus, finding a kangaroo in the States is kind of difficult - maybe an army of bunnies ??

I think you missed the whole point of my post - I want to have a little fun and learn something new. I'm not trying to empty my pockets either - my wife and kids that do that for me

The way I came up with my current plan is because I have a portable automotive jump starter (booster box): 12V 22Ah ("600A Starting Power" (seems like a advertising gimmick) ) that has 2 cigarette lighter ports built into it. Using the cig lighter USB adapters - I was able to get 6 cellphone (partial) charges and 2 power/battery banks (pocket charger) to charge off the booster box before it died. I was thinking that if I could recharge the booster box with a solar panel - I'd be set. Then I remember that I had these other 12V batteries laying around not doing anything - so I thought they could work and I could custom build an enclosure specifically for the charging station.

I found this: http://www.instructables.com/id/Sola...s-USB-Charger/ but my phone would chew that up in a matter of minutes - pretty sure that was intended for older phones.

In the end, I may just have to go with a handful of these: http://www.ebay.com/itm/like/3812861...lpid=82&chn=ps Not as much fun as building something - but seems more practical than a car battery and 4'x2' solar panel ...

[SunEagle]

@sensij - Good Info. I guess I will look for different batteries.



@Sunking
Yeah, I can use my truck, that was never a question. I could also shove a Faraday rod up a kangaroos arse and let my dog chase it around the camp site but, I wouldn't be in a solar panel forum if I wanted to pursue any of my other options. Plus, finding a kangaroo in the States is kind of difficult - maybe an army of bunnies ??

I think you missed the whole point of my post - I want to have a little fun and learn something new. I'm not trying to empty my pockets either - my wife and kids that do that for me

The way I came up with my current plan is because I have a portable automotive jump starter (booster box): 12V 22Ah ("600A Starting Power" (seems like a advertising gimmick) ) that has 2 cigarette lighter ports built into it. Using the cig lighter USB adapters - I was able to get 6 cellphone (partial) charges and 2 power/battery banks (pocket charger) to charge off the booster box before it died. I was thinking that if I could recharge the booster box with a solar panel - I'd be set. Then I remember that I had these other 12V batteries laying around not doing anything - so I thought they could work and I could custom build an enclosure specifically for the charging station.

I found this: http://www.instructables.com/id/Sola...s-USB-Charger/ but my phone would chew that up in a matter of minutes - pretty sure that was intended for older phones.

In the end, I may just have to go with a handful of these: http://www.ebay.com/itm/like/3812861...lpid=82&chn=ps Not as much fun as building something - but seems more practical than a car battery and 4'x2' solar panel ...

Getting into and playing with solar technology can be fun but it is not even close to being inexpensive. Like Sunking said you can get what you want for about $500 or go more practical with those portable USB batteries.

Also any of those small portable "solar" charging kits like the Altoids are "very expensive" and as you have witnessed does not really meet your demand.

It comes down in the end to what you want to learn and how much you want to pay for it.

Here is my "portable" solar charging system with an 80 watt panel, 65Ah battery and 300 watt inverter. I "built" it and it cost me about $550 which when I do the math is way more than what I would have spent going another way.

[AquaMoose]

I guess what is bothering me is why those cell phones would discharge so fast if they are swimming, hiking and fishing in the country. My cell will last more than a day with minimal use so I really don't have to recharge it every day. And for the cost of that solar charging system I could purchase 10 of those 20000mAh USB 5V Battery packs.

My wife and I have Galaxy Note3 phones - they are huge phones! At home, minimal use and strong signal - they are complaining of low battery after about 12 hours. Moderate use - maybe 8 hours. Continual use - about 2 hours. Both phones have been this way from day 1. Verizon even warned us of the terrible battery life - it's a trade off for the large screen. While out camping the signal cuts in and out - so the phones spend a lot of battery searching for signal.

One night camping I charged my phone to 100% and went to sleep with the phone unplugged. Woke up 6 hours later and it was at 18%. Hindsight - I should have put my phone in airplane mode ...

[SunEagle]

My wife and I have Galaxy Note3 phones - they are huge phones! At home, minimal use and strong signal - they are complaining of low battery after about 12 hours. Moderate use - maybe 8 hours. Continual use - about 2 hours. Both phones have been this way from day 1. Verizon even warned us of the terrible battery life - it's a trade off for the large screen. While out camping the signal cuts in and out - so the phones spend a lot of battery searching for signal.

One night camping I charged my phone to 100% and went to sleep with the phone unplugged. Woke up 6 hours later and it was at 18%. Hindsight - I should have put my phone in airplane mode ...

I understand how a cell phone battery can drain "searching" for a signal. My Droid has done that in areas with little reception which is why I put it in airplane mode or just shut it off until I need it. I really don't want to be bothered with a phone call when I am out in the woods trying to get away from the "noise" and relax so the battery lasts a lot longer.

I think those portable USB batteries is the best bang for your buck but if you are still interested in solar then it is easy to build a system like I did. You first have to know what your daily "watt hour" load will be before you can size the battery and then the panel wattage. Just using some old batteries you found is the best way to destroy them and making an assumption on the panel wattage will end up being a big waste of money.

[AquaMoose]

I understand how a cell phone battery can drain "searching" for a signal. My Droid has done that in areas with little reception which is why I put it in airplane mode or just shut it off until I need it. I really don't want to be bothered with a phone call when I am out in the woods trying to get away from the "noise" and relax so the battery lasts a lot longer.

I think those portable USB batteries is the best bang for your buck but if you are still interested in solar then it is easy to build a system like I did. You first have to know what your daily "watt hour" load will be before you can size the battery and then the panel wattage. Just using some old batteries you found is the best way to destroy them and making an assumption on the panel wattage will end up being a big waste of money.

That's why I'm here. I don't want to throw money at something without fully understanding it. Part of the fun of DIY is the research, learning, and others experiences. I could put $500 into this project without my wife saying too much. My only issue is the "portability". I just don't think the technology is where it needs to be for what I want to do.

[SunEagle]

That's why I'm here. I don't want to throw money at something without fully understanding it. Part of the fun of DIY is the research, learning, and others experiences. I could put $500 into this project without my wife saying too much. My only issue is the "portability". I just don't think the technology is where it needs to be for what I want to do.

I agree. Solar equipment "portability" does not yet necessarily meet the "sustainable" or "reliable" components.

[bcroe]

I guess what is bothering me is why those cell phones would discharge so fast if they are swimming, hiking and fishing in the country. My cell will last more than a day with minimal use so I really don't have to recharge it every day. And for the cost of that solar charging system I could purchase 10 of those 20000mAh USB 5V Battery packs.

The battery won't discharge if its completely turned off. Why do you need a phone in the country, except to turn on
for a real emergency, thought the idea was to get away?

Cell phones adjust their transmitting power to stay in range of the nearest cell towers. With lower population density
in the country, towers will be much farther apart (and taller). Your phone will need to turn up the power just to stay
in contact, and I suppose there is a big increase if you actually make or receive a call with continuous transmission.

Bruce Roe

[inetdog]

The battery won't discharge if its completely turned off. Why do you need a phone in the country, except to turn on
for a real emergency, thought the idea was to get away?

Cell phones adjust their transmitting power to stay in range of the nearest cell towers. With lower population density
in the country, towers will be much farther apart (and taller). Your phone will need to turn up the power just to stay
in contact, and I suppose there is a big increase if you actually make or receive a call with continuous transmission.

Bruce Roe

The other cause of rapid drain is when you actually get out of range of any towers.
The cell phone has to go to maximum power and frequent transmissions to try to initiate contact with a tower on its list of allowed frequencies (both same carrier and roaming) The result is much higher power drain than just the occasional keep-alive message to a reachable tower, even if at extreme range.

[bcroe]

The other cause of rapid drain is when you actually get out of range of any towers.
The cell phone has to go to maximum power and frequent transmissions to try to initiate contact with a tower on its list of allowed frequencies (both same carrier and roaming) The result is much higher power drain than just the occasional keep-alive message to a reachable tower, even if at extreme range.

I think that means that if you are in a no service area, you DEFINITELY need to turn it off and save the battery.
Phones have become so small, I wonder how much battery could be in there. City dwellers are surprised to
find how quickly their phones die in the wide open spaces. Bruce Roe

[SunEagle]

I think that means that if you are in a no service area, you DEFINITELY need to turn it off and save the battery.
Phones have become so small, I wonder how much battery could be in there. City dwellers are surprised to
find how quickly their phones die in the wide open spaces. Bruce Roe

Or how quickly they drain when you play games or stream video.

[lkruper]

That's why I'm here. I don't want to throw money at something without fully understanding it. Part of the fun of DIY is the research, learning, and others experiences. I could put $500 into this project without my wife saying too much. My only issue is the "portability". I just don't think the technology is where it needs to be for what I want to do.

If your problem is that your cell phones are draining because of no signal, then you would not be getting any calls anyway, would you? I will go one step further than the excellent advice to put them in airplane mode. Get another toy that gets your calls anywhere. Look at some of those portable satellite receivers for voice/text that work anywhere. Pricey. Or get an internet dish and use VoIP.