promise ill stop posting soon lol but im just playing with the lipo charger. how cool is this little thing.
portable solar charger
- Thread starter ateallthepies
- Start date
Did the same last night and charged a couple of 18650's. My charger terminated at 4.23 and 4.22 volts which is a little high for me and settled to 4.19 volts. I like to go to about 4.10 volts but with the mini voltmeter attached it's so easy to terminate early.
I scraped away a bit of the yellow heat shrink on mine where the red led is, makes seeing it is charging much easier. Still debating weather to get a cheap battery box and rig it to the li-on charger and volt meter as an all in one unit? The charger is a great thing for the size but if a lead pops off the battery it stops charging and the usb needs to be re-inserted to get it going again.
Steve.
I scraped away a bit of the yellow heat shrink on mine where the red led is, makes seeing it is charging much easier. Still debating weather to get a cheap battery box and rig it to the li-on charger and volt meter as an all in one unit? The charger is a great thing for the size but if a lead pops off the battery it stops charging and the usb needs to be re-inserted to get it going again.
Steve.
Ive done a comparison with my mates fluke multimeter and the .005 tolerance is about right so i will stop them at 4.18.
Stunning morning in the Midlands and ive got my iphone 4 charging direct from the panel with the supplied adapter. really chuffed with this kit. will need to split an iphone lead to measure the current being drawn but got to go play at family man for a bit 
Stunning morning here as well and I'm getting 400 mA into a nimh charger from each panel but when the two panels are connected I'm still getting the same current into the charger? Thought the current would double? The charger certainly would like to take 800 mA? I have PM'd the seller to see if I have a problem?
A bit more testing revealed that when the sun is fully out I'm getting the same current with either one panel or two combined. When the sun goes behind a cloud two panels do indeed double the current??
I have tried both my nimh and li-on chargers. The li-on is rated at 700 mA but to it with one or two panels it's taking just over 300 mA?
Steve.
A bit more testing revealed that when the sun is fully out I'm getting the same current with either one panel or two combined. When the sun goes behind a cloud two panels do indeed double the current??
I have tried both my nimh and li-on chargers. The li-on is rated at 700 mA but to it with one or two panels it's taking just over 300 mA?
Steve.
Last edited:
That's odd. The only thing I can think of is a diode blocking the current flow from one panel to the other. Can you try and plug two devices in and see what happens.
It's OK I'm just being a numpty I figured it out!!
I was trying to charge a 18650 cell that was over 4 volts and only getting about 300 mA to it. I discharged the cell to 3.6 volts and tried again and bingo, got the full charger rating of 700 mA! The charger must follow a sort of CC/CV algorithm even though I'm sure the seller said it is not a true CC/CV charger? The current needed must taper off as the cell gets full?
It seems my two usb fed NIMH chargers were just taking what current they needed, up to 400 mA, and one panel was enough in full sun and hence why adding another did not do anything! When two panels connected become apparent is when the sun goes behind cloud and two are able to still supply what's needed whereas one used the current supplied drops to half.
Basicley, my li-on charger rated at 700 mA is fully powered by two panels in full sun and drops to about 550 mA when only one is used. It will be interesting to see if one panel can supply the full 700 mA in full summer??
It looks like in full winter sun each 700 mA panel is capable of supplying up to 550 mA each?
Here are some pics of one panel versus two used with the 700 mA li-on charger with a 18650 cell....
Steve.
I figured it out!!I was trying to charge a 18650 cell that was over 4 volts and only getting about 300 mA to it. I discharged the cell to 3.6 volts and tried again and bingo, got the full charger rating of 700 mA! The charger must follow a sort of CC/CV algorithm even though I'm sure the seller said it is not a true CC/CV charger? The current needed must taper off as the cell gets full?
It seems my two usb fed NIMH chargers were just taking what current they needed, up to 400 mA, and one panel was enough in full sun and hence why adding another did not do anything! When two panels connected become apparent is when the sun goes behind cloud and two are able to still supply what's needed whereas one used the current supplied drops to half.
Basicley, my li-on charger rated at 700 mA is fully powered by two panels in full sun and drops to about 550 mA when only one is used. It will be interesting to see if one panel can supply the full 700 mA in full summer??
It looks like in full winter sun each 700 mA panel is capable of supplying up to 550 mA each?
Here are some pics of one panel versus two used with the 700 mA li-on charger with a 18650 cell....
Steve.
just loking at your pics and the window frame is casting a shadow on one of the panels. this will affect your output too. any shading will lower the power output across the entire setup. no biggy but you wont be seeing your full potential
Here is my completed set up with everything needed to charge li-on and nimh batteries plus a spare case each of batteries. It all fits in an old Erbauer soft drill bit case from Screwfix! I fixed a couple of bits of strip wood under the panels to the case and used lengths of velcro to secure the panels to the wood, works a treat!
The only bit I'm missing is a small male usb to usb lead. I needed one with angled ends to fit in the usb ports at the top to connect the panels together and ended up ordering one on Ebay from China as I could not find any sourced in the UK!
Quite a successful project I think and performs to spec?
Steve.
The only bit I'm missing is a small male usb to usb lead. I needed one with angled ends to fit in the usb ports at the top to connect the panels together and ended up ordering one on Ebay from China as I could not find any sourced in the UK!
Quite a successful project I think and performs to spec?
Steve.
looks really neat in the case 
. im just trying to persuade my wife to sew me up some neoprene cases for my gear. I have binned the nimh charger that came with mine as its pretty poor. Ive got a 7dayshop one too which ill substitute.
hopefully the sun will continue tomorrow and ill get some readings from mine.
. im just trying to persuade my wife to sew me up some neoprene cases for my gear. I have binned the nimh charger that came with mine as its pretty poor. Ive got a 7dayshop one too which ill substitute. hopefully the sun will continue tomorrow and ill get some readings from mine.
Yep I agree the one supplied was poor and he admitted that to another buyer. The 7dayshop nimh charger is rated at 1000mA output but I guess this is only if you use mains or 12 volt feeds in to it and is only drawing up to 400 mA via the usb supply port using the panels. I tried it with a 1 A mains to usb lead and it's the same.
I could do with finding a usb fed NIMH charger with better output as I use only eneloops at 2000 and 2500 mAh ratings and putting under 400 mA into them probably isn't the best and anyway takes too long to charge.
Edit... Just tested the current at the terminals the batteries touch in the charger and am getting over 700 mA but not constantly? It goes from this reading to nothing once a second, maybe it's the way chargers work? The current into the charger seems to be a steady 380 ish mA.
Steve.
I could do with finding a usb fed NIMH charger with better output as I use only eneloops at 2000 and 2500 mAh ratings and putting under 400 mA into them probably isn't the best and anyway takes too long to charge.
Edit... Just tested the current at the terminals the batteries touch in the charger and am getting over 700 mA but not constantly? It goes from this reading to nothing once a second, maybe it's the way chargers work? The current into the charger seems to be a steady 380 ish mA.
Steve.
Last edited:
looks like it must be a pulse based charger. it allows a higher current (or voltage) to be applied without overheating the cells
Not sure but the 7dayshop charger took a little over three and a half hours to charge four 1300 mAh AA batteries via the 1Amp usb supply! Could be looking at a six hour charge time for my Eneloops?
Steve.
Steve.
Biker
Bushcrafter (boy, I've got a lot to say!)
Hey Chaps you both seem to be well genned up on electron pushing, so here's my question to either of you.
At Christmas I bought myself a brand new Kindle 4, it came in the box as is and without a mains adapter/recharger. You need to plug it directly into your PC and it recharges via the USB socket. Now I got to thinking (dangerous I know) what happens if I don't have access to my PC? So I went on ebay and bought this little doo dah (see link below)
http://www.ebay.co.uk/itm/310368515567?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
for the princely sum of £2.69 with free P&P. Figured it was cheap enough to buy and if it was pants then what the hell I haven't wasted a bucket load of swag on it.
So my question to you both is: How will it fair do you think given the readings you're getting?
I went to a website which seemed to explain rather nicely what voltage I need to power the Kindle, at least from the specs given for it on this website:
http://wiki.answers.com/Q/Can_a_kindle_power_adapter_be_used_for_an_iPod
(I only direct you to this website sinmply because it has voltage details etc. hmm thinking about it I also have an Ipod shuffle which could be recharged as well)
Anyway the input needed for the Kindle is 5v and the solar charger delivers 5.1v. (on a VERY bright and sunny day I'm guessing) I figured whatever voltage the thing delivered by virtue of the fact it has a USB connection then it should be safe to plug a USB charged device into as it'll be no different from plugging it into a PC and getting a similar voltage into the Kindle.
So in essence have I wasted my £2.69 buying this tiny little charger or is there hope for me yet to use this to trickle charge my Kindle (or Ipod) if and when it runs down and my PC's at home?
Thanks for reading chaps, and I won't feel in the least put out if my questions are too much like hard work to figure out. Thanks in advance for any advice, suggestions or point a laugh at that dimwit Biker.
At Christmas I bought myself a brand new Kindle 4, it came in the box as is and without a mains adapter/recharger. You need to plug it directly into your PC and it recharges via the USB socket. Now I got to thinking (dangerous I know) what happens if I don't have access to my PC? So I went on ebay and bought this little doo dah (see link below)
http://www.ebay.co.uk/itm/310368515567?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
for the princely sum of £2.69 with free P&P. Figured it was cheap enough to buy and if it was pants then what the hell I haven't wasted a bucket load of swag on it.
So my question to you both is: How will it fair do you think given the readings you're getting?
I went to a website which seemed to explain rather nicely what voltage I need to power the Kindle, at least from the specs given for it on this website:
http://wiki.answers.com/Q/Can_a_kindle_power_adapter_be_used_for_an_iPod
(I only direct you to this website sinmply because it has voltage details etc. hmm thinking about it I also have an Ipod shuffle which could be recharged as well)
Anyway the input needed for the Kindle is 5v and the solar charger delivers 5.1v. (on a VERY bright and sunny day I'm guessing) I figured whatever voltage the thing delivered by virtue of the fact it has a USB connection then it should be safe to plug a USB charged device into as it'll be no different from plugging it into a PC and getting a similar voltage into the Kindle.
So in essence have I wasted my £2.69 buying this tiny little charger or is there hope for me yet to use this to trickle charge my Kindle (or Ipod) if and when it runs down and my PC's at home?
Thanks for reading chaps, and I won't feel in the least put out if my questions are too much like hard work to figure out. Thanks in advance for any advice, suggestions or point a laugh at that dimwit Biker.
Hi Biker,
The voltage is fine from the panel but it's the current that's important when charging, a gadget will only take what current it needs but if not enough can be supplied things may not work properly. I see from the listing that it's max output is 0.4 watts. At 5.1 volts then it's producing about 78 mA in full sun if the specs are to be believed which is very little to begin with and add in haze or cloud and you will be right down on current and either the charger won't work or be very, very slow.
My i phone for example has roughly a 1500 mAh battery and using the solar charger you got would take over 19 hours to charge in optimum conditions. Using the solar set up I have it would take the same time as plugging it in to the mains or there abouts as the current I can get from the panels is so much greater.
Edit... I think the kindle has a 1200 mAh battery so would need 15 hours of full sun to charge? But in your wiki link it stated the kindle takes 85 mA to charge but your only making 78 mA from the charger at full output so it may not charge at all or be very slow?
HTH,
Steve.
The voltage is fine from the panel but it's the current that's important when charging, a gadget will only take what current it needs but if not enough can be supplied things may not work properly. I see from the listing that it's max output is 0.4 watts. At 5.1 volts then it's producing about 78 mA in full sun if the specs are to be believed which is very little to begin with and add in haze or cloud and you will be right down on current and either the charger won't work or be very, very slow.
My i phone for example has roughly a 1500 mAh battery and using the solar charger you got would take over 19 hours to charge in optimum conditions. Using the solar set up I have it would take the same time as plugging it in to the mains or there abouts as the current I can get from the panels is so much greater.
Edit... I think the kindle has a 1200 mAh battery so would need 15 hours of full sun to charge? But in your wiki link it stated the kindle takes 85 mA to charge but your only making 78 mA from the charger at full output so it may not charge at all or be very slow?
HTH,
Steve.
Last edited:
Biker
Bushcrafter (boy, I've got a lot to say!)
Thanks for the frank reply. I'm not looking at a quick fix with this charger just something I could set up and trickle charge my Kindle (trickle charge being the operative word by what you say) over a lengthy period of time if need be. I don't expect to need the Kindle all the time, but just to have an alternate method of topping it up might just be handy.
Thanks again mate, and especially for not laughing at me.
Sheesh look at my post count. :yikes: Mesquite spotted it the other day, sorta creeps up on one doesn't it? I'll get my thinking cap on for a suitably canny comp soon. Hey the prize could be a Solar recharger
Thanks again mate, and especially for not laughing at me.
Sheesh look at my post count. :yikes: Mesquite spotted it the other day, sorta creeps up on one doesn't it? I'll get my thinking cap on for a suitably canny comp soon. Hey the prize could be a Solar recharger
I am by no means an expert on these things and have learned most of what I'm spouting over the last few days/weeks of research into the workings of elecy gadgets.
If I'm wrong with my calculations would love someone to correct me? I'm still trying to figure out if a charger can receive a current from a supply and then send out a higher current to the battery, or if what goes in must come out?
Steve.
If I'm wrong with my calculations would love someone to correct me? I'm still trying to figure out if a charger can receive a current from a supply and then send out a higher current to the battery, or if what goes in must come out?
Steve.
Whilst i cant find any minimum current spec beyond that in the wiki answer for the kindle to confirm, id be inclined to think it will fail to charge even in full sun. The USB charging specification dictates that all USB sockets must deliver 100mah minimum if on a bus but more normally 500mah. the kindle should be in line with the charging spec so im guessing it will want 100mah minimum to charge.
Steve the simple answer in this context is you are stuck with the current coming in. My RC charger allows me to select the amps applied to the battery but it draws from the mains. If the USB is maxed at 500mah then without some very sophisticated kit its not possible to amplify the current. Ohms law would say you cant increase the current without upping the voltage or decreasing resistance.
Steve the simple answer in this context is you are stuck with the current coming in. My RC charger allows me to select the amps applied to the battery but it draws from the mains. If the USB is maxed at 500mah then without some very sophisticated kit its not possible to amplify the current. Ohms law would say you cant increase the current without upping the voltage or decreasing resistance.
Makes sense and confirms what my testing has shown, cheers for all your help.
If the kindle battery is rated at 1200 mAh and the charger draws 100 mA and puts that into the battery it would take 12 hours to charge. I don't know how long a kindle takes to charge but if known should show how much current it takes.
Steve.
If the kindle battery is rated at 1200 mAh and the charger draws 100 mA and puts that into the battery it would take 12 hours to charge. I don't know how long a kindle takes to charge but if known should show how much current it takes.
Steve.
Similar threads
