Charging mobile phone with solar panel

[colmac]

Hi, as per the title. Does anyone have any experience of these small solar chargers for phones ? We don,t have a roof mounted one and can charge the phones in the usual way but were thinking one of these wee chargers may be handy. Thak you.

[rusty69]

I tried with one of the 2W type ones once. It didn't work. 

 

ETA. It was directly from a panel (no battery as Alan has described ) 

Edited July 28, 2018 by rusty69

[Alan de Enfield]

11 minutes ago, colmac said:

Hi, as per the title. Does anyone have any experience of these small solar chargers for phones ? We don,t have a roof mounted one and can charge the phones in the usual way but were thinking one of these wee chargers may be handy. Thak you.

Are you thinking of the 'Solar Power Banks' as seen on ebay for around £12 ?

 

Yes they work, but ignore the Ah claims (typically 30,000 mAh)

I have a couple of them for hiking / camping.

They are actually around 4Ah and recharge the phone / GPS / Watch / Headlight once or twice but can take up to 30 hours of good sunlight to recharge them.

I ran a 5v USB fan for 14 hours, it was drawing around 0.3 amps

 

Recharged an I-Pad from 3% to 54% and used the 'whole' power-bank.

Ignore the flashing blue lights - they flash when actually getting any light at all but actually flatten the battery because the lights use more power than the panel is putting in.

 

Yes get one, but don't expect great things from them.

 

 

 

Edited July 28, 2018 by Alan de Enfield

[Jess--]

Alan, your maths may be a bit off by using that usb power meter

 

the led readout of the meter would also have been taking power from the battery and this was probably not measured.

[tree monkey]

I've got a small fold up camping type that sits in a window, it will charge my bog standard "stupid" phone.

It will maintain my smart phone and slowly charge it if switched off.

I normally use it to keep a powebank type battery charged which I then use in the evening when the suns gone to bed

[matty40s]

Don't bother buying the fold up solar phone charger from Bimble either, only works in direct bright sunshine and even then struggles to maintain charging voltage, cycling on and off.

[Ian F B]

This may sound a bit obvious but why not buy a car charger for your phone?

Apologies for the above,I broke the golden rule,I didn't read the post correctly??

Edited July 28, 2018 by Ian F B
Ex

[Alan de Enfield]

53 minutes ago, Jess-- said:

Alan, your maths may be a bit off by using that usb power meter

 

the led readout of the meter would also have been taking power from the battery and this was probably not measured.

Yes, I did consider that, but there is no-way that that can be a 30,000mAh battery.

4Ah is more likely.

 

[Robbo]

1 hour ago, Alan de Enfield said:

Yes, I did consider that, but there is no-way that that can be a 30,000mAh battery.

4Ah is more likely.

 

Why no way?

[David Mack]

My daughter used one of those solar power packs to keep her camera batteries charged when climbing Mount Kilimanjaro a couple of years ago. No other option. She kept it strapped to the outside of her pack. But maybe there is more sunlight in Africa.

[Robbo]

5 hours ago, colmac said:

Hi, as per the title. Does anyone have any experience of these small solar chargers for phones ? We don,t have a roof mounted one and can charge the phones in the usual way but were thinking one of these wee chargers may be handy. Thak you.

This vlog has some comments on battery power packs they use.   I think you will need a good size fold up type like they have for it to be any use.

 

 

[rusty69]

I think the OP needs to clarify whether they want to charge the phone directly with a solar panel, or a device with a battery charged by a panel. Clearly the latter is possible whilst the former may not be with a small output panel. 

[Alan de Enfield]

19 minutes ago, Robbo said:

 

Why no way?

30,000 mA = 30Ah

The battery is not physically big enough to 'hold' 30Ah.

 

On my Test (which I accept isn't 100% accurate - but not far off) the battery went from 100% charged to 0% after drawing 0.3 amps for 14 hours.

 

From Non-Chinese suppliers of LiPol batteries :

 

20Ah 3.7v battery weighs 650g and has dimensions of 148 x 27 x 98

37Ah 3.7v battery weighs 750g and has dimensions of 148 x 27 x 98

 

the (alleged) 30Ah Solar Charger and battery bank weighs 240g, dimensions including the solar panel and the case is 124 x 23 x 78

 

 

 

 

I have a 7w folding Solar panel which will charge my phone etc directly as it is producing about 1a at 5v at the USB socket, (but it won't charge an Apple device that requires 2amps)

 

 

Edited July 28, 2018 by Alan de Enfield

[Robbo]

1 minute ago, Alan de Enfield said:

30,000 mA = 30Ah

The battery is not physically big enough to 'hold' 30Ah.

 

On my Test (which I accept isn't 100% accurate - but not far off) the battery went from 100% charged to 0% after drawing 0.3 amps for 14 hours.

 

From Non-Chinese suppliers of LiPol batteries :

 

20Ah 3.7v battery weighs 650g and has dimensions of 148 x 27 x 98

37Ah 3.7v battery weighs 750g and has dimensions of 148 x 27 x 98

 

the (alleged) 30Ah Solar Charger and battery bank weighs 240g, dimensions including the solar panel and the case is 124 x 23 78

I agree it’s not 30ah, but it’s not 4ah,   0.3ah at 14hrs at 5v is 21wh, the conversion from 3.7 to 5v is probably only around 80% efficient, so it’s probably about 6.8-8ah, which also is roughly right for your weights.

[Alan de Enfield]

2 minutes ago, Robbo said:

I agree it’s not 30ah, but it’s not 4ah,   0.3ah at 14hrs at 5v is 21wh, the conversion from 3.7 to 5v is probably only around 80% efficient, so it’s probably about 6.8-8ah, which also is roughly right for your weights.

Maybe somewhere between the two ?

 

When I recharge my GPS (which has a 2700 mAh battery) I get about 1.5 recharges - maybe almost 2 recharges.

I guess there are more losses recharging the GPS battery.

[Robbo]

9 minutes ago, Alan de Enfield said:

Maybe somewhere between the two ?

 

When I recharge my GPS (which has a 2700 mAh battery) I get about 1.5 recharges - maybe almost 2 recharges.

I guess there are more losses recharging the GPS battery.

You get losses converting it to 5v and will also have losses converting it from 5v back to 3.7v.   Both will be around 80% efficient, so it’s a big loss and shoves it my ball park of battery size.

[Robbo]

36 minutes ago, Alan de Enfield said:

(but it won't charge an Apple device that requires 2amps)

No Apple iOS device requires 2amps to charge.   All will charge from a standard 500mah USB if required, even the iPad (although takes a long time and the screen needs to be off to actually charge).

Edited July 28, 2018 by Robbo

[Alan de Enfield]

39 minutes ago, Robbo said:

No Apple iOS device requires 2amps to charge.   All will charge from a standard 500mah USB if required, even the iPad (although takes a long time and the screen needs to be off to actually charge).

Maybe that was the problem when I tried to charge my Son's I-Pad thru a 500mA lighter plug adapter - it was showing 26% SoC and after an hour was down below 20% SoC

[Robbo]

7 hours ago, Alan de Enfield said:

Maybe that was the problem when I tried to charge my Son's I-Pad thru a 500mA lighter plug adapter - it was showing 26% SoC and after an hour was down below 20% SoC

If your using it the device can take more than what the usb can provide.   If I turn the brightness way up on mine even with a 2.4 amp charger the SoC doesn’t change.   That’s usually on a long cable tho so the iPad maybe reducing the current if it’s getting voltage drop.

[Alan de Enfield]

9 hours ago, Robbo said:

You get losses converting it to 5v and will also have losses converting it from 5v back to 3.7v.   Both will be around 80% efficient, so it’s a big loss and shoves it my ball park of battery size.

OK, I understand what you are saying.

I think what I meant, and failed to say, was that the 'effective, usable' available is about 4Ah for recharging your mobile phone.

The battery may well be 6Ah.

 

I suppose its similar to having £60 in your pocket, but you have lost £20 thru a hole, so only actually have £40 you can spend.

[1st ade]

8 minutes ago, Alan de Enfield said:

The battery may well be 6Ah.

This figure (and all the others referring to battery capacity) are meaningless without knowing the battery voltage.

 

The manufacturer may well have some wonderful technology which squeezes 30Ah into that size case but at (say) 0.25 volts. They could correctly claim 30Ah on the advert knowing full well that even at 100% efficiency it's 1.5 Ah at five volts.

[Robbo]

49 minutes ago, 1st ade said:

This figure (and all the others referring to battery capacity) are meaningless without knowing the battery voltage.

 

The manufacturer may well have some wonderful technology which squeezes 30Ah into that size case but at (say) 0.25 volts. They could correctly claim 30Ah on the advert knowing full well that even at 100% efficiency it's 1.5 Ah at five volts.

They don’t state the voltage but they do state the wh at 111, so it’s 3.7v. 

 

Lots of power banks direct from China are over stated, even the weight is nothing to go by as they fill the cells with sand.

Here’s one of my favourite YouTubers on the case..

 

 

Edited July 29, 2018 by Robbo

[Dr Bob]

47 minutes ago, Robbo said:

They don’t state the voltage but they do state the wh at 111, so it’s 3.7v. 

 

Lots of power banks direct from China are over stated, even the weight is nothing to go by as they fill the cells with sand.

Here’s one of my favourite YouTubers on the case..

 

 

Very interesting. Thanks for posting.

[Robbo]

22 minutes ago, Dr Bob said:

Very interesting. Thanks for posting.

You may like this one

 

 

[Momac]

I recently fitted a USB charger socket in place of the din type 12  V  socket on my boat . It was inexpensive off ebay and seems to work fine. It has two outlets so two devices can be charged at one time. The current drawn for phone charging is tiny .

 

I considered a rechargeable power bank but decided it was not really necessary for use on the boat.

By the way they are sold at B&M fairly cheaply .

 

Since the current used to charge a phone is small the idea of a small solar panel specifically for phone charging also doesn't seem necessary on a boat . But if it is a cheap option I guess every little helps . For use when remote from any power source a solar charged power bank makes complete sense.