Battery to Battery (Solar) Charging

[Mark1]

Hi all,

I've been running some tests against a solar charger I bought vs my expectations. It's internal battery is rated at 1000mAh with a 1400mAh battery in the phone.

I was told on the phone that "as the capactites of both equalise then the charger will stop charging the phone". Wrong no? When the voltages equalise I would have thought. If the charger has a charge pump then it "should" be able to deliver most of it's capacity to my phone I would have thought?

I'm asking because this thing seems only able to increase the charge in my phone my 20% at best.

Thanks

Mark

 

[Resqueline]

Afaik there's a step-up inverter in those Chinese solar chargers, but also a very inefficient solar panel that takes a lot longer to charge the internal battery than stated.
If indeed the internal battery is as big as stated, which is certainly not likely.

 

[Mark1]

Thanks for the reply. Get the feeling I was being fobbed off. A good design should keep the charge pump at, let's say 5v (given the phone charges off the usb) for more that 20% of the internal charge of the solar charger.

 

[Resqueline]

The problem is most likely not with the charge pump, but with the battery being 300mAh instead of 1000, or the solar panel requiring a 5 x longer insolation than stated.

 

[Mark1]

Thanks - assuming the battery is 1000mAh and the charge pump is okay (I assume in actuallity one of them is faulty) then in theory it should do better than charging my 1400mAh phone battery by 20% is all cases?

 

[Resqueline]

Yes, given sufficient time in the sun it should in theory charge your phone to around 50%.

 

[Mark1]

okay - I think this is the point I'm missing. re: "to aroud 50%" - therefore if the phone is already @ 50% then no more (or v little charge) increase? I would have thought if should, so long as the source voltage is greater than that of the sink, then it would continue to charge until the source~=sink voltage?

 

[Resqueline]

With charge pumps (aka step-up or boost inverters) the voltages don't matter, meaning that a 3V battery can perfectly well charge a 6V battery with this technology.
So the more correct term I should've used is "increase the phone charge level by 50%".

 

[Mark1]

Hi Resqueline - thanks. I thought that was the case, but wanted to check

Cheers

Mark