Bitcoin donations to: 1CE9UfWJcHBYkWPns7iqBqZgKhd5xfqEaM thanks!
Buy Bitcoins easily by clicking HERE!


Use coupon radiopreppers for 20% off on the above site.

Author Topic: USB Solar charger 5V to 12V  (Read 482 times)

CPR

  • Full Member
  • ***
  • Posts: 105
  • SMeter: +2/-0
    • View Profile
USB Solar charger 5V to 12V
« on: March 19, 2018, 11:57:04 AM »
Hi,

I was wondering if it's possible to use a 5V 2Amps solar charger to charge 12-14V batteries if using a step up converter. I own an Anker 14W solar charger with two usb ports, apparently they can deliver 1Amps each. Looking at those 12V portable solar chargers, they are way over my budget. Somewhere I read that you should charge batteries with 10% of their Ah specs. So let's assume I get a 12V / 7Ah SLAB and using a step up converter, I should charge it with 800mAh.

So, taking the real power of my solar charger, which is not 14W rather 10W (5V x 2Amps) I could deliver
P = U x I => I = P / U => I = 10W / 14V = 0.710A of charging current with 14 Volts assuming the stepup converter has no significant loss.

Is that realistically possible?

Another approach would be to see if the panels are delivering 5V or rather 12V and then transformed to 5V. Or, combining the two USB outputs to one giving me 2Amps at a time and increasing the charging current. I really like the idea of charging my batteries when in the field, but the 12V portable solar panels are really over my budget.

Regards,
CP

gil

  • Administrator
  • Hero Member
  • *****
  • Posts: 2873
  • SMeter: +76/-3
    • View Profile
    • Radio Preppers
Re: USB Solar charger 5V to 12V
« Reply #1 on: March 19, 2018, 09:12:44 PM »
Probably. Julian would know better; he is the expert here on solar charging.

Personally, I also use a 14W panel to charge 18650 cells. I have two NiteCore UM-10 USB charger, so I can charge two 18650 cells at once, the third one later. It's no big deal for me because my radios draw so little current, I have never needed to recharge them within at least two weeks... If you need a bit more voltage and use four 18650 cells, I would use two panels and of course four UM-10 chargers. I do need to buy a larger panel for other batteries, but I might also buy a 7W panel so I can charge three 18650s at once...

Gil.

CPR

  • Full Member
  • ***
  • Posts: 105
  • SMeter: +2/-0
    • View Profile
Re: USB Solar charger 5V to 12V
« Reply #2 on: April 04, 2018, 07:11:04 AM »
I ordered a Li-Ion charger on Banggood and a step up converter. The converter seems to work fine, boosting voltage up to 30V.
With 2A on 6V I think I could enhance the battery usage in the field at least.
BUT...
They did not send me the charger I ordered. I was trying to figure out the specs of the charger by searching for the IC (which should be the way to go I guess) but can't find any datasheets on it. Does anyone have an idea where to get those specs on this charger CHN726RMY?





Thanks
CPR