- #1
Biycchu
- 8
- 0
Please help me. How many times I can charge my 5000mah mobile from 12 volt 7ah battery. I will use dc mobile charger.
How many times I can charge my 5000mah mobile from 12 volt 7ah battery?
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Discussion Overview
The discussion revolves around estimating how many times a 5000mAh mobile phone can be charged using a 12V 7Ah battery, specifically when utilizing a DC mobile charger. The scope includes technical considerations regarding battery capacities, charging efficiencies, and potential losses in the charging process.
Discussion Character
- Technical explanation, Mathematical reasoning, Debate/contested
Main Points Raised
- One participant notes that the efficiency of the charger plays a significant role in determining the number of charges, suggesting that a DC-DC converter would be more efficient.
- Another participant mentions that the phone's battery capacity is 5Ah at 5V, while the external battery has a capacity of 7Ah at 12V, estimating that 2-3 recharges might be possible.
- A different participant provides a specific example, stating that a Samsung Galaxy S5 battery rated at 5.6Ah could influence the calculations.
- One participant calculates that the phone requires about 18Wh to charge fully, based on the phone's battery voltage and capacity, and estimates that the 12V 7Ah battery contains about 85Wh of energy, suggesting a theoretical maximum of about 4.5 full charges, while acknowledging that losses will reduce this number.
Areas of Agreement / Disagreement
Participants express varying estimates regarding the number of charges possible, with some suggesting 2-3 charges and others proposing up to 4.5 charges, indicating that the discussion remains unresolved with competing views on the efficiency and losses involved.
Contextual Notes
Participants have not fully clarified assumptions regarding charging efficiencies, specific charger models, or the impact of losses during the charging process, which may affect the calculations presented.
- #2
berkeman
Admin
- 69,409
- 24,805
Welcome to the PF. 
It depends on the charger. The most efficient ones will use a DC-DC converter to convert the 12V input to the 5V output for your phone's USB charger input port. Still, your phone has a 5Ah capacity at 5V, and your external battery has 7Ah capacity at 12V? If so, you will only get 2-3 recharges out of that external battery, most likely. What model is your phone, and which external battery are you wanting to use?
It depends on the charger. The most efficient ones will use a DC-DC converter to convert the 12V input to the 5V output for your phone's USB charger input port. Still, your phone has a 5Ah capacity at 5V, and your external battery has 7Ah capacity at 12V? If so, you will only get 2-3 recharges out of that external battery, most likely. What model is your phone, and which external battery are you wanting to use?
- #3
- 11,326
- 8,755
It also depends on the phone. I had a spare battery for a Samsung Galaxy S5. It was rated at 5.6 AH
- #4
Biycchu
- 8
- 0
my mobile is asus zenfone max pro m2. I will buy 7ah smf battery from amazon.
- #5
essenmein
- 657
- 294
5Ahr phone bat is probably Li-ion single cell, therefore 3.7V. So your phone needs about 18Whrs (5Ahrx3.7V) to charge from 0% charge to 100% charge.
A 12V 7Ahr battery contains about 85Whrs of energy so assuming no losses you could completely charge your phone about 4.5 times from that battery. Now there will be some losses in both batteries and in the charger itself which will reduce the number of full charges.
A 12V 7Ahr battery contains about 85Whrs of energy so assuming no losses you could completely charge your phone about 4.5 times from that battery. Now there will be some losses in both batteries and in the charger itself which will reduce the number of full charges.