Hi,
I'm trying to use an old LG GT540 Android for surveillance on my allotment (garden away from my house, for those who don't know the term), which is off-grid, so I've got solar panels charging a leisure (Lead acid) accumulator.
My first thought was to leave the Lithium Ion battery, and plug in a car charger and power the charger from the lead acid battery. However, that apparently ruins the lithium ion battery and rapidly flattens the lead acid battery.
So I turned to stepping down the voltage from 12 - 14 volts to the 3.7V required for the phone. Research suggested that a switch mode regulator would give far greater efficiency so I set up an L200C to do the job.
The mobile battery ("LGIP-400N") contains protection circuitry. One component of that is a "strap battery device VLD P 220 SLF". The datasheet is not clear to me but it looks like a thermal shutdown device to protect things if the battery gets too hot. There are also two ICs and 7 resistors - they have no symbology and I don't know what they do. I tried leaving all this in circuit by connecting the battery terminals to the mobile via soldered wires and connected the regulated 3.7V to the place where the lithium ion battery used to be. I reasoned neither the phone nor the electronics would know the battery was... not what it used to be. However, it doesn't work; the phone does nothing.
So I removed the battery circuit components, and routed the 3.7V power from the regulator straight to the two outer pads in the mobile phone; the middle pin is ignored. Well, it works, and the phone comes all the way up and works fine.
However - two things:
1. There is an 80mA current drain from the leisure battery, even with the phone switched off
2. With the phone on, the regulator is too hot to touch and about 300mA is drawn, implying a 4 Watt consumption!
This is not going to fly with the meagre PV charging I have going, and anyway - it suggests something is worryingly wrong.
I wonder if anyone can shed any light on what if anything I'm doing wrong. I'd appreciate any help you can offer.
Regards,
Chris
I'm trying to use an old LG GT540 Android for surveillance on my allotment (garden away from my house, for those who don't know the term), which is off-grid, so I've got solar panels charging a leisure (Lead acid) accumulator.
My first thought was to leave the Lithium Ion battery, and plug in a car charger and power the charger from the lead acid battery. However, that apparently ruins the lithium ion battery and rapidly flattens the lead acid battery.
So I turned to stepping down the voltage from 12 - 14 volts to the 3.7V required for the phone. Research suggested that a switch mode regulator would give far greater efficiency so I set up an L200C to do the job.
The mobile battery ("LGIP-400N") contains protection circuitry. One component of that is a "strap battery device VLD P 220 SLF". The datasheet is not clear to me but it looks like a thermal shutdown device to protect things if the battery gets too hot. There are also two ICs and 7 resistors - they have no symbology and I don't know what they do. I tried leaving all this in circuit by connecting the battery terminals to the mobile via soldered wires and connected the regulated 3.7V to the place where the lithium ion battery used to be. I reasoned neither the phone nor the electronics would know the battery was... not what it used to be. However, it doesn't work; the phone does nothing.
So I removed the battery circuit components, and routed the 3.7V power from the regulator straight to the two outer pads in the mobile phone; the middle pin is ignored. Well, it works, and the phone comes all the way up and works fine.
However - two things:
1. There is an 80mA current drain from the leisure battery, even with the phone switched off
2. With the phone on, the regulator is too hot to touch and about 300mA is drawn, implying a 4 Watt consumption!
This is not going to fly with the meagre PV charging I have going, and anyway - it suggests something is worryingly wrong.
I wonder if anyone can shed any light on what if anything I'm doing wrong. I'd appreciate any help you can offer.
Regards,
Chris