USB charger base
Posted: Sun May 14, 2023 7:12 am
Guys
I thought some of you may be intersted some experiments I've been doing to use a USB power supply instead of the various DC PSU's which are supplied with these radios
I noticed that it was possible to buy USB charger module from AliExpress which would change 2S or 3S or 4S battery packs, with USB currents of either 1A, 2A or 4A
I have bought several different modules, and after doing some tests, the module which look like this one appear to be the best.
https://www.aliexpress.com/item/1005004503555987.html
However, as usual with such items from AliExpress etc, the module does not totally conform to its specification.
I found the 1A USB current version, consumed 950mA from USB, and the 2A USB current version consumes around 1.6A
I did not buy any "4A" versions becuase 4A USB chargers are not common, but most new USB chargers will deliver 2A.
The charge current to the radio, when the battery pack was at 8V was approximately 600mA for the "1A" module, and approximately 900mA for the "2A" module (consuming approximately 1.6A)
Doing some rough calculations, these modules over 90% efficient.
i.e.
USB: 1A * 5V = 5W
Radio 8V * 0.6A = 4.8W
4.8 / 5 = 0.96 = 96% effecient
USB 1.5A * 5V = 7.5W
Radio 8V * 0.9 = 7.2W
7.2 / 7.5 = 0.96 = 96% efficient
These figures are not 100% accurate, as the USB current sometimes reached 1.6A , so the efficiency would probably be 90%
I also tried anothe type of module, but the efficiency was terrible, only 60%, so I'm not going to post a link to that module type.
Trying the 2A module on a USB PSU which could only supply 1A resulted in only 300mA charge current to the radio, because the voltage of the USB PSU dropped to 3.5V. I don't remember how much current was taken from USB in this experiment, but I don't think it was stable.
Also some USB chargers completely shut off and then reset, if more current is taken, than they are designed to supply, and this results in a buzzing sound as the charger repeatedly resets.
So if you want to charge from 1A USB, then you should use the 1A version of the module, becuase the 2A version does not shutdown gradually
Modification of the charger base, requires that part of the plastic is filed away to allow for the USB socket to protrude enough.
I glued the module to the base plastic, becasue its then lower than the terminals that connect to the battery, and I have some short wires between the terminals and the module.
At the moment I have not filled in the large hole at the back of the charger base, in case I want to convert back to using the 10V DC charger, but I think I will fill this soon with hot glue.
One thing to be aware of when gluing the module, is that it dissipates about 0.5W and does warm up, and using hot glue to fix the module didn't guarantee that it was held firmly, so I used some contact adhesive instead. I also considered using epoxy glue, but this is probably overkill for the amount of force which is applied to the module when the USB plug is inserted.
This module type may be also available in other USB socket types, but I'm trying to standardise all my USB devices to USB C for all new devices.
I thought some of you may be intersted some experiments I've been doing to use a USB power supply instead of the various DC PSU's which are supplied with these radios
I noticed that it was possible to buy USB charger module from AliExpress which would change 2S or 3S or 4S battery packs, with USB currents of either 1A, 2A or 4A
I have bought several different modules, and after doing some tests, the module which look like this one appear to be the best.
https://www.aliexpress.com/item/1005004503555987.html
However, as usual with such items from AliExpress etc, the module does not totally conform to its specification.
I found the 1A USB current version, consumed 950mA from USB, and the 2A USB current version consumes around 1.6A
I did not buy any "4A" versions becuase 4A USB chargers are not common, but most new USB chargers will deliver 2A.
The charge current to the radio, when the battery pack was at 8V was approximately 600mA for the "1A" module, and approximately 900mA for the "2A" module (consuming approximately 1.6A)
Doing some rough calculations, these modules over 90% efficient.
i.e.
USB: 1A * 5V = 5W
Radio 8V * 0.6A = 4.8W
4.8 / 5 = 0.96 = 96% effecient
USB 1.5A * 5V = 7.5W
Radio 8V * 0.9 = 7.2W
7.2 / 7.5 = 0.96 = 96% efficient
These figures are not 100% accurate, as the USB current sometimes reached 1.6A , so the efficiency would probably be 90%
I also tried anothe type of module, but the efficiency was terrible, only 60%, so I'm not going to post a link to that module type.
Trying the 2A module on a USB PSU which could only supply 1A resulted in only 300mA charge current to the radio, because the voltage of the USB PSU dropped to 3.5V. I don't remember how much current was taken from USB in this experiment, but I don't think it was stable.
Also some USB chargers completely shut off and then reset, if more current is taken, than they are designed to supply, and this results in a buzzing sound as the charger repeatedly resets.
So if you want to charge from 1A USB, then you should use the 1A version of the module, becuase the 2A version does not shutdown gradually
Modification of the charger base, requires that part of the plastic is filed away to allow for the USB socket to protrude enough.
I glued the module to the base plastic, becasue its then lower than the terminals that connect to the battery, and I have some short wires between the terminals and the module.
At the moment I have not filled in the large hole at the back of the charger base, in case I want to convert back to using the 10V DC charger, but I think I will fill this soon with hot glue.
One thing to be aware of when gluing the module, is that it dissipates about 0.5W and does warm up, and using hot glue to fix the module didn't guarantee that it was held firmly, so I used some contact adhesive instead. I also considered using epoxy glue, but this is probably overkill for the amount of force which is applied to the module when the USB plug is inserted.
This module type may be also available in other USB socket types, but I'm trying to standardise all my USB devices to USB C for all new devices.