Homemade Battery Charger

[The alaskan]

Hi everyone so this is actually my first post and please forgive my ignorance, I'm 16 and I'm working on a prototype I've finished the majority of it but now I need to make it tick ( I need a circuit) so this is what I need a small circuit that can fit in a 58mm x 33mm x 10mm LxWxH area
the circuit will have to regulate a current that will vary between 2-3.7v and be able to safely charge a 3.7v battery ( **broken link removed** ) and show the battery life with 4 0805 smd leds, have an or off switch for charging, usb input for charging the battery ( along with what i mentioned before about the irregular current 2-3.7 v) and lastly output to a lightning connection. Thanks for any feedback and again sorry for being ignorant if I was but I need a schematic made for this so I can make the pcb, pay $20 if somone wants to make the schematic. pm me for details if you're interested thanks.

 

[jpanhalt]

Hi everyone so this is actually my first post and please forgive my ignorance, I'm 16 and I'm working on a prototype I've finished the majority of it but now I need to make it tick ( I need a circuit) so this is what I need a small circuit that can fit in a 58mm x 33mm x 10mm LxWxH area
the circuit will have to regulate a current that will vary between 2-3.7v and be able to safely charge a 3.7v battery ( **broken link removed** ) and show the battery life with 4 0805 smd leds, have an or off switch for charging, usb input for charging the battery ( along with what i mentioned before about the irregular current 2-3.7 v) and lastly output to a lightning connection. Thanks for any feedback and again sorry for being ignorant if I was but I need a schematic made for this so I can make the pcb, pay $20 if somone wants to make the schematic. pm me for details if you're interested thanks.

Welcome to ETO

Unfortunately, your question is a bit jumbled. Electrical current is measured in amperes (unit = A), not volts. Assuming you may have meant amperes, one also needs to know the voltage to build a charger.

You can show voltage with leds, but there is no way to accurately show battery life until you define what you mean. For example, do you mean remaining charge or remaining charge cycles. The former can be estimated, but the latter is impossible to predict with accuracy.

Finally, I can't see what a "lightning" connection has do do with anything. Do you want to use the battery for lighting something? What? What sort of connection do you intend to use?

John

 

[ronsimpson]

Please tell us more. Pictures are good.

The battery is a Li-Polymer 3.7V 1150mAh.
It can discharge as fast as 1C and be charged as fast as 0.5C.
It maximum charging voltage is 4.2V and it must not be discharged below 2.75V.

show the battery life with 4 0805 smd leds

By this do you want 4 LEDs on at full charge and the 3, 2, 1, 0 LEDs to show an empty battery?
What lighting thing?

 

[DerStrom8]

Hi The alaskan , welcome to ETO!

Descriptive titles are a must here. Your original title gave no hint as to what your question was about, so I have changed it for you. Please be mindful of this in the future.

Good luck!
Matt

 

[zahwi]

Another little question.
Is the device needed to be working in the climatic conditions of Alaska?





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I don't use simulators of any kind, I'm happily married.

 

[The alaskan]

Please tell us more. Pictures are good.

The battery is a Li-Polymer 3.7V 1150mAh.
It can discharge as fast as 1C and be charged as fast as 0.5C.
It maximum charging voltage is 4.2V and it must not be discharged below 2.75V.

By this do you want 4 LEDs on at full charge and the 3, 2, 1, 0 LEDs to show an empty battery?
What lighting thing?

yup that's exactly what I want as far the leds go and I mean a lightning connection for iphone
(https://www.jpcycles.com/product/13...whG2sBJqEo0dpq4yNzDIzAMBJ9HfAHxcDrxoCBWnw_wcB )

 

[The alaskan]

Another little question.
Is the device needed to be working in the climatic conditions of Alaska?





----------------------------------------------------------------------------------------------------------------------------
I don't use simulators of any kind, I'm happily married.

haha no

 

[zahwi]

yup that's exactly what I want as far the leds go and I mean a lightning connection for iphone

For the battery condition many on this forum can help, it needs 4 comparators.
For the charger you need DC to DC boost converter. You will have to buy one cause they are difficult to make. Look at these:

**broken link removed**

**broken link removed**

 

[The alaskan]

For the battery condition many on this forum can help, it needs 4 comparators.
For the charger you need DC to DC boost converter. You will have to buy one cause they are difficult to make. Look at these:

**broken link removed**

**broken link removed**

ok thanks and why do I need a dc to dc boost converter, what's it do ?

 

[ronsimpson]

You want to power an Iphone?

For charging from a USB source look at this part. Please read the data sheet.
You will need to change the resistor on the "program" pin to get 0.5A charging.

 

[zahwi]

ok thanks and why do I need a dc to dc boost converter, what's it do ?

The converter charges the 3.7V cell from the 2-3.7V current source.

 

[ronsimpson]

You have 5V from the USB computer or power supply.
This 5V needs to be converted to about 3.7V at about 0.5A to charge the battery. (see data sheet, this is complicated)
You have about 3.7V of battery but you need 5V for the Iphone.
The boost supply will take 3V and make 5V.

How much current for the iphone?
Do you want to charge and run the iphone at the same time?

 

[The alaskan]

You have 5V from the USB computer or power supply.
This 5V needs to be converted to about 3.7V at about 0.5A to charge the battery. (see data sheet, this is complicated)
You have about 3.7V of battery but you need 5V for the Iphone.
The boost supply will take 3V and make 5V.

How much current for the iphone?
Do you want to charge and run the iphone at the same time?

yes I'd like to charge and run the phone simultaneously

 

[alec_t]

1) What is the mystery source of this 2-3.7V supply?
2) Do you know the pinout and input voltage/current requirements of the Lighning adapter?
3) Are you aware that lithium cells need careful charge/discharge control to prevent them catching fire/exploding?

 

[ronsimpson]

I modified a schematic from the data sheet.
Here is a battery charger.
AND
The point labeled "system load" will be 4.5V if the USB power is applied or it will be the battery voltage if not charging.
Both the 4.5 and 3.x voltage is too low to power the iphone. Here is where the boost converter goes. It will take the 2.5 through 5V and make 5V for the phone.

 

[The alaskan]

I modified a schematic from the data sheet.
Here is a battery charger.
AND
The point labeled "system load" will be 4.5V if the USB power is applied or it will be the battery voltage if not charging.
Both the 4.5 and 3.x voltage is too low to power the iphone. Here is where the boost converter goes. It will take the 2.5 through 5V and make 5V for the phone.
View attachment 96410

awesome thanks

 

[ronsimpson]

Error, try this.

 

[Colin]

By the time you pay $30 for delivery of the components, you could have bought the charger on eBay for $10.00

 

[DerStrom8]

By the time you pay $30 for delivery of the components, you could have bought the charger on eBay for $10.00

That kind of defeats the purpose of learning how to do it yourself now, doesn't it?

 

[jpanhalt]

That kind of defeats the purpose of learning how to do it yourself now, doesn't it?

Not at all, IMHO. I learned about cars and airplanes by taking working models apart, not by trying to build one de novo.

Not that I hadn't at one time planned to build a monoplane version of a Chanute-like glider of my own design. The prospect of me doing something like that was enough to convince my wife that we could "afford" flying lessons.

When you are completely new to something, I believe the best way to learn is to study something that works, rather than things that don't work.

John

OOPS, I forgot to add that in most cases I got what I took apart back together again, and it worked. My success rate for airplanes was 100%.