I am looking for a lithium ion charger board with a USB output. The requirements are:
1. No soldering required - this means a micro USB connector for charging, USB type A connector for output, and JST connector for battery
2. Passthrough / load sharing - this means it will run the device and charge the battery simultaneously
3. 2A output
4. Small as possible
Let me go through some of the lithium-ion only approaches that I have experimented with:
A. Commercial passthrough USB battery/charger
Only one major brand supports this feature: MyCharge. Unfortunately their higher amperage units are too bulky for a small project.
B. Dedicated board #1
http://www.amazon.com/gp/product/B00WDQ ... ge_o04_s00
This does not support passthrough/load sharing necessitating an awkward wiring harness with switch for charging and running at the same time. Great charger though with a screen, flashlight feature and the battery leads are presoldered and strong.
C. Dedicated board #2
http://www.amazon.com/gp/product/B00VDP ... ge_o02_s01
This also does not support passthrough/load sharing. It also requires soldering battery leads and only uses a simple status LED. It is slightly more compact with a different connector configuration.
D. Dedicated board #1 or #2 as output ONLY with a separate external lithium-ion charger
1. This would require another custom wiring harness tied into the battery wiring with a female connector for external charging
2. This would no longer function like a typical device and require a specialized external charger
3. Depending on the charger characteristics, It could cause the output board to detect a fault and shut down
E. Adafruit Powerboost 1000C
This fits the bill in almost every way. Unfortunately it has problems too.
1. Requires soldering on the USB type A connector - this is by far the biggest problem. I am too mentally and physically handicapped for this.
2. Only available from a single source. Apparently no other storefront in the world has seen a need for this type of product. If a product based on one of their parts gets too popular they could pull the plug for any reason.
3. Adafruit does not provide phone or email support for their products! I've never even heard of such a thing before. This alone makes we want to find another alternative.
So you can see that is it not for a lack of trying that I am unable to find a reliable lithium-ion charger / output board. Indeed, my entire work is at a total standstill now because of this. Does anyone have any suggestions?