Battery not fully charging.

I bought 3x of the DFR0208 Lithium battery chargers (link below). I am using them to charge a 3.7v 1300mAh battery. The problem I am having is that one of the chargers never shows a completed charge. I switched the battery to the other two chargers and they both instantly show the green charged LED. I have also tried this with about 4 different batteries, all with the same result. It would appear to me that the battery is not the issue, and the charger is actually charging the battery, it just isn't showing the green "charged" LED.

Any ideas?

https://www.dfrobot.com/product-851.html