EEMB Lithium Polymer battery 3.7V 3700mAh 103395 Lipo Rechargeable Battery Pack with wire JST Connector for LED and Wireless Device-confirm device & connector polarity before purchase

Good quality 3700mAh battery but be mindful of the polarity of your application, as clearly stated by the manufacturer.These appeared to have a JST connector who's polarity is typically found in Radio Controlled toy world; the Internet of Things seems to use the opposite (i.e. there is no "standard" for polarity on these type of connectors)If you're very careful it's possible to poke out the metal conductors from the plastic housing of the JST connector and reinsert the desired way around.

Had to swap the connector polarity, it's annoying that there is no standardisation

Packaging could be a little better and more sturdy but okay

Always tempted to lick the terminals to check the charge, funnier if you get the cat to do it

Great battery with lots of power, the only disadvantage is the polarity of the connector appears to be reversed at least in terms of the TinyPico which was my intended use. Apart from that there were no problems and delivery was quick

I am currently amusing myself making portable audio equipment. The main concern with Lithium battery power is safety. This battery has battery protection built in. I can use it with cheap chargers and with cheap and poorly specified Bluetooth modules and class D amps with confidence that abuse cannot be catastrophic. It also has a handsom capacity. My diy Bluetooth amp lasts ages using it 3.7Ahrs! I must add a further caution for users after having read other comments. Li batteries are dangerous when charged incorrectly particularly when overcharged. This one has a protection circuit built-in. However, I would say that it should not be charged directly from the likes of phone or other plugin usb power supplies. Use one of the many cheap charger boards available that will automatically reduce the charge current near full charge and shut off charging when the voltage reaches 4.2v. the battery will also last longer and be safer if the charge current is limited to 1/3rd of capacity or less. No more that about 1A to 1.2A. This increases charge time but is safer and less fatiguing on batter life. Some usb supplies only limit at 2A or even 3A and have no shut down. Be cautious!

I plugged it into my charger and the charger started smoking. I use a small USB charger which wasn't plugged in at the time. It burnt the charger out. Tried it in another and the same thing. Realised the connector was fitted the wrong way round on the battery. In the picture you can see it next to a correctly wired connector

Before you plug this into a charger or device make sure the cable plus/minus <> red/black is the right way round, it is not a manufacture fault for your error when you're warned that you need to make sure that the cables are the right way round in the plug for your deviceseeing a few one-star reviews when it was their own fault that they destroyed their device or charger because they didn't check the red/black was correct for there device,, the plug or device socket has no standard +/- layout