One of the first accessories action camera owners usually purchase is a second battery of some description to give them a little more shooting time. I am no exception when it comes to this. Often the big issue comes down to the charging – namely with just the one camera to charge the batteries, it would take a long time to charge both (or more) batteries.
That was when I did some searching around and came across the Telesin YI-B&C-001 Yi Action Camera compatible battery and charger bundle. This bundle was bought for just under AU$17 and included two batteries, storage cases and a dual-bay USB powered charger. It seemed to be great value for the batteries alone, and the charger certainly would help ease the issue of rotating batteries to charge them.
Of course, these are not products of Xiaomi or Xiaoyi, and are compatible products from a third party manufacturer. As a result, they might not be made to the same standard, and you generally use them at your own risk. Lets see if it’s any good.
The unit barely survived the journey, being well-crushed by the time I received it.
The unit comes in a hanging box, with a window at the front through which the charger can be seen. The slogan of the company is “ready for your pro”, which sounds a bit odd to a native English ear. The rear of the box doesn’t have many specifications at all, but claims charging time is based on the input current.
The side of the box has the model number, barcode and list of inclusions. Notably missing is a charger cable, but this is no big issue as you will see later.
Inside, the product is packed in a plastic shell tray.
The charger itself has two bays, and a set of two LED indicators at the front which indicate the charging status for each bay. The frame with the logo slides upwards to open the bays for the batteries, and slides down to hold them in place. The contacts do not seem well aligned to the cut-outs in the plastic, and there is some evidence of blemishes in the plastic near the LEDs. The unit feels light and unsubstantial, with plastic that flexes quite easily under pressure. The rear cover has no feet, and claims a 1-2A input, with a model number of YI-BCG-T02.
The side is textured, and only the top half slides upwards. The power input is a standard MicroUSB-B connector, so most Android/Windows phone users should have such cables/chargers available. The cable with the camera is also suitable.
The batteries come inside their own plastic storage box which has bowed sides and feels a little flimsy. Each battery is packaged in a milky plastic bag as well. It claims to be 1010mAh, identical with the capacity of the original battery, but is branded Telesin and Made in China.
Using the Bundle
The batteries generally fit well into the camera and are a hair tighter than the original. Unlike the original, the contacts protrude slightly more from the bottom of the battery. Testing on non-stop recording 1080p/60fps gave the following times:
- 1h 1m 9s
- 1h 3m 26s
- 1h 0m 2s
For reference, the original battery provided 1h 7m 40s, so the recording times from the Telesin batteries are slightly less than the original but not by much. How well the batteries will hold up to cycle use and storage is unknown, and I have had many clone batteries fail from high internal resistance just by being stored. The level of safety and protection, and source of the cells are not known either. However, for the price, this seems quite acceptable.
The supplied cases themselves don’t open and close very well, and are a bit big, allowing the batteries to slide around in the enclosure.
The charger feels flimsy and light, but worst of all, has contact problems all around. The batteries frequently do not charge the first time on insertion due to a lack of contact pressure between the battery and the pins, but other times, the whole charger is inoperative due to a loose microUSB-B socket on the charger itself. The first issue is easily remedied by inserting wads of paper in-between the retention frame and the batteries, and the second requires careful positioning of the microUSB cable. So much for their claimed innovative battery frame system.
The charging current profile itself is also slight cause for concern, as while the charger can charge one or two batteries at a time, they operate independently at a sub-optimal rate.
Compared to using the in-camera charging, charging one battery using this charger takes just shy of two and a half hours when the camera can do the same in one and a half hours. Furthermore, due to a short CC phase, and long tapered charge phase, the amount of charge accumulated in the battery over time is slower than with the camera. If single battery charge speed is what you’re after, you’ll probably need to use the camera.
However, if you have two batteries in the charger, the charge time doesn’t change by much (this example has it about 15 minutes shorter), as each channel operates independently. As a result, it’s quicker than charging two batteries sequentially in the camera which would take three hours, but requires charging two at a time.
Regardless, it does fall short on the claimed 1-2A input current, as with a 2A charger, it consumed just about 1A at the most. This is not unexpected as the smaller cells do mean lower maximum charge currents, and we will understand why this is the case in the next section.
Lets see what makes the charger “tick” …
The PCB is dated 15th June 2015 with product code JBH-YU-002. The charger is basically two independent chargers as hypothesized earlier, using two MicrOne ME4057 Linear charger ICs. These ICs feature integral overheat protection, soft starting, preset voltage limits, thermal regulation ability (unused), and programmable charge current.
In this case, the charge current is set by R2 and R5 for each channel respectively, and the 2.4kohm resistor results in a maximum per channel current of about 541mA. As a result, it’s really only going to draw about 1A at the most by design.
The reason it isn’t wise to increase this is likely due to thermal reasons. While there are vias and large copper areas on the PCB, the unit is enclosed. As a linear charger, the power dissipation is approximately Icharge * (Vin – Vout), so for the pre-set current, we’re looking at 0.7W of heat per channel already. Increasing the charge current setting would make it worse and potentially stress the cells more, but the chips will throttle back the current to protect themselves from failure.
Sadly, as a linear design, it hasn’t got the best charging efficiency, so you are throwing away about 25% of the energy into heat.
All aftermarket compatible products are a gamble, and this one was a relatively low-cost gamble. On the face of it, the batteries performed adequately and fairly close in capacity to the original when fresh, but their safety and lifetime remain unknown. The charger could be better designed and more efficient, but with patience, can be made to operate and satisfactorily charge the batteries. At the price, it is nice to have the convenience of charging while the camera is in use, albeit rather slowly if it is set up with care to ensure the contacts are all made, but I wouldn’t rely on the product being reliable or durable in the long run.