BetaFPV released a new battery connector trying to replace the JST PH2.0 connector that most of us use on our 1S whoops. It is called the BT2.0 connector. But how do those connectors compare?
In this article I will compare the BT2.0 against the original JST PH2.0 connector with solid pins - not the commonly used knock offs with rolled pins. I think it is important to compare the best possible options against each other.
Both plugs are build in such a way that you should not be able to plug them in backwards. the JST PH2.0 connector has a couple of features which make it rather difficult to plug it in the wrong way. First of all, there is a notch on one side of the plug and second, the pins are offset to one side of the plug - this makes it really hard to plug the JST PH2.0 connector the wrong way around.
The BT2.0 connector is rounded on one side - very similar to XT30 and XT60 connector, but, with some force you are able to plug it in the wrong way - especially because the plastic of the plug is rather soft. There are some people who claim that this can be done easily. In my experience you really have to want to plug it in the wrong way around.
But technically - yes - it is possible and I think BetaFPV should work on a solution to this issue. I think this problem could be mitigated by having a notch on one side of the plug - and maybe using stiffer plastic for the plug.
On the JST connector the plug will also snap into place, making a pretty solid connection - there is no such feature on the BT2.0 connector and the plug disconnects rather easily - in my opinion a bit too easily - especially after a couple of connect/disconnect cycles.
Both plugs have the value 2.0 in their name, which means that their pins are spaced 2mm from each other (center to center).
A male and female PH2.0 connector pair weighs in at 0.22g, whereas the BT2.0 connector pair weighs in at 0.57g. So the difference of 0.35g is certainly something to consider. The BT2.0 connectors are thus twice as heavy as the PH2.0 connector.
The BT2.0 connector is rated for 9A continuous current - which is quite impressive in comparison to the 2A rating of the PH2.0 connector.
But how do they compare? I decided to do a static load test. For this I built a custom battery tester based on an Arduino Uno, current sensor and a Mosfet as a load. This device allows me to discharge batteries with a constant load and measure the batteries voltage during the discharge process.
I established baselines of my two BetaFPV 300mAh batteries with BT2.0 connector. Both batteries have the same amount of charge/discharge cycles and I charged them to 4.35V every time.
From the 5A baseline you can see that the two batteries are very close to each other - one battery has a slightly higher internal resistance resulting in slightly lower times to reach the discharge threshold of 3.5V. But in total they are only off about 0.014V in comparison to each other.
PH2.0 vs. BT2.0
The higher the load, the more significant the difference will be. I decided to compare both plugs at a constant load of 5A.
As you can see from the following graph, the battery with the BT2.0 connector takes around 25 seconds longer to reach the threshold of 3.5V. Also the sag is quite a bit lower than with the solid pin PH2.0 connector.
I could also feel the PH2.0 connector getting quite a bit warmer than the BT2.0 connector.
I am aware that Joshua Bardwell published similar results. I see his results as a confirmation of mine (or the other way around if you prefer).
Currently there are not many options for batteries wit the BT2.0 connector. Sure, you can mod all your PH2.0 batteries to have the BT2.0 connector, but this means additional time and money investment for every battery you have.
The other option is to simply use the BetaFPV batteries, which are not the greatest option as most of us know. They usually are good for the first couple of flights and then quickly degrade and get puffy.
You can also get a charger from BetaFPV with six BT2.0 connectors.
But BetaFPV is open about sharing or licensing their design, so it is quite possible that other companies will come up with batteries with the BT2.0 connector.
The BT2.0 connector is electrically definitely the superior connector.
I think that the BT2.0 connector is a big step in the right direction. Establishing BetaFPV as a company that want’s to push the hobby by trying something new, so big respect for this engagement.
But I also think, that there are a couple of problems that need fixing:
- Make the plug fool proof: it should not be possible to plug it in the wrong way. The solution to this should be easy and maybe even backwards compatible by making a small notch on one side of the plug.
- A snugger connection: the fit of the BT2.0 connector could be a bit tighter, preventing the connector from disconnecting so easily in a harder crashes.
- Battery choices: granted, this is not something that BetaFPV themselves can improve on, but we will see if other companies adapt this plug. Only when that happens I see a future for this plug.
UPDATE: According to Bob Roogi, a new connector from a different company is coming out mid February - so you might want to wait for this connector. Bob also mentioned, that he talked to GNB and the cooperation with BetaFPV regarding their connector does not seem to be the best one - we might not get GNB batteries with BT2,0 connector - at least not without modifying them ourselves.