RADCITY battery 5-pin connection signals?

[nafis]

Anyone know what the three small pins on the battery connector are for? The two large pins are +/-.
Looks like it's a Halong 5-pin connector. I'm trying to understand the communication protocol between the battery and the controller. I assume it a serial connection?

[DickB]

Surprisingly, they are unused.  There is no communication between controller and battery.

[nafis]

I wonder if my battery is a newer version? If I connect to the +/- terminals I get a voltage. As soon as I try to draw larger currents it shuts down. I also have a Bosch eBike battery. I found that to charge the Bosch I needed to provide 5V to one of the pins.
I'm wondering if it is some new sort of safety feature to prevent accidental shorting. I guess I will have to take it apart an look. I was hoping to wait until the warranty expired... did you take any pictures when you took yours apart? I suppose another test would be to just wire the +/- between the battery and the bike and see if it still works.

[DickB]

I have opened the Rad battery. The BMS uses semiconductor switches to connect and disconnect the cells from the power port. When "off" these switches do allow a small amount of what is called leakage current to pass. That is why you see a voltage with the key switch off. The amount of current is so low that even the high impedance of your multimeter loads it down, which is why you see a lesser voltage than nominal battery voltage.

[Altema]

I can confirm that the three small center pins are connected to nothing. Other brand battery with that connector are the same (I have five batteries).
Like DickB explained, you will see some voltage with the battery turned off on the large pins, but it won't support a load. Turn the battery switch on and it will support a load. Interestingly, the battery accepts a charge though these connections as well. Perhaps for regen braking? I found that out by accident when I turned one of my two batteries off, and the lower voltage battery started charging from the other battery.

[DickB]

Also interesting is that the charge port uses a completely separate path from the regen charge path. It also has a MOSFET semiconductor switch that is only enabled when charge voltage is seen at the charge port connector, so you do not see battery voltage at that terminal either.

[nafis]

Very interesting result. I just received my second RAD Power battery. This one works just hooking up the +/- ! The battery that came with my eBike doesn't. They are made by two different manufacturers or at least are marked differently. The one that works says model HL-RP-S1304. The serial number starts with DDLGRPE4814. The one that doesn't just says RP1304AA..... What does your's say? They both work in the ebike.

[nafis]

The two batteries are clearly made by different companies or are different revisions. Notice the size of the Fuse labeling, the different lock, number of case screws and case vents. The newer one that works has a serial number

[dedenburn]

I have opened the Rad battery. The BMS uses semiconductor switches to connect and disconnect the cells from the power port. When "off" these switches do allow a small amount of what is called leakage current to pass. That is why you see a voltage with the key switch off. The amount of current is so low that even the high impedance of your multimeter loads it down, which is why you see a lesser voltage than nominal battery voltage.

I know its been awhile since this convo started, but since you've taken the pack apart, could you tell me what series and parallel the pack is, and what voltage, ah, is?

[DickB]

4 cells in parallel 13 in series 48V 14Ah.

[dedenburn]

Awesome thanks. And is there non oem battery chargers, or are they brand specific? And what are the stats on the battery charger?

[DickB]

Li-Ion chargers are constant current - constant voltage (CC/CV). The only two parameters that matter are voltage and current and a CC/CV profile. The Rad charger is 48V 2A. (Keep in mind the voltage rating is nominal voltage. Actual float voltage of the Rad charger is 54.6V.) The electrical connector on the battery is a 5.5mm/2.1mm jack.

There are other non-OEM chargers out there, some at higher ampere rating. You can charge at a faster rate, but the batteries have a 5A fuse in the charge circuit, so that's a limit, and the higher the charge rate the less battery longevity. Personally, I would not go above 3A. But I am trying to maximize my battery longevity.