A2B METRO GEN 2 SECOND BATTERY

[westoe]

Hello,
My A2B generation 2 came with only the external battery fitted from the manufacturer.
I have just fitted a second battery in the down tube of the bike and what a hassle it was to get the controller back in place and all the wires tucked away into such a cramped area.

The problem I have is I cannot get the internal battery to show on the display gauge on the handlebars.
The original rear battery shows up as battery "A" on the switch and displays the battery level etc. but when I switch to the "B" battery the gauge displays the empty battery icon.
The battery functions OK and I get about 24 miles out of it and I have to judge how much power is left in the battery when riding it by using the trip meter to give me an indication of the remaining battery level.

There is only the two power inputs on the controller and I have tried swapping them around which then tells me the level of the battery in the tube but when I switch to the external battery - again that battery will then just show the empty battery icon when the positions are switched on the controller input cables.

Does anyone know a way of getting the display to show each battery level when on the handlebar gauge when the switch batteries are selected / changed on the key switch or is this a known problem with this kind of set up?

Any advise will be very grateful to help me get this sorted, thanks for reading.

 

[Nobuo]

it could be that the internal battery has a lower voltage than the external.

Do you have a multimeter? check both batteries voltages when fully charged.

Are both batteries lithium-ion?

 

[westoe]

Thanks for the reply.

Both batteries are 36v.
The external battery is rated at 13ah and the internal is rated at 11ah.

Running with the internal only at the moment.
I have also acquired the wiring diagram and cannot see why the both batteries will not register on the gauge when both installed - mystery!

 

[Nobuo]

I'm thinking that the switch position "B" for the external battery is maybe bad wired.

If you feed any battery meter with the same voltage, always will return with the same gauge level..

 

[Metro_E-cart]

I have a similar problem. I got a 48V external battery for my Gen2 Metro. I hooked it up via the port for the rear battery. When I turn the switch to B, the dashboard shows a fully charged battery, but when I engage the throttle nothing happens. When I switch back to A, everything works fine. Any ideas what might be wrong?

 

[Artec95]

I had the same problem, and so did my neighbour, so I emailed wearea2b which initiated a useful conversation with Steve Taitt. Basically, the cable for the display has three sets of connections at the controller end (frame bottom). There is a four pin connector which provides display Power, Earth, Signal and (according to the wiring diagram) State of Charge. However, this single SoC is not used on some A2B displays. There are two further single wires, one green and one blue, each having their own connector, which join with the other display wires further up the cable ( in the down tube). On some A2Bs, which were sold with a single battery, only one of these wires were connected (mainly because the internal battery didn't have a separate SoC lead). You need to join a wire from the internal battery positive lead (solder or splice) and then connect the other end of that wire (solder, splice, or socket) to the unused , (probably) single green but maybe single blue, wire.

You should then find you can monitor each battery in turn by selecting A Batt or B Batt on the display. Using the key switch does NOT affect which battery is displayed.

Hope this helps ( it definitely cured mine)

 

[westoe]

Thanks for the info - sorry I took so long to see your reply.

I will give this a try as soon as I am not using the bike - as it is used every day for commuting to and from work.

I have the wiring diagram and can see the wires you refer to - which method of connection did you use and was all the work done at the controller end of the tube?

 

[Artec95]

After I posted my first solution, I had another thought and came up with a solution which was more practical (for me). The end result was that the display only showed whichever battery was selected by the key switch. Changing from Batt A to Batt B ( and vice versa) on the display meant that I can still track the distance each battery lasts, but the display always shows the one currently selected by the key. If I need to check both battery states then I just use the key to switch between both. I found the A2B solution quite impractical, and this solution is even easier to implement.

From the display, a cable comes down the tube to the controller. There are three connections, a single blue, a single green, and a four pin round plug and socket. The single blue and single green supply the 'soc' from each battery when correctly (A2B) connected. From the controller end, four wires connect to the other side of the four pin round plug and socket. The blue wire from the controller does not do anything as it is disconnected in the plug, BUT, it still has the 'soc' of the battery currently selected by the switch. One of either the green or the blue single wires will be connected to a 'flying' lead from the rear rack battery.

Disconnect the 'flying' lead.

Cut the blue lead (from the controller), close to the plug, to give you a decent length to work with.

Connect the controller blue lead to both the green and the blue display leads. This is best done with a two pin plug and socket so you can disconnect it if required later. However, you could use 'choc block' or even solder.

I've had this solution fitted for a while now and find it perfectly practical.