Newbie - need some help please A2B metro gen 2

Hello

I'm new here as I've just come by my first electric bike. It's an A2B metro gen 2 16" wheels with key switch / speedo on the handlebars . I got it as a project as it wasn't running - and still isn't !

Issue is that when powered up the bike runs through startup on the screen as you would expect, but then the orange low battery light comes up along with one flashing block on the battery meter. I've read the low battery section in the gen 2 manual, and have tried the bike with 2 non- genuine batteries both reading 37-38 volts.

As I cant find a gen 2 service manual anywhere, I've used the Service manual from the gen 1 to label / check the wiring as best I can given the gen1/2 wiring differences , check the brake switches, ignition switch, relays etc which all seem good but no joy. Lights work !

I'm a bit stumped as to where to go next ....

Any ideas please ??

I have a few gen 1 Metros, but haven't played with a gen 2. It seems like the battery meter on yours thinks the battery is low when it is actually OK. The battery voltage should be around 42v if fully charged. 37-38v should still be plenty to make it run. I have had problems with wire connections in the 'rats nest' by the bottom bracket. Maybe try opening up the cover and unplug-replug all the connectors to see if there might be a loose one. I had problems with the bullet connectors used on the main battery connections. It's difficult to stuff all the wires back in there without smashing something.

Are you using the built-in frame pack or a secondary pack?

You might also try re-seating the connectors that go to the motor by the rear axle. Those can get wet and malfunction.

Hello Fechter thanks for your reply- I've checked/cleaned /labelled all the connections and retested to no avail. I reached out to A2B who suggested checking connections and also asked for photos as and I quote "The state of charge wiring on the Metro went through some changes over the years and adds to the complication." Any ideas what they mean by that ?

When you say "Rats Nest" thats precisely what had happened to the bike - It must have been stored in a rodent infested shed as the EPOCH grip shift rubber, cable casings and in some instances the cable itself on the rear light, motor and torque sensor had all been nibbled, so i soldered in new sections of wire where appropriate.

As for battery, the Bike didn't have either the A or B pack with it. I am temporarily having to use a lead acid pack that I cobbled together which is holding a steady 38 volts, If I can establish that the motor runs well then I dont mind spending more on it . When I got the bike, the vendor demonstrated the fault using an 18650 pack from his other bike.

Is there a way that I can test the motor directly to prove it runs ? there are so many connections in the motor 3 phase socket and then at least I'd know that my efforts were worth continuing with !

I know the gen2 had a real state of charge indicator vs. a dumb voltage indicator and there is serial data going between the BMS and the display. Possibly it doesn't like not having the serial data to tell the system the battery is alive (wild guess).

Do you know if it has the controller built into the motor? At some point they got smart and started using an external controller. On the older ones with internal controller, there will be just two heavy wires coming out of the motor and a cable of skinny signal wires.

There should be a Service Manual around for those somewhere that would at least have a wiring diagram. Can UltraMotor supply a manual?

I would pull the battery and check along the string that the grouped cells have fully charged with a meter, if so I would suspect a bms problem the wheel and controller are separate on your model and fairly robust.
I received mine spares or repairs and it had a faulty bms aswell as the switching relays so I suspect someone had potched with mine trying to ding the bms fault and knackered more while they were at it there was evidence of were naughty electrical mice had been playing.
ah I've read the lead acid suprise now
I would say the bms is knackered like mine was would see voltage in output but it would bleed away with even a multimeter across it so I suspect it's just the capacitance on the output side getting charged some how but the fets are shut not opening