Page 1 of 1

A2B throttle wiring

Posted: Aug 01 2018 3:15pm
by imagen15
Hi everyone. I'm brand new here, so bear with me. I just picked up an A2B 36 volt, 750 watt hub motor on a Craigslist deal for $50. I have the "switch" module. I've watched a lot of YouTube on Ebikes and have always seen that the throttle connection to the motor controller is a 3 wire connection. I'm looking at the connection on the A2B module, and it's 4 wire. I'm then looking at the wiring schematic in the A2B service manual an I'm seeing this fourth wire, both at the throttle and at the motor (the controller is inside the motor) That is a "grey" wire labeled "Eal". Does anyone know what this Eal wire is for? I'd appreciate any and all help! Thanks!

Re: A2B throttle wiring

Posted: Aug 01 2018 3:38pm
by 2WheelsMovesTheSoul
If its like my old A2B Metro, that 4th wire is for the State of Charge (green, yellow, red) LEDs on the half twist.
a2b-velociti-twist-throttle.jpg
a2b-velociti-twist-throttle.jpg (206.63 KiB) Viewed 272 times

Re: A2B throttle wiring

Posted: Aug 01 2018 3:43pm
by fechter
In the wiring diagram, it has two wires that are both +5v. No clue why they used two. You can see they're connected to each other in the module. One may be the power for the LEDs.

The EAI is the throttle signal. This goes approximately from 1v to 4v.

The SOC indicator LEDs are on a separate connector.

A2B Metro wiring diagram.JPG
A2B Metro wiring diagram.JPG (55.42 KiB) Viewed 272 times
The A2B is a great beginner ebike. There is a lot of info for them now. I have 3 of them in various stages of functionality.

Here's one of mine:
viewtopic.php?f=6&t=50590

Re: A2B throttle wiring

Posted: Dec 05 2018 12:52am
by imagen15
OK. Thanks for the info. It looks like I just need to "jumper" the two red wires in parallel. Essentially still making a 3 wire connection to the 3 wires from the (twist) throttle.

Re: A2B throttle wiring

Posted: Dec 05 2018 9:29am
by fechter
imagen15 wrote:
Dec 05 2018 12:52am
OK. Thanks for the info. It looks like I just need to "jumper" the two red wires in parallel. Essentially still making a 3 wire connection to the 3 wires from the (twist) throttle.
Seems like that should work. I've done sort of the reverse. I used the stock throttle with an aftermarket controller and it works fine.

Re: A2B throttle wiring diagram

Posted: Dec 05 2018 8:24pm
by imagen15
I have this same diagram. Have you noticed that the leads from battery "B" change polarity as they go thru the connector. Positive magically changes to negative and vice versa. I'm hoping that this is a typo, or am I that dumb? If this is an accurate diagram, then I'm not getting it. Or, was the French guy who drew this stoned? Anyway, I just hooked up power to the "switch module" and tested the key wires (yellow/red and green/black) and got the relay to click for both batteries. Only the right-hand relay clicks on either battery input and key wires closed. What is the left-hand relay for? Appreciate any and all feedback. Thanks!

Re: A2B throttle wiring

Posted: Dec 06 2018 12:19am
by fechter
I never noticed that before. That's funny. I'd guess the French guy was stoned. The positive wires go to the relays and are red. One relay is for the A battery and the other one is for the B battery. The switch logic prevents both from coming on at the same time.

Re: A2B throttle wiring

Posted: Dec 06 2018 10:25am
by imagen15
OK. something new to consider. I have an aftermarket battery selector switch (no key) that I was going to use that allows selecting battery "A" or battery "B" or "both". Was going to connect the positive side (per diagram) wires, yellow and black then to the respective selector terminals. I'm gathering that the original key switch did not have the option for "both". Am I going to blow up the module when I select "both"? Doesn't really matter as I'm eventually going to go with an aftermarket controller also as I want to overvolt the motor as well. Just wanted to use the A2B module at first (it came with it) to get the bike going. Thanks again!

Re: A2B throttle wiring

Posted: Dec 06 2018 11:11am
by fechter
imagen15 wrote:
Dec 06 2018 10:25am
I'm gathering that the original key switch did not have the option for "both". Am I going to blow up the module when I select "both"?
Yes, if the two batteries don't have exactly the same voltage when you select "both" there is a chance of destructively high current to pass from one pack to the other. If you want to use both, they should be connected upstream of the relay and need to be at the same voltage before connecting. Another option is to place large diodes in series with both packs to prevent current flow from one to the other. Downside of this is the diode will drop about a volt from the output and need to dissipate a lot of heat.