A2B Hybrid Odessy

[A2BNEW2ME]

I have been reading e-bike articles here for a while before I started looking for an electric bike. I saw an A2b Hybrid model on ebay with a bad battery at a discount so I bought it. When I tried to charge it, nothing happened. So I started looking for a replacement battery pack. Just before I was about to buy one I decided to try charging the old one again. This time I used the output connector and five hours later had a fully charged pack. So I opened it up and found that the voltage across the charge wires was .5v
So I moved the positive wire to a lug on the circut board next to the main output wire. Looks like maybe there is a defect with the original wiring of the BMS board. Has anyone had a similar problem with their A2B Hybrid model?

 

[Jason27]

I never had that problem with my bike.

 

[ecowheelz]

Didn't A2B go out of business? Not 100% sure... but it may be hard to find parts. Snatch up anything that you find

 

[oaktowntandem]

I have found that they do occasionally go bad. However, they are made to use the Ultramotor charger. The bms will not allow the battery to charge if you simply apply 42 volts across the charge wires.

 

[A2BNEW2ME]

The battery would not recharge through the port intended for the charger. When I turned on the charger after it was plugged in, the led turned to green right away.

So I used the stock charger and manually made a connection between the chargers positive and negative pins and the corresponding pins on the battery packs 5 pin output connector. I did not expect it to work. The charger applied a very low current for a while and then ramped up to its normal charge current.

There must be some kind of defect on the BMS board.

 

[oaktowntandem]

Ok, you do have the stock charger. For safety reasons these A2B bms's are made to deny the ability to charge the battery from the charge port if the battery voltage drops below 30 volts. That is what may have happened in your case when the charger's green light went on. Now that you have charged the battery more directly, first, check to verify that you have >30 volts across the battery leads going into the bms. If voltage is good, try reconnecting the charge wires where they were originally and check to see if it will now accept charge through the normal charge port from the stock charger. Let me know if that works. Lots of these batteries are discarded because they were run to low-voltage cutoff, let sit for months, and then when attempting to charge the next riding season, it will not charge because the pack voltage got too low. I have found that, using a technique like yours, many of these batteries still have good capacity even if the pack voltage got very low.

 

[A2BNEW2ME]

After I charged the battery, I measured the voltage across the charge wires. It read .5v so I just moved the positive wire to an empty lug that showed the full voltage. I am getting a decent range from the battery so I think the bms just has some kind of minor defect.

The two wires that power the blue light on the on/off switch show full pack voltage continuously, so I disconnected it. Don't want the pack drained unnecessarily.

The guy that sold it to me knew there was a battery issue but wouldn't say where the bike came from. Have seen a few on Ebay with the same issue.

 

[oaktowntandem]

Your bms may still be ok. I tried to explain this and how to test it above. What you are doing is bypassing the bms when charging. As you have discovered, this works, but you should be aware that when bypassing the bms there is no longer a mechanism to balance the cells. Bulk charging lipo, which is what you are doing, without some way of ensuring that no cell group is overcharged can lead to problems, sometimes bad problems.

 

[A2BNEW2ME]

My BMS is O.K. with the exception of the lug where the positive charge lead was attached ( the pack would not ever take a charge there even after it was revived ).

Thanks, but I am just doing the same thing that all of the other packs I see are doing when I charge at the BMS output connection ( not to be confused with the pack output wires). When I charge this way, the current is going through the BMS to reach the cells. I think you misunderstood where I was charging.

The main reason I posted this was to let anyone interested in an A2B Hybrid thats been sitting unused for a long time ( WITH AN APPARENT DEAD BATTERY ) to know they might not have to throw the battery pack away if they are willing to try what I did. Something the manual does not tell you, imagine that.

 

[miro13car]

does his A2B uses actually LIPolymer?
If so charging it like with no BMS and balancing put not only bike but also place where you charge in the risk of fire.
Just read post how to safe charge LPolymer!!!
Is not a joke!!!