LCD Display going blank?

[Signguy-Everett]

I built my ebike a few years ago 48V 1000W rear hub and have put over 100 hrs on it and over 1750 miles commuting. I have a 48V 15 Amp Lion battery. In the past couple of days it has started acting up. The display (like this one http://preview.tinyurl.com/y9ztecxt) is going blank for no apparent reason and I loose all power. Today it was on for a second then shut off. I unplug the battery, plug it back in and hit the middle power button and it flashes on for a second then off. I turned my battery off and on and it would sometimes flash on for second then off.

Is the display bad? Is the controller going bad? I looked at all the connections and everything was tight and secure. Anything else I should try to look at? The bike has been bulletproof until this past week when it has started acting up.

Thanks for your help.

 

[amberwolf]

Does the bike still operate while the LCD is blank?

If not, you should measure the voltage of the battery while it's attached to the biek and the bike is "on". If possible, measure it at the controller's battery input connectors.

If it is a normal voltage like it had before (when it all worked) then the problem is somewhere on the bike (LCD, controller, or wiring/connectors).

If it is a low voltage, then the BMS of the battery is trying to protect the pack, and is shutting down as soon as a load is put on it. That could mean it's not charged up enough, or that it has bad cell(s), etc.

Could be as simple as the charger isn't working right (or has a bad connection) and isn't charging the pack at all, so now the battery is too dead to operate the bike.

 

[d8veh]

The LCD and controller work independently, except that the LCD contains the switch that powers the controller, so when the LCD is off, the controller is off.

The LCD has its own power supply, which is on a connector from the controller, but the controller has no influence on it. It's simply a branch taken off the main battery wire inside the controller, so when the battery supplies power to the main connector on the controller, the power wire for the LCD is always live.

All this means that if the LCD goes off, the most likeky cause is that the power to it is being interrupted either because the battery is faulty or because there's a fault in the LCD.

The first thing to check is that the battery isn't cutting out. Next, check that there's not a bad solder joint where the power wires connect to the LCD's pcb. Wiggle the wires where they go in to see if you can make it go off. The last common cause I can think of is that the cable to the controller is damaged, particularly by zip ties that are so tight that they broke a conductor inside the cable. Loosen off any zip-ties and wiggle the wires in that location to see if you can make it go off.

Occasionally, water gets into LCDs. It can cause all sorts of problems, and it normally ends up killing the LCD. Obviously, that can only happen if you ride in the rain.

 

[Signguy-Everett]

Thanks for the help.

Amberwolf - The bike does not work when the LCD goes off. It works like a regular bicycle but just 20-30 pounds heavier (ha, ha) I have 2 chargers and charge when I get to work and then when I get home. I've had total charged up bars on the display every time I finish charging and the bike goes like crazy when fully charged so I don't think it's the charger.

d8veh - looks like I'll be getting out my multi-meter and start doing some checking on a variety of places starting with the battery then over to the harness and display wires. I doubt it's water getting into the LCD as I haven't ridden in rain/mist in probably a year or more and then it was just a short duration.

Thanks for the tips, I'll report back after I do some tests.

 

[fechter]

The logic power for the controller usually goes though a display like that. I would check all the plugs between the battery, display and controller. Unplug and inspect the contacts. I have also seen a bunch like that where the display unit went dead. I think it's possible to "hot wire" the controller power but you would lose the ability to change the PAS setting.

 

[dogman dan]

Look hard at the battery after you check the wires as well. But chances are its just a loose connection someplace on the bike.