Turbo Levo battery discharge by watching TV

[MountainHead]

I need to discharge the battery for storage from 100% to about 50% on my Specialized Turbo Levo using purely electrical means, avoiding any drivetrain wear.

I got a turbo levo battery cable (S206800004) then found that, bizarrely, the molded elbow is rotated 180 degrees from the way the bike's plug is. It would not plug in with the elbow going down, not up like on the bike. So I had to chop the rubber off the elbow and pull back a washer that locked the wires in. Then I could bend the wires enough to get it plugged in to the bike correctly. If you try this, be very careful not to cut the wires while removing the rubber.

I used a USB charger to put +5 volts on the enable pin relative to ground.

After plugging in the modified cable with +5 volts on the enable pin, the battery powers up for about 60 seconds, then turns off. It needs for the controller to talk to it to stay powered on. To work around this, plug the battery in normally, power up the bike TCU, then pull the plug without turning it off. Now plug in the discharge cable. The power will now stay latched on, and you can start discharging.

The initial voltage measured across the output with it enabled was 41.31 volts. This is obviously 10 lithium ion cells in series (4.2 volts fully charged). There is an inverter series that takes a DC input of 42-60 volts. So we need to boost the battery voltage a bit. I used a 5 volt, 15 amp power brick to do this. My inverter is 600 watts max. So at 41.31 volts, the max current is 600/41.31 = 14.5 amps. The "booster" brick must be able to carry this much current since its in series with the battery.

Now connect the booster brick in series with the battery. The total voltage is now 41.31 + 5 = 46.31 volts. In the range for the inverter to operate. Additionally, when the voltage drops to 42 volts and the inverter drops out, the battery voltage will be 42 - 5 = 37 volts. Which is the recommended target voltage to store lithium ion batteries at. So this will discharge to the 37 volt target, then stop.

Here is the schematic:

Now comes the fun part: watching Netflicks using your Turbo Levo battery as the power supply.

When the TV went dark my battery had 47% remaining.

Success!

 

[Mikerb]

...or just jack up the back wheel and engage walk mode+ some tape.

 

[Alexbn921]

Or put it in turbo and ride around the block for 30 minutes.

I do wish discharge was possible with the charger as I had a wheel problem and couldn't discharge my battery

 

[Aussie78]

“Rosenberger - C003-03-2000-C Charging connector jack straight 25 amp”


is what you want to use to avoid cable elbow issues.


Beware to anyone else stepping outside the normal here, pinouts for the connector change over the years. Do not assume, do your own discovery.

Once I have everything documented I will publish.

 

[Konanige]

Or just don't worry about it, all this hype about leaving batteries fully charged is just bollox!

 

[Jamsxr]

 

[Alexbn921]

Or just don't worry about it, all this hype about leaving batteries fully charged is just bollox!

No it's not, but you got cash to burn buying replacements.

 

[boBE]

Or just don't worry about it, all this hype about leaving batteries fully charged is just bollox!

And even if it is not bollox we still don't know what Specialized calls "100%". Most EV batteries call 100% about 85-90% of actual full charge and 0% is about actual 10-15% in order to get better life from the battery. It is likely the bike manufacturers limit their batteries in a similar manner.

 

[Alexbn921]

And even if it is not bollox we still don't know what Specialized calls "100%". Most EV batteries call 100% about 85-90% of actual full charge and 0% is about actual 10-15% in order to get better life from the battery. It is likely the bike manufacturers limit their batteries in a similar manner.

Actually we do. Some people that care have tested it. Specialized for example uses 100% of the battery and full charge is 4.2 volts per cell. All the rest do too.

No manufacture protects the battery outside of over temperature and absolute min/max voltages.

 

[repli]

Hello - great and exciting DYI discharger build, many kudos!
I am thinking about a different path using a LiIon discharger with an optional extra resistive load. Avoids doing all the DC/AC power conversion and 5V beef-up. Looking at the Junsi X12 discharger - it can handle up to 50W by itself and accepts voltages up to 12s = 50V. Only culprit might be it seems to to the BMS comm over balancer cable, not sure it can be set to a 'manual voltage-only cutoff mode' for discharging. Gettign in touch with Junsi, let's see what they have to say

 

[repli]

Progress: It seems the junsi x12 can handle voltage-based discharging protocols, you only need to select eg NiMH battery type to get access to them, plus set the threshold cut-off voltage manually. I am now thinking about wiring up a circuit like @MountainHead, but based upon a wall socket power plug supplying both 12V DC (to DC-power the Junzi) and USB 5V for the battery charge enable pin.. I thought about using the battery itself for the charge enable and Junsi power supply, but it seems it's hen&egg issue: The battery needs to see the 5V high signal on the enable pin FIRST and then provides voltage to the +/- pins of the Rosenberger plug, thus using the battery for putting the 5V on the enable pin does not work :-(. I thought the battery might stay on after removing the original plug from the battery while TCU is still powered on, but it seems the battery only stays in a kind of 'idle' state for 60 seconds, but you still have to connect the enable pin to 5V BEFORE you receive a voltage singnal on the mains..

 

[repli]

Success finally: Using the iCharger/Junsi X12 successfully for a well-controlled discharge of my Turbo Levo Gen 3 battery: Have prepared a cable with Rosenberger plug as per descriptions of @MountainHead, bought a special power plug which provides bnoth 12V (via cigarette lighter coupling) and USB-A. Used the USB-A 5V to connect it to the 5V charge/discharge enable pin of the Rosenberger plug, and the 12V supply voltage to power my Junsi X12. Set the Junsi to NiMH discharge program (since all other programs seem to require individuell cell balancer inputs which are not available on Levo batteries from the outside) and to 37V discharge voltage.
Connected battery to the bike TCU as usual for some seconds and power it up, then disconnect it without switching off the TCU to make the battery stay in 'charge/discharge enabled mode). Then connect it to the modified Rosenberger plug and Junsi charger and start the discharge program. Running beautifully. Theoretically, I could also operate the X12 in recuperation mode with another large battery attched to it instead of the 12V supply voltage form the power socket. It would then recuperatively charge the attached 2nd battery from the Levo battery. E.g. if you hold 2 batteries, and one is depleted completely after the ride and you want to store both of them for a while, you could connect them as just described and end up with both batteries charged to 50% . Don't forget to 'prime' both batteries by normally connecting them to the TCU before connecting them to the X12. Doing this with 2 batteries will require some hurried action on your side since the charge/discharge enable latching by TCU connect stays live for only approx 1 minute! You can verify this in the X12 display, where both the X12 supply voltage and the attached-for-discharge battery voltage are shown.
And final word: The Junsi X12 is quite costly - if I didn't have further use for it like charging/discharging my drone batteries, I wouldn't have done it. Good luck, modders - and pls don't blame explosions or fails on me, not taking any liability - running these mods on your own risk!

 

[Ndanger]

"Bi Directional charging" is a feature that would be a great utility for utilizing the power storage off grid.