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[Terraplane]

Evening,

Total noob to electric bikes here who probably made a costly mistake.  Yesterday I took delivery of a 2020 FXS ZF7.2 from a salvage auction.  It was listed as running and driving and the pics showed the LCD powered up but with a very low battery level (and 360 miles on the clock :-)  However, it's completely dead - no LCD, no lights blinking anywhere, no movement obviously, and as expected not detected by the app.  When I plug it in, nothing happens either.  It pulls 5w of power over the 120v power cord.  Damage is minimal - broken mirror, a few plastic parts scraped here and there, a rash on the brake lever.

Of course I didn't know about all the warnings about not allowing the battery to discharge.  It looks like the hazard lights may have been left on judging by the position of the switch, and maybe the key (it arrived late at night so that part's a little fuzzy).

I've poked around the forum a bit but I'm still at a loss as to where to start troubleshooting.  I figured I could start with the battery (check voltage) but the latch is locked and apparently the ignition key doesn't unlock it?  Would a battery damaged by going lower than 30% cause a fault such as this?

I was pretty excited to try this out, I haven't had a bike since college but now I've got a sinking feeling that I could be in for some expensive repairs...

Thanks for any thoughts

 

[Crissa]

Leaving the battery drawing at 0% would damage it, yes, but it may have other hidden damage.

Diagnosing this will need to be done quickly (to save the battery) but you'll need an offboard charger and some way to connect to the mainboard.

The dash not displaying while plugged in is a bad sign.

Seems like we should probably write a diagnostic flow chart to prevent these sorts of situations.

-Crissa

[Gains]

On the plug of the DC-DC converter you can check the battery voltage.
It has five pins and they are marked : - out  +out   - in   +out  enable

If you measure between -in and + out you ll see the battery voltage since it is hot wired.
There is a fuse to check in this too,on the S/DS it is on the left side of the "dog house" but I don t know were it is on a FX .
If the voltage is too low it will go very fast further down and the battery can t be saved anymore.

[Curt]

It was listed as running and driving and the pics showed the LCD powered up but with a very low battery level (and 360 miles on the clock :-)  However, it's completely dead - no LCD, no lights blinking anywhere, no movement obviously, and as expected not detected by the app.

I'd say the hazard lights don't matter and probably don't function anyway without the key on. Also, I've accidentally left my key on and the bike graciously turned itself off after a while (it's a 2016).

The FX is pretty robust and it must have been a bad crash to disable it. Do you have grounds for returning the bike, given that the seller grossly misrepresented it in both the auction listing and pictures? Or at least getting some cash back? Some aggressive threats about small claims might get their attention.

Since you got a salvage you must be willing to do some disassembly and repair. I'd start taking things apart. This could also be something like a bad fuse, connector loosened in a fall including circuit board connectors, pinched wiring harness, physically damaged circuit board, etc.

I have a hunch the battery is OK if there is no visible damage. What are the chances it was nearly flat when crashed? Definitely measure the voltage like Gains said. If you completely disconnected the battery, I believe you can also measure between the big ground pin and pin 1. A good battery should be 84 to 116 volts DC.

[TEV]

Download the manual from Zero website, and check the "Low Power B+" fuse.
Unfortunately,  if the contactor doesn't activate, the charger won't be connected to the battery,  and if the voltage is too low, the BMS (battery management system) won't activate the contactor.  More likely that the battery have to be pulled of the motorcycle, and slowly charged bypassing the contactor , see if your local dealer will be willing to do it. This should be done as soon as possible.

[TEV]

What was the battery level on that picture, that picture was probably taken a whyle ago, it seems that there is a long time process untill a salvage vehicle is getting to be actually auctioned.

[Terraplane]

Evening,

Total noob to electric bikes here who probably made a costly mistake.  Yesterday I took delivery of a 2020 FXS ZF7.2 from a salvage auction.  It was listed as running and driving and the pics showed the LCD powered up but with a very low battery level (and 360 miles on the clock :-)  However, it's completely dead - no LCD, no lights blinking anywhere, no movement obviously, and as expected not detected by the app.  When I plug it in, nothing happens either.  It pulls 5w of power over the 120v power cord.  Damage is minimal - broken mirror, a few plastic parts scraped here and there, a rash on the brake lever.

Of course I didn't know about all the warnings about not allowing the battery to discharge.  It looks like the hazard lights may have been left on judging by the position of the switch, and maybe the key (it arrived late at night so that part's a little fuzzy).

I've poked around the forum a bit but I'm still at a loss as to where to start troubleshooting.  I figured I could start with the battery (check voltage) but the latch is locked and apparently the ignition key doesn't unlock it?  Would a battery damaged by going lower than 30% cause a fault such as this?

I was pretty excited to try this out, I haven't had a bike since college but now I've got a sinking feeling that I could be in for some expensive repairs...

Thanks for any thoughts

So, a bit of an update.  The Low Power B+ Fuse checks ok.  More telling though, the DC voltage reading between the B+ and B- large terminals on the SEVCON reads 0.0.  Tomorrow I'll go a bit deeper but I'm not hopeful of finding anything different directly on the terminals.  Unless this fabled contactor cuts the HV lead or something.  Is this a good location to take a reading?  The DC/DC connector seems like a pita to get to.  As a matter of fact a number of things are a pita to get to.  Whose idea was it to bury the dc fuses where they are?  Why use tiny plastic fasteners whose heads snap off if you look at them funny?

Anyway, again, thanks for the comments and any further input.  The nearest official Zero dealer is a 2.5 hour drive away and I'm always up for some shade tree mechanic action.

[BrianTRice@gmail.com]

Sevcon B+ and B- are downstream of the contactor, so a 0V reading just confirms that the contactor(s) are open. Check the DC-DC converter terminals as indicated on the post above. That is your safest way to test battery voltage.

The contactor is inside the doghouse (raised plastic enclosure) in the battery. If you take full electrical precautions (removal all metal from your person and only use tools with insulated shafts and probes, etc), you could uncover it and measure carefully inside, but the safety point there is that the battery has live voltage within it at all times.

FX electrical stripdown guide for getting to the DC-DC converter etc: https://zeromanual.com/wiki/XMX_Platform/Electrical_Routing

[Terraplane]

Verified this evening via two different methods (thanks for the replies and PMs, it was very helpful) that the battery is at 18.6v.  I have no idea how long it might have been discharged to this level.  I guess at this level it's a catch-22 - the battery can't be charged because it needs to be charged.  Nearest dealer is 2.5 hours away.  Anyone have any luck bringing a pack back from the brink?  Trick the charger into charging?  Direct connect a DC source (I have an adjustable DC supply that goes up to 30v @5A) for a while to boost it up?  Give up and use it as a boat anchor?  Does Zero refurbish batteries?

I have no recourse with the auction source, and I'm not going to try to lie to Zero or a dealer.

I've added a peek under the skirt in case anyone is interested.

[TheRan]

There are 28 cells so that means they're at an average of 0.66v (they're unlikely to be well balanced so many are probably much lower). Nominal is 3.65v and minimum is 2v, I'm fairly certain there's no recovering that pack without damaging it.

[Demoni]

Cells discharged to that low of a voltage will have permanent damage, the internal resistance of the cells will be much lower.

Please do not try to recharge your pack. Even if you are successful (unlikely) the risks involved in the process are high.
I have personally recharged cells (not packs) from sub 1v, some will maintain a charged voltage of 4.1v. However when tested the cells max discharge rate and capacity were greatly impacted (~20% of original).

Due to each of the cells having different resistances charging them as a pack is a very bad idea. Let's say you have a pack with 2 cells in series and you provide them with 8v. If one of the cells is damaged all of that voltage will be going into the good cell.

I know it's not what you want to hear but I would suggest reaching out to Zero about a replacement battery pack. Not the cheap option but a lot less expensive than your home. There is a DIY powerwall group on Facebook, if you want to see the results of thermal runaway.

[Terraplane]

Cells discharged to that low of a voltage will have permanent damage, the internal resistance of the cells will be much lower.

Please do not try to recharge your pack. Even if you are successful (unlikely) the risks involved in the process are high.
I have personally recharged cells (not packs) from sub 1v, some will maintain a charged voltage of 4.1v. However when tested the cells max discharge rate and capacity were greatly impacted (~20% of original).

Due to each of the cells having different resistances charging them as a pack is a very bad idea. Let's say you have a pack with 2 cells in series and you provide them with 8v. If one of the cells is damaged all of that voltage will be going into the good cell.

I know it's not what you want to hear but I would suggest reaching out to Zero about a replacement battery pack. Not the cheap option but a lot less expensive than your home. There is a DIY powerwall group on Facebook, if you want to see the results of thermal runaway.

Point taken, I do understand the basics of cell balancing and on a much smaller scale have revived battery packs by addressing each cell (18650s) individually and removing the duds.

I will attempt to contact Zero regarding options.  My bargain bike may turn into an MSRP bike at least I would suspect, so at that point I will have to decide if I should cut my losses and sell it as-is or forge ahead.

Thinking ahead, especially if there is no refurbish or core charge option, what cells comprise one of these?  I saw a youtube from several years back repacking one from a Tesla array but it was a different bike and tech changes rapidly.  As I say, just going through the options in my head.

Thanks again for the input

[TheRan]

That would have been a very old bike, ever since 2012 they've used pouch cells.

https://zeromanual.com/wiki/Battery/Cells

[Terraplane]

That would have been a very old bike, ever since 2012 they've used pouch cells.

https://zeromanual.com/wiki/Battery/Cells

OK, thanks for that link.  Found another "hacking a zero battery" video where it looks like the pouch cells are stacked and potted, not so much a home gamer endeavor though not impossible.  This would be moderately difficult but the biggest problem might be sourcing the cells as they seem to be in great demand.

[Critchie]

If you have any interest in selling the dead battery I am in need of all the parts attached to it (bus bars, contactor, wiring, etc).