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[Kill3rT0fu]

There seems to be a rumor I heard that you shouldn't get a power tank after you purchase the bike as the ages of the two battery packs might cause issues. Is there any truth to this? I bought the bike a year ago and was considering getting a power tank.

Side question: Can you still wire a diginow 3 charger setup with a power tank, since everything should get wired to the controller anyway?

[jnef]

Zero uses the powertank sales as a way to sell their older module inventory that would have been noticeable on the FX/FXS bikes.  So, if you purchase at the same time, you may get a PT that is up to a year older than the main pack.  You can infer past evidence of this practice by the fact that the PT capacity may lag FX/FXS capacity in any given model year, despite them being the same modules.

[Kill3rT0fu]

Zero uses the powertank sales as a way to sell their older module inventory that would have been noticeable on the FX/FXS bikes.  So, if you purchase at the same time, you may get a PT that is up to a year older than the main pack.  You can infer past evidence of this practice by the fact that the PT capacity may lag FX/FXS capacity in any given model year, despite them being the same modules.

That would make sense from a business standpoint. So I'd say there's no issue then, since you can't guaranty the batteries are the same age internally.

[jnef]

Yup.  For the first at least ~4 years, it doesn't seem to matter if they are a bit different.  If you are charging at Zero's charging rates, it will probably never make a difference.  If you are going to charge with three digi's, and the packs are mismatched, and they're getting old, and you have the PT going bad prematurely, and you have the faulty SOC firmware, you may see the PT disconnect.  Even then, if you have all of that go wrong, ...just charge with two.

[MVetter]

It's not a rumor, nor is it a secret. I'll attempt to break it down so it makes sense to all, though.

Battery cells degrade. Sometimes from heat. Sometimes from charge cycles. Sometimes from constantly pushing high discharge rates. Sometimes all of the above. When you have a 4 brick pack like Zero's monolith, you've got 4 packs of cells that are, more or less, aging the same. They're experiencing the same heat, charge, discharge, and other factors. Let's say a couple years down the road you decide you want to add a Power Tank for extra range, so you purchase a new one from your local dealer.

You have just introduced 28 shiny new cells at full strength into a pack that has some wear and tear to it. The controller doesn't really have the ability to exclude or include specific cells from draw requests. It just sees that the user has requested power by opening the throttle, and it pulls from the cells that are in the best shape. In short, the bike is going to hammer the SHIT out of this small battery pack, with abnormally high amp draws both to and from it. This will likely cause premature degradation of the Power Tank, and often cause other issues like de-synching it  which will cause it to disconnect until a slow charge re-balances the voltage.

If possible, try to buy a used Power Tank if you're adding it onto an existing bike. Or, if you're set on a Power Tank from day 1, get it installed at the time of purchase of your new bike. You have a much higher chance of success that way.

[Crissa]

Also, the FX line of bikes doesn't get the Power Tank, that's the S and SR lines of bikes.

-Crissa

[Richard230]

If possible, try to buy a used Power Tank if you're adding it onto an existing bike. Or, if you're set on a Power Tank from day 1, get it installed at the time of purchase of your new bike. You have a much higher chance of success that way.

That is what I did for the reasons that you mentioned. I special ordered my 2018 S from the factory with a Power Tank already installed. On my 2014 S, the factory was not offering the bikes to be assembled at the factory with a PT (for some odd reason), so I had it installed by my dealer before I picked up the bike. Unfortunately, the PT apparently had a defective BMS and had to be sorted by a factory technician who installed a new PT box at the dealership's shop. That bike has lived an easy life and has been running perfectly since new (with no firmware updates, I might add). The only issue has been a goofy OBC, but then they all do that, sir.