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[TheRan]

My understanding is the main reason was because regulations required an always on diagnostic port, and then being able to have an always on cellular connection was a side benefit. I can't imagine safety was of any concern, they went nearly a decade without adding a dedicated 12V battery and wouldn't add traction control despite how many people requested it and how many accidents occurred due to a lack of it.

[Ingineer]

There are no regulations about having a diagnostic port at all on an Electric Bike.  We are a manufacturer of large Electric Vans, and we don't even need to have one.  Only vehicles that have emissions controls are required to have this.  (OB2 et al)

There are no regulations requiring a 12v battery or an always on DLC3.   If that was the case then how do other bikes such as Energica not have them?

It's strictly an engineering choice or about liability.   Once you have ABS on a bike, if it fails on a rider and they get injured/killed if it malfunctions, the lawyers will come.

From an engineering choice, power conversion is always high-stress, so prone to failure.   It's made worse if you have a lot of inductive loads on a 12v bus.  Bikes aren't anywhere near as bad as cars, but it's still a concern.   If you had a DC-DC failure and have a 12v battery, you can still ride probably for long enough to make it to your destination before the bike dies.   Without it, if the DC-DC fails, the bike is instantly dead, whether you are at speed, braking hard, or just waiting at a stop.   Same for cars, with much higher risk, so all engineers opt for the low-cost redundancy it provides. 

[flynnstig82r]

Thanks for the explanation, Ingineer. Now I understand the trade-offs a lot better, and why decision-makers would want to choose the solution that’s perceived to have less liability.

[Richard230]

The DC-DC converter on my 2018 Zero S died. When it did, the bike still ran fine and the instrument display worked too. The only reason that I realized there was a problem was that the bike's headlight, tail light, brake light and turn indicators stopped working.

[Specter]

it must have been a partial failure.  what ran the computer, the abs pump etc?  small motorcycle style batteries always seem to be sub par pieces of shit.  they have a warranty of what 6 months? they get beat to hell, very rarely get charged properly and lately of the ones i tore apart, even the top of the line ones, are poorly put together.

if you have lead acid, the best thing you can do for your bike is put one of those battery tenders on it to keep it topped off at night / over weekends etx in the garage.  otherwise well,  have fun.

aaron

[Curt]

On Gen 2 at least, the motive part of the bike runs fine without the DC-DC. Since the MBB is connected to the full pack voltage, I always assumed it had its own small DC-DC for its local electronics.

[Specter]

thats what i seen curt, the dc dc  goes from full batt voltage to the 12volt for the stuff. this helps with balancing a bit too.   some of the bikes i believe have a 12v batt as  a backup in case the dc converter goes out.  as that battery ages  and cooks off it can eventually load the converter down significantly with 4, 5, 6 amps which is basically being turned into heat because the battery is cooked and dried out. this can lead to premature wear and failure over time.

aaron

[Zelidar]

My experience: it might be luck or good engineering from Zero, probably a mix of both. My SR/F was assembled in the summer of 2019. Today with nearly 84'000 km it has its third battery, but the little 12 V one is still original. Never had any issue with it, always plugged in. Winter storage has never worried me, I keep the main battery between 40 and 60%, checking every 4 to 8 weeks, that is all.