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[flattetyre]

Looks like my FXS gets around 4kwh max out of the pack according to the app. Haven't bothered adding a shunt and CA to confirm. I guess that's normal, in any case it works for my riding.

Also, what do I need to run a non-zero battery? I'd like to use a small RC lipo pack for certain rides but presume the BMS has to communicate with the bike to make it go. Or is that not an issue?

[MostlyBonkers]

I'd forget that idea straight away, mate. I can't imagine why you'd want to use an alternative battery pack in the first place and you'd certainly void your warranty.  Also, getting the voltage right would be tricky and then there's the small matter of the BMS and how that wouldn't be able to handle an alternative battery pack.

Honestly, I think you'd be nuts to try it.  By all means explain what you're trying to achieve further as others might chime in. However, I'd take silence or similar comments to mine as a strong signal not to try.

[MVetter]

I would definitely not recommend a DIY battery addition. What makes you believe your FX is only getting 4kWh? Even if you have a 2014 5.7 battery that's still 44 Amp hours which is ... about 4.5kWh usable.

[flattetyre]

I'm very small-minded

Charge to 4.1 / cell, discharge to ~3.65 minimum, check balance frequently. Protect from physical damage. It's not hard to take care of RC lipo. No BMS needed / I am the BMS. I want the pack for fun, that is drag racing and short trail rides near my house. I think a 25 lb battery would be badass. I don't need a warranty. I've made a lot of packs for hotrod ebikes from lipo and 18650. I already know how to build the pack and power the bike including precharge. I'm just wondering if it will go when I do this or if I need additional stuff to please the computer.

What makes you believe your FX is only getting 4kWh?

Try reading the entire first sentence, not just the first couple words.

[MVetter]

oh ok. Well have fun.

[flattetyre]

Nobody has numbers to share from the app? Last ride I got a reported 1.7kwh to 50% soc in 70f latest firmware.

[flattetyre]

I figured out how to connect my own battery, you need to bypass the MBB and power the controller and optionally 12vcdc directly. It's pretty simple.

Lipo should be badass. Light packs with full performance for most of the discharge.

Now, anyone ever get a chance to check your kWh consumed in the app?

[BrianTRice@gmail.com]

I'm merely commenting as a thought exercise, and do not estimate success based on what I've read here. I suggest you check a forum like Endless Sphere to increase (but not ensure) your chances of a thorough critique.

Just to forewarn others what issues might arise here:
- The controller B+ and B- terminals are on the outside of the main contactor.
- This extra battery deserves its own circuit protection against outrush and inrush, and shouldn't be shut if conditions would cause a current spike in excess of component and cabling limits.
- The charge and discharge curves of your LiPo battery will differ in meaningful ways from the lithium NMC chemistry of Farasis' cells. That includes the dynamic effects of lift and sag with incoming or outgoing current.
- The controller has its own capacitor bank which you'll be interacting with, and the batteries have precharge circuitry that is exposed to bus voltage even while the contactor is open. You can burn out precharge circuitry by powering the bus without closing the contactor.
- I'm a little fuzzy on the controller's own contactor but it could be a factor.
- The DC/DC converter is typically powered (on the S platform; haven't reasoned through X in detail) but doesn't turn on without an enable signal from the MBB, which is only in communication with the two supported BMS units.

As far as this question you're posing that you suppose is easy to answer, Zero has been hiding that information for a long time. I think you need a more specific technical question.

[Crilly]

92.7 miles today.  Down to 7%.  10.13 kWh used.  That means 10.44 kWh useable out of 18 kWh.  The bike and my heated gear could of used  one kWh for the 2 hours of riding.  So maybe I used about 11.5 kWh.

[flattetyre]

Thanks Crilly. Anyone with a FX / FXS? Today I drained it to 0% / .8 miles range and the app reported 3.55kwh consumed.