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[T.S. Zarathustra]

As you all know, range anxiety has long been a challenge for electric motorcycles. Many people—smarter than I—have tackled this issue, usually in one of two ways: adding more battery cells to the existing battery or installing faster chargers.
The problem with adding battery cells (rather than charging faster) is finding packs with identical characteristics to the stock battery—same voltage, discharge curves, and so on. Both approaches also require hacking into the bike’s electrical system.

Then I had an idea. A company called EcoFlow recently appeared in my ad feed. For just over $700 (on special offer), you can buy a 2 kW, 2 kWh battery-powered AC power station. Other companies offer similar products and there are larger and smaller power stations available.
Suppose I bought one of these units—weighing about 20 kg, it would fit in a large top box. When my bike’s charge nears zero, I could stop on the side of the road or trail, plug in the power station, and add up to 30 km of range using the bike’s built-in AC charger. I could even make a cup of coffee with a small kettle and charge my phone while I wait. This approach avoids the hassle of matching battery specs and is removable without tools.

The idea evolved, as ideas often do. Instead of buying a portable AC power station (though they do look like a nice piece of kit, with features like solar input, monitoring apps, and more), what if I made my own? All I’d need is a row of inexpensive cells and a matching DC-AC converter with enough capacity for the bike’s charger. These components are affordable these days. This DIY approach would let me distribute the weight optimally on the bike. If I want to hack a bit I could possibly increase efficiency by bypassing the bikes built-in AC charger, using a DC-DC converter in the battery pack to top up the bike’s batteries automatically when the charge runs low.

Stupid idea? Probably. But I thought I’d share it in case someone wants to try it.

[Specter]

First off, you are lugging around the 40 lbs of dead weight, that'll cut into your current range a bit.
Secondly, those inverters on those boxes are not known for being super efficient. so you are going to lose a good ten percent of that in conversion.

now on that.  2 kw / 2 kwh battery, trying to sell you their shit, many of them will give you the battery's ratings, at a 20 hr or even a 100 hr rate.  The lighter you sip out of a battery, the more you can get from it.  if you plan on charging at 2 kw, that 2 kw/hr battery is probably more like a 1.3 kw / hr battery now.  if you want to spend 2 hours charging you might get 1.5-1.6 hours out of it. 

less bang for your buck.

30 km of range, so you are saying you get 15 km / 10 miles per kilowatt from your bike?  That's pretty impressive.  Having a kettle of tea while you wait, water takes a lot of energy to boil, that's going to cut your range down quite a bit too.,

in an emergency to get you out of a bad situation, and with little fussing around, yah it could work, but as a planned thing, not the greatest spend of the money and i think you might end up disappointed when you see what was promised/perceived .vs. reality.  Very interesting idea though, and one ive though of often times with my bike, when i bring it to the track, have an electric truck to tow the trailer and just recharge it off the trucks 240/ 10 kw system, and keep the truck on a slow charge off thr 115 volt plug to keep it topped off.

oh and after re reading your post,  having an on the fly dc / dc converter to top off your bike on the fly, that's just asking for trouble, and would be a lot more expensive out the door in the end imo.  because that converter is basically, the bikes built in battery charger just one step removed.

Aaron

[princec]

tbh all I want is to take out the 6kW charge tank I've got and replace it with something that takes a DC charge for my SR/F at 2C... I'd pay proper money for that. Obvs. it would have to step down the voltage from 200V to 100V and kinda bypass Zero's firmware somehow....

Cas

[Specter]

being the bike tops off at 100 ish volts, i think that is too low for most fast chargers, so you wont be finding any DC charging stations for it even if you did find a dc input for it sadly.

ive used these people before in the past for odd projects.  they also do custom work, might want to call them and ask if they can do/ or got something that might work for you.   its worth a try and at least can give you an idea toset you down a better path

https://www.powerstream.com/

Aaron

[TheRan]

That's why he wants a DC-DC converter to bring the voltage down, however I imagine something that could handle the voltage and current would be quite expensive and large. That said there was one charging standard that technically went low enough and that was chademo and Zero even offered bikes with a factory installed connector, however in practice very few EVSEs actually met the standard and were able to charge the bikes so it wasn't on sale for long.

[princec]

In practice 200VDC is the minimum operating voltage for all of the CSS chargers out there so that's what we've got to work with. If a 200V->100V step-down could be achieved in the necessary space (and cooling!) then I'm up for it. It would be wired in at the same point the AC charger outputs its DC and require some shenanigans with the firmware and of course a whole CCS protocol handler integrated. This would need to leave the existing AC charging in place underneath of course.

Zero have no chance of selling me a new bike in the next 3 years but they have a very high chance of selling me such a widget. Well in fact 100% chance, I want it.

Cas