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[Specter]

Here is what I got going on.
Photo 1:  My bike sitting on my driveway.
Notice the solar panels laying on the concrete in the background.

Photo 2:  It feeds into my truck, it's all portable, i can literally pick up and throw those panels out anywhere
in the truck it goes into  front left charge controller,  background 48 volt lith battery bank, front right inverter and top left white plug which is the J plug I plug into my bike to charge it.

Edit:  Cant really see it, I forgot but there's a 175 Amp circuit breaker in there too for the DC

Aaron

[MyFirstElectric]

I think you guys know way too much for me to understand (or swampnut at least misunderstood me when I spoke of AC-DC).

Aaron: "You can absolutely charge your bike from solar!  I do it all the time at home here." ?
"what is the voltage your battery is running at?"

That is the problem: So, my tiny house system is 25.6V nominal Lifepo4 (which means actual is always higher). Yet obviously nowhere nearly enough to charge the bike batteries directly (without boost converter, but through controller) from the house batteries (I would never charge any batteries straight from solar without charge controller, swampnut, no).

The bike batteries (also Lifepo4 but 24S) come with a 87.6V AC-DC charger (foolishly: The Chinese haven't studied Lifepo4 lifecycle, else they'd limit their chargers to 85.2V max!).

To answer your question: IDEALLY, I'd like to:
- use another switch that allows me to generally keep sending the power from the 8 roof panels (each 20.98VMP 7.15IMP, but connected 4S2P, ie 84VMP 14.3IMP) to my 25.6V charge controller house system (in addition to that from the rear wall panels),
- but when full sun and when I need to charge the bike batteries, I can turn the switch,
- to send said roof panel power to SEPARATE EXTRA charge controller that I BUY and which would be 84V charge controller, and is programmable like my existing two charge controllers.
- This way, I could program the NEW EXTRA 84V charge controller to safely charge the bike batteries straight from solar (DC to DC) when full sun.
- My understanding (currently) is, that I would need a 84V rated MPPT charge controller that I can program to charge the bike batteries CC - CV (first constant current as per their rated amps, and then constant voltage at 84V with diminishing current, the fuller the batteries get).

Though, I may still have some error in my thinking, maybe that's why I haven't connected the new roof panels yet (or, because it's always raining...).  The above is just the current PLAN.

HOW WOULD YOU DO IT? ""You can absolutely charge your bike from solar!" ?

[MyFirstElectric]

Woah, those are some decent charger cables, yes! Such I don't have (nor have seen here).
Your bike there is that the 17.6kW Zero (I thought I understood you mentioned) ?
That looks like a serious bike also, like your plugs.
Yes, way more professional than my setup (even the planned one).

The DC - DC solar charging you do would interest me. Then again, I reckon your system is so much bigger that I cannot replicate your way anyway.
Just maybe it gives me an idea, how I could do it for my "baby" system.
 

[MyFirstElectric]

I think, going forward, I will actually call my ev bike my "baby". Referencing its weakness (compared to you guys' bikes).
My "baby bike", I like that phrase 

[MyFirstElectric]

For tomorrow we have ONE day sunshine forecast (but frickin cold), I don't think I will be able to install my Fardriver 72360 controller....

The wiring (see my earlier post with the complicated mess under the bike's decking) looks so elusive, it will take me a good while to get my head around, which wire does what.... 
A few wires I identified the other day, just before the rain returned.

I need to be careful: Don't want to blow up my costly controller.

[Specter]

Some charge controllers you can program for what you want them to do, and they'll automatically adjust to the battery voltage.  For example the one I am using I can plop the thing onto my 24 volt system for the tilapia pond or the 48 volt system for the house / bike etc etc etc.  For your, turn a switch and it charges the other battery, entirely possible just make sure you disconnect BOTH sources of power from the charge controller, that totally deadens it, so it forgets it's running voltage, and mppt voltage and most important you are not hooking a cap charged to 48 volts to a 24 volt battery and popping your terminals.  When you hook battery back up it'll see the new voltage and begin tracking off that.

I believe midnight solar has one that will go up to 96 volts.
As for boost or buck converters,  go check out powerstream.com  they have all kinds of converters and you might find something that  might work for you.  Worse case your  bike batteries, charge them in pairs,  ie charge them parallel at 48 volt, but  run them in series at 96 volt.  You can probably get away with an SSR to do the switching if you need but Id prefer a good solid manual switch to KNOW it's good and not have to worry about an electric failure griefing you.

Aaron

EDIT:  That's another thing that's nice about charge controllers, like the outback ones for example.  You can push them at 150 - 200 - 250 volts depending on which one you get!! and from there it'll walk down to whatever your battery bank is.  If you hook it to a 96 volt battery you will charge to that if you hook it to yoru battery but only want it to charge to 81 then you program it to float at that voltage, so when it hits that, it essentially stops charging.

[MyFirstElectric]

Thanks, I am not 100% sure I understood you right Aaron?
So, I checked midnitesolar, all their controllers can handle only up to 72V battery systems: https://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=21&productCatName=Charge%20Controllers%20-%20Classics

(Not to confuse 96AMPS charge capacity with 96V battery system) 
While my house system is 25.6V nominal, my Lifepo4 bike batteries will be the >80V that I had detailed.
My (current) understanding is, that a new, third, solar charge controller would need to ** Nominal System Voltage ** of >80V matching the bike battery system.
Right?

Not to be confused with a charge controller's Rated charge current, Rated discharge current, and Max. solar input voltage. All of these are different, additional values to check. However, all of these will be FINE then: Already charge controllers for ** Nominal System Voltage ** 24V can easily do 40A and 134V (my Solarepic too), both of which values are higher than what the 8 new roof panels will provide: 84VMP 14.3IMP

Again, my only trouble is (if my understanding is right?) that I cannot find a solar charge controller with Nominal System Voltage
>80V to match the bike battery system. But that I would need one, to do direct DC Solar to DC bike battery charging (with controller, of course). Like you do you said, right?

DDG cannot find ANY such highly rated solar charge controller. And midnitesolar's sales page (of 72V max systems) suggests that such one would cost > $1000 anyway.

I assume, all of these reasons were what made the guys on the solar forum agree that direct solar DC to bike DC charging is sort of impossible. ?


But you wrote: "You can absolutely charge your bike from solar!  I do it all the time at home here." - How? Got a photo of setup? Was that the one with the panels on the concrete?

Sth I seem to be misunderstanding still?

[Specter]

One other thing, constant amps is NOT a requirement in this method, Lith tech is very unforgiving about volt .vs. amps.  NiCd would shit on you quickly if you started playing with volts amps or swinging stuff.  NiMh was not a heck of a lot better.    Lead Acid will tolerate it and Lith will tolerate it very well.  This is why they are in demand on solar farms,  when the clouds roll by and the voltage and current is swinging all over the place, the battery don't give a shit, as long as you don't over current it, it'll suck in whatever you put at it.

another nice thing about Lith technology is a charge cycle is a FULL charge cycle, not just the attempt. so if you do have less than optimal charging days it's not swinging your battery all over the place trashing it's cycle life left.

The Flexmax 80 controller will let you program it up to 80 volts.  If you look around I am sure there are others which will let you go even higher.  I know i seen them before.  Some of the electric riding mowers, Ryobi comes to mind, I think the battery pack voltage is 80 volts on some of them, so worse case, grab a charger from one of those z turn mowers and use it to charge your bank.

Go look around on the internet, do searches on Charge Controllers,  80 Volt battery charger, stuff like that and see what pops up.
it's pretty useless for me to do it for you, since I am in the states and you are?  my results won't be very useful for you, you'll need to find someone who services where you live.

Aaron

PS. you really NEED to understand how this all works, to be good with it and not cause a problem down the road.   May I recommend a website called
batteryuniversity.com   it's free and is very in depth on different battery types, their quirks how to charge etc, i t might give you a decent background to help you better understand some of the stuff we are taliking about here.

[MyFirstElectric]

Lifepo4 charging is nothing new to me, don't know why you elaborate on that, like I wrote earlier, I studied Lifepo4 in more depth than anyone I know personally. So, don't worry about me not understanding my batteries. 
If everyone understood their batteries like I do, none would burn, none would explode, none would offgas, none would leak, none would be wrecked in under a mediocre 1000 charge cycles.

I hear, Zero bike batteries don't do more than that. ??

All my batteries in the past have had >5000 lifecycles before they even reached 80% SOC.

"Go look around on the internet, do searches on Charge Controllers,"
Like I wrote: "DDG cannot find ANY such highly rated solar charge controller. "
DDG means Duckduckgo. I detest google.

"If you look around I am sure there are others which will let you go even higher."
Nope.

"I know i seen them before"
Cool. Can you remember where? 

Either way, as modest as always indicated, I am not sure it needs a solar charge controller rated for ~86V system.

Aaron: "You can absolutely charge your bike from solar!  I do it all the time at home here." ??
What is the voltage YOUR battery is running at that you charge "all the time" straight from solar? And with which CC?
I may have missed that.

"May I recommend a website called batteryuniversity.com" ?
OMG, please not, no.
I've been amazed for years, how many people fall for that pseudo wisdom I've found on there.
Is that just because it calls itself "university", I wonder?

[Specter]

Well since you seem to have all your ducks in a row then this project should be eazy peazy for you.
The classic 250 will handle the volts you are looking at, but you knew that already.

You flip flop back and forth from saying I will never know this stuff to, I already know everything, too bad everyone is not as smart as I am.

I am not sure how much more I can help you, you seem to have all the answers you need already.

Aaron