eBike charging questions from complete newbie

[DougfromdaUP]

Genasun makes a boost controller that will charge a 48 volt battery from any input between 5-60 volts. They are a fantastic company to deal with, and the equipment is built like a rock. They will also do custom programming (the float and absorb voltages are not user adjustable.)
Make sure you look for the boost controller (-b) and the proper chemistry (Li)

 

[eTouringOldie]

Post #11 already has a boost MPPT from a reputable tier 2 seller (renogy). Not sure why the research needed to proceed past that point, unless it can’t actually go to 48v? That is what you need for a single panel setup.

No, after a long chat w/ Renogy, it turns out they don't have a portable charge controller which will work with my requirements (12 or 18V PV, 48V battery).

 

[Zwy]

My wife and I have fat tire ebikes, Class 3. I purchased a 35Ah LFP battery to install on one of the bikes to see how far the range would be under assist and just throttle. I haven't completed that project yet. I would suggest switching to a larger LFP instead of dragging a solar panel and charger around, this would greatly extend the range where you can move from AC power to AC power plus you will benefit from a much larger C rate of discharge from the larger Ah LFP battery.

 

[zanydroid]

No, after a long chat w/ Renogy, it turns out they don't have a portable charge controller which will work with my requirements (12 or 18V PV, 48V battery).

Oh ok. Did you consider maybe expanding the possible AC charging sources you can use while touring? For instance you could charge 150W off someone’s random car 12v port, shore power at a campground, …

Dragging solar panels around for traction battery level of power seems at best on the edge of practicality. If a 100W panel is built to permanent install standards that would probably be ~10lb. That may not be fast enough for you, and a complete deadweight in bad weather.

 

[Supervstech]

I have an idea... brb

 

[Supervstech]

Ok, the below 300W portable panel with a boost converter and appropriate cable should net you a sweet 5.4A charging speed with ideal sun.

https://www.amazon.com/DOKIO-Portable-Solar-160M-300M-Bracket/dp/B07JPH4PHG/ref=sxin_21_pa_sp_phone_search_thematic_sspa?content-id=amzn1.sym.37e3b3b9-8d0e-45b0-93aa-6b62717fdd17%3Aamzn1.sym.37e3b3b9-8d0e-45b0-93aa-6b62717fdd17&crid=269XO0HL4FCOI&cv_ct_cx=portable+solar+panel&keywords=portable+solar+panel&pd_rd_i=B07JPH4PHG&pd_rd_r=a5b38716-b4c8-4187-a3ef-a8b9e00989ea&pd_rd_w=4oezt&pd_rd_wg=S7XVp&pf_rd_p=37e3b3b9-8d0e-45b0-93aa-6b62717fdd17&pf_rd_r=ASP922B0VSZ8ACCH26ZQ&qid=1680910392&sbo=RZvfv%2F%2FHxDF%2BO5021pAnSA%3D%3D&sprefix=portable+solar+%2Caps%2C199&sr=1-2-364cf978-ce2a-480a-9bb0-bdb96faa0f61-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyN0kxTkk3MTVETFdPJmVuY3J5cHRlZElkPUEwOTU5NDgyMkhXQ1lDV08wNFpOQiZlbmNyeXB0ZWRBZElkPUEwMzQ1MTUzMlY5SDdBSTgwSUhWQSZ3aWRnZXROYW1lPXNwX3Bob25lX3NlYXJjaF90aGVtYXRpYyZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[eTouringOldie]

Ok, the below 300W portable panel with a boost converter and appropriate cable should net you a sweet 5.4A charging speed with ideal sun.

https://www.amazon.com/DOKIO-Portable-Solar-160M-300M-Bracket/dp/B07JPH4PHG/ref=sxin_21_pa_sp_phone_search_thematic_sspa?content-id=amzn1.sym.37e3b3b9-8d0e-45b0-93aa-6b62717fdd17%3Aamzn1.sym.37e3b3b9-8d0e-45b0-93aa-6b62717fdd17&crid=269XO0HL4FCOI&cv_ct_cx=portable+solar+panel&keywords=portable+solar+panel&pd_rd_i=B07JPH4PHG&pd_rd_r=a5b38716-b4c8-4187-a3ef-a8b9e00989ea&pd_rd_w=4oezt&pd_rd_wg=S7XVp&pf_rd_p=37e3b3b9-8d0e-45b0-93aa-6b62717fdd17&pf_rd_r=ASP922B0VSZ8ACCH26ZQ&qid=1680910392&sbo=RZvfv%2F%2FHxDF%2BO5021pAnSA%3D%3D&sprefix=portable+solar+%2Caps%2C199&sr=1-2-364cf978-ce2a-480a-9bb0-bdb96faa0f61-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyN0kxTkk3MTVETFdPJmVuY3J5cHRlZElkPUEwOTU5NDgyMkhXQ1lDV08wNFpOQiZlbmNyeXB0ZWRBZElkPUEwMzQ1MTUzMlY5SDdBSTgwSUhWQSZ3aWRnZXROYW1lPXNwX3Bob25lX3NlYXJjaF90aGVtYXRpYyZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

Yes, that's one of the kits I've looked at. Those panels are at the max size I can imagine handling (41 inches long dimension when folded). But I think the controller that comes with it only outputs 18V, so it won't charge a 48V battery, will it? I guess you're saying that kit plus a boost charge controller, right?

But you're right, 300 watts would be sweet -- probably the close to the max power I can use without over-heating the battery during charging?

Annoying to have to buy a kit which includes a controller I'll never use, but ... oh well

 

[eTouringOldie]

Oh ok. Did you consider maybe expanding the possible AC charging sources you can use while touring? For instance you could charge 150W off someone’s random car 12v port, shore power at a campground, …

Dragging solar panels around for traction battery level of power seems at best on the edge of practicality. If a 100W panel is built to permanent install standards that would probably be ~10lb. That may not be fast enough for you, and a complete deadweight in bad weather.

Yep, probably 10 - 15 lbs with controller and cables.

Good news is that thanks to your suggested search string, I did find several 'boost' charge controls, including the exact item which would be included with the Sun200 from 'ElectrifyBikes' -- only $60.

I get that this is sort of a hair-brained scheme and your point about dead weight in bad weather is well taken. But a kid can dream of getting completely off the grid, right?

The thing about AC charging is the whole '...but what happens when I can't find an outlet or a friendly stranger?' The bike is a beast. Without juice it's a huge amount of deadweight (between the 4 inch tires/wheels, heavy-duty frame, 1000W motor and 10 lb battery, totals about 75 lbs vs 32 for my MTB and 26 for my road bike. If I hope to tour with gear in a trailer, I wouldn't be able to ascend even a moderate grade on pedal power only -- certainly not for more than a few 100 meters.

The solar idea would give me the freedom to go 'wherever' and not worry about whether I'm about to get stuck, as long as I'm willing to wait out some bad weather. It's a completely different thing to say

Well, I guess I'm stuck here for a few days until this storm passes, good thing I've got enough food
vs
Well, I guess I'm stuck here until someone comes along and lets me charge off their vehicle battery, hope I don't run out of food

I do want to say how much I appreciate the way this community has responded to my novice questions. Thank you all very much!

 

[eTouringOldie]

My wife and I have fat tire ebikes, Class 3. I purchased a 35Ah LFP battery to install on one of the bikes to see how far the range would be under assist and just throttle. I haven't completed that project yet. I would suggest switching to a larger LFP instead of dragging a solar panel and charger around, this would greatly extend the range where you can move from AC power to AC power plus you will benefit from a much larger C rate of discharge from the larger Ah LFP battery.

Do LFP batteries have advantages over Lithium ion batteries? Power to weight? Charging time? Usable cycles?

Also, at a quick glance I’m not seeing 48V LFP e-bike batteries. None of the 48V unit seems to be made to mount on the frame.

 

[zanydroid]

Do LFP batteries have advantages over Lithium ion batteries? Power to weight? Charging time? Usable cycles?

Also, at a quick glance I’m not seeing 48V LFP e-bike batteries. None of the 48V unit seems to be made to mount on the frame.

Glad to here the project is progressing. Re: charging source, if you have a 12V boost SCC you could probably also charge off a 12-15V power source as an alternative. Esp if it can disable the MPPT and has adjustable input current limits. Without a current limiter you would be blowing fuses in the car.

Charging time is pretty much equivalent probably if you want to maximize lifespan and are building your own battery. Probably kind of scary to charge NMC at high speeds.

LFP has more durability, probably, and is less volatile.

LFP has worse density — weight and volume. Trend seems to be in EVs for the medium and short range models to use LFP, while the same platform with NMC has maximum range for the same size battery pack.

Not exactly sure which is better for a bike. By default I would say not LFP, but then if the bike is going to be a super heavy monster anyway…

Probably good to ask on Endless Sphere etc about the charging question and what the tradeoffs are on the battery to get.

 

[zanydroid]

You would probably still want a backup charging plan in case you mess up planning for a good place to charge (like area you wanted to set up panels in is closed or has more shading than you expected). Also good solar conditions = not necessarily the best for a break. Your panels want sun, your body may not.

 

[eTouringOldie]

You would probably still want a backup charging plan in case you mess up planning for a good place to charge (like area you wanted to set up panels in is closed or has more shading than you expected). Also good solar conditions = not necessarily the best for a break. Your panels want sun, your body may not.

Oh, I absolutely plan to carry an AC charger.

Interesting idea about using the solar charge controller to charge from a car.

I imagine the solar vs AC charging ratio might vary wildly from trip to trip, destination to destination.

 

[HRTKD]

Interesting idea about using the solar charge controller to charge from a car.

Many MPPT solar charge controllers require +5 volts over the system's voltage to begin charging and then +1 volt over the system's voltage to continue charging. Consequently, the 13 volts you might see from a running car, may not be enough volts to get the solar charge controller to begin charging your LiFePO4 battery.

What you need to charge from a car is a DC-DC charger that takes in 12 volt and outputs 48 volt.

 

[zanydroid]

Many MPPT solar charge controllers require +5 volts over the system's voltage to begin charging and then +1 volt over the system's voltage to continue charging. Consequently, the 13 volts you might see from a running car, may not be enough volts to get the solar charge controller to begin charging your LiFePO4 battery.

OP is shopping for Boost MPPT charge controllers (this appears to be a niche of SCCs for charging e-mobility stuff from portable to ~400W full size panels, all of which would be too low voltage otherwise) which should solve this unless the minimum starting voltage is 12V charge voltage (which would be above what the car battery would deliver).

 

[DougfromdaUP]

Many MPPT solar charge controllers require +5 volts over the system's voltage to begin charging and then +1 volt over the system's voltage to continue charging. Consequently, the 13 volts you might see from a running car, may not be enough volts to get the solar charge controller to begin charging your LiFePO4 battery.

What you need to charge from a car is a DC-DC charger that takes in 12 volt and outputs 48 volt.

Like the one in post 21

 

[Zwy]

Do LFP batteries have advantages over Lithium ion batteries? Power to weight? Charging time? Usable cycles?

LFP is heavier but more usable cycles.

Also, at a quick glance I’m not seeing 48V LFP e-bike batteries. None of the 48V unit seems to be made to mount on the frame.

Install on a carrier on the back. You could get range up over 100 miles easily and cheaply.

 

[eTouringOldie]

LFP is heavier but more usable cycles.


Install on a carrier on the back. You could get range up over 100 miles easily and cheaply.

LFP == LiFePo4, correct?

Dang, wish I’d looked into this sooner as I already have a 22 Ah Li-ion battery. Seems like there are trade-offs between the two chemistries. The lithium ion batteries are going to be lighter, the LFP batteries are going to be cheaper, but mounting the LFP‘s will be a bit of a hassle. However, to me, the most interesting benefit of the LFP batteries is it they advertise faster charging times — 2 to 3 hours versus 4 to 6 or more. I recognize that solar charging times will be driven by the output of my solar system, so no advantage there. But if I can get most of a charge on the LFP battery in 2 to 3 hours via AC, that would significantly increase my flexibility. I guess the faster charging times of the LFP batteries is due to the increased charging current they can use.

As far as range, you may be a little optimistic. Given that I’m a pretty big guy, over 200 lbs, the bike weighs 75 lbs, and I’ll probably have close to 100 lbs of gear between panniers and a trailer, plus whatever weight the LFP battery adds, I think that motor will be working pretty hard a lot of the time. But more range is more range, whether we’re talking 30 versus 60 or 50 versus 100 miles.

I’m wondering if it be possible to use both on my bike, keeping the frame mounted 22Ah lithium ion battery, but adding an LFP to more than double amp hours, connecting one battery and then the other to the input of the bike controller. I can image having 55 - 60 amp hours available.

 

[eTouringOldie]

Like the one in post 21

Yes, and I eventually found several others.

 

[Zwy]

LFP == LiFePo4, correct?

Yes.

Dang, wish I’d looked into this sooner as I already have a 22 Ah Li-ion battery. Seems like there are trade-offs between the two chemistries. The lithium ion batteries are going to be lighter, the LFP batteries are going to be cheaper, but mounting the LFP‘s will be a bit of a hassle. However, to me, the most interesting benefit of the LFP batteries is it they advertise faster charging times — 2 to 3 hours versus 4 to 6 or more. I recognize that solar charging times will be driven by the output of my solar system, so no advantage there. But if I can get most of a charge on the LFP battery in 2 to 3 hours via AC, that would significantly increase my flexibility. I guess the faster charging times of the LFP batteries is due to the increased charging current they can use.

As far as range, you may be a little optimistic. Given that I’m a pretty big guy, over 200 lbs, the bike weighs 75 lbs, and I’ll probably have close to 100 lbs of gear between panniers and a trailer, plus whatever weight the LFP battery adds, I think that motor will be working pretty hard a lot of the time. But more range is more range, whether we’re talking 30 versus 60 or 50 versus 100 miles.

You can get some pretty good sized LFP batteries for use on an ebike. 40Ah and even 60Ah. One could have 2 LFP and swap them out along with the original Li-Ion.

I’m wondering if it be possible to use both on my bike, keeping the frame mounted 22Ah lithium ion battery, but adding an LFP to more than double amp hours, connecting one battery and then the other to the input of the bike controller. I can image having 55 - 60 amp hours available.

My original plan has been to use the original battery and have the ability to swap by unplugging one and plugging in the other. Use XT60 connectors. Everything is here, the only snag was the bag for the bike I wanted to put the battery one didn't snap right into the carrier and I need to rig it up. If I end up taking out the controller, I'll probably go to Bolton Ebike (Area 13) and get one of his hot rod controllers. Used to watch his videos all the time, good stuff. I have purchased from him before.

 

[eTouringOldie]

So, after quite a bit more research and phone calls, I've come up with this:

https://www.amazon.com/ATEM-POWER-Monocrystalline-Foldable-Batteries/dp/B08Z7BKHX5

and one of these:

https://www.amazon.com/dp/B0B74HF4X3

https://www.amazon.com/dp/B0B5HPPZDP

(there are many others with similar specs)

Seems like either of those controllers will get me to 48V. And they could even accept 36V input if I got a second panel and ran them in series -- which actually seems very unlikely due to the weight and space issue. I mean sure, if the scheme becomes vehicle-assisted, then I could carry another panel ... but why not just charge off the vehicle in that case.

I guess a separate question is, if one did have two panels, assuming the charge controller could deal with the input voltage in either case, would one get better results connecting them in series or in parallel? Meaning is is more efficient to have more current at lower voltage (parallel), or the same current at higher voltage (series)? Or would the difference be minimal, or dependent on the characteristics of the charge controller or the device being charged?

Thoughts?