Solar Charging - Is 5V/1A trickle charging possible?

[Cameron Newland]

So I've got a 2015 IZIP E3 Dash that I absolutely love, and I also own a portable solar panel that is only really useful for charging cellphones, tablets, and USB power banks, as it only gives off 0.5-2 amps at 5 volts, and only gives off more than 1 amp in strong, direct sunlight. Obviously, my portable solar panel is too weak to add meaningful power to my ebike's battery, but would it be possible to connect the solar panel to my ebike's battery using a USB-to-3-pin-XLR connector, and then trickle charge the battery a bit?

The original charger states that it needs 100-240 volts at 50 or 60hz, so using the original charger to cut off the charge at 54.6 volts (a full charge) wouldn't work.

Is it even possible to charge a 48v e-bike battery with a 5v power source?

I don't think this is going to work, but I'm just curious if it is, because at some point, someone is probably going to set up portable solar charging for their e-bike (or perhaps it's already being done!).

 

[George S.]

Given the current cost of a 100 watt solar panel ($130 Amazon) you'd want to start there. The easiest way to do it is to charge a 12v deep cycle battery with the solar panel, plug an inverter into the 12v battery, and then plug your charger into the inverter. You probably have about a 350 watt hour battery, so a 5w panel like you have takes 70 hours of full sun to recharge, even if you could plug it in.

Anyway, 3 parts to the basic solution:

1) a 100w solar panel
2) an 85 amp hour or higher deep cycle battery (Costco, Autozone)
3) a 500 watt inverter (DC to AC) (Online anywhere)

 

[J.R.]

Given the current cost of a 100 watt solar panel ($130 Amazon) you'd want to start there. The easiest way to do it is to charge a 12v deep cycle battery with the solar panel, plug an inverter into the 12v battery, and then plug your charger into the inverter. You probably have about a 350 watt hour battery, so a 5w panel like you have takes 70 hours of full sun to recharge, even if you could plug it in.

Anyway, 3 parts to the basic solution:

1) a 100w solar panel
2) an 85 amp hour or higher deep cycle battery (Costco, Autozone)
3) a 500 watt inverter (DC to AC) (Online anywhere)

I like it George. You've put some thought into this. I have two of those items, just need a good solar panel. Info to keep in the back pocket.... For now.

 

[Shea N Encinitas]

If you could eliminate the inverter and replicate the DC output of the OEM power supply I think you'd be looking at a more efficient solar charging array. Not that I know exactly how to do it but have seen it discussed in previous searches. -S

 

[Cameron Newland]

If you could eliminate the inverter and replicate the DC output of the OEM power supply I think you'd be looking at a more efficient solar charging array. Not that I know exactly how to do it but have seen it discussed in previous searches. -S

True, but I'd rather stick with the factory charger just for the peace of mind of knowing that I'm not voiding any kind of warranty by using an unapproved charger. If I were an electrical engineer, I'd probably feel a lot safer designing and using DIY charging systems like that! ;-)

 

[J.R.]

True, but I'd rather stick with the factory charger just for the peace of mind of knowing that I'm not voiding any kind of warranty by using an unapproved charger. If I were an electrical engineer, I'd probably feel a lot safer designing and using DIY charging systems like that! ;-)

Could also help protect from over charging.

 

[Cameron Newland]

I like it George. You've put some thought into this. I have two of those items, just need a good solar panel. Info to keep in the back pocket.... For now.

Thanks for the info, George!

It looks like this would be a $250+ project, and though I think that's reasonable, it would take a very long time to recoup my investment on a 100W solar setup versus charging up my ebike from the wall socket ($0.05/charge). I bet the economics of solar make a bit more sense once you scale up the solar array to 500+ watts, when you can use the solar array to power your home A/C and reduce your monthly electric bill significantly -- the savings would add up quicker and the benefit (electric bill savings) might outweigh the cost sooner rather than later. Plus, a deep cycle SLA battery will have to be replaced every so often, which makes it even less of a winning proposition.

It seems like building a solar array just to charge up an e-bike with 0.4kWh/day isn't cost effective today.

 

[George S.]

Shea -- Yes. This is terribly inefficient, but it's too hard to engineer the shutdown circuits in the charger. The other thing is the chargers get to around 45 volts or higher, and that's where you want everything sealed so people don't touch. So you don't see the ten dollar DC-DC boosters on Ebay or Amazon to get you where you need to be.

The RC Lipos use chargers that are meant for 12 volts, but these packs are just the cells in series, with balance leads.

The economics are horrible. If you have a travel trailer or camper with a solar panel and deep cycle battery, it works.

 

[Ravi Kempaiah]

If you want to just accept the conversion losses and weight gain, there are systems that are commercially available off the shelf for make AC
power that you can then plug your OEM brick charger into for charging the e-bike battery; however, this approach is very expensive in energy cost terms and not recommended.

Direct DC PV to DC battery is definitely doable as long as you have an appropriate PV panel and MPPT Solar Charge Controller in the middle. The system has to be designed for the specific battery that you are solar charging. The battery voltage, acceptable charge rate and chemistry all have to be known. One approach is to carry a 246W folding PV panel, but these are more appropriate for stationary charging arrangements. If you are more interested in charging while on the go, then you will need to develop your own custom charging system.

While it is possible to fabricate a 'Solar PV Canopy' over the bike rider, if you are planning to make a long trip, then I would recommend that two spare batteries be taken on that trip.

Here are some images of such a solar charging trailer that were taken from the Tour-de-Mongolia Pedelec webpage: http://www.tour-de-mongolia.com/

 

[George S.]

Ravi,

The old tractors I see sometimes have an aluminum shade that covers the driver. I was thinking you could do something like that with bendable panels. The stuff in your pictures looks like it would work quite well. If you had a trailer, you could make one large pack and configure it for solar charging. This is a project for a rather younger person than myself, at least going cross country with it.

This is the famous bike from the closing credits of The Prisoner, a 60's British TV show. The parts of the bike gradually appear, including the shade similar to what I am thinking.

 

[Ann M.]

Wow @George S. had forgotten about that bike! You can get a canopy from J&B Importers designed to work with their Sun tricycles & recumbent bikes. Had a customer who took the better sealed, more rigid solar panels designed for RVs and mounted them on the top of one of those canopies on his version of a quadricycle. He chose these instead of the more flexible marine panels to gain higher wattage. The controller was critical to keep the voltage & amperage input stable while the sun was out since this was a direct to dc solar system and to control the charging of the backup batteries. There was a series of backup batteries in the basket for grey days or when the range was beyond what the solar system could provide. It was a bulky thing, but cool!

 

[George S.]

One of their products looks like it would adapt. The idea would be to use something like this:

(Link Removed - No Longer Exists)

People have reported problems with flexible panels. I wouldn't want anything that would catch the wind. So it's probably more suitable for a stable bicycle or trike, anyway.

The Prisoner will be coming up on 50 years pretty soon. People still discuss it. I liked the Lotus going in, the bike going out. I guess it was all about the motion in the 60's. You couldn't let people slow you down. Had to keep moving.

 

[Ravi Kempaiah]

Ravi,

The old tractors I see sometimes have an aluminum shade that covers the driver. I was thinking you could do something like that with bendable panels. The stuff in your pictures looks like it would work quite well. If you had a trailer, you could make one large pack and configure it for solar charging. This is a project for a rather younger person than myself, at least going cross country with it.

This is the famous bike from the closing credits of The Prisoner, a 60's British TV show. The parts of the bike gradually appear, including the shade similar to what I am thinking.

View attachment 2543

Cool stuff, George.
I'm looking forward to seeing your MAC conversion. Smart choice I say.

 

[George S.]

Thanks Ravi,
As they say, the MAC is in the mail frm HK. Hoping to be as minimalist as possible. The Karmic is a great example of a minimalist bike. Court J @flymeaway does great things with his bikes. He understands the power assist algorithms awfully well. I might go down that road, eventually. When people say the ST2 sets the standard for elegance in the drivetrain, the power bicycling experience, I'm guessing it's a lot of what he does. You might actually know?

 

[Cameron Newland]

Here's an ebike with solar panels mounted on its wheels:

http://www.engadget.com/2015/04/06/the-solarbike-is-a-very-real-thing/

 

[Ann M.]

Nice design, but I bet there is an external charger port on that battery unit, peeps!

 

[sophiewilson0191]

This are great ideas.
Solar power for urban and secluded areas.

I read some great article about fabric that produce electricity while moving that can charge minor gadgets like phones.
Here is the ink. Even while working you can charge gadgets this is cool.