Solar Panels to charge Electric bike batteries

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Solar Panels to charge Electric bike batteries

Postby seedlinks » Thu Mar 03, 2011 11:13 am

I am seeking a solution to charge 48v batteries for e-bikes, using solar power of course.
Is anyone aware of the most efficient way to do this, using only 1 solar panel?
I believe I will need a regulator, or the charger may come with one built in.
But I'm having trouble finding a 48v solar panel, and believe if I use a voltage converter, the losses may outweigh the benefits.
Any advice on this topic would be helpful, as electric bikes are really becoming popular, but we don't want to put more demand on our dirty electricity grid.
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Re: Solar Panels to charge Electric bike batteries

Postby Gordon-Loomberah » Fri Mar 04, 2011 5:36 pm

High voltage panels do exist, Sinosolar make them at least, and no doubt other companies as well. However, there are a number of things to consider, such as battery type, LiPo, NiMH, Pb-acid etc, and what input is required by any on-board charger. Maybe you want to do it with just 1 solar panel, but you may find it more convenient, ie you can fold to half the size, by using 2 X 24V panels.

You really shouldn't put the panel output directly onto the battery, and in any case, some sort of MPPT regulator will get you significantly more power from the panel(s) than a PWM regulator, but they are more expensive.

If you plan to do the charging at home, the most efficient way to do it may be to purchase green power and plug it in.

Personally I prefer my bike without the weight of motors and batteries :)
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Re: Solar Panels to charge Electric bike batteries

Postby Electric Madness » Sat Jan 14, 2012 2:38 pm

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Re: Solar Panels to charge Electric bike batteries

Postby Electric Madness » Sat Jan 14, 2012 5:18 pm

It comes down to your battery murdering system (BMS) too.
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Re: Solar Panels to charge Electric bike batteries

Postby offgridQLD » Thu Sep 06, 2012 9:48 pm

They way I was doing it was to use a 200ah or bigger 12v AGM as a buffer. Feed all your Pv into the AGM and run 12v RC lithium chargers.they run directly from the AGM or if you already have a 240v charger than came with your pack use a small efficient 200 - 500w inverter and 240v lithium charger. This way the agm is collecting and storing energy all day even when your out using your bike

Sure you loose some from inverter inefficiency and double handling charging two battery's. It sure makes it easier that trying to charge directly to the lithium pack. PV's are cheep so the 20-30% you loose can be made up with larger panel.

Now that Im off grid I just charge from the wall socket as its all coming from PV anyhow.

Another option is purchase a 48v PV regulator one where you have control over the charge settings and adjust them to your lithium battery's charge profile.Most of the time the BMS isn't a issue as it just prevents over charge and under charge along with bleed off balancing when doing a full charge. as long as your regulator and PV didn't go over the input rating of the BMS

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Re: Solar Panels to charge Electric bike batteries

Postby Privatteer » Fri Sep 07, 2012 12:55 am

Here is a Sino one with Vmp of 50 http://www.solarenergyproducts.com.au/ecommerce/review/product/list/id/33/category/52/

Little low still possibly depending on battery. Also just realised you want it on the bike, not at the home charging it so might be too big.
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Re: Solar Panels to charge Electric bike batteries

Postby Tracker » Fri Sep 07, 2012 7:01 am

.
And there is the link to a mob building Lithium MPPT devices, that I placed in the LITHIUM thread..

And, you might check the CdTe panels being sold with a Vmp of 70v... First Solar..
Oatley Electronics is selling them

So, there you have a practical combination of higher voltage and a purpose built Li charger...

Ps.. the CdTe panels are not as efficient as eg monos, but they do give the voltage.. ..
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Re: Solar Panels to charge Electric bike batteries

Postby karlajensen » Mon Mar 17, 2014 10:34 pm

i'm using 82.5W first solar panels VOC is ~60V and BMS cutout is 55V on the pack hence by the time its up towards 55V the current has dropped off alot.

in the ebike community there is what is described as "bulk charging" which doesn't do alot interms of balancing.

I describe the Fistsolar solution as just that (bulk charging) as there is no regulator required, panel only makes a couple of amps and BMS cutout protects the cells from getting overcharged.

Nothing more simple really, i keep an eye on it with the wattsup, typically home to work is ~20kms and 150Wh of battery hence don't bother charging at home, simply put the pallet with the first solar panel sitting on it in the carpark and plug in the battery via the wattsup, pull it off at 54V if i'm around (cycle life improved if operating at 10-90%SOC) if not BMS kicks it off at 55V or so. (4.23Vper cell)

My battery is Samsung 2.9AH Lithium in 13S4P configuration, hence around 11-11.6Ah and i operate it mostly between 4 and 10.5AH.

Saturday morning ride 55kms for 9.5AH which panel will put most of back in the arvo.

In all fantastic solution and cheap as chips
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Re: Solar Panels to charge Electric bike batteries

Postby offgridQLD » Mon Apr 07, 2014 8:03 am

personally I prefer my bike without the weight of motors and batteries :)


I can enjoy both variations.

Off Road where you are not limited to the 200w - 250w AU road rule. The weight of the motor + battery is lost in the roundings in the power to weight ratio. 3.5kg motor, 2kg battery total 5.5kg - 2500w ;)

The (rider + bike 75kg+10kg- 85kg- 250w) (rider+bike+ebike gear 95.5kg - 2500w+ 250w = 2750w) 6% more weight over 10 times the power.

This assumes you have have placed that 5.5kg on the bike in a way that doesn't upset the handling of the bike to much.
Don't get me wrong .I got myself a reasonable mountain bike not long ago and I have a lot of fun on that without a motor and plan to keep it that way.

The way I charge my ebikes from PV when I am at the house or away from the house is by using a RC model charger. They run are inexpensive ($30 - $50 ) and run on 12v DC input. They have settings for all kinds of battery chemistry from PB to nicad, lifpo4, and various lithium chemistries over a wide voltage range (use two chargers for higher voltage packs) They also balance the cells and offer all the monitoring and protection during charge you could ask for.The one charge can more or less charge everything.

What I do to charge in the bush is use a small 20AH lipo4 12v battery as a buffer battery (just takes the load when clouds pass over) My solar panel out in the sun charging the buffer battery and the RC model chargers run from the 12v battery.

If I have my ute then I just use the anderson connection at the back for a 12v supply and there is a 200AH agm in the tray. PV on the canopy of the ute charges the 200 Ah agm and continues to charge it while I am out riding. With my Imiev I just charge from the 12v lighter socket and the DC/DC converter keeps the 12v power flowing to the socket from the 16kwh traction pack. ;)

At home I use a 40A 240v- 12vDC power supply that runs off the mains in my garage. Mains power is provided from off grid solar system.

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Re: Solar Panels to charge Electric bike batteries

Postby Tracker » Mon Apr 07, 2014 12:05 pm

offgridQLD wrote:Off Road where you are not limited to the 200w - 250w AU road rule.

Just a silly question... how is any cop' going to know the difference between 250w and 2500w, other than suspicion when he's not able to catch up to you... :o
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