Solar Charging My 36V 14 Amp Hr Polly Battery Pack

[Jaffasoft]

Australia has a fair amount of Sun esp up North where i aim to do a lot of riding in future travelling around so i am looking into a portable solar system that can trickle charge a 36V 14amp hr (edited this is supposed b 15amp hr) polly battery pack.

I'm not real sure of what could be done in that regard so hopping to pick some brains here to devise a system get some specs etc. I have purchased some solar cells which could be customised to make an panel or perhaps panels that unfold while camping for a day or two. And or there could be "wings" on the rear or a front visor with them. The main thing is i want a system that works and in portable and convenient.

I will post the exact amps and volts ect that my charger draws. Hoping to get suggestions on inverters to use (hopefully cheap to). I would like a 12V charger rather then 240 volt so open to totally re assess a new system if new be. And been looking at some 12V solar panels on extremedeal.com for example would a few of these in series work? http://s.dealextreme.com/search/12v+solar

The faster it charges the better but a trickle charge over time like a day or an afternoon of full sun would be at least good enough. Thanks in advance for any suggestions and help, not to sure about the electrical stuff !

 

[Kent]

Check out these sites. They get into solar charging an e-bike and go into details about different panels. http://www.cisolar.com/catSolarebike.html
Also there is an Australian company called Solarbike (solarbike.com.au) which has done alot of research on this very subject. Keep us posted.

 

[Jaffasoft]

Thanks for the site links will spend some time in there researching. Hopefully make some sense of it.

I said l would post my current Bat Chargers details, it runs 26 Volts and 6 Amps into the polly battery pack over about 4 hrs to fully charge from dead flat!

 

[Hillhater]

..... my current Bat Chargers details, it runs 26 Volts and 6 Amps into the polly battery pack over about 4 hrs to fully charge from dead flat!

i am looking into a portable solar system that can trickle charge a 36V 14amp hr polly battery pack.

what is the pack voltage ? 36 or 26v ?
..there are many Lipo chargers that will work on a 12v supply,... available from RC hobby shops such as hobby King

 

[Jaffasoft]

The pack voltage is the same as the thread title. 36 Volts is that normal for the charger and the pack voltages to be different?

 

[Jaffasoft]

These were the bike specs built by hyenaelectricbikes.com.au. The key specs are 2000w peak power with a 12 cell 15ah lithium polymer battery. It's a 500w rated motor and the controller is a 12 fet 4310 infineon.

 

[dogman dan]

As a general rule, the best bet seems to be setting up a solar charging station that charges a 12v battery, then run the charger from that.

 

[ZOMGVTEK]

12S 15AH of LiPo should mean 666Wh... The best way to do this, would be to charge a 12V battery, and then run a 12V charger off the battery. The only issue here, is you would need to be able to carry it with you.

Mobile solar charging is not practical at all currently, however it absolutely can be done if you are willing to wait a day or two for the bike to charge, and can carry LARGE panels with you. I would say you would want something like 200W of panels, which would hopefully be enough for the bike to be charged in one day of direct sun. The only issue here, is finding a way to safely charge right off the panels, or carrying a 12V battery with you to run a hobby charger off.

I dont see the setup being less than 40-80 Lbs and fairly large... This really isnt very practical to carry around, but would absolutely work for a permanent install.

 

[Jaffasoft]

A 12 Volt battery would not be to much to add on. Is a second battery to level out the amp, etc while it's charging so it's more constant? I have got 195 wat in cell wattage in total and could be built in any shape and quiet thin and foldable.

I spent some time researching into the links above. And found this very interesting since it's exactly what i do normally but i'm using 240 volt charger in terms of it taking 4-5 hrs for a full charge. It will not matter however if my system is not as efficient i can easily be waiting a day or two beteen rides travelling etc.

http://solarbike.com.au/solar_success.php

Copied from the web site:

"Current Attempts: Get 48V panels and find regulators that can be used to reliably charge the 36V lithium iron phosphate batteries we employ with our electric bicycles.

Result: So far no commercial regulator seems to be available that actually works. However, through this business I've been fortunate to meet many electrically able people and Brett from Balmain has been kind, able and active enough to design a custom made regulator to suit 100W 48V panels I've ordered. The panels have an open circuit voltage of approximately 80V and a closed circuit voltage of approximately 70V. The regulator can work with this voltage and current to put a steady output of approximately 42.5V into the battery. The system fully charges our 36V 10Ah lithium ion batteries in approximately 4-5 hours from dead flat and so far hasn't damaged them. It has also been tested with a variety of 36V lithium ion batteries with different capacities successfully. It has now been setup for longer testing at the University of Western Australia and hopefully will encourage further development of such systems. It was set up on the 20th October 2010 and I've been using this system solely for re-charging purposes daily with no issue. Please click the link below to see some pictures of it:"

 

[Pure]

I've given this some thought. My idea was for use with an electric lawn bis but could still be practical in this application. Really the best way to go about this is to use a bike trailer. There are some available that you build yourself. PM Aroraslip for a link as that's what he used for his lawn care trailer. One like this could be made long enough to support enough panels to give you enough current to charge wile you ride and be a place for you 12 volt SLA and charger..not to mention anything you may want to carry for your trip. Using the right materials the weight could be kept to a minimum with the solar panels making up the majority of the added weight. Hell if you were to design it right you could make the panels to where they can ride flat or be angled left or right for optimum sun absorption.

 

[theRealFury]

A 12 Volt battery would not be to much to add on. Is a second battery to level out the amp, etc while it's charging so it's more constant? I have got 195 wat in cell wattage in total and could be built in any shape and quiet thin and foldable.

well a 12v lead acid battery which can fully charge your 666wh 36v 15ah lipo battery would be something like http://www.amazon.com/UPG-UB121000-...8DJW/ref=sr_1_1?ie=UTF8&qid=1312368583&sr=8-1

As you can see, the battery alone is 60lb... and this is the minimum battery you could get away with as due to inefficiencies in charge/discharging the 2 batteries and also ineffieciencies in the charger and peukert effect on the lead storage battery you would need at least 1kwh of 12v storage, id probably say 1.5kwh (~90lbs) of 12v battery would be best to not kill the lead too fast.

There really is no way to use solar as a portable ebike charging solution. the only way it would be remotely possible is if you rigged your solar pannels as a 12v system and directly linked to a lipo charger with a voltage tolerance of 10-22v minimum to tricle charge the battery , this would obviously mean that you can not ride the bike during the day (while its charging) which makes it pretty inconvenient to sy the least and i would not be sure what the effects would be on the charging with the fluctuation of available amps from the solar panels under varying sunlight intensity. I would immagine the voltage regolation circuit inside the lipo charger can handle the fluctuations but its not something i have seen done before.

we really need 50% efficient solar cells before we can start to dabble in portable ebike charging solutions.

 

[Jaffasoft]

Ok, Thanks for that!

Is there anything wrong with the practicalities of a possible two 36Volt system, with a switch on a currently charging 36Volt pack effectively changing it as a 12Volt pack ONLY while charging? While either parked or riding using the other batteries energy. I generally get a full days activities into my riding day. Doing bout anything from 30-45k (bike is parked in the meantime. Only been using one battery.

Bare in mind there is other alternative charging sources while traveling, the solar i guess is the emergency as you often find a power point to plug into 240 volts and or a caravan park, barbeque ect to charge up at plus the occasional place such as new friend meet etc. So Solar Cells do not have to be the totally dependent energy course all the time! Everything ads up would be the theory and you jut adjust with how much fuel you have got left in the tank, so to speak, is my plan basically!

 

[gsmgsa]

Hi all! I have almost the same problem with an e-scooter. I figured there is a cheap solution, only this type of solution does not disconnect any load off the battery bank when undervoltage on battery is detected. My type of battery is a LiIon self made one out of lots of cell phone baterries. I considered the following:

1. Using a 12v to 220v inverter of about 100W as they are pretty cheap and about 90% efficient, and its minimum input voltage is around 10V.
2. Using a 36V power supply that came with the scooter when it had the old lead-acid batteries that came with it, or a more powerful source in your case. This is usually a comutation power supply type and wheighs almost nothing - about 90% or more efficiency;
3. To achieve smooth operation when voltage from the solar panel would fluctuate, just after the solar panel we can use a supercapacitor bank made out of six 2,7V say.. 5F (cheaper) capacitors in series (for about 12 - 15V - wich is the exact voltage that's necessary for the inverter to function properly)
4. Build a series constant current source just before the 36V battery bank, so as to charge it at a certain desired current like trickle charge, and when battery would be topped off, current will not flow anymore from the original power supply of the e-scooter, as its output voltage is the same as battery bank voltage, (say 42V)
For the beginning we could use a battery like a gel lead-acid type instead of supercondenser bank, and then calculate the desired buffer capacity of the supercondenser bank to use finally. For the 36V battery bank I planned to use just a 12 cell cheap monitor device for LiIon or LiPo's just to make sure they do not have an undervoltage or overvoltage condition. One other ideea would be to corelate the supercapacitor bank's voltage with the constant current source device so as to control the current delivered to the 36V battery bank. So when there's a lot of sun and the capacitors are charged more quickly and the overall voltage of the bank rises above a certain level, the current delivered to the 36V battery bank would increase, and viceversa when the voltage accros supercapacitor bank drops under a certain level.

What about that? I would like to hear some other ideeas. Best regards,