Electronics/Solar Power Help

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RileyB

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#115707 4-Apr-2013 00:02

Looking for some help with an electronic project, not for my home but hopefully someone come help any way.

I'm planning on going on a 7-10 day cycle tour and am looking for a way to keep my phone and GoPro cameras charged. The closest product I've found is this: http://www.trademe.co.nz/electronics-photography/other-electronics/other/auction-577709926.htm

However the battery in it is pretty small (most AA batteries have close to the same charge), and has a very small solar panel, just 4 watts. I figured I could probably make something that would suit pretty easy?

I'm getting one of these to carry all my stuff:

Figured I could chuck the solar panel on the rack, and the rest inside with all my gear. Keeping the weight down is the main priority. I don't really know a lot about solar power, but from what I know, I'll need a solar panel (~10-20 watts?), a solar regulator/charger, small rechargeable 12v battery, and something to drop the voltage down to 5v, and feed it into a USB port.

If anyone can help me with what parts to use for this, or if you know a better solution I would love your help.

Cheers

Riley

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#792862 4-Apr-2013 07:27

Look at solar chargers and battery storage on ebay. If you get one with a decent sized battery you may just be able to plug it in every few days and charge from that.

illicit

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#792910 4-Apr-2013 08:47

Solar panel
Charge Controller
12v Battery
Cigarette lighter socket
Cigarette to USB adapter
Multi-port USB Hub

DONE.

EDIT: Dont forget to fuse it - no fires!

wellygary

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#792957 4-Apr-2013 09:56

The panel efficiency on a moving object like a bike trailer could be poor,

Another option is to use some of the considerable energy that you are going to expel propelling your self along,

In the last few years Nokia have released a bike dynamo based USb Charger,

http://www.amazon.co.uk/Nokia-DC-14-Charger-CR-124-Holder/dp/B00475BGHA

"Charging time depends on cycling speed, for example a Nokia 1202 with a 860 mAh battery can be charged with about 20 minutes of cycling at a speed of about 10 km/h"

860 mAh over 20 minutes is over 5 times faster than the panel you cite (3000mAh over 6-8 hours) + it will work in cloudy and wet weather with similar efficiency,

Bolting one of these to you trailer would probably solve all your volts problems,

deadlyllama

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#792964 4-Apr-2013 10:02

Last time I was at Super Cheap Auto I saw quite a few solar panels for sale, bigger than 4W, intended for charging car batteries. That's probably one part of the solution right there. Faster than going through ebay too.

RileyB

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#792978 4-Apr-2013 10:21

That seems like an interesting solution, not sure how well it work on the small tires of the trailer, but it's not that expensive if it doesn't work.

I'll take a look at supercheap, there is also a lot of them on trademe. Anyone know the best type of battery for something like this?

ubergeeknz

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#792980 4-Apr-2013 10:26

Probably a sealed lead acid, charging pattern for a car battery will work fine with these - although they are a bit heavy. Try Jaycar for options. They also have solar panels etc.

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RileyB

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#793035 4-Apr-2013 11:22

Wow SLA batteries are huge/heavy for their relatively small charge. Because I'm taking a rather easy route with no real inclines it probably doesn't matter to much but could be looking at 3kg+ pretty quickly.

Just a quick look on jaycar I came up with these:

Solar Regulator:
http://www.jaycar.co.nz/productView.asp?ID=AA0348&form=CAT2&SUBCATID=1004#12
or
http://www.jaycar.co.nz/productView.asp?ID=MP3128&form=CAT2&SUBCATID=1004#12

Solar Panel:
http://www.jaycar.co.nz/productView.asp?ID=ZM9091&form=CAT2&SUBCATID=1004#12
or
http://www.jaycar.co.nz/productView.asp?ID=ZM9093&form=CAT2&SUBCATID=1004#12

Battery:
http://www.jaycar.co.nz/productView.asp?ID=SB2485&form=CAT2&SUBCATID=997#12

While I was there saw there home solar power kits, $43,000! No wonder solar power hasn't taken off.

timmmay

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#793041 4-Apr-2013 11:30

The dynamo idea seems most efficient, and lightest. Also like I said a big LiIon battery that can be charged by solar or mains could be an option that's easy, light and low cost.

Building it yourself seems time consuming, expensive, and more prone to failure.

RileyB

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#793047 4-Apr-2013 11:37

Seems like making a AA battery USB charger is a cheaper/lighter option and plenty of easy guides on the web. For the same weight as all that solar stuff I could carry more power in AA batteries then that solar system would create probably.

An example here:http://ibj.co.nz/science/energy/6-portable-aa-usb-charger.html

Being a photographer I have a large amount of Rechargeable AA's lying around already so wouldn't be much cost.

ubergeeknz

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#793049 4-Apr-2013 11:42

RileyB: Wow SLA batteries are huge/heavy for their relatively small charge.

Keep in mind comparing batteries of different voltages that mAH is only meaningful in relation to voltage. So a 12v 2400mAH battery has over 3x the capacity of a 3.6v 2400mAH cell.

However yes, li-Ion batteries are lighter/smaller for same capacity. Just be sure to use the right charge circuitry.

deadlyllama

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#793060 4-Apr-2013 11:55

If all your devices charge off USB, you could probably skip having an intermediate battery and just couple the solar panel directly to a DC-DC converter that outputs 5V. When the power sags you won't get any charging at all, though. But you won't need the weight of an intermediate battery.

Suitable DC-DC converters are pretty cheap on eBay, I imagine Jaycar will have something suitable too.

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RileyB

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#793065 4-Apr-2013 11:59

Only problem with those prebuilt ones on trademe Timmmay, is that most of them have tiny solar panels that take 1-2 days to charge the battery in direct sunlight.

I didn't take that into account ubergeeknz, so I guess SLA batteries are not as bad as I first thought.

RileyB

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#793067 4-Apr-2013 12:03

And guess what is on 1 day today: http://www.1-day.co.nz/products/AAMLCN3BC

timmmay

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#793082 4-Apr-2013 12:13

RileyB: Only problem with those prebuilt ones on trademe Timmmay, is that most of them have tiny solar panels that take 1-2 days to charge the battery in direct sunlight.

True. Will you have access to mains power at all, for example in a kitchen at a camp ground, or are you staying in tents in random fields? If so you may just get a big battery and forget the solar panel.

RileyB

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#793189 4-Apr-2013 13:51

I'm hoping to stay away from campgrounds, as from what I've seen they are about $15 a night to pitch a tent!

I might grab the battery and 5v regulator and see how many charges I can get out of it, then add the solar stuff later if I really need it. I have a fancy digital charger that I can use to charge the SLA for now.

Might pop down to jaycar so I can take a look and get an idea of the size/weight of everything.

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