Bicycle alternator - TuneCharger, Zener Diodes, Enclosures

[JordanOfOz]

Hi all,

I'm going on an extended bicycle tour later this year and I'm looking to use a TuneCharger not unlike Alex Lockhart's system:

http://www.crazyguyonabike.com/doc/page/?o=3Tzut&page_id=68041&v=Fy

I'm hoping to keep things a little simpler. I will be using a Son Dynamo hub and the TuneCharger to charge a ~12v bank of Lithium Ion batteries. Unlike Alex's system, I won't be powering lights directly from the 12v supply - I'll be powering a AA battery charger with a 12v input and a USB hub with a 12v input. All my lights and nerdy devices will use AA batteries and/or can be powered via USB or 12v

When used with a hub dynamo, the TuneCharger manual recommends using two zener diodes back to back to limit the input voltage, which in turn limits the drag experienced:

(page 22)
http://www.tunecharger.com/wp-content/52_mtc_43_evaluation_module_d.pdf

So I was thinking it would be nice to have a three-way switch that would give me the following options:

1: Disconnect the dynamo from the TuneCharger - minimal drag for climing hills
2: Connect the dynamo to the TuneCharger with the zener diodes in place - for normal cycling on flat terrain.
3: Connect the dynamo to the TuneCharger bypassing the zener diodes - for cycling downhill, giving maximum battery recharging and providing some extra drag.

Ideally I would have the TuneCharger and the above circuit all contained in some sort of rain-proof enclosure.

The enclosure will need:

- an input connector from the dynamo hub (RCA?)
- an output connector to the battery (or maybe not)
- two output connectors to power the USB hub and AA charger

I'm still debating with myself whether to include the 12v lithium ion pack in the TuneCharger enclosure, or use something like this:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2819

I've even considered including the powered USB hub inside the enclosure and wiring up waterproof USB sockets. This would be really handy, as I'll be using a Garmin eTrex right next to it, which can be powered directly by USB, and it would be nice to be able to mount any other USB/5v powered gadgets nearby on the bike.

If anyone could help me with any of the following questions (or if you have any other comments) I'd appreciate it:

1: What sort of 3-way waterproof switch should I use and how would I hook up the power input/zener diodes/power output? Would it be better to have two switches: connection to dynamo on/off - and - zener diode on/bypass
2: Can you recommend an enclosure to use?
3: Everything I've read seems to indicate that I can just hook up the 12v AA charger and the 12v supplied USB hub (and any other 12v devices I need) in parallel to the output of the TuneCharger. Is this correct?

Thanks in advance!

 

[cdev]

Hi JordanOfOz,
Just a note to warn you about running the tunecharger from the son dynohub. I am currently on an extended tour using the tunecharger/son dynohub combination to charge a lithium Ion battery pack. It is a very similar system to Alex Lockharts. I have lights, a usb output for GPS and cigarrette lighter output for charging various other things. I was originally using zener diodes to limit the power input to the tunecharger but removed them from the circuit for more power. Oops..This is the only thing that I did prior to the tunecharger circuit failing after a downhill run of around 50-60km/h . The manufacturers will not replace the circuitboard under warranty as they say that the damage incurred "can only occur when high voltage has been applied at the entry for many minutes and far beyond the limits of 25V defined in the user manual" . I explained to them the circumstances but they choose not to believe me that it was caused from a dynohub. So my only option is to buy another circuitboard. Not very convenient when travelling. So, I would say that do not under any circumstances run the tunecharger unprotected unless you want to waste time and money. If you want to see some pics of the system I use click here and feel free to ask any questions.
I have a toggle switch to switch charging on and off but only use this if the temp is below freezing, I've never noticed any difference in drag when climbing hills, but then I go pretty slow.
Hope this is of some help.
cdev

 

[JordanOfOz]

For anyone who comes across this thread looking to build something similar - my device is now complete:

http://jordanofoz.com/?p=20

Feel free to contact me if you have any questions!

 

[TheWind777]

A Bike Charger for AA, AAA, 9V and Li-Ion

I've been across America twice by bicycle. The first trip was 5000 miles and the second was 3800 miles. The first trip I used an LM314 as a constant current source to charge AA NiCad batteries off a side-generator which worked well down to Georgia, but then failed because the metal wheel wore as smooth as a mirror.

On my second bike trip I designed a tiny solar panel that hinged on my front right pannier box (I made it out of lexan plastic). It was pitifully underpowered for the rainy areas I went through. The charger was set up to charge a lantern-sized Gel-cel. The battery proved to be too big for the big mountains we went over (we crossed the Continental Divide six times).

So, now I want a better system that would charge up AAA, AA, 9V and Li-Ion (on different days, of course). So, for about two years I've been experimenting with various ways of charging AA, AAA, 9V and Li-Ion batteries via bicycle.

I use a 12V connector throughout the system that I purchase at Pep Boys. THey have red and white wires. I use white to mean negative and red to mean postitive. The same connector can be used on either end, so be careful that you don't plug an output into an output. I color code each side with shrink tubing. Red is an output (from the bike generator, from the solar panel, from the buck/boost power supply), blue is an input (to the 21 LED light, to the battery box with switches, etc.)

It has one two-conductor connector, heavy-duty, on each end of a red/white wires that are 12 inches long. If I need it to be longer, I cut it in half and splice in with solder two longer wires of the same guage.
I started using that connector because it's what's on my 12 Watt SunLinq folding solar panel, so that way I can plug the same things into my solar panel and into the bike generator.

http://www.batterystuff.com/solar-chargers/PF12w.html
I also use the same charger that I designed with a folding 23W solar panel, as well. Works like a charm.

So, if you have few electronics skills I'd recommend the following. First, get a SON28 hub dynamo to generate the power.
Next, you need to raise the voltage from the dynamo because a hub dynamo puts out only about 7 volts at less than 12 mph. You can get as much as 15 volts out of them (open-circuit) if you go really fast.

They give an almost steady 500 ma output at 6 volts when loaded. So, in order to actually charge four AA or AAA batteries you'll need what is termed a Buck/Boost supply to do that. The one that's designed to be used on a bike is called the E-WERK by Bucsh&Muller. It changes the AC to DC, boosts the voltage to any voltage between

Then just buy a four-battery AA or AAA holder at DigiKey or an electronics place and make sure that your plus and minus are set properly.

Set the voltage on the E-WERK to equal about 1.5 volts for each cell and the current limit at about .1 amp if AAA and .2 amp if AA.

Be sure that you don't overcharge the NiMH batteries. Feel the batteries to see if they're hot. Because it will take so long to charge the batteries, you will most-likely be using the power BEFORE they ever overcharge, though. Set the voltage at 1.5 volts for each battery (four batteries, set it at 6 volts. You can try raising that and see if the batteries heat up).
That's if you don't know electronics.

If you do know electronics, use the lowest forward voltage drop Schottky diodes on the market such as the STPS2L40U which has a .3 volt drop in a full-wave bridge rectifier mode (look it up). DigiKey's part number is 497-5574-1-ND. They're a surface-mount device, so they are hard to solder to unless you create a tiny circuit board. Then wet the solder pads with solder and hold the soldering iron on the end a second as it flows.

To raise the voltage to any voltage between 3 volts and 24 volts use the AnyVolt3. It is a little miracle. Set the output to any voltage between those two voltages and from then on the output will stay rock-solid at what you set it at (unless the device needs the voltage to be lower, then you'll see the voltage drop as the current rises). It costs $57 with shipping.

http://www.dimensionengineering.com/anyvolt3.htm

Finally, to charge almost any kind of battery at all, use the Texas Instruments BQ2000EVM.

http://focus.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=SLUU270&track=no

Get it directly from TI. It costs $50

http://www.ti-estore.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=BQ2000EVM
It is an evaluation module for the unit that is all pre-assembled with jumpers to set the voltages (regular hard drive jumpers work), screw adjustments for volt in and battery out and it even comes with a thermistor that you can mount near the batteries to have it automatically shut down if the batteries overheat.

The BQ2000 can charge NiMH, Ni-Cad and LI-ION, ***AND*** it can figure out automatically what kind of battery you're charging. The board is set to charge at 1 amp rate as the highest current, so it is greatly more than you'll need from a bicycle.

You can choose to top off the battery (you should) with a jumper. Then you choose C, C/2, C/3 or C/4 (1 amp, .5 amp, .33 amp or .25 amp), you choose the number of cells (NiMH 4, 5, 6, 8 or 10) or Li-Ion 1,2,3 or 4 (you know because one Li-Ion is 4.2 volts, so if it is 8.4 volts, it's 2).
Set the AnyVolt3 to 12 volts (set it without any load) while monitoring with a volt meter.

That's it. The batteries should charge at about a 300 milliamp rate. Each time you stop your bike and start it up again the computer in the BQ2000 will re-evaluate the kind of battery and automatically start charging again. There's a little surface-mount LED on the board that you can't see, so I removed it and soldered in an external LED so I can see the charging cycle. It blinks when it can't figure it out (has only happened twice). If that happens, just stop the bike and start again. It will start charging again.

The BQ2000 is incredibly smart, so it will first figure out what battery it is, then it will start fast charging it at full current that it can without destroying the battery or even heating up the battery (the big danger with NiHM batteries. If they heat up they won't explode, but it will greatly affect their lifespan).

I built a box to put it all in that velcros to my front rack. It can charge four AAA, four AA, 1 9V and 1 7.2 volt Nikon EN-EL1. I use a cheap 3 pole four-position rotary switch Alpha rated .3 amps at 125 vac (which works out to 1 amp at 30 vdc).

This swiches the voltage to the corresponding battery, the charge rate for each corresponding battery (solder the common to one of the top line of pins on the charge rate header), and the number of cells (solder the common of that one to the top row of pins on either the NiHM or Li-Ion header).

Then, when you select each battery, it will automatically set the charge rate and number of cells. Make sure you stop your bike, move the switch, and start your bike back up or the charger might get confused and start charging the AAAs at a 9V charge.

For overkill I built my own buck/boost power supply that has a voltage and current reading so I can keep track of how it's charging.

I can't afford a SON, so I just use one of those cheap $16 Tang-Lin generators. It works fine.

......

Settings that I use... I use DuraCell Pre-charged batteries (they hold their charge a long time). 2000mAh AA, 850 mAh AAA. I set the charge rate at C, set Top-off to yes, choose the Y side of the C charge rate. Then I set the jumper for 4 cells.

To charge 9V batteries, I use a Tenergy 250 mAh 9V battery. I set the BQ2000EVM at C/4 with Top-off. I set the cell count at 8 NiMh cells (charges at about 10.5 volts).

Although I haven't yet experimented with Li-Ion, I'm planning on charging the Nikon's Li-Ion battery for my Nikon e4300 camera, which is 7.2 volts by setting the jumper on the Li-Ion side to 2 cells and setting the jumper to full C (1 amp) charge with Top-off. I'll also be trying it without top-off as well.

I'm going to use this cheap charger, yank out the guts and use it as a battery holder.

http://www.amazon.com/dp/B000AO8NHI/?tag=cpf0b6-20

...

The Buck/Boost supply that I designed is a 3 amp unit that can put out anywhere from 5.4 volts to 28 volts DC. Although I bought the low-voltage drop Schottky diodes, I'm currently just using a bridge rectifier I pulled from an old computer's power supply and it seems to be working fine. I'll have to create a circuit board to try out the four low-drop diodes. I don't expect to get much improvement over what I'm already getting, though.

I've also tried using it without the buck-boost power supply. In my case, because the cheap generator I used

http://www.amazon.com/dp/B000OBWMGK/?tag=cpf0b6-20

(it's $24 with shipping)

... can easily push out greater than the 10 -24 volts that are needed by the BQ2000EVM... it works fine without the buck-boost supply at the front end. You'll probably need one with a SON though, as it would drop to 7 volts and that's not enough to power the BQ2000.

IMPORTANT: You MUST put a zener diode shunt (associated resistor has to be big in order to absorb all the wattage over the 25 volt level) if you think your generator might go above the 25 volt input level when you go down hills. Generators, particularly the cheaper versions, can give out as much as 40 volts AC when you're really going fast.

After rectification, put a 30-40VDC axial computer-grade electrolytic around 3000 mf. Make sure you get the polarity right. I attached the bridge rectifier to the axial capacitor and used zip ties to affix it under the front bag mount.

My camera currently needs new batteries to be ordered, so can't upload any photos at the present time.

If you have any questions, contact me at [email protected]
h

 

[TheWind777]

Concerning 9v Tenergy Rechargeable NiMH Batteries

Just a thought about the Tenergy 9V battery that I mentioned. 9V batteries tend to use different number of cells inside their NiMH 9V batteries.

These Tenergy are actually only 8.4 volts, not 9.6 as an 8-cell 9V battery should have. This means it is really a 7-cell battery, not an 8-cell battery. Unfortunately, with the BQ2000EVM board there's an 8-cell choice and a 6-cell choice. You'd have to interpolate the resistor value for an 8-Cell and solder it onto the board in the area they left blank and called 'User' if you wanted it to properly charge those batteries.

I just charge them at the 8-cell selection; I'm sure it reduces the longevity of the 9V battery.

It would be better to keep searching for a 9V NiMH which says it's 9.6 volts (8-cells) if you need to charge 9V batteries (like if you're a bicycling painball player, heh, heh...).

 

[TheWind777]

More on not using 8.4V nine volt Tenergy Batteries on an 8-Cell jumper setting.

So, charging with the generator worked OK with 9V, but when I used a more powerful 1.2 Amp-capacity 12 Volt AC Adapter/charger on the box in the 9V setting with the 9V Tenergy (8.4V) battery (7-cell) it ruptured the case of the 9V battery and I had to throw it away.

So, you can't use the 8-cell setting for a 7-cell 9V (which I already knew, but was hoping it would work).

I was leery of it anyways because almost 800 milliamps were going into that tiny little 9V 250 mAh battery. I should have felt the battery's case again; but trusted it too much. I know that many 9V chargers charge all three different 9V battery voltages, so thought maybe it would work.

Don't use 8.4 Volt 9V Batteries with the BQ2000 circuit on an 8-Cell jumper position (which probably should have been obvious to me, but had to try it out anyways).

 

[TheWind777]

Another update.

I tried installing a 128,000 ohm resistor in the 'User' defined place on the board to change from 8 cells to 7 cells for the 9V battery. It was the value that I had determined by linear regression would be the next value for 7 cells (8.4 volts). I had many different 120,000 resistors and kept measuring them until I found one that was almost exactly 128,000 ohms.

When the 9V was charged at the smallest 'C/4' setting, it still started heating up the 9V too much. If you had the thermistor installed to shut it down when it started overheating, then it might work just fine. However, my need to charge 9V is extremely small so that will be my last test of that type of battery.

However, AA and AAA are still charging perfectly. I've now charged about ten sets of AA and AAA batteries as a four-pack and it's working great.

The 9V is just too small a battery for this board. It only has a 250 mA-hour rating. It needs to be charged at a much slower rate than 300 -450 mlliamps that this board is trying to push through the battery, which is what the board is trying to charge it at.

Haven't yet tried using the board to charge my Nikon e4300 camera battery. It should charge at a Li-Ion 2 cell rate (8.4 volts. Although it says 7.2 volts on the battery, the cheap chargers on-line charge at 8.4 volts and say they charge the EN-EL1 at a 8.4 volt rate)