TylerDurden
100 GW
I have yet to come across anyone here that qualifies as ordinary.JEB said:
DeWalt made the brilliant move of embracing A123 before the other guys... not bad, for a household appliance company.
Eric's Project #002
- Thread starter Beagle123
- Start date
DeWalt made the brilliant move of embracing A123 before the other guys... not bad, for a household appliance company.
JEB
100 W
does average sound better? I know know one that posts here is average!!
TylerDurden
100 GW
JEB said:
I know know one that posts here without proof-reading.
Tyler, know know! 
The cobalt based Li-ion batteries are doomed to a 3-4 year life, but I've seen some estimates that LiFePO4 might last over 10 years if the cycle life is not exceeded. This would be perfect for somebody like me that doesn't have enough time to ride much.
NiCds can last over 20 years. I'm using a set now in my hedge clipper that were made in 1987.
NiCds can last over 20 years. I'm using a set now in my hedge clipper that were made in 1987.
JEB
100 W
where I once worked, they used nicad batteries, the chargers they used did not have a auto shut off, after reaching their fully charged condition. 200ma (into a "c" cell,) was being pumped into them for weeks at a time, the batteries were used, placed back into the chargers till the next use.
The electronic eng. commented that they should have had a longer life, I sawed a few in half- just powder inside, no jell.
they were usable just a little over 2 years
The electronic eng. commented that they should have had a longer life, I sawed a few in half- just powder inside, no jell.
they were usable just a little over 2 years
Beagle123
10 kW
Like all technology, li-ion will advance and be even better in the future. I know that prius' batteries have some incredible lifespan. I'm sure smart engineers could optimize batteries to last forever using an advanced design that doesn't deteriorate, and an advanced BMS etc. They could study the ranges of discharges and use the best ones. THe prius for example never comes close to being fully charged or dischraged (if I remember correctly). They say they'll go 200,000 miles.
The challenge isn't technological, its political. If we used a fraction of the money from the military or space program etc to develop this stuff, we'd have an awesome battery system. Or if tax incentives were given for green transport, we'd see a shift immediately.
I'm gald y'all are out there spreading the word.
The challenge isn't technological, its political. If we used a fraction of the money from the military or space program etc to develop this stuff, we'd have an awesome battery system. Or if tax incentives were given for green transport, we'd see a shift immediately.
I'm gald y'all are out there spreading the word.
Beagle123
10 kW
Headlamp Made
I made a headlamp from three led lights. I bought these lights on ebay for about $6 each. They're perfect because they're powered by three AA batteries (3.6v) so I can use a few 4v emoli cells to power the unit. Its working great.
To attach the lights to each other, I cut a length of PVC pipe lengthwise on my table saw to make a semi-circle, then I glued the curved portion of the lights inside the piece of pipe. In the pictures, the gray primer area is PVC.
I cut a couple of pieces of wood to mount it to my handlebars. I glued one end to the bottom of the light, and the other end fits over the handlebars. I used some foam pieces to cushion the contact with the handlebars, and I"ll use 4 plastic wire ties to strap it onto the handlebars.
I have a question:
When I connect the lights directly to a 4v emoili cell, it uses about 2.4 amps. However, fetcher told me that connecting directly to the cells might use too much energy and burn out the lights. I noticed that if I used a 1 ohm resistor, they used only 0.8 amps. When I added another 1 ohm resistor, the lights burned brighter, and used about 1.35 amps. This seems about right to me. They burn about as bright as with the AA batteries.
Is using 2 one ohm resistors the right way to limit the current? They're the "power resistors" from radioshack called "wirewound."
Thanks
I made a headlamp from three led lights. I bought these lights on ebay for about $6 each. They're perfect because they're powered by three AA batteries (3.6v) so I can use a few 4v emoli cells to power the unit. Its working great.
To attach the lights to each other, I cut a length of PVC pipe lengthwise on my table saw to make a semi-circle, then I glued the curved portion of the lights inside the piece of pipe. In the pictures, the gray primer area is PVC.
I cut a couple of pieces of wood to mount it to my handlebars. I glued one end to the bottom of the light, and the other end fits over the handlebars. I used some foam pieces to cushion the contact with the handlebars, and I"ll use 4 plastic wire ties to strap it onto the handlebars.
I have a question:
When I connect the lights directly to a 4v emoili cell, it uses about 2.4 amps. However, fetcher told me that connecting directly to the cells might use too much energy and burn out the lights. I noticed that if I used a 1 ohm resistor, they used only 0.8 amps. When I added another 1 ohm resistor, the lights burned brighter, and used about 1.35 amps. This seems about right to me. They burn about as bright as with the AA batteries.
Is using 2 one ohm resistors the right way to limit the current? They're the "power resistors" from radioshack called "wirewound."
Thanks
Attachments
Using a resistor is the right thing, just figure out the correct value.
If you loaded up one light with the recommended AA batteries, and measure the current draw, you'd want to choose a resistor that will give you the same current with the Li battery.
Once you determine the correct resistance, then you want to check the power dissipation of the resistor to make sure it won't burn up. You can do the math if you know the the current and resistance. The other way is to just stick a resistor in there and see if it gets hot.
If you loaded up one light with the recommended AA batteries, and measure the current draw, you'd want to choose a resistor that will give you the same current with the Li battery.
Once you determine the correct resistance, then you want to check the power dissipation of the resistor to make sure it won't burn up. You can do the math if you know the the current and resistance. The other way is to just stick a resistor in there and see if it gets hot.
Beagle123
10 kW
Headlight Finished
It took me about 6 hours to make my headlight, but its done. I soldered three emoli 4v cells in parrallel to make a 4v, 9ah pack for the light. I'm connecting the battery to the light with a wire and a small dean's micro-plug. So when I need to charge the batteries, I can just unplug the light, and plug the charger into the plug.
I decided not to use any resistors with it because it was drawing 2.4 amps of current without any resistors. This is exactly the same amount of current used by the AA batteries that it uses from the factory. Fetcher told me to use similar current. And they burn really brightly. In the picture, they are so bright that it looks like the picture was taken at night. That pic was taken in a well lighted living room.
I think it came-out great, but I do have one issue with it. What if I leave my headlights on by accident? My understanding is that the worst that can happen is ruining the cells with "reverse polarization." I'm not sure what that means, but it sounds bad.
I haven't heard of any cells exploding from being run-down. I don't imagine that's the case. Let me know if anyone has heard of that happening.
I always have the option of adding a BMS to prevent the voltage from dropping below 3.7v.
The headlight is held in place with 4 wire ties. There's enough friction so it won't move, but you can adjust it with your hand.
It took me about 6 hours to make my headlight, but its done. I soldered three emoli 4v cells in parrallel to make a 4v, 9ah pack for the light. I'm connecting the battery to the light with a wire and a small dean's micro-plug. So when I need to charge the batteries, I can just unplug the light, and plug the charger into the plug.
I decided not to use any resistors with it because it was drawing 2.4 amps of current without any resistors. This is exactly the same amount of current used by the AA batteries that it uses from the factory. Fetcher told me to use similar current. And they burn really brightly. In the picture, they are so bright that it looks like the picture was taken at night. That pic was taken in a well lighted living room.
I think it came-out great, but I do have one issue with it. What if I leave my headlights on by accident? My understanding is that the worst that can happen is ruining the cells with "reverse polarization." I'm not sure what that means, but it sounds bad.
I haven't heard of any cells exploding from being run-down. I don't imagine that's the case. Let me know if anyone has heard of that happening.
I always have the option of adding a BMS to prevent the voltage from dropping below 3.7v.
The headlight is held in place with 4 wire ties. There's enough friction so it won't move, but you can adjust it with your hand.
safe
1 GW
- Joined
- Dec 22, 2006
- Messages
- 5,681
Living in Los Angeles means you get to ride and work year round. For those of us that live in places with bad weather we spend months and months not being able to do much of anything. There's a lot to be said about the efficiency of living in a warmer dryer climate.
I grew up in Northern California and remember the great weather... and the high prices for everything.
I grew up in Northern California and remember the great weather... and the high prices for everything.
xyster
10 MW
Beagle123 said:
The cells won't explode if over-discharged; since there's only one in series, they probably won't reverse polarity either. If run down all the way, most likely you'll have three cells that won't hold a charge again. Emoli's have been reported to come back to life from voltages as low as 1.0v though.
I think those LEDs will pretty much stop drawing any current when the voltage gets down to around 2.5v or so. Self limiting 8)
TylerDurden
100 GW
Very nice work! I also got three LED lights (12v ) for headlights, but I think I will use them in my van for courtesy lighting and get some brighter ones like yours for my bike.
RLT
10 kW
A few things:
On that other thread you mentioned being interested in input on your battery pack assembly. I don't see anything to comment on at the moment, but I'll be glad to TRY to answer any specific questions you can come up with.
Now, on your LED headlights, I am a little ahead of the game and have some advice.
First of all, VERY neat assembly! It looks 'bitchin' as we used to say back in the '60s
But you should use a protective circuit on your battery pack. Those LEDS will drain it down to nothing eventually (although with 9AH you are probably talking days to drain below the danger point). Those Chinese 5mm LEDS will keep operating down to micro-amps.
I've got one that has been burning on two Energizer Lithium AAA primaries (1.7v nominal each) continuously for about three years. I just checked, and it is drawing .005ma at about a volt. A rechargable LiIon or LiPo would be long past recovering.
I'll be glad to send you a protective circuit (free) Just four solder points on a 1in. X 1/4 in. X 3mm circuit board anywhere between the end of your battery string and the light. That way you don't have to worry at all. Just PM me with your address and I'll get it in the mail ASAP.
I'm not familiar enough with the Emoli cells to give a definitive answer on 'catastrophic' failure due to over discharge. I know that they are safer than LiIon or LiPo batteries, but it is supposedly possible for the Lixx batteries to 'vent with flame' if over- discharged: Super rare, compared to over charging them or puncturing the case. but according to the manufacturers, within the realm of possibility.
Here is a good source of info on LEDS, batteries, lights and stuff.:
http://www.candlepowerforums.com/vb/
I've been a member there for about 7-8 years, and have learned a whole lot.
Of particular interest might be the 'Batteries included' forum:
http://www.candlepowerforums.com/vb/forumdisplay.php?f=9
The RC forums may be more cutting edge on battery technology, but the CPF guys can be just as obsessed over battery stuff, and if you want to build or just be well informed about cutting edge portable lighting of any kind, there is no better place.
On that other thread you mentioned being interested in input on your battery pack assembly. I don't see anything to comment on at the moment, but I'll be glad to TRY to answer any specific questions you can come up with.
Now, on your LED headlights, I am a little ahead of the game and have some advice.
First of all, VERY neat assembly! It looks 'bitchin' as we used to say back in the '60s
But you should use a protective circuit on your battery pack. Those LEDS will drain it down to nothing eventually (although with 9AH you are probably talking days to drain below the danger point). Those Chinese 5mm LEDS will keep operating down to micro-amps.
I've got one that has been burning on two Energizer Lithium AAA primaries (1.7v nominal each) continuously for about three years. I just checked, and it is drawing .005ma at about a volt. A rechargable LiIon or LiPo would be long past recovering.
I'll be glad to send you a protective circuit (free) Just four solder points on a 1in. X 1/4 in. X 3mm circuit board anywhere between the end of your battery string and the light. That way you don't have to worry at all. Just PM me with your address and I'll get it in the mail ASAP.
I'm not familiar enough with the Emoli cells to give a definitive answer on 'catastrophic' failure due to over discharge. I know that they are safer than LiIon or LiPo batteries, but it is supposedly possible for the Lixx batteries to 'vent with flame' if over- discharged: Super rare, compared to over charging them or puncturing the case. but according to the manufacturers, within the realm of possibility.
Here is a good source of info on LEDS, batteries, lights and stuff.:
http://www.candlepowerforums.com/vb/
I've been a member there for about 7-8 years, and have learned a whole lot.
Of particular interest might be the 'Batteries included' forum:
http://www.candlepowerforums.com/vb/forumdisplay.php?f=9
The RC forums may be more cutting edge on battery technology, but the CPF guys can be just as obsessed over battery stuff, and if you want to build or just be well informed about cutting edge portable lighting of any kind, there is no better place.
RLT
10 kW
Oh, here is a little more on LEDs, resistors etc.
Here is a handy dandy online calculator for determining what size resistor to use.:
http://ledcalc.com/ There are a few different calculators as links on that page, a nice collection for just about any combination of series, parallel setups.
It has been a while since I have worked closely with the 5mm LEDs, but on most of the chinese ones, you want to stay under 25 ma current per LED. 20 ma is better. They don't usually keel over and die if you hit them with 40-50 ma, but their lifetime is shortened drastically and their light output value falls rapidly and permanently.
If you get the good Japanese made Nichia 5mm LEDS, you can overdrive them significantly... a constant 40ma to each doesn't bother them much, and 30 ma is no problem at all.
For future consideration for LED headlights, though, think Cree, Seoul SSC or Luxeon LEDS; not big clusters of the low powered ones. The newer high power ones can be made to 'stand up and do tricks' with optics or reflectors at reasonable currents.
I have built quite a few LED flashlights that 'throw' a usable amount of light 100 yards down the road or across the field with a tight beam through a 2 inch mirror optic, or light up wide but flatter or tall but narrow (depending on orientation) areas with inexpensive linear optics on about 2 amps and 4V... With just one LED. And they are, surprisingly, more efficient at pumping out photons at sub 20ma currents than the 5 mm LEDs are too. The only real downside is that heatsinking becomes an important design factor when you are running more than about 400 ma into them.
Here is a handy dandy online calculator for determining what size resistor to use.:
http://ledcalc.com/ There are a few different calculators as links on that page, a nice collection for just about any combination of series, parallel setups.
It has been a while since I have worked closely with the 5mm LEDs, but on most of the chinese ones, you want to stay under 25 ma current per LED. 20 ma is better. They don't usually keel over and die if you hit them with 40-50 ma, but their lifetime is shortened drastically and their light output value falls rapidly and permanently.
If you get the good Japanese made Nichia 5mm LEDS, you can overdrive them significantly... a constant 40ma to each doesn't bother them much, and 30 ma is no problem at all.
For future consideration for LED headlights, though, think Cree, Seoul SSC or Luxeon LEDS; not big clusters of the low powered ones. The newer high power ones can be made to 'stand up and do tricks' with optics or reflectors at reasonable currents.
I have built quite a few LED flashlights that 'throw' a usable amount of light 100 yards down the road or across the field with a tight beam through a 2 inch mirror optic, or light up wide but flatter or tall but narrow (depending on orientation) areas with inexpensive linear optics on about 2 amps and 4V... With just one LED. And they are, surprisingly, more efficient at pumping out photons at sub 20ma currents than the 5 mm LEDs are too. The only real downside is that heatsinking becomes an important design factor when you are running more than about 400 ma into them.
Beagle123
10 kW
Headlight In Action
Thanks you guys. It sounds like RLT's circuit will fix everything. I'd like to understand how it works, but I guess I'll just have to take a look at it. By the way, will it handle 2.4 amps? I didn't know circuit boards could handle that amount of current.
When I got home tonight I tested the headlight in the dark. It's fantastic. This is definately powerful enough to see everything on the road. It might be brighter than a car headlight. Definately comparable.
Look for yourself. One pic is with my garage light turned on so you can compare how bright the headlight is. The garage light has two 60 watt bulbs. You can see that its much brighter than the garage.
The other pic is with the garage light off, but there's still residual light from the house (but its overpowered).
I'd really reccomend this light.
Thanks you guys. It sounds like RLT's circuit will fix everything. I'd like to understand how it works, but I guess I'll just have to take a look at it. By the way, will it handle 2.4 amps? I didn't know circuit boards could handle that amount of current.
When I got home tonight I tested the headlight in the dark. It's fantastic. This is definately powerful enough to see everything on the road. It might be brighter than a car headlight. Definately comparable.
Look for yourself. One pic is with my garage light turned on so you can compare how bright the headlight is. The garage light has two 60 watt bulbs. You can see that its much brighter than the garage.
The other pic is with the garage light off, but there's still residual light from the house (but its overpowered).
I'd really reccomend this light.
Attachments
RLT
10 kW
Very impressive! Looks like it will be great, at least if you aren't really 'hauling' at night. How far ahead will it provide useful illumination?
Anyway, that protection circuit I offered to send you is a new ~4V one that is SUPPOSED to handle up to 8.5 (+-1.0) amps. I haven't actually tried them yet... I just got them in a couple of days ago . But your ~ 2.5A should be no sweat at all.
The only thing I'd worry about is the charging cutoff voltage. These are supposed to cutoff at 4.35V... Which might be too high if you are using a 'dumb' charger. So; depending on your charging system, you may have to monitor the voltage and cut it off manually.
Low voltage cutoff is supposed to be 2.4V, which should be just right
Anyway, that protection circuit I offered to send you is a new ~4V one that is SUPPOSED to handle up to 8.5 (+-1.0) amps. I haven't actually tried them yet... I just got them in a couple of days ago . But your ~ 2.5A should be no sweat at all.
The only thing I'd worry about is the charging cutoff voltage. These are supposed to cutoff at 4.35V... Which might be too high if you are using a 'dumb' charger. So; depending on your charging system, you may have to monitor the voltage and cut it off manually.
Low voltage cutoff is supposed to be 2.4V, which should be just right
Beagle123
10 kW
Hi RLT:
I can tilt the headlight up so I can see as far down the road as I want.
My chargers only get up to about 4.2v, so cutoff shouldn't be a problem. I'm not sure if a BMS is overkill. It wouldn't be a disaster if If I ran the batteries low. They'd probibly still function fine at half power for the purposes of a headlight. As long as there's not any danger, it seems ok to me.
I can tilt the headlight up so I can see as far down the road as I want.
My chargers only get up to about 4.2v, so cutoff shouldn't be a problem. I'm not sure if a BMS is overkill. It wouldn't be a disaster if If I ran the batteries low. They'd probibly still function fine at half power for the purposes of a headlight. As long as there's not any danger, it seems ok to me.
xyster
10 MW
Beagle123 said:
I'd think the bright light would be sufficient reminder to turn them off at the end of a ride. Overcharge is no concern either because the single cell, 4.20v chargers can't possibly overcharge the batteries (unless there's a highly unlikely, catastrophic short through to the 120v AC source voltage). So a BMS is overkill, IMO.
Beagle123
10 kW
Another Varioation for Batteries
I was thinking about my plug idea again for the batteries, and I thought that perhaps the connections could be made electronicly with MOSFETs or relays.
Here is an example of a mosffet I could use:
http://www.allelectronics.com/cgi-bin/item/STB55NE06/search/N-CHANNEL_POWER_MOSFET,_SURF-MT_PKG_.html
The configuration is pictured below.
As a safety precaution, I'd make another "dummy plug" that fits into the charging plug except this time the "dummy plug" would just have one wire in it that activated the MOSFETs. This insures that I can't short the system by connecting the charger when the MOSFETs are activated. (I must remove the "Dummy plug" to plug-in the charger, thus disconnecting the system (idiotproof)).
However, I've never worked with electronics before, so I have some questions:
What voltage does it take to activate a MOSFET? is it different on each one?
How much current do they draw? This could be an issue because sometimes I leave my scooter turned on accidentally.
What are their resistance? Would they hamper my performance? Keep in mind that I'll have to use 14 MOSFETs in series.
Will this idea work?
I really need to learn how to build electronics. I'd like to get a book or two. Any suggestions?
I need to learn the following:
1) soldering. When I soldered my batteries, the solder pooled-up into a brown liquid, and the solder beaded like water on a duck's back) I clearly don't understand what's going on here.
2) components--MOSFETs, diodes, transistors
3) building boards. I have no idea how to assemble those little components into a working unit. This is perhaps my biggest drawback.
4) integrating chips. I can understand chips, but how do you solder them onto a board and use them? They're so tiny?
Edit: This plan has been sidelined in favor of just using connectors.
I was thinking about my plug idea again for the batteries, and I thought that perhaps the connections could be made electronicly with MOSFETs or relays.
Here is an example of a mosffet I could use:
http://www.allelectronics.com/cgi-bin/item/STB55NE06/search/N-CHANNEL_POWER_MOSFET,_SURF-MT_PKG_.html
The configuration is pictured below.
As a safety precaution, I'd make another "dummy plug" that fits into the charging plug except this time the "dummy plug" would just have one wire in it that activated the MOSFETs. This insures that I can't short the system by connecting the charger when the MOSFETs are activated. (I must remove the "Dummy plug" to plug-in the charger, thus disconnecting the system (idiotproof)).
However, I've never worked with electronics before, so I have some questions:
What voltage does it take to activate a MOSFET? is it different on each one?
How much current do they draw? This could be an issue because sometimes I leave my scooter turned on accidentally.
What are their resistance? Would they hamper my performance? Keep in mind that I'll have to use 14 MOSFETs in series.
Will this idea work?
I really need to learn how to build electronics. I'd like to get a book or two. Any suggestions?
I need to learn the following:
1) soldering. When I soldered my batteries, the solder pooled-up into a brown liquid, and the solder beaded like water on a duck's back) I clearly don't understand what's going on here.
2) components--MOSFETs, diodes, transistors
3) building boards. I have no idea how to assemble those little components into a working unit. This is perhaps my biggest drawback.
4) integrating chips. I can understand chips, but how do you solder them onto a board and use them? They're so tiny?
Edit: This plan has been sidelined in favor of just using connectors.
Attachments
xyster
10 MW
I'm missing your point of why you wish to break the connection between the subpacks.
The system can be "on" while charging without shorting. I turn mine on while charging in order to check the pack voltage via the on-board voltmeter, which only functions when the main power switch to the controller is turned on.
So twenty chargers all connected through a single power strip and actively charging the 20 still-interconnected subpacks, main power on, controller switched on = no short.
The system can be "on" while charging without shorting. I turn mine on while charging in order to check the pack voltage via the on-board voltmeter, which only functions when the main power switch to the controller is turned on.
So twenty chargers all connected through a single power strip and actively charging the 20 still-interconnected subpacks, main power on, controller switched on = no short.
dirty_d
10 kW
the ends of the cells need to be something that solder will stick too, like copper, tin, or zinc. solder wont stick to aluminum or steel, unless its galvanized steel. or maybe you just didn't do it right try cleaning it a little with sandpaper and putting some paste flux on it first.beagle123 said:
the fets will probably have an on resistance of about .010ohms thats about the same as 10 feet of 10 gauge copper wire, so 14 fets would be like 140 feet of wire separating all of the packs.
RLT
10 kW
OK, Cool.
I must admit a lot of my LiIon lights that I keep for myself don't have a protective circuit either. I always put them in the ones that other people get though.
Being careless is kind of my normal mode, so if I'm using devices that are smarter than I am, I just feel a little more secure.
Let me know if you change your mind on wanting the circuit..
I must admit a lot of my LiIon lights that I keep for myself don't have a protective circuit either. I always put them in the ones that other people get though.
Being careless is kind of my normal mode, so if I'm using devices that are smarter than I am, I just feel a little more secure.
Let me know if you change your mind on wanting the circuit..
Beagle123
10 kW
Hi xter. You're charging with individual chargers. I'm talking about one big charger charging all the batteries. If you connect the positive from one battery to the positive of another battery at the other end of the pack, you'll get a big short.
Dirty: I was soldering to steel. My emolis as I understand are made of steel. But in the end it did seem to stick. I hope it won't unstick.
RLT: Thanks again for your offer. I spent the day reading about electronics. I'm sure I'll be interested in your circuit at some poiint because it will serve as a great example for me. I think battery packs and BMSs are our biggest hurdle, so after I'm done with this bike, I may try some tinkering.
Similar threads
