|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
Okay. I see most new external battery pack lights are using lithium ion battery packs. I have a number of perfectly good Nimh batteries. If the voltage is the same is there any reason I can't use those NiMh battery packs with a light that came with a lithium ion battery pack?
Cheers |
Ads |
#2
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Mon, 21 Sep 2015 20:43:31 -0700 (PDT), Sir Ridesalot
wrote: Okay. I see most new external battery pack lights are using lithium ion battery packs. I have a number of perfectly good Nimh batteries. If the voltage is the same is there any reason I can't use those NiMh battery packs with a light that came with a lithium ion battery pack? Lithium Ion is a nominal 3.7 VDC per cell. NiMH is 1.35 VDC. If the total voltage of the LiIon battery pack is something closely divisible by 1.35 VDC, it might work. However, then you'll have to deal with the battery charger circuitry, which is very different between different battery chemistries. I don't think it's worth the risk of frying the LED's. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Tuesday, September 22, 2015 at 1:23:18 AM UTC-4, Jeff Liebermann wrote:
On Mon, 21 Sep 2015 20:43:31 -0700 (PDT), Sir Ridesalot wrote: Okay. I see most new external battery pack lights are using lithium ion battery packs. I have a number of perfectly good Nimh batteries. If the voltage is the same is there any reason I can't use those NiMh battery packs with a light that came with a lithium ion battery pack? Lithium Ion is a nominal 3.7 VDC per cell. NiMH is 1.35 VDC. If the total voltage of the LiIon battery pack is something closely divisible by 1.35 VDC, it might work. However, then you'll have to deal with the battery charger circuitry, which is very different between different battery chemistries. I don't think it's worth the risk of frying the LED's. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 Thanks Jeff. I have the NiMh charger too. If I did get the Lion powered light it'd come with Lion battery charger. thus there's no concern about using the wrong charger on the battery pack. Cheers |
#4
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Mon, 21 Sep 2015 20:43:31 -0700 (PDT), Sir Ridesalot
wrote: Okay. I see most new external battery pack lights are using lithium ion battery packs. I have a number of perfectly good Nimh batteries. If the voltage is the same is there any reason I can't use those NiMh battery packs with a light that came with a lithium ion battery pack? Cheers LED lights have a constant current regulator. As long as the input voltage is close it will work OK. But don't mix chargers. |
#5
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Tuesday, September 22, 2015 at 2:48:49 AM UTC-4, somebody wrote:
On Mon, 21 Sep 2015 20:43:31 -0700 (PDT), Sir Ridesalot wrote: Okay. I see most new external battery pack lights are using lithium ion battery packs. I have a number of perfectly good Nimh batteries. If the voltage is the same is there any reason I can't use those NiMh battery packs with a light that came with a lithium ion battery pack? Cheers LED lights have a constant current regulator. As long as the input voltage is close it will work OK. But don't mix chargers. I don't know much about Lions and Nimh but from building radio-controlled boats i do know not to charge one with the other type of charger. The thing is my Cygolite at the high setting of 250 lumens is pretty decent and I have extra battery packs for it. the new Cygolites i referenced are all Lion battery packs which I knew meant my existing batteries couldn't be charged with the new Lion charger but i was hoping to be able to use those Nimh battery packs as backups on my really long night rides that i frequently take. I'm thinking that perhaps the 800 lumens Cygolite might meet my needs and it's about $150.00 less than the Cygolite 1300 or 1700 lumens ones. Cheers |
#6
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Mon, 21 Sep 2015 23:24:25 -0700 (PDT), Sir Ridesalot
wrote: On Tuesday, September 22, 2015 at 1:23:18 AM UTC-4, Jeff Liebermann wrote: On Mon, 21 Sep 2015 20:43:31 -0700 (PDT), Sir Ridesalot wrote: Okay. I see most new external battery pack lights are using lithium ion battery packs. I have a number of perfectly good Nimh batteries. If the voltage is the same is there any reason I can't use those NiMh battery packs with a light that came with a lithium ion battery pack? Lithium Ion is a nominal 3.7 VDC per cell. NiMH is 1.35 VDC. If the total voltage of the LiIon battery pack is something closely divisible by 1.35 VDC, it might work. However, then you'll have to deal with the battery charger circuitry, which is very different between different battery chemistries. I don't think it's worth the risk of frying the LED's. I have the NiMh charger too. If I did get the Lion powered light it'd come with Lion battery charger. thus there's no concern about using the wrong charger on the battery pack. What nominal voltage is the LiIon pack and what voltage does the light expect? These should be the same, but with LiIon packs being "rated" at anything between 3.6 to 4.2 VDC per cell, there may be some variation. The light may also have a range of acceptable voltages as controlled by a series current regulator. I would put the light on a bench power supply and see what it can do over a range of applied voltages. Then, the idea is to adjust the number of cells in the NiMH pack, possibly adding a diode or two to make the voltages roughly equal, to produce roughly the same voltage. NiMH is a tolerable replacement for LiIon but only for fairly low currents. If your light is in the mega-lumen class of photon torpedo offensive bicycle weaponry, the NiMH battery pack may not be able to deliver the current. So, I need an estimated current consumption figure for the light in order to check if this is a problem. Incidentally, I tend to go the other direction. Some of my older NiCd/NiMH Makita power tools now have an internal LiIon batteries. Running on LiIon power, they last longer, charge faster, and are MUCH lighter. I'm waiting for some of my NiMH battery packs to die so I can fill them with LiIon cells. I wouldn't dream of going the other direction with these tools. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#7
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Mon, 21 Sep 2015 23:24:25 -0700 (PDT), Sir Ridesalot
wrote: I have the NiMh charger too. If I did get the Lion powered light it'd come with Lion battery charger. thus there's no concern about using the wrong charger on the battery pack. I guess this is for one of the Cygolite LiIon lights that you were considering purchasing. (Sorry, I missed the previous thread on the topic). Cygolite seems to standardize on a 7.6v DC LiIon battery pack for the lights. No NiMH packs available. http://www.shop.cygolite.com/category.sc?categoryId=24 7.6 VDC would be two 3.8 VDC LiIon cells. To produce that using NiMH cells would requi 7.6 / 1.35 = 5.6 cells which isn't going to work. The best I can do is 6 cells, for: 1.35 * 6 = 8.1 VDC which requires a voltage drop of: 8.1 - 7.6 = 0.5 VDC which can easily be accomplished with a single power diode in series with the battery pack. I don't like the power loss in the diode, but it should work. The diode should be built into a plug and jack power adapter installed between the NiMH pack and the light. That way, you can use the NiMH charger, without the diode getting in the way. That will also allow you to use a LiIon pack, but simply removing the diode adapter. Permit me to offer an alternative approach. Instead of reverting to NiMH cells, just find a cheaper LiIon battery pack. I suggest you look at the various radio control batteries. What you want are the biggest LiIon batteries possible in a 2S pack (possibly with the balance charger connector). 2S packs sorted by price: http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?cwhl=XX&idCategor y=86&v=&sortlist=P&LiPoConfig=2&CatSortOrder=desc I can't calculate how many milliamp-hrs will be needed without knowing which light you plan to use. After that, it's packaging (stuff it in a water bottle) and adapters for the power connector. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#8
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Tuesday, September 22, 2015 at 12:56:34 PM UTC-4, Jeff Liebermann wrote:
On Mon, 21 Sep 2015 23:24:25 -0700 (PDT), Sir Ridesalot wrote: I have the NiMh charger too. If I did get the Lion powered light it'd come with Lion battery charger. thus there's no concern about using the wrong charger on the battery pack. I guess this is for one of the Cygolite LiIon lights that you were considering purchasing. (Sorry, I missed the previous thread on the topic). Cygolite seems to standardize on a 7.6v DC LiIon battery pack for the lights. No NiMH packs available. http://www.shop.cygolite.com/category.sc?categoryId=24 7.6 VDC would be two 3.8 VDC LiIon cells. To produce that using NiMH cells would requi 7.6 / 1.35 = 5.6 cells which isn't going to work. The best I can do is 6 cells, for: 1.35 * 6 = 8.1 VDC which requires a voltage drop of: 8.1 - 7.6 = 0.5 VDC which can easily be accomplished with a single power diode in series with the battery pack. I don't like the power loss in the diode, but it should work. The diode should be built into a plug and jack power adapter installed between the NiMH pack and the light. That way, you can use the NiMH charger, without the diode getting in the way. That will also allow you to use a LiIon pack, but simply removing the diode adapter. Permit me to offer an alternative approach. Instead of reverting to NiMH cells, just find a cheaper LiIon battery pack. I suggest you look at the various radio control batteries. What you want are the biggest LiIon batteries possible in a 2S pack (possibly with the balance charger connector). 2S packs sorted by price: http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?cwhl=XX&idCategor y=86&v=&sortlist=P&LiPoConfig=2&CatSortOrder=desc I can't calculate how many milliamp-hrs will be needed without knowing which light you plan to use. After that, it's packaging (stuff it in a water bottle) and adapters for the power connector. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 Thanks Jeff. I guess I'll stick with Lion packs for whatever Cygolite i get. BTW, all my NiMh batteries for my RC boats are 7.2 volts according to the battery info on the battery. cheers |
#9
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Tue, 22 Sep 2015 11:21:42 -0700 (PDT), Sir Ridesalot
wrote: BTW, all my NiMh batteries for my RC boats are 7.2 volts according to the battery info on the battery. That would be 1.2 V per cell (for a 6 cell pack) instead of my 1.35 V per cell. Googling around, that seems to be todays nominal NiMH voltage. Looking at my discharge curve: http://802.11junk.com/jeffl/NiMH/Energizer-NiMH-2300.jpg it could be 1.35 V if I use the unloaded voltage immediately after charging, or down to 1.00 V if I use the voltage of an almost depleted battery. At 50% of full charge, it's about 1.17 V, which is close enough to call it 1.2 V. I guess I'll have to change my calculations to 1.2 V to accommodate todays cells. I think you made the right decision by NOT trying to change battery chemistry for a rather expensive light. I would worry more about warranty issues than performance or cost. If the manufacturer suspected that you've been juggling battery packs and using non-approved chemistries, they might void the warranty. However, since you haven't bought the light yet, it would be interesting if you asked the manufacturer what they think of substituting battery packs. They may already have tried it. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#10
|
|||
|
|||
Can replace Lthium with Nimh external battery pack?
On Tuesday, September 22, 2015 at 11:21:48 AM UTC-7, Sir Ridesalot wrote:
On Tuesday, September 22, 2015 at 12:56:34 PM UTC-4, Jeff Liebermann wrote: On Mon, 21 Sep 2015 23:24:25 -0700 (PDT), Sir Ridesalot wrote: I have the NiMh charger too. If I did get the Lion powered light it'd come with Lion battery charger. thus there's no concern about using the wrong charger on the battery pack. I guess this is for one of the Cygolite LiIon lights that you were considering purchasing. (Sorry, I missed the previous thread on the topic). Cygolite seems to standardize on a 7.6v DC LiIon battery pack for the lights. No NiMH packs available. http://www.shop.cygolite.com/category.sc?categoryId=24 7.6 VDC would be two 3.8 VDC LiIon cells. To produce that using NiMH cells would requi 7.6 / 1.35 = 5.6 cells which isn't going to work. The best I can do is 6 cells, for: 1.35 * 6 = 8.1 VDC which requires a voltage drop of: 8.1 - 7.6 = 0.5 VDC which can easily be accomplished with a single power diode in series with the battery pack. I don't like the power loss in the diode, but it should work. The diode should be built into a plug and jack power adapter installed between the NiMH pack and the light. That way, you can use the NiMH charger, without the diode getting in the way. That will also allow you to use a LiIon pack, but simply removing the diode adapter. Permit me to offer an alternative approach. Instead of reverting to NiMH cells, just find a cheaper LiIon battery pack. I suggest you look at the various radio control batteries. What you want are the biggest LiIon batteries possible in a 2S pack (possibly with the balance charger connector). 2S packs sorted by price: http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?cwhl=XX&idCategor y=86&v=&sortlist=P&LiPoConfig=2&CatSortOrder=desc I can't calculate how many milliamp-hrs will be needed without knowing which light you plan to use. After that, it's packaging (stuff it in a water bottle) and adapters for the power connector. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 Thanks Jeff. I guess I'll stick with Lion packs for whatever Cygolite i get. BTW, all my NiMh batteries for my RC boats are 7.2 volts according to the battery info on the battery. cheers LED's require about 1.5V per light. Since the Lion puts out over 3 volts the usual circuit is to use a low voltage controller driving a constant current source and powering the LED's two in a serial configuration. The constant current source probably has a .6 volt or nearly that drop so in order to power the blinky you'll need a power source of about 3.6 volts or a little higher. So you could drive it with three NiMH batteries in series and any number of those set ups in parallel to supply the expected lifespan before requiring a charge. You can recharge them via a normal NiMH recharger by taking the cells out of the battery box and inserting them individually into the charger. There are high speed smart chargers all over the Internet including Amazon and Ebay. Lights are not rocket science. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
mentor 8 uhh cybman? had to replace battery on a spdmtr odoetc | [email protected] | Techniques | 11 | May 9th 15 01:40 AM |
Found: Headlight Battery Pack - Paddington NSW | 20cents | Australia | 0 | July 31st 08 08:34 AM |
make a battery pack for a bike light | [email protected] | Australia | 3 | July 17th 07 09:47 AM |
nimh rechargable battery packs - drain and charge when new? | Jack Murphy | General | 10 | October 28th 06 02:34 PM |
dynamo battery chargers AA Nimh | Mark Taylor | UK | 0 | February 7th 05 11:42 AM |