Guide: Rechargeable AA batteries / 14500 batteries / Chargers

43 posts / 0 new
Last post

Pages

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light
Guide: Rechargeable AA batteries / 14500 batteries / Chargers

Hello all,

 

Well, you guys might have managed to convince me to start using rechargeable batteries.. Maybe!  I hope your answers to my questions will be helpful to other beginners as well...

 

Alkaline vs. Rechargeable 1.2V vs. 14500 in a Flashlight

  • Do 1.2V rechargeables produce longer runtime in a flashlight than 14500's?
  • Do 14500's produce longer runtime in a flashlight than an alkaline AA?
  • How is the output of a flashlight running a 1.2V AA rechargeable compared to an alkaline AA?
  • How is the runtime of a flashlight running a 1.2V AA rechargeable compared to an alkaline AA?

Rechargeable Types

  • How much difference is there between the extremely cheap $0.75/ea rechargeables and the name brands that DX sells?
  • How many charge cycles can I reasonably expect a cheap rechargeable and a high-quality rechargeable to withstand?
  • What do you recommend for a low-end, mid-range, and high-end rechargeable 1.2V from DX?
  • What do you recommend for a low-end, mid-range, and high-end rechargeable 14500 from DX?

Chargers

  • What do you recommend for a low-end and high-end charger from DX?

 

Thanks a lot!

Budget Light Forum ...where Frugal meets with Flashlight!

Edited by: sb56637 on 02/16/2010 - 23:09
Don
Don's picture
Offline
Last seen: 2 years 4 months ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

NiMH batteries under the sort of load that things like the Uniquefire AA-S1 put on a cell (2195mA measured) will perform way, way better than alkalines which won't give you the output. Or the runtime. It is pulling 2.6W from the cell and will do so for 69 minutes to 50% of original brightness with a 2000mAh Eneloop freshly charged.

 

It gave me 2830 lux at 1m for throw and 693lux in my lightbox. On a 14500 it gave me 6100 throw and 1535 total output - so it is more than twice as bright on a 14500.

These figures are not precise enough to be absolutes, but in comparison they are perfectly adequate.

 

I'll do this in tabular form where it will make more sense. Remind me... I'll need to do a runtime on an alkaline - I think I have 14500 runtimes somewhere.

 

Cheap rechargeables are usually not too bad as long as you don't go for high claimed capacities which are always overestimates (This is China we are talking about after all). Avoid anything with a claimed capacity of over 2100mAh altogether - it will be flat within a week of charging. The lower capacity cells (1700-1800mAh aren't usually so nasty and don't self discharge as quickly) But all the non LSD (low self-discharge) types will need to be charged within a month of charging even when not used.

 

Many of the 2500mAh+ claimed capacity ones are too physically large to fit in a lot of things and are very, very delicate. Some reputable "2700mAh" ones I bought a couple of years back never gave better than 2400mAh and wouldn't hold that charge for more than a couple of days.

 

Actually I'd only recommend the Sanyo Eneloops for NiMH cells. And I've been through a great number of rechargeable AAs over the years. Since I bought myself a stock of Eneloops I've not used the other ones much at all. Sanyo claim 1500 cycles for their latest (Japan only) version and 1000 cycles for the ones we can buy.

For a cheaper alternative, the GP LSD cells are well regarded. http://www.dealextreme.com/details.dx/sku.8746 They do them with a charger for $23. I bought some Vapex LSD cells. There's nothing really wrong with them, but for my purposes the Eneloops work better. The Eneloops cost almost 2x as much but were well worth it. In my very picky digital camera the only rechargeable AAs that work well are the Eneloops.

 

After 150 cycles in a digital camera, cheap NiMH cells are toast. Older digicams are very, very hard on their batteries. I never could persuade the person I share an office with to buy decent NiMH cells - she probably owned more of them than I do. By 250 cycles even if gently treated most cheap cells are going to be toast.

 

Chargers:

Completely avoid 15 and 30 minute chargers. They kill cells. Quickly. If you must use such things get 15-1800mAh cells of very good quality and expect to junk them annually. Even 1 hour chargers are pushing it. Slower chargers tend to be gentler though many people charge NiMH cells at high currents and then use them hot off the charger for maximum capacity. The RC model crowd expect to get very few cycles out of their cells but then they are very, very hard on them.

 

I own two Angeleyes chargers that I got from KD. Unless you want the battery analysis features these are OTT $35. Anyway, I can't find them on either KD or DX any more - both used to stock them.

For a straightforward charger that won't cook your cells at a reasonable price I'd go for this one. http://www.dealextreme.com/details.dx/sku.6152 $13.98

There are plenty cheaper ones but they tend to cook batteries. Heat is not good for any sort of cell/battery. I'd check the reports on any of them to see about their heating up batteries. Yes, they should be warm, but not too hot to touch - if they are, they have been damaged by the charger.

 

The Vanson BC1-HU is a decent charger, reasonably priced. It has been rebadged by many, many companies and is of distinctive appearance so is easily enough spotted.

 

The larger Maha chargers are excellent, but not cheap. Avoid LaCrosse chargers, they melt.

 

The upcoming NiZn cells and their chargers seem well worth watching but there aren't enough of them out in the field yet to see how they will bear up under hard use.

 

Apart from their environmental nastiness and generally low capacity, NiCd cells have a lot going for them. They will withstand incredible abuse and keep going. I own some NiCd D cells that were bought in 1984 and still provide above their nominal capacity though they won't give 20-40 amps on a dead short the way they once would. Their self-discharge is much lower than NiMH and they can be used to do things like start cars (I once did this with the 10 Ds mentioned above) - which NiMH cells might do once, they will be good for nothing afterwards. However nobody makes good ones any more. Cadmium is nasty stuff.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

Excellent info, thanks Don!  So I can expect longer runtime and brighter output with 1.2V NiMHs?

 

It appears that the charger with batteries that you mentioned is a 220V version from the comments.  Here we have 110V power.

Budget Light Forum ...where Frugal meets with Flashlight!

brted
brted's picture
Offline
Last seen: 1 week 5 days ago
Joined: 01/12/2010 - 19:44
Posts: 2371
Location: Atlanta

I wouldn't buy NiMH batteries from DX. People have reported getting Eneloops from them that turn out to be fake. And crazy offbrand NiMH's aren't worth the trouble unless you know people have been getting good results from them. If possible get a charger that charges cells individually instead of in pairs. Usually you only know that because it will say "charges 1-4 batteries" instead of "2 or 4 batteries" or it has two indicator lights for 4 bays. The Soshine charger Don linked to should be decent, but I got a Maha C9000.

Lithium-ion batteries won't typically last as long because they are driving the light harder and draining power faster than NiMH or alkalines. NiMHs outperform alkalines unless the device just needs that extra voltage (some cameras).

For lithium-ion batteries at DX, people seem to like Trustfires more than Ultrafires. But I have a set of 18650 Ultrafires that are better than the very similar Trustfires (both gray, protected, 2400mAh). Be aware that some of these batteries are way off in size, for example there are some 3000mAh 18650's which are 20mm in diameter (or something like that) and while they should all be 65mm long, most are 67mm and some are 69mm. Also not all protection is equal. Some protect for overcharge and undercharge, but not for a short (too much draw). Don't rely on the protection to tell you when to recharge the battery. Recharge them at 3.5 to 3.6V.

Don't get li-ion batteries unless you also have a multimeter to monitor voltage. I got a cheap one someone recommended by someone at CPF at Amazon to measure currents and it seems to work pretty well though it measures a few hundreths of a volt less than the meter I bought from Home Depot a few years ago. I just use it for currents, but it does all kinds of things.

http://www.amazon.com/Sinometer-DT830B-20-Range-Battery-Tester/dp/B001T3Y8XW/

Don
Don's picture
Offline
Last seen: 2 years 4 months ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

Didn't think to check the voltage as almost everything DX sells is 110-240V. China uses 220V I believe, and I thought that most of South America did too. After a spot of digging, it would appear that most of South America does use 220V, apart from the bits that don't. 

 

Looking through both DX and KD they don't have nearly the number of NiMH chargers they once did.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Don
Don's picture
Offline
Last seen: 2 years 4 months ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

At low current drains, the story is different though. An alkaline has a higher nominal voltage and will hold it happily at a few tens of milliamps. At 10mW power (say 8mA) out of the cell you'll get over 3000mAh

At 1A you'll be lucky to get 900mAh. The higher the current the better the rechargeable will do. To take the Uniquefire AA-S1 again as an example it is pulling 2.2A from the cell. A Duracell will be lucky to give you twenty minutes of that sort of abuse though since LEDs will consume every last scrap of power and still produce light this may not be so evident. I'd guess that after 30 minutes it'd be dimmer than an NiMH by a long way. I have some decent NiMH and alkaline cells and plenty of junk ones of both flavours so will do some runtimes etc to see what happens.

 

NiMH cells are intrinsically capable of higher currents anyway as their internal resistance is lower. Short good NiMH cells and something is going to melt. This is not a good thing to keep up as it'll kill the cell if you let it.

 

Basically, alkalines decline gently and may have a rather long "tail" if the device will still light up. NiMH cells have a much flatter profile, but then they drop off a cliff. You will know when NiMH cells need recharging...

 

Here's where I dug up this information from. http://www1.duracell.com/oem/Pdf/new/MX1500_US_UL.pdf

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

I would also like to chime in but the points have been made.  This is what i get for working...lol.  I have a lot of Titanium LSD's that are good for the money,  but the only downfall is that they need to be cycled and broken in.  Its nice to have a couple of sets of rechargeables so that way you know that you have a fresh batt depending on usage and you can keep your primaries for that just in case moment.

With Darkness, there will always be Light.

 

 

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

And another thing that you might consider is that lith rechargeables lose there capacity as where HQ nimh cells gain.  As Don said stay away from the higher capacity cells.....my powerex 2700's only got about 2400mah and its been going downhill from there. 

With Darkness, there will always be Light.

 

 

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

Great info all of you, thanks to Don, brted, and Al.  I'll do some deeper research into brands and model numbers during the next few days and I'll let you know what I come up with.

This post is going sticky.  Just PM me if you find any other very useful posts that you want to see on the top of the list.

Budget Light Forum ...where Frugal meets with Flashlight!

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

alfreddajero wrote:

And another thing that you might consider is that lith rechargeables lose there capacity as where HQ nimh cells gain.  As Don said stay away from the higher capacity cells.....my powerex 2700's only got about 2400mah and its been going downhill from there. 

 

NiMH's gain capacity you say Al?  Could you explain a bit for me please?  And what about decharging in storage, NiMH vs. Alkaline?  Thanks!

Budget Light Forum ...where Frugal meets with Flashlight!

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

This will only occur in good quality cells, in a small test that i did on duraloops and titaniums because of the price per cell.  You will see an increase in mah, the more you use the cell the more mah capacity it has.......this is also true for going downhill as will.  You want to treat your batts like babies because you want them to last long.  When i first got the Titaniums when they were first introduced i was getting about 1600 mah on a R/A cycle- Refresh and Analyze-.  Because of the price per cell the cells were never ran through a break in at the factory hence the cheapness of price.  I ran them through 5cycles of charge and discharge and then a disharge with a day of rest to equalize the cells and then ran them through a break in.......the capacity of the cells improved to about 1800-1900 mah.  There was a lot of cpf members that did'nt like the cells at all because of the the work one had to do to bring the mah up but for me im not one to pout so i was able to put in the work.  To this day they still R/A about the same mah, and i do one every three months.  And for choosing nimh vs. alkies i would go with nimh for the simple fact that the voltage doesnt sag when using a high powered light as with alkies.  And it puts a smile on my face that your really thinking about going nimh.  Remember the more capacity a cell has the more fragile the insides are and you will tend to lose capacity in the long run.  And as for chargers go with a smart charger if you can, they will be good for the cells in the long run.  And as for the batts in storage you should always keep some energy in them, lsds can be fully charged and put away.  This is the part where skimping is not an option, better to buy good cells and have them last for years, or by cheap ones and have them for only a couple of months.  I would like to go on and on but im here as usual if you have any questions.

With Darkness, there will always be Light.

 

 

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

Ah, OK, I got you Al.  Good, great information.  I am looking at the LSD (new readers note: Low Self Discharge) cells per the recommendations here.  I often store batteries, so I want them to hold their charge.  It looks like I can get possibly genuine Eneloops 4x for $12 - $14.  But since this is BudgetLightForum and I am a self-proclaimed tightwad, so I wonder are there any other LSD models/brands that are "pretty good?"  If an Eneloop is "elite" like a Nitecore flashlight, what LSD NiMH battery would be like a "pretty good" Tank007?    How are Duraloops compared to Eneloops?

 

I still have no idea what sort of a charger to get.  I don't need a super-duper charger, but I do want it to have an automatic shutoff circuit and "Charged" indicator.  As Don cautioned, I don't want it to be an ultra-fast charger, I can wait for half a day or all night long for it to charge.  And it needs to run on 110V.  And it would be nice if it didn't catch fire very much.

 

I'm looking on eBay too for this stuff, they have great selection and almost DX-cheap prices for batteries and chargers, but the problem is that there are no product reviews.

 

Thanks to all for the help!

 

Budget Light Forum ...where Frugal meets with Flashlight!

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

Well you have the white top Duraloops which are made in japan and the supposedly black tops which i see a lot now that are made in China. The white tops are considered to be rebranded Eneloops..........and lets say that the ones made in China are okay but dont compare to the white tops.  I was taking a look at these because of the price for my rc radio, they seem to have great reviews.  http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=10456&Product_Name=Turnigy_AA_LSD_2200mah_Low_Self_Discharge_(ready_to_use)  I havent put my order in yet since my job is cutting hours right now.

 

I know that you want to save some money as well.....i also have a ton of these rayovacs, there about 1400 mah but with little discharge in the long run........when topped off and stored for about 2 weeks the chager puts about 80-100 mah before the charger says its done....not bad i say, especially when you can get an 8 pack for close or under 10bones, i think i paid about 8bones.  Another good lsd i keep hearing about are there hybrids.......

http://rayovac.com/recharge/easy_batteries.shtml

http://rayovac.com/recharge/hybrid_batteries.shtml

With Darkness, there will always be Light.

 

 

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

Budget Light Forum ...where Frugal meets with Flashlight!

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

alfreddajero wrote:

 I was taking a look at these because of the price for my rc radio, they seem to have great reviews.  http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=10456&Product_Name=Turnigy_AA_LSD_2200mah_Low_Self_Discharge_(ready_to_use)  I havent put my order in yet since my job is cutting hours right now.

 

Good price.  Do you know anything about shipping costs from these guys?

Hope all goes well with your job Al.

Budget Light Forum ...where Frugal meets with Flashlight!

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

I take it from looking at there site that its by weight.........i hope so too.

With Darkness, there will always be Light.

 

 

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

OK, I'm looking at the following items:

 

Eneloops

Chargers:

 

This should run me a total of $18.00 - $20.00 for a cheap charger + 4 Eneloops.  

 

I'm looking at the cheaper chargers because most of them seem to have very low power charging, so I won't ruin the batteries.  Most are supposed to charge at ~200mA.  Does that sound ok?  The one that Don recommended says AA Charge Current: 1050mA when charging 2 AA rechargeable Batteries - 525mA with 4 AA Batteries, so the cheaper ones I listed above are actually much lower.  I would really prefer that it have a "Charged"  indicator and automatic shut-off in case I leave it charging.  However, Soshine claims the following:

Quote:
The red light on my new battery charger NEVER went off or changed color, even after 30 hours recharging. Is this correct?
Some Soshine chargers do not have auto-cut off protection. For example, the SC-Z23b charger is a standard economical charger with 6 individual channels. As the charging current is not big (160mA for AA and 80mA for AAA), there is no auto cut-off system designed in it. The LED light will stay on when charging and will not turn to green. For 1-4pcs of AA1600 battery, it will take about 12 hours to be fully charged. However, since it is a slow charger with a low charging current, there will be no issues from over-charging, and your battery will not be damaged.
Does that sound correct?  Or is 200mA so little current that it doesn't matter if I leave the batteries in there for 24 hours without a shut-off?  And any idea if these chargers can charge single batteries or do they need to be in pairs?
At any rate, please let me know!  Thanks a lot!

Budget Light Forum ...where Frugal meets with Flashlight!

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

The BTY and Power looks like your best bet.....to me the chargers would be able to charge in singles as well since each slot has there own indicator light.  200ma is not much at all.....going to take a long time for the batts to charge up.  Im basing my decision on the charger specs, the ones that have them.

With Darkness, there will always be Light.

 

 

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

OK, I finally pulled the trigger and bought some AA Eneloops + cheap charger.  The charger comes with 6 cheap rechargeable NiMHs too as a bonus, which I'll use for my wireless mouse.  It appears to have 4 individual charging channels, auto-shutoff, and it has VERY low power (80-200mA) output so it doesn't fry my batteries.  As for the Eneloops themselves, I hope they're genuine.  The seller swears that they are genuine, and the pictures show an anti-piracy hologram.  Note to potential buyers: don't buy Eneloops from DealExtreme.com, they are confirmed as fakes.  That's why I bought on eBay this time.  Total price for 4 Eneloops, a charger, and 6 cheap AA NiMHs, $22.15.  At least I'll save the environment a bit and reduce battery costs in the long run.  Here's what I bought:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390173375222#ht_2221wt_941

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390183203971#ht_2259wt_941

 

Budget Light Forum ...where Frugal meets with Flashlight!

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

Nice to see you go rechargeable....you will be saving in alkalines and spending the extra cash on new lights.  You will love the performance of the eneloops.

With Darkness, there will always be Light.

 

 

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

Yeah, I'm pretty excited too.  Thanks for the help in choosing.  You know, all my AA lights are so efficient I hardly ever have to change the batteries.  It's my wireless mouse that eats batteries like they were going out of style.

Budget Light Forum ...where Frugal meets with Flashlight!

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

I didnt help out at all,  you already had your heart set on getting some.

With Darkness, there will always be Light.

 

 

Don
Don's picture
Offline
Last seen: 2 years 4 months ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

Also quite a few lights will be brighter on rechargeables as they have a much lower internal resistance and so will happily deliver more current. The only disadvantage can be for very voltage sensitive devices - my grandmother's hearing aid needed to use alkalines as it didn't give her enough volume on rechargeables.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

alfreddajero
alfreddajero's picture
Offline
Last seen: 1 year 9 months ago
Joined: 01/14/2010 - 00:28
Posts: 1795
Location: Virginia Beach VA

But for power hungry lights rechargeables are def the way to go.  You will be happy.

With Darkness, there will always be Light.

 

 

fishinfool
fishinfool's picture
Offline
Last seen: 1 month 2 weeks ago
Joined: 03/09/2010 - 00:30
Posts: 4342
Location: Hilo, Hawaii

I LOVE ENELOOPS!   Kiss

Don wrote:

"But as I said long ago, you are more likely to be killed by a dead fish dropped by a seagull in the Sahara Desert than by a lithium ion

Don
Don's picture
Offline
Last seen: 2 years 4 months ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

I've been using rechargeables since the mid 80's but there were always hassles. For he first time I'm now able to just take a battery out, stick it in a device and expect it to work - and go on working for a reasonable time. It means I don't have to drag around a charger (Though I usually do) because the batteries will have enough charge in them that they'll do what I want them to. I need fewer chargers and a lot less messing around.

 

Yup, Eneloops are great.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

Hello all, another question:  Can NiMH cells be run to 0 without damaging them?  Is the "cell protection" feature of some lights only for Li-Ion cells?  Thanks a lot!

Budget Light Forum ...where Frugal meets with Flashlight!

Don
Don's picture
Offline
Last seen: 2 years 4 months ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

From memory, NiMH cells really don't like being run to 0 volts. Of course, it happens sometimes, but it is best not to run them much below 1V - there's nothing useful left by then anyway.

 

Some useful info here, though it dates from before LSD cells. 

 

http://www.batteryuniversity.com/

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Don
Don's picture
Offline
Last seen: 2 years 4 months ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

sb56637 wrote:

Is the "cell protection" feature of some lights only for Li-Ion cells?  Thanks a lot!

 

There might be a light out there with cell protection for NiMH, but I don't know of it. This is mainly because Bad Things can happen when you try to recharge over-discharged lithium cells - it is possible to make NiMH cells go bang, but you do have to work at it. The RC modelling crowd are downright vicious to their batteries and have documented every possible nasty thing that it is possible to make all sorts of cells do - but then they will do things like try to ram 50A into small cells to charge them faster. On the whole, nickel based cells are far safer.

 

With NiMH the discharge curve is pretty flat till it falls off a cliff so the usual advice is to recharge them when they start to dim. Once the light starts to dim its output will drop like a stone anyway so it will be obvious in all but the lowest power consumption lights that they are close to the end of their charge anyway.

 

This is a typical NiMH output/voltage chart.

discharge

As you can see, it is very obvious when the cell is running out of power.

 

And here's a typical alkaline discharge graph at a reasonable current.

disch

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

sb56637
sb56637's picture
Offline
Last seen: 1 hour 31 min ago
Joined: 01/08/2010 - 09:29
Posts: 6508
Location: The Light

Ah I see.  Interesting.  That is a nice flat runtime.  And if I run it to the ground, could it possibly not take another charge?  Or blow up?  Keep in mind I will be using a 80 - 200 mah charger.

Budget Light Forum ...where Frugal meets with Flashlight!

Don
Don's picture
Offline
Last seen: 2 years 4 months ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

sb56637 wrote:

Ah I see.  Interesting.  That is a nice flat runtime.  And if I run it to the ground, could it possibly not take another charge?  Or blow up?  Keep in mind I will be using a 80 - 200 mah charger.

 

I have never managed to make an NiMH cell go pop. I did manage to make an NiCd cell leak but that took charging it for a year. (I forgot about the charger in the loft) - I was flooring the loft and had modded an electric screwdriver to take AAs as I had a lot of screws to put in and the screwdriver kept going flat. Got the job finished, moved a pile of junk up there and wasn't up there again for a year.

 

Even if discharged to 0 volts, they'll take another charge but the capacity of the cell drops when you are cruel to them like that.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Pages