Best rechargeable batteries in winter.

[erd]

Fair point--"flawed" is a bit strong; "inappropriate to low-temperature use" would be a more reasonable way to state it. Still, I must say that when I run the numbers on alkaline AAA cells at 68 degrees and even 40 degrees the fall-off in efficiency is impressive. Looking at the 10 degree numbers, one realizes that lithiums in winter are a truly worthwhile investment for GPS and headlamp.

Ted.

 

[teloshykr]

more battery stuuf

mah=milliamp hours,standard measure for a batterys' output is rated in amp hours- unless your talking smaller batteries then they scale down to milliamps and yes the bigger the number the better. I tried rechargables- cheapoes they leaked and/or like everything else thats easy to lose I lost them. I was looking at non-rechargable lithium batteries..I dont recall where I was but the price was $8.00 for a pair of AAs' !

 

[erd]

Target is approximately $9 for 4. My wife also grabbed a box of 8 for me, which was presumably less per battery. It occurs to me that if we on VFTT bought this kind of thing collectively we might be able to get a heck of a good price.

Ted.

mah=milliamp hours,standard measure for a batterys' output is rated in amp hours- unless your talking smaller batteries then they scale down to milliamps and yes the bigger the number the better. I tried rechargables- cheapoes they leaked and/or like everything else thats easy to lose I lost them. I was looking at non-rechargable lithium batteries..I dont recall where I was but the price was $8.00 for a pair of AAs' !

 

[spider solo]

Monster Cable Charger

I went looking for a Maha charger which I haven't found yet, but I did see a couple of chargers made by Monster Cable.
One was a rapid charger which I shied away from. The other was a bit more pricey but not a rapid charger. Both included their own batteries. (AA)
Any experience with these ?
I didn't buy either one as I thought others might know more on the subject and I see it is advised to stay away from any type of rapid chargers.
thanks

 

[Rick]

Last year I picked up a rapid charger (15 minute charger from Wal-Mart for $25. it included 4 1850 MAH batteries. I use this primarily for my GPS.
I then picked up 4 2250 MAH batteries and I can see a bit of difference between the 2 sets - I get about an hour more time with the 2250's.

I am very impressed at how quickly the charger charges and that I always can have 8 fully charged batteries within 1/2 hour.

Recently I saw this Solar Charger on sale for $20 and thought it might be greater for car camping or charging batteries at a base camp -
any body have any thoughts on this (I'd appreciate any information)
Thanks
Rick

 

[DougPaul]

LASt yerar I picked up a rapid charger (15 minute charger from Wal-Mart for $25. it included 4 1850 MAH batteries. I use this primarily for my GPS.

The 15 minute chargers require special batteries with internal temperature sensors. (Some professional quality chargers have external temp sensors.) Overheating during charging damages the battey. (A 1-hr charger became notorious for overheating and damaging batteries.)

I stick to slower smart chargers to preserve my batteries. My current favorite is the Maha MH-C401FS. Switchable slow (~4hr) and medium (~2hr) speeds. Charges each cell individually--useful for 3 cell devices and as the cells become mismatched with age. (Many chargers charge only in pairs--not good if the cells are mismatched.)

Available at http://thomas-distributing.com. I'm sure froogle can find other outlets. (Disclaimer: no ties with Maha or Thomas Distributing.)

Recently I saw this Solar Charger on sale for $20 and thought it might be greatr for car camping or charging batteries at a base camp -
any body have any thougths on this (I'd appreciate any information)
Thanks
Rick

Solar chargers are not likely to be useful if you are moving camp daily. Perhaps useful if you basecamp. (Do the math: calculate how long it will take to charge a set of batteries. Don't forget that you may only average 1/4 or less of the rated maximum current from the solar cells and the charging system will not be 100% efficient.) If you car camp, just charge the cells from the car. (Many chargers, including the one mentioned above, can run off 12DC.)

Doug

 

[Neil]

I have a Panasonic 5 hr. charger. I put 4 Energizer 2500 mAh's in it and when I figured they'd been there long enough I pulled them out. They were pretty hot. I could hold onto them but if I squeezed them tightly they were almost too hot to hang on to. I know it's normal that they heat up but almost to the point of burning you?

 

[DougPaul]

I have a Panasonic 5 hr. charger. I put 4 Energizer 2500 mAh's in it and when I figured they'd been there long enough I pulled them out. They were pretty hot. I could hold onto them but if I squeezed them tightly they were almost too hot to hang on to. I know it's normal that they heat up but almost to the point of burning you?

Too hot.

If the batteries get too hot during charging, it will shorten their lives.

I presume the batteries are NiMH.

I don't know this particular charger, but if it is a "timed" charger, it will destroy the batteries because there is no way of knowing the correct time. You should use a "smart" charger which will automatically detect when the cell is fully charged and stop charging.

My favorite charger is the Maha MH-C401FS. Smart charger, 4 separate charging circuits, 2 speeds: fast (1000 ma for AA, 300 ma for AAA) and slow (300 ma for AA, 200 ma for AAA). I use the slow unless I'm in a hurry. The batteries never get too hot to hold. Available from http://thomas-distributing.com (usual disclaimer: no connection).

The MH-C204F (charges 2 pairs) and the Ray-o-Vac PS-4 (4 separate circuits, on the NiCad setting only--the NiMH setting will overheat the cells) are also good.

Doug

 

[NH_Mtn_Hiker]

I have a Panasonic 5 hr. charger. I put 4 Energizer 2500 mAh's in it and when I figured they'd been there long enough I pulled them out. They were pretty hot. I could hold onto them but if I squeezed them tightly they were almost too hot to hang on to. I know it's normal that they heat up but almost to the point of burning you?

I use the same batteries with a Radio Shack computer controlled charger. They get warm, but never hot.

My sister has a 15 minute Energizer charger and the same batteries, she's told me her batteries get very hot. Sounds like the result of fast charging.

 

[DougPaul]

My sister has a 15 minute Energizer charger and the same batteries, she's told me her batteries get very hot. Sounds like the result of fast charging.

Make sure you use ONLY the matching batteries with this charger--it will destroy any others.

In general, if the batteries get hot enough that they are uncomfortable to hold, they are too hot (which will shorten their lives).

Doug

 

[Neil]

I don't know this particular charger, but if it is a "timed" charger, it will destroy the batteries because there is no way of knowing the correct time. You should use a "smart" charger which will automatically detect when the cell is fully charged and stop charging.

That explains it, they were almost fully charged when I put them in just to top them up. That also explains why I've noticed hot batteries before but not always. I feel much better now.

 

[DougPaul]

That explains it, they were almost fully charged when I put them in just to top them up. That also explains why I've noticed hot batteries before but not always. I feel much better now.

Yep--you keep doing that and you will damage the batteries. (Get a smart charger--you won't regret it.)

During charging, the energy is initially absorbed in the chemical reaction. Once the cell is fully charged, the energy is dissapated as heat.

Some chargers use a temperature sensor to detect the rise in temperature when the cell is full and stop charging.

The less expensive consumer chargers detect a drop in voltage caused by the increased temperature and stop charging.

Both enter a trickle (low current) charging phase to top off the cell.

Doug

 

[Neil]

Roughly how many recharges can I expect to get out of my Energizer 2500 mAh rechargeables (or any rechargeables for that matter)? I use the MAHA C401FS recharger and usually end up recharging my batteries when they are down to about ½ charge.

As they get older will they lose their charge more quickly?

 

[DougPaul]

Roughly how many recharges can I expect to get out of my Energizer 2500 mAh rechargeables (or any rechargeables for that matter)? I use the MAHA C401FS recharger and usually end up recharging my batteries when they are down to about ½ charge.

As they get older will they lose their charge more quickly?

The nominal numbers are up to 500 recharges for NiMH and up to 1000 for NiCad. Of course, this assumes that you have been nice to the batteries--no reverse charging, over charging, or over heating.

The C401FS charger is a good one--I use mine on the slow setting (300ma for AA) rather than the fast setting (1000ma) to keep the batteries a bit cooler during charging.

It is ok to recharge partially discharged NiMH cells (minimal memory effect). Some experts claim that an occasional full discharge is good for them--I don't bother to intentionally do a full discharge. (An occasional full discharge is required for NiCads to prevent loss of capacity due to the memory effect.)

Old age (or just being defective or damaged) may show up in several ways--loss of capacity, faster self-discharge, and/or inability to recharge (the battery is rejected by the charger). (A trickle charger can sometimes be useful in starting/charging the rejects.)

If the batteries are treated well, they may just gradually develop one or more of the above symptoms.

Doug

 

[Neil]

Which is better for rechargeable battery longevity: Letting them self discharge and then recharging them the day brfore a hike or maintaining them fullt charged indefinitely on trickle charge?

 

[Chip]

I don't know , but it made me happy to see a winter thread today !

 

[Jay H]

I've read that you should store a battery fully charged. If you fail to keep track of a battery and it drains out, you risk damaging the battery I believe. No expert but just passing on what I've read. I have a bunch of NiMH batteries in various sizes I've bought from www.batteryspace.com that are pretty good. I even use 5 D-cell NiMH batteries for a 6V bicycle battery I use in winter to run a dual beam 32W light system, bought from batterspace and wired to a custom battery pack I soldered up with D-cell holders from Radio Shack.

Jay

 

[DougPaul]

Which is better for rechargeable battery longevity: Letting them self discharge and then recharging them the day brfore a hike or maintaining them fullt charged indefinitely on trickle charge?

Depends on the kind of battery. NiCad and NiMH can be stored in pretty much any state of charge. (The charge will last longer if you store them in the refrigerator.) Lion rechargables will last longest if stored in the refrig at about 40% charge.

Ways to shorten the lifetime of NiCad and NiMH:
1. overheat (particularly when charging)
2. reverse charge
3. overcharge
4. If treated well, NiCad can last ~1000 cycles, NiMH ~500 cycles.

Ways to shorten the lifetime of Lion cells:
1. deep discharges (complete discharge can destroy them)
2. overcharge (also destroys them, can even explode them)
3. overheat them
Lion cells are delicate--they reqiure computer control of both charge and discharge to protect them. The better Lion batteries (eg laptop batteries) have connections between all the cells brought out so the cells can be monitored individually. They also include internal temperature sensors. Lion cells die by the calendar whether you use them or not (ie don't buy a spare with the intent of saving it until a current battery dies. Buy a fresh one .).

Lots more info on batteries at http://www.batteryuniversity.com/index.htm.

Doug

 

[imarchant]

Recently I saw this Solar Charger on sale for $20 and thought it might be greatr for car camping or charging batteries at a base camp -
any body have any thougths on this (I'd appreciate any information)
Thanks
Rick

My opinion is, for the weight just bring a few extra batteries. It depends on how long you will be outdoors. For me I am usually camping for only a few nights. I don't use that many batteries anyways. Only for LED headlamp and GPS. 2 extra sets should be fine. I alway carry a set of Lithiums.

 

[bill bowden]

Recharging batteries for winter hiking

Neil:

There is all sorts of nuance to this game to getting the best possible results but it's an excellent question as to whether yu will find a difference you can actually detect by your own observation and experience. factors such as outside temperature and time from th elast charge will play a big role in your experience as well.

A couple of more or less basic points; 1. there are several rechargeable battery chemistries out there and they give batteries different characteristics and 2. there are several types of charger out there and they function somewhat differently as well.

Lead acid-batteries aren't usually used for man portable applications in the US. They work poorly with deep cycling but well when kept on a "float" charge. The remainder of rechargeable batteries are best fully cycled from heavily discharged to fully charged, but it takes numerous cycles to build up the sort of "memory effect" one occasionally sees discussed.

Ni-Cd batteries or NICAD cells are quite robust but store relatively little energy. They will tolerate a constant charge and very high charge rates and are comparatively heavy and cheap. They are usually charged ina fiarly cheap charger. If you are environmentally conscious, cadmium is about the most toxic thing there is, leading to symptoms associated with cadmium toxicity at about 600 ppb (billion) in the body when the "normal" amount in your body is 200 ppb so conscientious recycling is very desirable.

Nickel metal-hydride batteries supply more energy and hold their charge better than NiCd cells. They usually need a more sophisticated charger that sense temeprature and voltage to function well. On the whole they are quite robust and a good solution for a winter hiker.

Li ion batteries are lighter and supply more energy. On charge they require electronic control to maintain a safe voltage and constant charging really reduces their lifetime. Both the cells and the charger are more expensive than NiMH solutions.

Feel free to PM me if you have more questions, but remember that basically all these thing swill work well and all the details are intended to get the very best possible results rathe rthan just to keep things functioning. (My background includes 30 years now in the battery industry research and development)