Recharging alkaline batteries

[dichotomy]

Is it possible to safely and effectively recharge standard alkaline (AA, AAA and 9v) batteries with a standard off the shelf NiMH battery recharger? And if so, how many times would it work.

I'm thinking of energizer batteries with an energizer recharger.

 

cheers.

[insane_alien]

not really no. the process of producing the energy sort of mushifies some of the internals. it doesn't tend to fare very well after that.

[dichotomy]

not really no. the process of producing the energy sort of mushifies some of the internals. it doesn't tend to fare very well after that.

 

I did try to recharge some flat ones with some success. But the down side is they eventually tend to leak. Which is something alkaline batts pride themselves on not doing...when not recharged of course. Back to using NiMH's now.

 

Cheers.

[insane_alien]

yeah, just stick to the rechargables. Li+ batts are good.

[YT2095]

you Can charge regular batts, infact abroad they sell chargers specifically for this, and there is also no warning on the batts that we export saying do not recharge.

 

you Do need a special charger that uses PCR though, but you can use these chargers on ANY batts, incl normal rechargables.

[dichotomy]

http://michaelbluejay.com/batteries/chargers.html

 

this chap wasn't too impressed with the 'Battery Xtender' (the all in one charger) either.

 

May only be worth recharging alkaline if you can get your hands on a supply of free used ones. But even then like this guy says - "AND you have to constantly keep them topped off, rather than just letting them run down like you would with NiMH's." Sounds like a little too much stuffing about to me. But, at least it doesn't make them LEAK!

[YT2095]

try here: http://en.wikipedia.org/wiki/Periodic_current_reversal

and use a 10% reverse bias, you will get a good 20+ charges out of normal batts, they start to drop off after that.

 

it`s also the Easiest circuit to make too! you`ll need a suitable transformer, a battery holder and a diode with a resistor (value calculated to load).

 

I`ve made several and never once had the problems he mentioned???

 

perhaps those overpriced gadgets he tested used something different?

[jon2121]

This video by MattBlytheTheOne answers most of the questions about this subject.

http://www.youtube.com/watch?v=UDwMxISYojM

[YT2095]

works for me!

[Norman Albers]

Is there a low amperage rate to maintain a moderate charging?

[jon2121]

Try this site:

http://www.afrotechmods.com/reallycheap/batteries/batts.htm

[Norman Albers]

Clear and funny reference site! Yes, this guy ran 65 milliamps and warned against lengthy overcharging, measurable by voltage or acid rupture (after two days' time when a few hours are needed for the capacity).

[Norman Albers]

YESSSSS! THIS WORKS! Very cool, folks. I have an auto (12V) cigarette lighter charger rig I once made with a ballast of 100 ohms, charging two AA cells. This feeds 50 ma. On 15 hours, maybe a half-charge. On 23 hours, notably more. I just took a dozen pictures and the indicator meter still reads 'full voltage'. Is the capacity of the cell more than 1 amp-hour (1,000mah)?

 

SCOTTY, RAISE THE CURRENT TO 65 MILLLIAMPS! 'Sounds good, captain.' I soldered in a 330-ohm resistor in parallel with the 100-ohm, so this is what I have now, a net resistance of about 75 ohms. The voltage I read across this resistance is 5+ V.

[Norman Albers]

Now after five good recharges with a straight-on 65 maDC, my AA cells do not work the camera. Hey YT is pulse reversal necessarily at typically 60 H, or could I somehow do a longer cycle like a handful of reversals during the 24 hours of charging?

[YT2095]

IIRC the ratio has to be 1:10 and constantly throughout the charge, so you would have 60ma Forwards bias say for half a second, and then 6ma Reverse bias for the Other half of the second.

 

a Nice way to do this is to use a correctly rated transformer and a single Diode in line to give you Half-wave rectification, but Across this Diode you would put a Resistor calculated to deliver 1/10`th of the forwards voltage, so while the Diode was Reverse biased (switched off) the resistor would leak current across it anyway at 1/10`th

 

so lets say you have a 6VAC transformer, put a diode and a 1Ohm resister in series with one of the output wires.

but then put a 10 Ohm resistor Across (in parallel) with the diode, then connect you`r 4x 1.5v batts.

 

this is a nice way to exploit the 60Hz mains frequency you have in the USA, no need for full wave rectification and oscillators and other stuff, 1 Transformer, 2 resistors and a diode

[Norman Albers]

Ah, nice and simple, thanks. The discharge was a smaller percent of time in one of the articles, I'll look back, but your plan is handy to be sure. I am inspired to hacksaw an old wall-wart.

[YT2095]

I think you Can do it on Time also, but making that would be much more elaborate.

I have done one in the past that used a DPDT relay that clicked on/off once a second, and used the contacts to make the Pseudo AC (square wave) and the 2 resistors and a diode to charge a Watch battery once, while I was Camping (had an old Science-Fair electronics kit in the back of the car for some reason) and it worked quite well

 

had to put it behind a large rock about 50m down the beach though as the constant click...click...click really got on my nerve after a while.

[Norman Albers]

Cute. I've got some old 555 timer circuits and maybe SCR's. By cutting out fully a half cycle we double the total charge time, but I really don't care. If I do I'll try a timer circuit later.

[YT2095]

well... the beauty of the trip5 is that you can alter the mark-space ratio, and so get the best of both worlds, try one with 1:10 in time and the same current, and one at a 1:1 time ratio and adjust the Current to 1:10.

see which one performs best.

 

although I would say unless your Ears are very good (I`m a Synth User so mine are good) you May need to use an oscilloscope to get the correct mark-space.

 

oh yeah, Edited to Add; Don`t go TOO high in frequency as the internal capacitance of the cells will themselves act as rectifiers and just give you a mean AVG, try to keep it less than 60Hz.

also don`t expect to get more than about 18-20 charge cycles out of an alkaline batt, it won`t happen, and about 5 cycles for Zn/C types

[Norman Albers]

Yah, the watchword here is simple. I just recircuited my wallwart and will let the glue dry. With the 75 ohms in the charging line, and 1.6kilohms shunting the diode, should be close. I looked up spec on a 555 timer chip and it sources/sinks 200 ma, plenty with no output stages needed, nice. . . . . . .OK there is a cool trick question here. I measure the charging current by reading the voltage on the 100 ohm ballast resistor (now, not 75). However, this current is flowing only half the time, and the meter reads average DCV, right? So to drive the 65 ma I want, half the time, what should be the average DC volts across the ballast??? I was about to drive twice what I wanted. It will be interesting to see if I can recondition this pair of AA cells. Tune in tomorrow, folks!!