Recharging non-rechargeable batteries

[andyf]

They say these things come in threes.

I'm going out for a pint. At least I should manage that without getting the glass the wrong way up Here's hoping for a better tomorrow....

Andy

[Fergus OMore]

I, too, have been out. I feel that I need fresh air or something because one of the local cheap jack shops is selling cards of 20 AA batteries- for the princely sum of £1 with a penny change

I've got a set of AAA's for the same price and a heap of assorted titchy things that I stick in my ears or drive my best all glittering solid gold watch- for a couple of years.The cards- in this case- cost a penny more. Naturally,I'm looking for a discount as I am an old age pensioner.

In a further whimsical way, the French call 'batteries' Pile Wonders.

Anyone know if they work

[dsquire]

I, too, have been out. I feel that I need fresh air or something because one of the local cheap jack shops is selling cards of 20 AA batteries- for the princely sum of £1 with a penny change

I've got a set of AAA's for the same price and a heap of assorted titchy things that I stick in my ears or drive my best all glittering solid gold watch- for a couple of years.The cards- in this case- cost a penny more. Naturally,I'm looking for a discount as I am an old age pensioner.

In a further whimsical way, the French call 'batteries' Pile Wonders.

Anyone know if they work

 

Cheers 

Don

[Andromedac]

Hello Everyone,

This thread sparked more than a memory, it reminded me of a long forgotten project started when I was 16 ...

In answer to previously answered Q's, yes there is a timing specific for each size battery: AAA, AA, C, D

I remember that I found an expensive, but accurate timer cct, based around a ZN1034E 14-pin dil.

I have just purchased the original EE Mag dated Sept '91 from ebay, and will post again.

~~#{Kudos for original publisher, he will be named}#~~

With regs to the ZN1034E timer cct. I will post later.

Cheers

D

PM me if u want; I will post any personal fixes tho...

[John Swift]

Hi Andromedac

Welcome to Mad Modders

I remember the Ferranti ZN1034E being in a number of photographic timer projects in
 various magazines

today I guess it will be cheaper to use the CD4060 oscillator/ divider plus some additional logic or a PIC chip if you can program it

Ferranti used to make a number of usefull devices

the only ones I can remember using are the ZN1066 in switch mode power supplies , ZN1040 4 digit counter / display driver , ZN429 D/A converter and the ULA's (Uncommited Logic Arrays) in Sincair ZX81 and Spectrum computers

John

 

[Noitoen]

I remember the ZN414, a 3 legged am radio ic

[NickG]

Brilliant, I too have seen them advertised but didn't know how they worked or whether they did. Just chucked loads of duracells and bought 4 more rechargables 

[Andromedac]

Thanks for the welcome!

I was very wrong about the timings posted in the magazine article, they referred to the lower and upper
capacities of zinc carbon and alkaline, and gave a rough guided time for each – I was sixteen!:-(

I have since done a fair amount googleing and have found a formula for a guide:
Charging time = mAh / mA

Monitoring the battery voltage in the last 4 hours or so down to make sure I don’t over charge them past
100%, then adjusting the timing cct accordingly.

The magazine was not totally fruitless. The diagram shown is slightly different than the reconstructed
one done on page one, I have attached a screen print from expresssch/easypcb.
I think the idea is have at least two batteries charging at any one time, and have them in either the 1
& 2, or the 3 & 4 positions, to ‘balance’ out the cct.

I have dug out all the various incarnations of the project and was pleased to find two printed cct
boards made for the timer and timing selection, albeit that there were omitted tracks for power – bloody
sixteen year olds! I also found I’d bought a 12VA with two secondary outputs, coupled with enough
ZN1034E’s and RS 348-582 reed relays I’m cooking with gas.

In true Darren style I have not tested the ‘AA’ resistor array that I found already constructed, I have
calculated Ra/b values for a PP3 9V battery after finding an old 30VA 13V(16.5VAC) transformer and am
currently testing my timer cct with it! I’ll let you all know if there is any success.

I was a little puzzled with the original writer’s W values for the resistors?!? Take the ‘AA’ Rb value
of 47R posted at 1W. If you use the original formula I=(Vsupply-Vdiode-Vbatt)/Rb:

I=(4.5-0.7-1.5)/47=49mA
P=I2*R=0.0024*47=113mW – not even a 1/8W and P=IV=0.049*2.3(Vs-Vd-Vb)=113mW

Anyone who can corroborate my sanity eitherway, please post…!

[PekkaNF]

....
I was a little puzzled with the original writer’s W values for the resistors?!? Take the ‘AA’ Rb value
of 47R posted at 1W. If you use the original formula I=(Vsupply-Vdiode-Vbatt)/Rb:

I=(4.5-0.7-1.5)/47=49mA
P=I2*R=0.0024*47=113mW – not even a 1/8W and P=IV=0.049*2.3(Vs-Vd-Vb)=113mW

Anyone who can corroborate my sanity eitherway, please post…!

I reached for dictionary and then skratchen my head - got splinters under my nails. That circuit looks a little dodggy (not really a current regulator or anything of that nature) - I believe succes depends on fitting the battery and transformer characteristics close enoug. Something similar to tricle charge e.g. when battery voltage rises "full", very little charge current is left over battery, making charging SLOW but dispenses with delta cutout and timers and such.

RE: resistance and wattage ratings of the shunt resistor you are calculating. You are assuming in your calculation nice constant book value of battery internal resitance. Real life batteries always don't behave well. The ones building and using circuits don't behave taht well either.

What about if the battery has short circuit or fully charged battery is inserted wrong way? Or someone changes resistanced for big fat D-battery and then accidentaly rams in NiCd? Your variables here are transformer and resistors.

And resistors are not that ideal either, sometimes fairly much bigger wattage resistor is choosen to prevent it heatting (bad for circuit, fire, or resistance changes too much) and sometimes bigger is choosen because wirewound might suplly a inductance needed (very unlikely in this app). Then again if the writer/designer does not tell, it just might be what he had in the box and what worked for him!

PekkaNF

[vtsteam]

I used to recharge alkaline cells a couple years ago, and found that I could typically recharge AA cells 4 to 6 times. However their tendency to leak was increased to the point that it was a bad idea to leave them in anything unless you were using it within a month. I was only using them to fly small $29 store bought R/C planes, so a leak wasn't a major tragedy. And it was certainly more ecopnomical to recharge hem.

I wouldn't want to put them in important equipment, unless there was a pressing momentary need for a battery. And I'd take them out afterwards.

My guess is that the charge cycle does take a toll on the case or seals, and the batteries probably don't hold a charge as long in storage -- thus the greater tendency to leak.

Just my experience -- others may differ.

[the_chip_man]

I too read the article 20 years ago, after checking the the circuit worked, I realised that I needed to check the battery voltage periodically with a multimeter otherwise the battery would become overcharged I decided to take it to the next level.

So I built a pic controller to automatically sample each battery in turn using a simple op-amp as a comparator.
I was charging up to 10 batteries, 4off AAA, 4off AA and 2off PP3 so I used 2 op-amps one set to 1.5v the other set to 9v, both were adjustable.

Relay contacts switched each battery in turn from the charging circuit to the comparator circuit, then if the battery as reached the charge level then it would bring on a “green LED” indicating it was charged, It it was below the charge level then it would be switched back to the charging circuit.
I had 3 LED's for each battery

Red - Charging
Amber – Testing
Green – Done

At switch on all the 10 batteries are connected to the charge circuit then every 10 mins each battery is tested one after the other against a 1.5v or 9v op-amp (each is adjustable with a pot)
I've added a small bleeper so I get a bleep when anyone of the batteries is charged.
I also added a pic controlled 4 digit voltmeter so I can see the voltage of each battery as its being tested
This way I can leave all 10 batteries in the battery holders for a full day knowing that once they've reached the right level there safely switch off charge.
Yes I also agree batteries can only be recharged up to 10/20 times then thrown away, I've also found a good supply of still usable batteries from shops using a tub where people can deposes of there used batteries, sometimes the tub gets too full so people leave bags full of fresh batteries which I just pick up most of the batteries are slightly low AA/AAA read 1.3 volt and the PP3 read 7 volt.
Any which  read too low or don't show a increase in charge voltage after an hour I just bin.
If you have any questions just ask.

Dave

[DavidA]

... I've also found a good supply of still usable batteries from shops using a tub where people can deposes of there used batteries, sometimes the tub gets too full so people leave bags full of fresh batteries which I just pick up most of the batteries are slightly low AA/AAA read 1.3 volt and the PP3 read 7 volt..


Love it !

At least I know that I'm not the only one here that does this.

(a few week ago I was up at the tip, And in the electronics bin were three cards of CR2016 and CR2025 Lithium cells. I'm set up for life .)

[Muzzerboy]

Don't be tempted to recharge CRxxxx button cells. That could be very dangerous - there have been some spectacular explosions.