• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Rechargable Batteries

MrAl

Well-Known Member
Most Helpful Member
Pixel3 is the top phone camera in almost every comparison I've seen. I haven't heard o a problem unless someone has some unreasonable expectation - taking a photo of a running deer in the dark.
Hi,

Well when i looked it up i found lots of problems, but you could look yourself and maybe you know of some problems that actually got fixed.
 

gary350

Well-Known Member
WOW that's a lot of photos. You need some automatic photo editing software then. You could do the whole batch at once.
If you run Windows on your home PC and you can use that to edit, i could make a program for you. I make ALL my photo editing software but it has to run on the Windows platform.
One of the resizing programs i made takes about 15 seconds to blow though 200 photos, sometimes less if they are small pics. It can also enhance in certain ways.
I take lots of photos then delete the bad ones it is quicker and easier than edit.

These days all I need it a nice camera to take photos when we, travel, camping, lake, family, friends, garden, special occasions, and to sell a storage building full of stuff I don't need.
 
Last edited:

MrAl

Well-Known Member
Most Helpful Member
I take lots of photos then delete the bad ones it is quicker and easier than edit.

These days all I need it a nice camera to take photos when we, travel, camping, lake, family, friends, garden, special occasions, and to sell a storage building full of stuff I don't need.
Hi,

What i meant was for the ones you want to crop or change in some way. Sure you can take more photos and that is one of the first lessons i learned in photography years ago: take several pics of the same scene then pic out the best shot later.
Problem back then though was there was only film so it was costly to do that so i kept it down to two pics unless it was really important.

I made so much software for pictures i cant even count it all :)
I like to modify in many ways such as brightness, contrast, picture size, etc. It's amazing what you can do.
 

gary350

Well-Known Member
They do all have a limited number of cycles.

Also, although NiMH are often claimed to have no memory effect, they still do in my experience.
That is, if they are not usually completely discharged, the crystal structure of the plates changes in the parts that are never used and the internal resistance goes up when you get to the "normal" discharge point.

With something that needs high current like a camera, that can cause it to indicate the batteries are flat.

Try connected eg. a ten ohm resistor across each cell and leave them for about a week, then fully charge them and try them again.
I've found that frequently brings them back to life, by discharging them past the high resistance point so the full depth of the plates gets reformed on the next charge.

(And you can ignore the usual rule of not discharging below 1V/Cell. That applies to cells in a pack, to avoid reverse polarising any weak ones.
By discharging each cell separately, that cannot happen).
I don't have battery holder for 1 batteries so I put 2 batteries in a 3 battery holder with jumper between the to batteries. I connected two 10 ohm resistors in series 5w each with 2 batteries in series. Will this work? I hope this is safe & not start a fire on my deck while we are asleep or gone?

At first batteries got warm. 30 minutes later batteries are cold. Wires not warm. Resistors not warm.

100_3263.JPG
 
Last edited:

audioguru

Well-Known Member
Most Helpful Member
Each battery cell will be about 1.4V when fully charged. Then Ohm's Law says the current in the total of 20 ohms is 2.8V/20 ohms= 140mA which is fairly low for AA cells. Each resistor heats with only 1.4V x 140mA= 0.2W.
You can safely use two or three cells and one 10 ohms resistor to discharge quicker.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
don't have battery holder for 1 batteries so I put 2 batteries in a 3 battery holder with jumper between the to batteries. I connected two 10 ohm resistors in series 5w each with 2 batteries in series. Will this work? I hope this is safe & not start a fire on my deck while we are asleep or gone?
It is rather important to do one cell at a time, so there is no possibility of a cell in a series combination being reverse-polarised.
The point is to take them down to zero volts and any imbalance between series cells could cause a weak one to be reverse charged while a stronger one is still discharging.

Check the open-circuit cell voltage with a multimeter after giving the cell some time to recover from a full discharge. It should be 1V or less.
If not, give it more time discharging - it can possibly take several days overall.

With ten ohms per cell, the maximum discharge current should be somewhat under 150mA and that should not be anywhere near enough to make the cells heat up, or at least not significantly?

ps. This process is nothing to do with the old style "discharge fully before charging" procedure someone mentioned, as required with some early or badly made chargers.
That was required as those chargers used high current for a fixed time and if the cells/battery were not fully discharged first, the result was over-charge and often cooked batteries....
 

gary350

Well-Known Member
Now each battery has a 10 ohm resistor. OK so I leave batteries like this for 1 week then recharge the batteries.

100_3264.JPG
 

rjenkinsgb

Well-Known Member
Most Helpful Member
That should work!

See how they work in the camera again, after that process and then fully charging them?
 

gary350

Well-Known Member
I am getting ready to charge 2 AA batteries just double checking to see if my math is correct.

Battery charger says 2.8v 160ma
Batteries say, 1.2v 1900 ma

1900 / 160 = 11.8 hours charging time.

Do I need to consider charger is 2.8v charge when batteries are 1.2v?

Or am I only concerned with charging amps only?

Batteries are completely dead.
 
Last edited:

audioguru

Well-Known Member
Most Helpful Member
You forgot to say the chemistry of your battery so I assume Ni-MH and not Lithium-Ion.
A Ni-MH cells is about 1.4V to 1.5V when fully charged and is about 1.2V when discharged a little.

We talked before about your cheap and dumb Rayovac charger because I found one that was thrown away. It overcharges forever instead of detecting a full charge. If the batteries were completely dead then charge for 14 hours and no longer. if the batteries were not completely discharged then simply guess how long to charge them.
 
Last edited:

gary350

Well-Known Member
You forgot to say the chemistry of your battery so I assume Ni-MH and not Lithium-Ion.
A Ni-MH cells is about 1.4V to 1.5V when fully charged and is about 1.2V when discharged a little.

We talked before about your cheap and dumb Rayovac charger because I found one that was thrown away. It overcharges forever instead of detecting a full charge. If the batteries were completely dead then charge for 14 hours and no longer. if the batteries were not completely discharged then simply guess how long to charge them.
I can not buy a battery charger like you say with no part number. None of them say they discharge battery until it is dead before recharging then when green light comes on it has stopped charging. Even Duracell CEF27NA2 charger says nothing on the advertisement.
 
Last edited:

audioguru

Well-Known Member
Most Helpful Member
1) A stupid charger will try to charge a battery all night long even if the battery is already fully charged because it does not detect a full charge.
2) My Energizer charger also does not detect a full charge but at least it has a timer so it does not overcharge forever.
3) My Duracell charger is smart. It refuses to charge batteries that have a half-charge or more and it charges quickly, detects and full charge and shuts off with a green light.

One person in your other thread wrongly said that a Ni-MH battery must be fully discharged before being charged. Maybe because of the timer with the Energizer charger or that the batteries in a Duracell charger might need to have the same amount of charge in each pair of cells.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
am getting ready to charge 2 AA batteries just double checking to see if my math is correct.

Battery charger says 2.8v 160ma
Batteries say, 1.2v 1900 ma

1900 / 160 = 11.8 hours charging time.

Do I need to consider charger is 2.8v charge when batteries are 1.2v?

Or am I only concerned with charging amps only?

Batteries are completely dead.
Remember that at 1/10C charge ("ten hour rate") the nominal charge time is 12 - 14 hours, not 10 hours - or at 1/5C the time is 6 hours.
Charging cells like that is not 100% efficient, so some extra is needed to ensure full charge.

11.8 x 1.2 = 14.16 or x 1.4 = 16.5 hours.

The charger is giving less that 1/10C so leaving on slightly longer, eg. a couple of hours or so, should not do any harm.
Keep checking them after 12 - 14 hours and make sure they are not getting significantly warm; take them out if the are.

(At 1/20C rate or lower, you don't have to worry about time at all, they can be left on charge for days).
 

gary350

Well-Known Member
Remember that at 1/10C charge ("ten hour rate") the nominal charge time is 12 - 14 hours, not 10 hours - or at 1/5C the time is 6 hours.
Charging cells like that is not 100% efficient, so some extra is needed to ensure full charge.

11.8 x 1.2 = 14.16 or x 1.4 = 16.5 hours.

The charger is giving less that 1/10C so leaving on slightly longer, eg. a couple of hours or so, should not do any harm.
Keep checking them after 12 - 14 hours and make sure they are not getting significantly warm; take them out if the are.

(At 1/20C rate or lower, you don't have to worry about time at all, they can be left on charge for days).
Someone said, a fully charged battery will test 1.2v. I tested my 12 hr charge batteries they are 1.380v & 1.387v and test 7.68 amps I assume that voltage means they need to charge a bit longer. I will charge them 1 hr more then test them again. Then charge them another 1 hr an test them again. I want to see if voltage keeps going down to 1.2v & maybe amps go up.

I tested the 2 eneloop batteries that have been on discharge for 12 hrs they test .680v. I will leave them on discharge an test them every day for a week. Is it ok to change 100 ohm resistor to 50 ohms to speed up the discharge and not damage batteries?

The red dollar store battery is 1.56v brand new 2 amps. Camera will take about 10 pictures with these batteries.

118192
 
Last edited:

rjenkinsgb

Well-Known Member
Most Helpful Member
I tested the 2 eneloop batteries that have been on discharge for 12 hrs they test .680v.
If that is after the resistor has been disconnected and they have had an hour or two to recover, it should be OK.
If it's with the resistor still connected, they need more time.

Lower resistance is fine; you should be OK down as far as ten ohms, it's still only a fraction of the current the cells should be capable of.
 

gary350

Well-Known Member
After charging battery 90 more minutes voltage on the 2 charged batteries is up to 1.425v and are down to 7.44a.
 
Last edited:

audioguru

Well-Known Member
Most Helpful Member
My Duracell charger charges each cell to 1.5V for a fast charge and to 1.43V for a slower charge, then the voltage drops a little after sitting for a few hours. Just now I measured 10 cells that were fully charged about 1 week ago. They measure from 1.355V to 1.399V with no load. Two cells are 5 years old and were used hundreds of times. Their voltage is the same as the newer ones but their charge runs down sooner.

I never measure the shorted circuit current of AA size Ni-MH cells because it might burn out the expensive 10A fuse in my multimeter and I never use a load that is a dead short. I measured the shorted current of the 300mAh Chinese AAA Ni-MH cells in my solar garden lights but their quality is too cheap for high current so I dispose them. The American Ni-MH AAA cells produce a shorted 0.8A for an old one to 5.7A for a 2 years old one.
The resistance of the leads and shunt of my multimeter limit the battery shorted current somewhat.

I never fully discharge my Ni-MH cells but I guess some in my solar garden lights are fully discharged if the weather is cloudy for a few days.
 

gary350

Well-Known Member
Batteries were resting on the desk for 2 hours now voltage has dropped to 1.406 & 1.391

Next time dead batteries need to be charged it looks like they should be charged 14 or 15 hrs that should put final charge closer to 1.5v.

Now I need a 15 hr off timer.

2 hrs later batteries on the decharger are .282v

118193
 
Last edited:

Latest threads

EE World Online Articles

Loading

 
Top