How do I know when this finishes charging? Photo attached

[grangervoldemort]

Is there any way to know when this has finished charging the batteries? When turned on two green lights come on above each battery. They never turn off. 

 

I charged these batteries for about 12 hours. They don't have the mah rating on them. Anyone know what rating they are with proof? 

 

 

 

[Arkyo0]

No you can't afaik. I do have GP powerbanks, and their green lights are constantly lit as long as batteries are aligned properly.

[grangervoldemort]

25 minutes ago, Arkyo0 said:

No you can't afaik. I do have GP powerbanks, and their green lights are constantly lit as long as batteries are aligned properly.

.... Don't we need to know when the batteries are full to avoid overcharging? Afaik these chargers are dumb chargers that constantly charge and do not go into trickle mode charge once the batteries are full nor do they ever turn off. What madness. 

[DubMFG]

You could measure the current draw across the battery to see if it is charging after it should have completed charging. Otherwise, the best bet is to recycle it and get a better battery charger for peace of mind.

[grangervoldemort]

I wonder if I could use my Panasonic cordless phone to charge these batteries? It takes the exact same batteries and the phone indicates how charged the batteries are.

[mariushm]

Read this :

AN1384: Ni-MH Battery Charger Application Library

http://ww1.microchip.com/downloads/en/AppNotes/01384A.pdf

 

It goes through a lot of detail about how NiMH batteries are made and how the charging should be done, and so on.

Basically, when the battery is fully charge, for a short time the voltage will be quite high at a bit over 1.5v and then it will slowly go down a bit, at which point the battery will still accept some current but at a relatively low amount... what's generally coined as "trickle charging"

 

So you could measure the current going into the battery and when it's reasonably low, like 10-50mA or something like that, you could say the battery is fully charged.

 

Anyway, the battery charger says it does 130mA at 1.4v for AA batteries, so a typical AA battery with 1800-2200mAh capacity will fully charge in around 12-15 hours (15x130 = ~2000) ... but your batteries are not always fully discharged... and also the battery charger is not quite that accurate in controlling the current it uses in the first place.

[grangervoldemort]

4 minutes ago, mariushm said:

Read this :

AN1384: Ni-MH Battery Charger Application Library

http://ww1.microchip.com/downloads/en/AppNotes/01384A.pdf

 

It goes through a lot of detail about how NiMH batteries are made and how the charging should be done, and so on.

Basically, when the battery is fully charge, for a short time the voltage will be quite high at a bit over 1.5v and then it will slowly go down a bit, at which point the battery will still accept some current but at a relatively low amount... what's generally coined as "trickle charging"

 

So you could measure the current going into the battery and when it's reasonably low, like 10-50mA or something like that, you could say the battery is fully charged.

 

Anyway, the battery charger says it does 130mA at 1.4v for AA batteries, so a typical AA battery with 1800-2200mAh capacity will fully charge in around 12-15 hours (15x130 = ~2000) ... but your batteries are not always fully discharged... and also the battery charger is not quite that accurate in controlling the current it uses in the first place.

What mah rating are those batteries in the photo?

 

Thanks

[mariushm]

How would I know?

As I said, the average standard AA rechargeable battery is between 1800mAh and 2100mAh ... some higher end ones will reach 2500-2800mAh.

 

IF you go on Rayovac's website, they have plain Rayovac and Rayovac Plus

 

Rayovac plain (LD715-4OP GENE) are 1350mAh : http://www.rayovac.com/products/rechargeables/recharge/aa-4-pack.aspx

Rayovac plus ( PL715-4 GENE) are 2400mAh : http://www.rayovac.com/products/rechargeables/recharge-plus/aa-4-pack.aspx

 

So assume your batteries are towards the lower end, doubt they're even 2000mAh.

[grangervoldemort]

43 minutes ago, mariushm said:

How would I know?

As I said, the average standard AA rechargeable battery is between 1800mAh and 2100mAh ... some higher end ones will reach 2500-2800mAh.

 

IF you go on Rayovac's website, they have plain Rayovac and Rayovac Plus

 

Rayovac plain (LD715-4OP GENE) are 1350mAh : http://www.rayovac.com/products/rechargeables/recharge/aa-4-pack.aspx

Rayovac plus ( PL715-4 GENE) are 2400mAh : http://www.rayovac.com/products/rechargeables/recharge-plus/aa-4-pack.aspx

 

So assume your batteries are towards the lower end, doubt they're even 2000mAh.

Mine are AAA not AA. 

[mariushm]

Then they'll be in the 650..1100mAh range.

[grangervoldemort]

On 2/28/2019 at 2:37 AM, mariushm said:

Then they'll be in the 650..1100mAh range.

OK but this doesn't answer:

On 2/27/2019 at 8:47 PM, grangervoldemort said:

I wonder if I could use my Panasonic cordless phone to charge these batteries? It takes the exact same batteries and the phone indicates how charged the batteries are.