Battery Confusion

[keyboardcowboy]

Iam pretty confused with battery voltage ratings,may it be any battery.
For example a fully charged 3V battery always shows a higher terminal voltage with a DMM but when it expires it gives a reading of 3V ,shouldn't it give a DMM reading of 3V when charged and below 3 when dead?

[PlainBill]

Re: Battery Confusion

Iam pretty confused with battery voltage ratings,may it be any battery.
For example a fully charged 3V battery always shows a higher terminal voltage with a DMM but when it expires it gives a reading of 3V ,shouldn't it give a DMM reading of 3V when charged and below 3 when dead?

There are several effects here. First of all, the voltage is the nominal voltage. For example, a 12 Volt lead acid battery (car, motorcycle, UPS) actually is a 12.6 volt battery.

Second, the rated voltage is with some load - and a DMM doesn't place a significant load on a battery. For example when fully charged a 12 Volt car battery will read slightly above 12.6 volts; place a load on it and it quickly drops down to 12.6 volts, and continues to drop slowly as it discharges.

Also, the voltage of a battery depends on the electrochemical system used. A carbon zinc battery does not produce the exact same voltage as a alakaline battery; a NiCad battery does not produce the same voltage as a Ni-MH battery.

PlainBill

[Gianni]

Re: Battery Confusion

Plainbill has already answered but you can read a lot about battery on wikipedia.

Ten years ago I worked for a company that produced industrial battery chargers for several kind of batteries.
IIRC the Nickel-Cadmiun battery were charged at 1.6V maximum and were considered completely discharged at 0.85~0.95V.
For lead-acid batteries the voltages were completely different: minimum voltage was 1.7V and maximum 2.35V.

I remember also that you can't wait too much (6 - 8 hours) to charge lead-acid batteries when you have filled them with electrolyte otherwise they can deteriorate, at least this is what I remember: once I was starting an emergency system for a manufacturing plant, there were 8 battery chargers 24V 800A and 10 battery chargers 110V 50A; the electrician boss of the company asked me to turn on quickly some chargers because they had already filled some batteries.

I miss this job because was exciting and interesting to test/repair and set up this kind of chargers, but unfortunately the company had financial problems and I changed job before it was sold to a bigger company that moved administration and production very far from original place.

Ciao
Gianni

[PlainBill]

Re: Battery Confusion

Plainbill has already answered but you can read a lot about battery on wikipedia.

Ten years ago I worked for a company that produced industrial battery chargers for several kind of batteries.
IIRC the Nickel-Cadmiun battery were charged at 1.6V maximum and were considered completely discharged at 0.85~0.95V.
For lead-acid batteries the voltages were completely different: minimum voltage was 1.7V and maximum 2.35V.

I remember also that you can't wait too much (6 - 8 hours) to charge lead-acid batteries when you have filled them with electrolyte otherwise they can deteriorate, at least this is what I remember: once I was starting an emergency system for a manufacturing plant, there were 8 battery chargers 24V 800A and 10 battery chargers 110V 50A; the electrician boss of the company asked me to turn on quickly some chargers because they had already filled some batteries.

I miss this job because was exciting and interesting to test/repair and set up this kind of chargers, but unfortunately the company had financial problems and I changed job before it was sold to a bigger company that moved administration and production very far from original place.

Ciao
Gianni

There is a lot of information available about batteries; enough to make your head spin. Manufacturers are always trying to make improvements to improve storage capacity, shelf life, etc.

Early in my career I shared laboratory space with the 'Electrochemistry Department' at a major manufacturer. I remember some of the tales told by 'JC' and the other guys there. Workig with lead-acid batteries, you probably appreciate one bit of wisdom he imparted: "You can always spot a battery chemist - when he goes to the bathroom, he washes his hands FIRST."

PlainBill

[kc8adu]

Re: Battery Confusion

Plainbill has already answered but you can read a lot about battery on wikipedia.

Ten years ago I worked for a company that produced industrial battery chargers for several kind of batteries.
IIRC the Nickel-Cadmiun battery were charged at 1.6V maximum and were considered completely discharged at 0.85~0.95V.
For lead-acid batteries the voltages were completely different: minimum voltage was 1.7V and maximum 2.35V.

I remember also that you can't wait too much (6 - 8 hours) to charge lead-acid batteries when you have filled them with electrolyte otherwise they can deteriorate, at least this is what I remember: once I was starting an emergency system for a manufacturing plant, there were 8 battery chargers 24V 800A and 10 battery chargers 110V 50A; the electrician boss of the company asked me to turn on quickly some chargers because they had already filled some batteries.

I miss this job because was exciting and interesting to test/repair and set up this kind of chargers, but unfortunately the company had financial problems and I changed job before it was sold to a bigger company that moved administration and production very far from original place.

Ciao
Gianni

not sure about them deteriorating if you dont charge right away after filling.
i have filled military batteries made in 1944,left them sit overnight to absorb acid,load tested them and then charged them till the gravity came up.
as a test we installed one of these cells in a military radio that had been converted for ham use.i turned it on and then filled it.
the rig fired up and we then made several contacts on 20m voice several of them "across the pond".
i still have a bunch of delco dc12 "tar top" car batteries from the 60's.
so far every one that i filled worked well enough to start a car without charging.they usually settle out at about 40% charged once the reaction ends and it cools down.of course we charge them fully!

[Gianni]

Re: Battery Confusion

not sure about them deteriorating if you dont charge right away after filling

I was wrong about the time, I have asked to a friends still working with batteries: they should be charged within 48 hours after you have filled them with electrolyte otherwise the plates inside start to oxidize.

Ciao
Gianni

[Harvey]

Re: Battery Confusion

http://www.batteryuniversity.com/

[Krankshaft]

Re: Battery Confusion

The thing that gets me is I know AGMs and other sealed types can't be filled for obvious reasons.

But lead acid flooded cells have an infinite self life unfilled.

Is there anyone still selling flooded cells unfilled anymore?

[kc8adu]

Re: Battery Confusion

The thing that gets me is I know AGMs and other sealed types can't be filled for obvious reasons.

But lead acid flooded cells have an infinite self life unfilled.

Is there anyone still selling flooded cells unfilled anymore?

oh yes.the idea is to be able to ship them without restrictions.
most motorcycle batts are dry charged.
i suggest you read this as far as replacing lost water in agm batts.

i have 2 8d agm here that were replaced due to capacity loss from a misadjusted charge controller in a solar system.being less than a year old i subbed 2 worn out ones for the core charges and did the add water trick.float charged at 14.8v a few days and tested with my rct.
they were within a few ah of the new ones.
i found this out because the customer wanted to know if his new $400.00 each batts were ok from the start.did the rct test on them.