New battery charge Question

[FNQCairns]

I bought a new lead acid battery 6 weeks ago and gave it a charge then a trickle until it was full on the LED lights on the charger but didn't check what it was with the multimeter at the time.

Just checked it's charge and it is currently at 12.1V, the battery has never been used or connected to anything and has done nothing but sit in it's box under the centre console for this entire time as a backup.

Is this a typical discharge rate for a lead acid battery? anyone know the rule of thumb?

thanks fnq

[station-rat]

Hydrometer (calibrated to electrolite temperature)will give you a very accurate measure of the charge

[FNQCairns]

Thanks S-R, was wondering if the charge left in it was typical, did some searches and come across this interesting table, looks like the lead acids loose more over time than I thought, mine is OK it seems.

http://www.madkatz.com/ev/batteryTec...omparison.html

cheers fnq

[Spaniard_King]

fnq,

did you know its bad for a lead acid battery to sit on the ground.. especially concrete, a residual voltage of over 12V is acceptable. Your voltage is the what I find most batteries hang at

[station-rat]

FNQCairns
All I was getting at was that the battery may not be fully charged, as some battery chargers cut off well before a full charge is reached

[FNQCairns]

Yeah no worries S-R mine is an ultra low tech manual charger, I know I should use a Hydrometer to take away the uncertainty over what is actually going on and you are right, even right now this battery is not behaving quite like it should under charge compared to my other older one.

cheers fnq

[Simmo2]

fnq,

did you know its bad for a lead acid battery to sit on the ground.. especially concrete,

Why is this?

[Fed]

If you're working on losing 20% per Month then your 12.1 Volts doesn't quite add up.
Here's some Voltage Vs Charge numbers that seem to be fairly well accepted.

100% 12.7 Volts
75% 12.4 Volts
50% 12.2 Volts
25% 12.0 Volts
0% 11.9 Volts

I'm not so sure about measuring the open circuit Voltage of batteries to work out the remaining charge but a lot of people seem to rely on it.
I've seen plenty of batteries read 12+ Volts then drop their bundle as soon as a load is applied.

[station-rat]

I would agree with FED Specific Gravity is the only way, but have seen batteries that charge and read 100% and drop their bundle as soon as you apply enough load

[FNQCairns]

If you're working on losing 20% per Month then your 12.1 Volts doesn't quite add up.
Here's some Voltage Vs Charge numbers that seem to be fairly well accepted.

100% 12.7 Volts
75% 12.4 Volts
50% 12.2 Volts
25% 12.0 Volts
0% 11.9 Volts

I'm not so sure about measuring the open circuit Voltage of batteries to work out the remaining charge but a lot of people seem to rely on it.
I've seen plenty of batteries read 12+ Volts then drop their bundle as soon as a load is applied.

Ok thats interesting thanks, I was assuming incorrectly now it seems the 20% was based on Voltage, will charge this one right up let it sit for a day then see what happens using the multimeter.

cheers fnq

[FNQCairns]

On face value if a battery has been charging until 13V straight off the cahrger but just before disconnecting the charger all of the cells are gassing well except one which is bubbling away at 1/3 or less compared to the others, should this raise an eyebrow?

thanks fnq

[station-rat]

It would pay to do a few test on that cell compared to the others

[FNQCairns]

Thanks s-r, will take it back for them to check out, it is brand new afterall.

cheers fnq

[Dignity]

On face value if a battery has been charging until 13V straight off the cahrger but just before disconnecting the charger all of the cells are gassing well except one which is bubbling away at 1/3 or less compared to the others, should this raise an eyebrow?

thanks fnq

FNQ Thanks for the link - found it useful - that cell bubbling away is going to drop the bundle when you put the load on it. Used to play with model aircraft and used batteries that had dropped a cell as they were free to get. Only need 2 volts to get the glow plug glowing. What we used to do is hammer a nail into each cell and run our supply between the nail and the negative terminal, soon found the dead cell. S-R Where does one get a hydrometer that is calibrated against the temperature as I would be interested in something like that.

[station-rat]

All hydrometers should be marked with the temp that they are calibrated at, if there not don't buy it