What voltage should my battery be?

[Choppski]

Just tested my starter battery and got a reading of 12.46V and 12.34V on my leisure battery, both are 60amh.

Are these readings good, if not what should they be?

Also, i have a zig unit and when i hook up to mains with 240V the leisure battery goes up to 13.04V so it is trickle charging. Can i leave it like this over winter or is there a better procedure?

Is the starter battery supposed to increase in voltage too?

thanks

[Footprint]

A fully charged 12V battery will give about 12.8V, and is discharged when reading about 12.0V, these figures are not to be read when the battery is just off charge, either on the van or from a charger, of after trying to start the engine - false readings will be got doing that.

Both of those figures assume an accurate meter, and a battery in reasonable nick, but if you're not having problems with them you can probably assume they are.

The scale is not linear, by the above measure your 12.46V battery is about 75-80% charged, and the 12.34V is about 55-60% charged.

Also, i have a zig unit and when i hook up to mains with 240V the leisure battery goes up to 13.04V so it is trickle charging. Can i leave it like this over winter or is there a better procedure?

Unless it is a intelligent charger don't leave it permanently connected.

Is the starter battery supposed to increase in voltage too?

In all the fitments I've seen no, the starter battery is connected only to the vehicle elctrical system.

[kevtherev]

Just tested my starter battery and got a reading of 12.46V and 12.34V on my leisure battery, both are 60amh.

Once charged on a charger and the battery left over night, should the battery discharge itself slowly, then 12.6 V is considered a point where a battery is useless.

[California Dreamin]

These are general voltage ranges for six-cell lead-acid batteries:

Open-circuit (quiescent) at full charge: 12.6 V to 12.8 V (2.10–2.13V per cell)
Open-circuit at full discharge: 11.8 V to 12.0 V
Loaded at full discharge: 10.5 V.
Continuous-preservation (float) charging: 13.4 V for gelled electrolyte; 13.5 V for AGM (absorbed glass mat) and 13.8 V for flooded cells
1.All voltages are at 20 °C (68 °F), and must be adjusted −0.022V/°C for temperature changes.
2.Float voltage recommendations vary, according to the manufacturer's recommendation.
3.Precise float voltage (±0.05 V) is critical to longevity; insufficient voltage (causes sulfation) which is almost as detrimental as excessive voltage (causing corrosion and electrolyte loss)
Typical (daily) charging: 14.2 V to 14.5 V (depending on manufacturer's recommendation)
Equalization charging (for flooded lead acids): 15 V for no more than 2 hours. Battery temperature must be monitored.
Gassing threshold: 14.4 V
After full charge, terminal voltage drops quickly to 13.2 V and then slowly to 12.6 V.

I'm not sure I would be throwing away a fully charged battery because it only reads 12.6volts....

Martin

[Choppski]

These are general voltage ranges for six-cell lead-acid batteries:

Open-circuit (quiescent) at full charge: 12.6 V to 12.8 V (2.10–2.13V per cell)
Open-circuit at full discharge: 11.8 V to 12.0 V
Loaded at full discharge: 10.5 V.
Continuous-preservation (float) charging: 13.4 V for gelled electrolyte; 13.5 V for AGM (absorbed glass mat) and 13.8 V for flooded cells
1.All voltages are at 20 °C (68 °F), and must be adjusted −0.022V/°C for temperature changes.
2.Float voltage recommendations vary, according to the manufacturer's recommendation.
3.Precise float voltage (±0.05 V) is critical to longevity; insufficient voltage (causes sulfation) which is almost as detrimental as excessive voltage (causing corrosion and electrolyte loss)
Typical (daily) charging: 14.2 V to 14.5 V (depending on manufacturer's recommendation)
Equalization charging (for flooded lead acids): 15 V for no more than 2 hours. Battery temperature must be monitored.
Gassing threshold: 14.4 V
After full charge, terminal voltage drops quickly to 13.2 V and then slowly to 12.6 V.

I'm not sure I would be throwing away a fully charged battery because it only reads 12.6volts....

Martin

right, well it was around 14C in air temp when i tested at night, so by your variance on 20C that gives me a 0.12V dip by my calculation. My multi meter is a basic one that only has the nearest setting at 20V DC so that will obviously play into the accuracy of the reading.

California dreamin - Nice set of stats by the way - thanks

Anyone got an answer to my other questions regarding charging via the zig?

The other reason for asking is that my engine turns over very slowly but then fires after about 5 seconds and it is getting worse (feels like it anyway). i relpaced the starter motor in april with a part used, but only about 6 months old one.

[kevtherev]

Did you change the bronze bush in the bell housing?

[Choppski]

Did you change the bronze bush in the bell housing?

No i didn;t - is this critical?

[kevtherev]

yes

[Choppski]

yes

oh,

[California Dreamin]

The oilite bush that supports the armeture end (starter motor end) wears oval and as a consequence the pinion does not mesh squarely with the ring gear on the flywheel. This results in 'slow and irratic cranking'
The bush itself is very cheap (under a fiver) but can be a little awkward to change....definately worth it tho.

Martin

[OliJones]

you might wanna check your battery voltage when its under load too ie cranking, a knakered battery will still look healthy when its not discharging, also if your batterys not a sealed type its worth checking your acid level, and top them up with distilled water if needed

[chriscburgess]

Once charged on a charger and the battery left over night, should the battery discharge itself slowly, then 12.6 V is considered a point where a battery is useless.[/quote]

Hi Kev

Please could clarify this for me? I can charge my battery until the battery charger says it is fully charged but when i check it, it seems always to be between 12.5 to 12.6v. The reason i ask is that i am charging it and it has just not seemed to have enough power to start anymore. The battery is just over 3 years old and came with a 2 year warranty.

Do you reckon i should replace it?
Cheers
Chris

[kevtherev]

Are you removing it from the van to charge it?
What I meant by that is, if you charge the battery up for a couple of days on a trickle charger, then after an hour you check the voltage and make a note of it.
After 12 hrs if it's gone down past 12.5V it's considered not holding charge, and therefore liable to let you down in the coming cold weather.

Every battery I've had reads over 13 volts when charged

[chriscburgess]

Thanks Kev. I'll try what you suggest and see what happens, although I have resigned my self to getting a new battery now.

cheers

[Choppski]

yes

oh,

Right, i replaced the bronze bush after a few curses trying to get the bugger out. Replaced it with a new one (soaked on oil for a few hours), fitted and the the van started straight away no issues. But.... i then tried her again today after fitting it yesterday and the slow crank came back, albeit no where near as much as before. Could be back to the start with the battery up the duff.

i'll try out the advice from kev and charge it out of the van.

will keep you guys updated!