Car battery - new one or recharge!?

Pew_Pew_Pew_Lasers!

If it can't reach full voltage then you either have a cell imbalance which indicates the battery is reaching the end of its life, or a poor-quality charger. Why your 'charged' battery would read 13.1V isn't really clear, unless your multimeter isn't zeroed correctly.

I'd vote for the former. If that proves to be the case, and you keep flattening it, eventually it will never reach its nominal voltage.

You really should take it to a battery supplier and have it load tested. That will tell you immediately if it needs replacing, without any fuss.

pogofish

Due to the internal resistance of the battery itself, it is quite possible that it will never quite indicate fully charged but will still be perfectly usable. So long as it is still heading in that direction, then you will probably be ok.

A newer battery will give the lowest internal resistance and keeping it regularly charged will help maintain that for the longest time. Typically, a good condition battery will be trickle charged in 12-16 hours but larger ones may need up to 36 hours to full charge - At 45Ah, yours is reasonably hefty, so 24hrs would seem a sensible amount of time.

Bung-it back in and see would be my next step, if its not enough, stick it back on for another twelve hours.

If it is taking a lot more than that, or still not giving an adequate charge, then replacing the battery would be the next step and if the new one, once fully charged, still gives you problems, then it would be a good idea to get the alternator/voltage regulator checked.

It woukl not be that unusual for a battery to read 13v straight off the charger IME. This would settle back in an hour or so. Always let your newly off-charge battery sit for a few minutes to let any gas dissapate.

Im not entirely convinced about load testing myself as I've had a battery fail on me within a week of being tested and approved without any other electrical problems on the vehicle and the last time I replaced a battery on my current car, the old one passed a load test at the factor's despite being barely able to turn-over the engine!

thenap80

Hi again

I am just putting the battery back in the car. However, when I connect the terminals, the alarm is going off so have to disconnect again!! How do I stop this please!!??!?!?!?!?!

Hopefully I can get this done by dark!

Ta

goldspanners

pogofish wrote: »

Im not entirely convinced about load testing myself as I've had a battery fail on me within a week of being tested and approved without any other electrical problems on the vehicle and the last time I replaced a battery on my current car, the old one passed a load test at the factor's despite being barely able to turn-over the engine!

it must have been a rubbish tester, the best ones are either expensive digital ones that give more than just a reading, or an analogue one. i use my analogue one regularly in the winter and its never let me down once.

Inactive

thenap80 wrote: »

Hi again

I am just putting the battery back in the car. However, when I connect the terminals, the alarm is going off so have to disconnect again!! How do I stop this please!!??!?!?!?!?!

Hopefully I can get this done by dark!

Ta

Just use your key blipper to switch it off.;)

thenap80

DONE

Many thanks for everyone's help!

pogofish

goldspanners wrote: »

it must have been a rubbish tester, the best ones are either expensive digital ones that give more than just a reading, or an analogue one. i use my analogue one regularly in the winter and its never let me down once.

Either way, its two different instances where a dud battery had been deemed ok.

Enough to raise an amount of suspicion IMO.

goldspanners

pogofish wrote: »

Either way, its two different instances where a dud battery had been deemed ok.

Enough to raise an amount of suspicion IMO.

are you sure it was a high rate discharge tester that was used or just a multi meter? a multi meter can suggest a battery is ok,even when under engine load but actully be faulty.

pogofish

Nope, not a multimeter - I know them well enough!

This was in one case, a big thing with spikes on a bar that was held firmly across both terminals and the result read off a central meter, the other device was like a very large multimeter with auto-grade cables and clips to both terminals

Battery was out of the car in one case.

goldspanners

pogofish wrote: »

Nope, not a multimeter - I know them well enough!

This was in one case, a big thing with spikes on a bar that was held firmly across both terminals and the result read off a central meter, the other device was like a very large multimeter with auto-grade cables and clips to both terminals

Battery was out of the car in one case.

that is very strange, mine is the one with the jump lead style clips and a big resistor behind an analogue meter,never fails.