Flat Battery

[benchan]

I had a flat Battery whilst I was on holiday - the odd thing was the inspection eye on the Battery was still showing green.

What is the purpose of this inspection eye?

After the car was jump started and after a couple of hundred miles, I checked the Battery and alternator readings and both were healthy, 12.75V and 14.3V.

How long can I expect the battery and the alternator to last?

Ben

[Red Yaris 54]

The inspection eye is in fact a built in hydrometer to measure the specific gravity of the Battery electrolyte

Bear in mind that it only is in one cell of.the Battery and only gives a basic indication of the Battery health

[Mooly]

_{How long might it last ? Impossible to answer. All I can say is that my last Toyota was 8 yrs old and on the original Battery when I changed cars, and our Corolla is still on the original at 10 years old.}

_{Once fully discharged, it takes a long time to bring a Battery back to full charge, longer the older the Battery is. I would estimate around 36 hours running. Don't be tempted to connect an "ordinary" charger in the hope of trickle charging it. That can do more harm than good.}

[rajivrattna]

use a smart charger (C-Tek) and charge it for 48 hours before you give up on the Battery. It may come to life with good charging cycle.

[eygo]

my advise to you would be if you feel uncomfortable and on edge with having the original Battery fitted not knowing if it will let you down then go and buy a new Battery

euro car parts have them here is one i have seen lion is the make i think 390cca £56.34 check for any offers / discounts they have may bring the price down.

444772021 is the euro part number

[MikeSh]

A smart charger is going to cost as much or more than a new Battery and won't necessarily fix the problem at all or for any length of time, so unless you have one already I'd go with eygo's advice - new Battery.

That's assuming this one is a few years old and out of any guarantee - I've bought batteries in the distant past that had 2 or 3 year warranties, so may be worth checking.

[dwilson]

I also just buy a new Battery when there is the first hint of trouble. I probably expect about 5 years from a Battery but they can last much longer.

David

[Syncopator]

_{Don't be tempted to connect an "ordinary" charger ...... That can do more harm than good.}

Will you please explain why you think that?

[rajivrattna]

I personally believe that having and using your smart charger to "top up your Battery charge" and to recondition it may actually prolong your Battery life and is worth a consideration (since you are unlikely to live a life without a car in future, it is almost a life long investment). I live in cold climate and here the Battery really needs topping up in winter from time to time. It may actually save you money by not having to change your battery. The smart chargers are really cheap nowadays. They should not cost more than 20-30 pounds/Euro.

here is one such.

http://www.amazon.co.uk/Intelligent-Automatic-Motorcycle-Battery-Charger/dp/B002RL4KY2/ref=sr_1_22?ie=UTF8&qid=1370056891&sr=8-22&keywords=smart+charger

[Mooly]

_{Don't be tempted to connect an "ordinary" charger ...... That can do more harm than good.}

Will you please explain why you think that?

Its because an ordinary charger simply outputs rectified AC. Look at the diagram for "full wave rectification"

http://en.wikipedia.org/wiki/Rectifier

The simple charger has a transformer chosen so that the peaks are around 18 (or more) volts in value. When connected to a discharged Battery the current drawn is high and this voltage falls to a safe value. It relies on the poor "regulation" of the transformer to achieve that. In other words the transformer can't maintain that voltage under heavy load. As the Battery approaches full charge however, the terminal voltage of the Battery rises and the current drawn falls dramatically. This is where the simple charger does its damage. The voltage across the battery rises toward the peak voltage of those pulses, the cells start to gass and the plates become damaged.

The correct way to charge a battery is with a charger that limits the voltage to around 15 volts and then tapers it down to around 13.8 volts where its safe to leave on charge for long periods. The applied voltage should really be "pure" DC rather than the pulses of the simple charger.

Also... a new battery that is say partially discharged (eg, you leave lights on for 10 minutes) has the ability to accept charge very quickly indeed. This is because the "internal resistance" of a new battery is low. An old battery has a higher internal resistance and so, given the same applied charge voltage, the current the battery "wants" to take is lower, so it take longer to come back to 100% charge.

[benchan]

Thanks for the replies.

I left the car unused for nine days and the Battery output has now dropped to 12.5V (while the alternator ouput is still the same).

Is this cause for concern?

Ben

[Mooly]

12.5 volts is fine for a Battery that has stood unused for that time. I assume when you say the "alternator output is the same" you mean the car started OK and the voltage rose to similar levels as you measured in post #1. If so then it seems all is well.

[benchan]

Yes, I did mean "the car started OK and the voltage rose to similar levels as you measured in post #1".

I will see and if I get another flat Battery, I'll get a new one before this winter.

Cheers.