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Two week old Yuasa battery was profoundly flat this morning after being left unused for only four days. Put it on charge with a decent charger conditioner this morning. The power light came on but the charging light didn't.

Still completely flat when I came home from work. Put the standard charger on it tonight. Initially it quickly dropped from drawing 6A down to 3A but soon afterwards was back to drawing 6A where it stayed for 5 hours.

The battery is still completely flat. Checked both chargers on other batteries and both are working correctly on them.

The supplier has already agreed to replace the battery but I'd appreciate the thoughts of those who know better about what the fault is and if a replacement one is likely to be as bad.

Final random thought - Is it possible the issues my tuner has had with getting the alternator to work with the Haltech have resulted in the alternator being able to fry the battery?

Thoughts appreciated if possible please.

Stranger again, after removing the battery from the car this morning ready to return it tomorrow, I gave it a final check on the charger/conditioner and this time the power light has come on as before, but this time the charging light is also on. I've checked for loose connections in the charger cables. All good.

What's going on here?

I'm pretty sure I demolished one of my good batteries by charging with a big old battery charger that delivered about the same amperage as yours. I chucked it and went to a much smaller and less powerful electronic unit (about 1A from memory) which takes anything up to a day or two to fully charge a dead one in three stages. No problems since, except that when a battery is totally flat the controller in the charger can't recognise it's there and I have to temporarily connect a good battery in parallel to get things started.

Thanks guys. The battery was 10 days old. Only ever been charged by being on the car.

Normal process is that supplier would do a check on the battery and presumably the distributor would also look for a root cause- battery will be date and batch coded and it's actually possible that a fault ie process was out of control for a time eg a single shift and that is often known from later field complaints. They should ask what were the circumstances / observations of the buyer ie you. Of course there can be a manuf fault but early failure would be a low incidence for a capable process. With agm batts it is a no no to use quick chargers but not saying either applies to Daves situation.

I'd be having an auto electrician look at the car to make the sure the alternator etc are working correctly.

I know that a buggered (or the wrong) alternator can cause the battery to be stuffed, among other things.

From memory if the voltage regulator isn't working the battery can be overcharged and burst cells or something, as well as other electrical bits getting damaged.


Bear in mind, I'm not an electrician..... I'm pretty sure an electrician would need therapy after seeing some of the stuff I've wired up.

one of my friend faced same problem few days back but get out of it easily with the help of an electrician.