Battery charging query

[chimpboy]

Is there something about very new car batteries that I haven't heard?

My mum has a three week old Honda Civic that she left the interior light on in. She didn't realise that was the issue and after calling the dealer ended up with RACV there (roadside assist was part of the purchase deal).

The guy ascertained that the light had been left on and that the battery was flat. She said, "so if I drive it around a while, will it be okay?"

He said, "Lady, if you drove it all the way to Sydney it still wouldn't be charged. All you would get is a 'surface charge'. It needs to be on a charger overnight. You can get one at kmart for $50 or so."

So she came over to my place (when the RACV guy left the car was still running), and I put the charger on while we had a coffee and a chat, and then she left.

So anyway. My response was, "that is the biggest pile of shit I've ever heard in my life." And I told my mother, "you can borrow my charger but it is not going to get your battery charged anywhere near as fast as your alternator will." And I remain of that view.

But I wondered if anyone wants to support the RACV guy or if he is just subscribing to the same myth we've all heard a million times about alternators.

[-Scott-]

I vote "pile of shit" - so that probably means it's true.

I suspect all these fancy new multi-stage chargers (which will do things which an alternator won't) are creating confusion about what an alternator can and can't do.

Here's your opportunity to do some research for us all. Monitor your mum's battery voltage for a few days, and tell us what you find.

[tweak'e]

a car generally only does a part charge. the good thing is the alternator is high current so it will do the bulk charge very quickly. however has most people don't drive for a long time at one go, so they never get fully charge.

you can drive for an hour and put a charger straight on and it will still be charging it.
to get a full charge it needs to sit on charge for a long time. its a time problem rather than a charge problem.
mind you these new multistage, pulse chargers etc etc can quicken things up a fair bit. but then again a cheap automatic charger and leaving it on overnight is cheap and easy to do.

[bansheebuzz]

if it is a calcium battery(most likely will be) with will require charging with a proper calcium battery charger or your battery will never recharge properly and shorten its life

[chimpboy]

if it is a calcium battery(most likely will be) with will require charging with a proper calcium battery charger or your battery will never recharge properly and shorten its life

I didn't look closely at it but noticed it was a sealed and maintenance free type. No idea whether it was calcium but given the age (or youth) of the vehicle I would assume it might well be.

The thing barely even needs a battery, I have never heard a car crank for such a short time before starting. It is nicely built I have to say.

[drivesafe]

Hi chipboy, being as it is a new car then it is highly likely that it is a Ca/Ca battery as all the battery makers are changing to them, because they are heaps cheaper to manufacture.

Now as to charging a battery in a vehicle, it’s partly correct that a battery will not fully charge in many vehicles because they don’t get driven long enough to allow the alternator time to fully charge them, I call this the Shopping Trolley Syndrome, BUT most vehicles now have Ca/Ca batteries and they come with what would seem grossly over sized alternators.

These two items go a long way to resolving the charging of cranking batteries even when the vehicle is not getting enough drive time.

Ca/Ca batteries are actually easier to charge, in other words, they charge faster than conventional flooded wet cell batteries, and by having a bigger alternator, while you get more amps at highway speeds, more importantly and the reason for the bigger capacity alternators, you also get more amps at idle.

So combine the Ca/Ca batteries with high current supplies at low speeds and you have just about eliminated the Shopping Trolley Syndrome in new vehicles.

As to fully charging Ca/Ca batteries. While it can take voltages as high as 16.5v to fully charge these batteries, this high voltage charging only raises the battery capacity by 3 to 5% because the average alternator can easily charge Ca/Ca batteries to 95 - 97%.

Furthermore, as these batteries have now been around in fairly common use for the last 5 to 7 years and as the vast majority of vehicle will never have a battery charge connected to them, these Ca/Ca batteries don’t seem to need this extra charging as many are now lasting 5 and 6 years and as the average cranking battery life span is 2 to 4 years, you don’t need to do anything special for these batteries to give better than average operating life spans.

Just some observations