Yeah I have a multimeter, I'll test it in the morning.

that will be the ultimate test really and tell you what sort of condition the battery is in

Battery voltage dropped from 12.66V (9pm) to 12.48V (6am) and the car started just fine this morning. This was after a series of 15 minute drives yesterday. The Exide website says "Sealed batteries must produce a voltage of 12.5 or greater before a load test may be performed.". That suggests it's on the way out, contrary to the test done yesterday.

@Jase2985 the guy who tested the battery told me the Exide battery I have shouldn't be charged, other than perhaps with a trickle charger.

IMO and due to the age of the battery and how its used its probably suffering sulfation or stratification, which reduces the charge the battery holds. smart chargers with a maintenance cycle can reduce or remove the sulfation/stratification in the battery and restore the standing voltage level.

Smart chargers also charge the battery slowly and apply differing levels of current and voltage to get the best from the battery.

its up to you but at the of the day you have 2 choices, buy a new battery, or buy a smart charger. The second option has the potential downfall that the battery could be well and truly stuffed and the charger doesn't do a lot for it.

Looking at the voltage levels and only being slightly lower than the norm I would say the smart charger could work well.

I would lend you mine to try, but im in Auckland.

Given the Exide battery guys said "be really careful charging this battery as it's not designed for fast chargers, just trickle", I'm not sure I want to just throw a charger on it. Yes it would probably help, but maybe it's worth just buying a new one and getting another 5 years of zero maintenance. I'll give it a couple of weeks to see how it goes when it gets colder I think.

They are arse covering against someone hooking up a braindead 40 amp charger they found in grandpa's shed to it and baking it.

There are still unregulated chargers made, so if you hook it up on a day that the line voltage is high because the sun it out so its 250ish, then you will actually be overcharging the battery considerably.

Any modern smart charger will be switch mode, so immune to line voltage changes, and step the charge down as it sees the battery charge up, and move to an appropriate float charge when it decides it is complete.

and given a smart charger is essentially a trickle charger (it take 6-24h to complete a cycle deepening on the state of the battery). Any lead acid battery is not designed for a fast charger because it creates excess heat and can lead to a bit of hydrogen gas being given off which is highly flammable.

should be able to get a lot more than 5 years out of a battery with regular maintenance and if the car is being driven regularly (not sitting for long periods)

Some info in this video might be useful, especially the surface drain part.

https://youtu.be/MhnVZ7ZPunw

Given the battery is mostly to fully charged most of the time, would hooking up a smart charger help? Or would it just say "battery full, won't do anything?"

Thanks for the youtube link. I'll try to watch it some time at home. I find youtube videos a slow way to gather information.

A smart charger will get it full to the point where a car will start much faster than a trickle charger. Also trickle ones usually do not cut back to a float charge when they are full, they just sit there putting too much into a full battery at their only option.

Supercheap auto have specials on their battery's this weekend for club members.

timmmay:

 

Given the battery is mostly to fully charged most of the time, would hooking up a smart charger help? Or would it just say "battery full, won't do anything?"

 

Thanks for the youtube link. I'll try to watch it some time at home. I find youtube videos a slow way to gather information.

 

A smart charger will most definitely do something. My one still goes through the charging phase, it just doesn't take anywhere near as long. it skips a few steps if its not doing the recondition mode.

http://www.marineelectricalsolutions.co.nz/uploads/76410/images/133505/pid575851/photos/CTEK_8_step_charging_graph.gif

Ah cool, I might get a smart charger at some point. Do you have to disconnect the battery from the car before you put the charger on? I would assume yes.

I never have, and the manual for the ctek says you can charge it on the car

Standby voltage isn't a great guide, but it's better than nothing and 12.4v (even 12.6v) isn't fantastic.   It would be more informative to monitor the voltage while someone puts moderate load on the battery e.g.headlights and see how much it drops then.

I agree with others that a good multistage charger may inject a bit of life back into your battery.  A charger with a de-sulphation stage will do this.