Well, that was fun...

[Rocky]

Tuesday - "Drive Day" for Crystal.
This week the big drive to Mt Morgan up the Range.
Enjoyed my usual drive up the range and at the top I knocked it into neutral to coast down the other side (cool the engine) for a few klms until the road rises again.
Soon after I knocked it into neutral the battery light came on (at about 100kph). Without thinking I popped it back into (6th) gear and it did a little bit of bucking/surging, like the power was coming on and off intermittently. I stayed on a light throttle and the engine kicked-in and we were fine again.
I then headed the 30klms back to Rocky along the Capricorn Highway making a bee-line for my trusty Auto Electrician. No further problems.
Peter tested the battery before I turned the engine off and battery gave a normal charge reading. Then we turned it off and it wouldn't restart. Battery showed about 1/3 normal charge. Peter then hooked up his small pocket-sized emergency battery pack and it started first go.
He explained that what had actually happened was that as soon as I put it into neutral the alternator stopped charging and the engine died. When I dropped it back into gear it 'kick-started' the engine (at 100kph) and the alternator started charging again, keeping it running.
Existing Battery was fitted on 25 June 2010 so almost 12 years is not too bad for $390. The new one will cost me $475.
Kind of took the edge off my drive but all's well that ends well.

[ManiacLachy]

I was always told you shouldn't put a car in neutral to coast like that. I guess that's why. Also, it wouldn't help with engine cooling, because the engine turns the water pump, if you're in neutral and the engine is simply idling the water isn't moving through the motor very fast, letting it heat more.

[greenMachine]

Sounds to me like the alternator might be a little suss. Did he check that too? Seems like more to it than a simple bat flattery ...

[Rocky]

Yeah, I did wonder about the Alternator. He was flat out with cars and customers everywhere - I will wait until I get the new battery in and give him a call and see what he thinks about the Alternator.
You make a good point ML, coasting is an old (bad?) habit that I have had all my driving life. Maybe it is time to stop doing it.

[rascal]

Coasting was also something used to be done down hills to save fuel.
My dad used to do it all the time, mostly as old habit. I had to keep reminding him that modern cars now shut off the fuel on overrun, so rolling down hill in gear actually uses no fuel whereas knocking it into neutral requires fuel to keep it idling.

[PaulF]

I agree with ML that the coasting isn't a great idea for numerous reasons, but an alternator should still charge when the engine is idling.

[Red_Bullet]

Tuesday - "Drive Day" for Crystal.
This week the big drive to Mt Morgan up the Range.
Enjoyed my usual drive up the range and at the top I knocked it into neutral to coast down the other side (cool the engine) for a few klms until the road rises again.
Soon after I knocked it into neutral the battery light came on (at about 100kph). Without thinking I popped it back into (6th) gear and it did a little bit of bucking/surging, like the power was coming on and off intermittently. I stayed on a light throttle and the engine kicked-in and we were fine again.
I then headed the 30klms back to Rocky along the Capricorn Highway making a bee-line for my trusty Auto Electrician. No further problems.
Peter tested the battery before I turned the engine off and battery gave a normal charge reading. Then we turned it off and it wouldn't restart. Battery showed about 1/3 normal charge. Peter then hooked up his small pocket-sized emergency battery pack and it started first go.
He explained that what had actually happened was that as soon as I put it into neutral the alternator stopped charging and the engine died. When I dropped it back into gear it 'kick-started' the engine (at 100kph) and the alternator started charging again, keeping it running.
Existing Battery was fitted on 25 June 2010 so almost 12 years is not too bad for $390. The new one will cost me $475.
Kind of took the edge off my drive but all's well that ends well.

I put a battery in my NB for about $150, got it from autobarn. It was on special though, about $40 off.

Century NS60LS MF

I'd swap the battery and stick a multimetre on it while running, if it's at around 14.3 volts then the alternator is fine.


https://autobarn.com.au/ab/Autobarn-Category/Shop-our-Full-Ranges-by-Brand-%7C-Autobarn/Century/Century-Hi-Peformance-Battery-NS60LS-430CCA/p/SP56624

[Rocky]

Thanks for the suggestions. I remember having a bit of a discussion on here 12 years ago when I was getting ready to do my first battery replacement.
I eventually stumped-up for the expensive OE Panasonic because people noted the issue of "terminals in the wrong place" and I didn't want to mess around with the battery leads. Maybe that's not an issue anymore - you obviously didn't have any problems with the battery you mention.
In the end I thought $475. for 10 - 12 years? Yeah, not too bad.

On reflection, I think Peter may have tested the Alternator as well. He is a very clever and thorough fellow and it would be like him to think of that. I will ask him.

I had been putting the battery on trickle-charge every few weeks but the device did not give any indication of deficiencies. Just appears to have dropped it's guts after the 10 minute run up the range (very hot day but only medium revs - about 4000 in third.)

[Red_Bullet]

you obviously didn't have any problems with the battery you mention.
In the end I thought $475. for 10 - 12 years? Yeah, not too bad.

That battery has the terminals in the correct position and has the vent tube, it's a drop in replacement.

[KevGoat]

I bought a Fullriver HC35 AGM from Springer Solar (Qld) for my SE a couple years ago for my SE. Cost me $225 including freight to SA which I thought was good value. Fitted perfectly and has been great.

Sent from my SM-G781B using Tapatalk

[Rocky]

Hard to get good help. When I ordered the battery from the local Dealer I particularly asked that they charge it for me. Paid for it on the phone.
Got the call to pick it up yesterday - when I got there the Parts guy passed it to me across the counter in a sealed box. Not charged.
I went back and picked it up today and dropped it into the car but I won't be going for a drive until the car has been to my Auto Electrician to have the Alternator thoroughly inspected. It just doesn't make sense to me that what happened was due to a weak battery.

[The American]

12 years is an outstanding run for a battery. Mine seem to routinely fail at about 4.

[rascal]

12 years is an outstanding run for a battery. Mine seem to routinely fail at about 4.

Usage makes a big difference to lifespan.

My DD which does 100km every day of the week has batteries that outlast the car. Had the last one for 9 years and sold it still with orig battery. The tow cars on the other hand, which sit in the shed most of the time chew through one every few years

[Rocky]

12 years is an outstanding run for a battery. Mine seem to routinely fail at about 4.

You'd be talking about an 'aftermarket' battery though, wouldn't you? Like RB is using (?)
I only get 3 - 4 yrs out of a regular battery in the Mazda 6 which gets used every day.
The MX5 only gets a run once a week but it is an hour or more on the open road and it gets to sit on the trickle-charger for a week once a month.
For $475. I expect 10 yrs minimum. In any case, I am 70 yrs old so this will almost certainly be the last battery I will put in the MX5.

[The American]

Yes, I barely drive anything anywhere these days, and the car cover has not been off the MX5 since before Christmas. This can’t be great for battery health.