New battery for 911SC

[TheBaywatchKid]

My 82 SC has been struggling to start when left for a few days (not often!) and now this evening  it's just dying when cranking, so I think the battery is dead. Just wanted to see what options I have for replacement battery? NRMA do a call out service, but not sure how good what they put in will be (seems like their best option is AGM battery, and around 430$. TIA! 

[tomo]

1 hour ago, TheBaywatchKid said:

My 82 SC has been struggling to start when left for a few days (not often!) and now this evening  it's just dying when cranking, so I think the battery is dead. Just wanted to see what options I have for replacement battery? NRMA do a call out service, but not sure how good what they put in will be (seems like their best option is AGM battery, and around 430$. TIA! 

How old is the battery? 

[TheBaywatchKid]

41 minutes ago, tomo said:

How old is the battery? 

Not sure to be honest. I've only had the car 18 months, and was in it when I bought it. 

[tomo]

13 minutes ago, TheBaywatchKid said:

Not sure to be honest. I've only had the car 18 months, and was in it when I bought it. 

That makes it bit hard to say, But I thought a battery was had it ,Went to buy a new one and the bloke tested the old one , All good recondition charge and its still in my ute today

[TheBaywatchKid]

Hmm okay. I just tested it with a multi meter. With the car off, it does read the 12 volts. But if I try to crank, it drops down to 7.2 volts. So doesn't seem to have the cold crank amps

[tomo]

6 minutes ago, TheBaywatchKid said:

Hmm okay. I just tested it with a multi meter. With the car off, it does read the 12 volts. But if I try to crank, it drops down to 7.2 volts. So doesn't seem to have the cold crank amps

Might be stuffed it should show around 12.6 - 12.8  volts when fully charged.

[Peter M]

Slow down there Mitch Buchanan Jr!

Assuming you only drive the car occasionally, have you been keeping the battery on a trickle/float charger (read this as a multi-stage battery charger) between drives?

If not, I'd follow Tomo's suggestion first and fully charge the battery.  If you haven't been keeping your battery on a charger between use I'd suggest a CTEK 5 amp charger or similar.  About 100 bucks.

However if the battery has spent a good deal of time over the 18 months not fully charged, it's likely buggered. (As an aside, have you checked the level of the electrolyte?)

As for the battery, I'd suggest the cheapest name brand battery you can get.  I can't see any value in getting anything fancy like AGM or even a fancy brand like Varta.  If you are a brand snob, just pull the stickers off your new Supercharge or Repco one.  The critical factor for long battery life is keeping them fully charged.

Probably worth checking your alternator is working OK too and is not the root cause of this motoring turmoil.  Using your multimeter, with the engine idling, it should be sitting around 14 volts.

Good luck! 

[TheBaywatchKid]

Thanks all!

4 hours ago, Peter M said:

Slow down there Mitch Buchanan Jr!

Assuming you only drive the car occasionally, have you been keeping the battery on a trickle/float charger (read this as a multi-stage battery charger) between drives?

If not, I'd follow Tomo's suggestion first and fully charge the battery.  If you haven't been keeping your battery on a charger between use I'd suggest a CTEK 5 amp charger or similar.  About 100 bucks.

However if the battery has spent a good deal of time over the 18 months not fully charged, it's likely buggered. (As an aside, have you checked the level of the electrolyte?)

As for the battery, I'd suggest the cheapest name brand battery you can get.  I can't see any value in getting anything fancy like AGM or even a fancy brand like Varta.  If you are a brand snob, just pull the stickers off your new Supercharge or Repco one.  The critical factor for long battery life is keeping them fully charged.

Probably worth checking your alternator is working OK too and is not the root cause of this motoring turmoil.  Using your multimeter, with the engine idling, it should be sitting around 14 volts.

Good luck! 

Thank you for the detailed response!

 

So I daily the car, so it's used 4-5 days a week, but given I'm in the city it's all short runs. I try to take it for  decent stretch when I can just to get everyone running smoothly, but it definitely does a lot of short trips.

I have a trickle charger so I'm going to charge it this afternoon and then see will it crank after that. If it does start, I'll check the alternator then for the 14amps, thank you!

 

I hadn't heard of the electrolyte level! Will check that this eve too, just looked at instructions online. 

[Peter M]

Mitch Jr,

Do you have a trickle charger or a multistage charger?  A trickle charger won't provide enough oomph to recharge a flat battery and is only designed to maintain a charged battery.  If you are seeking to recharge the battery overnight, the charger will need to have a current rating of at least 5 amps I would guess.

As for you short runs, as long as the engine runs for about 15 minutes between starts the alternator should easily maintain the battery without assistance, especially if it is being driven a few days a week.  This assumes you haven't a mega watt stereo playing "Looking for Freedom" and your Dad's hairdryer operating from the car at the same time of course.

Oh for your battery check, 13.8 to about 14.2 VOLTS is what you expect to see. 

[TheBaywatchKid]

1 hour ago, Peter M said:

Mitch Jr,

Do you have a trickle charger or a multistage charger?  A trickle charger won't provide enough oomph to recharge a flat battery and is only designed to maintain a charged battery.  If you are seeking to recharge the battery overnight, the charger will need to have a current rating of at least 5 amps I would guess.

As for you short runs, as long as the engine runs for about 15 minutes between starts the alternator should easily maintain the battery without assistance, especially if it is being driven a few days a week.  This assumes you haven't a mega watt stereo playing "Looking for Freedom" and your Dad's hairdryer operating from the car at the same time of course.

Oh for your battery check, 13.8 to about 14.2 VOLTS is what you expect to see. 

It's a 12v multi-stage, so I think it should have enough kick in it to charge it?

Okay, good to know on the alternator. Thank you!

Yeah, I actually have the radio disconnected even most of the time, but I definitely think something is drawing current from the battery. I'll investigate once the battery is charged. Any advice on steps around that would be very much appreciated! I imagine it's like finding a needle in a haystack.

Just now, TheBaywatchKid said:

It's a 12v multi-stage, so I think it should have enough kick in it to charge it?

Okay, good to know on the alternator. Thank you!

Yeah, I actually have the radio disconnected even most of the time, but I definitely think something is drawing current from the battery. I'll investigate once the battery is charged. Any advice on steps around that would be very much appreciated! I imagine it's like finding a needle in a haystack.

I just had a look at the multi-stage, it's 2.5amp, so that's not great. Imagine it'll just take ages?

[Peter M]

Mmmm, I guess this all depends how much time and money you want to invest in this.

I suggest you put the battery on charge overnight with the expectation it won't be full charged and you will need to jump start it and take it for a drive of for maybe an hour to get it fully charged.

If it doesn't want to start again later in the week, I'd replace the battery then.

As for the the possibility of slow discharge, an SC doesn't have much equipment that would do that.  Probably the aftermarket alarm/immobiliser would be the most likely candidate.  If you disconnect one of the battery leads, you could use your multimeter to measure the steady state current draw.  If it's only say 100 mA or less, this should not cause you too much problem with battery life.

My view with batteries is that they don't cost all that much to replace when compared to how much inconvenience they cause when they fail, especially if my wife is involved!  Consequently, assuming there is no other reason for a flat battery - lights left on, faulty alternator etc - I just replace them as soon as they falter with anything off the shelf from Repco or Supercheap.  

[TheBaywatchKid]

Agreed, you're a man after my own heart. Keep it simple. Thanks mate!

[LeeM]

12 minutes ago, TheBaywatchKid said:

Agreed, you're a man after my own heart. Keep it simple. Thanks mate!

 I've had 2 batteries in 6 years in my SC, and both were under $200 from Supercheap and never a problem unless I've not driven the car for coupla weeks. Now that I haven't driven it for 3 months, it's probably time for a new one

[TheBaywatchKid]

Car started this morning after leaving it on the multi-stage over night, so thats good at least. Will take it for a long drive today and see if it starts with leaving it a few days again. When I go on Supercheap and input my car, it says none of the Centurys are compatible. Assume given my current battery is 70Ah  (760A), I just get the corresponding Century? (Something like this https://www.supercheapauto.com.au/p/century-century-ultra-hi-performance-car-battery-75d23l-mf/602502.html?cgid=SCA01060101#prefn1=output&prefv1=70AH&sz=60&start=1 ) 

 

Thanks again for all your help on this @Peter M, @tomo and @LeeM, this forum has made owning my dream car easy peasy! 

[P-Kay]

I am pretty sure I went with one of these in my SC --> https://www.centurybatteries.com.au/resources/battery-finder/fitment-options/3773

The only thing to look out for is the size (length) to fit in with the battery clamp. The biggest bugger is the location of the poles whereby they are close to the body.

I think the one you are looking at is taller? Good luck

 

[TheBaywatchKid]

29 minutes ago, P-Kay said:

I am pretty sure I went with one of these in my SC --> https://www.centurybatteries.com.au/resources/battery-finder/fitment-options/3773

The only thing to look out for is the size (length) to fit in with the battery clamp. The biggest bugger is the location of the poles whereby they are close to the body.

I think the one you are looking at is taller? Good luck

 

Thanks mate, saving me some hassle for sure! 

[jakroo]

On 05/10/2021 at 08:40, P-Kay said:

 

.....The only thing to look out for is the size (length) to fit in with the battery clamp. The biggest bugger is the location of the poles whereby they are close to the body.....

 

Many batteries come in a left and right configuration. The poles are often offset front to rear, so simply turning 180 might not suit the wiring length.  For example you might need the poles at the front (when facing it in the vehicle) but also need the negative on the left side.  Depending on whether it's a left or right handed model will determine what configuration of battery you need. 

[Peter M]

I've learnt in these situations to attach the positive first and the negative last so it doesn't matter if the spanner touches the bodywork while tightening the terminals.....

[TheBaywatchKid]

So I charged it, left it three days and it started right up. So I guess the battery is still okay! Maybe just needed a cyclical charge. Will keep an eye on it. Thanks all!