Strange electrical fault need help

[Peted40]

Hey guys have had to jump start my ute 4 times this week in the mornings. Once I've driven it a bit it's all good for the day. So alternator is working fine.

Battery tests good at local mechanics. Showing 425cca , so something is draining it overnight.
Bluetooth doesn't connect and my radio gets louder when I honk the horn. Strange I know. Are they related?
I 've got the 12v rust protection system, is it possible that is draining my battery overnight

It's a 2013 d40 st dual cab
Cheers guys

 

[Old.Tony]

Battery should be well over the 500CCA that your car requires to turn over. It's possible that the battery is compromised. Overnight, both the NATS (Nissan Anti Theft System) and the electronic rust prevention system will consume some power and that might be enough to make the car difficult to start in the morning.

Part of the problem is that the battery might have enough amps in it to turn the engine over, but once the starter begins drawing power, the volts drop below a level that can keep the ECU going. Without the ECU, the injectors don't open and that's pretty much the end of it.

It won't matter how good the alternator is - if the battery takes in a few amps and its surface voltage rises more quickly than it should because of an internal fault (sulphation being a common cause) then it won't get the charge restored like it should.

Monitoring the surface voltage in the morning and during the initial starting process will give you the answer. Surface voltage should be somewhere in the 12.6-12.7V region. If it's down around 12.0-12.2V the battery is not doing too well. While cranking, the battery should show 10.5V or better. Any less and you'll find the problem will go away with a new battery.

Trouble is, you need to find out why your battery failed. It might be age, it might be a poor charging regimen. That can happen either because the car is left too long between drives and it's not driven long enough - or because there's an issue with the alternator/pulley/belt. If it's a faulty alternator, a new battery will resolve the issue for a short period - but it will come back again soon after.

 

[Peted40]

Thanks tony, always full of helpful information
Battery showed 12.3v when got home from work and 12.57v after a few hours on the ctek. My question is does charging the battery effect/increase the cca?
I'll check the volts again in the morning.

Ute is daily driven and only ever been charged by the alternator since new. The battery is just coming up to 2 years, so maybe it's life span is coming to an end.
Was just hoping for a little more life than that out of a battery.
Thanks again tony

 

[user 10312]

I believe Suspect number 1 would be the rust protection system. I'd be disconnecting it and see how you go from there. I know of one bloke who has rust protection system on his vehicle that has little use. It spends more time on the battery charger than it does on the road.

Charging the battery probably has little effect on CCA. More the state of the battery itself. On cranking, the current flows and the and voltage drops, it's the battery's ability to maintain that voltage under high draw situations.

As for the radio getting louder when blowing the horn I don't know. Strange one. I wonder if there is something to do with radio volume controls mounted on the wheel near where the horn is. Maybe something related in that area. Wh it's related to the battery drain overnight. Dunno but I would be surprised if it is.