Battery charge issue

[1965 fastback]

Jumped into my 65 on Monday (standard v8) and it started first pop. Starter spun nicely before it fired up. Hadn’t been started for at least a week.
Drove about 30-40mins including the freeway for most of it. Parked for about 40mins and when I returned, starter would barely spin. Battery flat.

Happened before a few weeks ago. Placed a charger on it overnight and battery seemed charged up. Obviously charge isn’t staying in the battery.

Any ideas? Assume alternator may be failing? Don’t have a multimeter to check.

[Dwayne]

Are you an NRMA/RAA etc member?

Call them about your flat battery (don't charge it), they'll jump start it for you and then chuck their multimeter on and tell you if battery or alternator.

[AussiePhil]

Hey Tony,
If it started first time and then didn’t start later sounds like battery connections or alternator, connection.
Take one of your two break down items, the WD40 (not the duct tape) give them a spray, and wiggle or tighten then.
Cheers Phil.

[1965 fastback]

Thanks guys. Might be the connections.

[AussiePhil]

Hey Tony,
Check the starter solenoid connections also.
Cheers Phil.

[Tang67]

Deja Vu indeed!

Same thing happened to me a few weeks ago. The battery was old and wouldn't take a charge, got it replaced but that drained overnight. Called out the NRMA and he said the battery was okay but the alternator looked shot.

To avoid chasing everything, replaced the alternator, regulator, and starter solenoid together - she starts better than ever now and hold a charge. (Though I now keep it on a trickle charger just to keep the battery humming along.)

So, as Dwayne suggested, get the NRMA out to check it.

[Gallop]

A multimeter is a useful tool with these old cars. I don't drive my cars regularly so check the battery voltage every time before I start them because the starter solenoids can stick if the voltage is low. Easy way to check if the battery is charging also.

[AussiePhil]

Hey all,
I’ve always struggled with multimeters and the range of ohms.
I needed to measure amps out of my thermo motors.
I bought one of these from Jaycar.
They have an automatic scale.
I could not recommend one of these enough.

https://www.jaycar.com.au/600a-true-rms-ac-dc-clamp-meter/p/QM1632

Cheers Phil

[pmb0186]

A cheap and easy solution is a cigarette to usb adapter with  a voltmeter built in
12.6v battery charged engine off
Greater than 12.6 v engine running battery charging typically 14v with an alternator

[efi Coupe]

Dont write off heat soak of the starter.   Are you sure battery is flat ?
If it starts easy again when cold - consider one of the new mini starters

[1965 fastback]

Further investigation with a multi revealed the alternator wasn’t charging the battery. Replaced alternator and wired it up correctly and seems to be ok. Alternator light now off on the dash.

Thanks for all the advice