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Been thinking about the alternator / battery in my '72 with 350, ac/pw.
Background,
The alternator is the original 61A for a/c cars, rebuilt back in April 2012, and the Northstar 880cca AGM battery is 9yrs old.
A new Lectric Limited engine bay harness was installed around Feb 2014.
I have a battery isolator switch and the only thing connected when off is the quartz clock and radio memory.
Have just installed a Sniper 2 system with Hyperspark distributor and Hyperspark 2 CD Ign box, Holley in-tank efi pump.
Measured the amp draw during the install at idle, pulling about 14.5amps at the PDM on the direct to battery connected wires, (PDM also supplies the fuel pump power).
Measured 7.7amps on the fuel pump alone.
Been driving around getting the tuning done, and during the last long drive I did, the car struggled to restart after a 20min rest stop.
So been wondering if the alternator is not up to it or the battery is not charging adequately, or both.
Started the car in the shed and let it warm up, then took a few voltage measurements, idle is 750rpm, Alternator @ idle 14.5v - @ battery 14.15v
Then turned headlights on, including hi beam, Alternator @ idle 13.8v - @ battery 13.3v
Have also noticed whilst driving around the amp gauge sitting slightly on the "+" side.
Switched off and let car cool down for couple of hrs, then measured 12.68v at the battery.
Two days later I measured it again after sitting isolated and got 12.45v.
Thoughts? do I need a higher output alternator, 80-100amp or new battery? or both?
Hello fellow Aussie. So. When I converted to electric fans. I left the stock alternator. And was questioning just as you are shortly after moving to Australia. I upgraded to a 100 amp alternator. My battery lasted several more years. In fact that battery went 13 years total.
Then about 5 years ago or so I went EFI. (My pump pulls about 9 amps.)
At first, thought I was fine.
NOT SO MUCH.
Upgraded to a 140 amp Tuff Stuff alternator.
Holds 14.2 volts at idle. With the fans running.
My take on it.
Your asking for trouble with the stock Alternator. Upgrade the wiring of course and bump up the Alternator. At least a 100 amp 3 wire with EFI. 140 -150 Amp with electric fans plus EFI.
I thought you had changed that amp meter for a voltage gauge a few years ago. Perhaps I'm thinking of someone else.
As per your battery. Get the alternator up to speed first. Then you'll be able to properly access the battery.
Also of note, my last battery, a AC Delco purchased here in Oz lasted only 8 years. Just bit the dust the other day here.
Also, a one wire alternator can be converted to 3 wire operation with a simple diode from Jaycar.
But look for a quality alternator. Way to many threads on here about parasitic drain from poor quality alternators.
I've run both one wire and 3 wire alternators. I can assure you there is a difference. Go 3wire.
12.7 -12.8 is a fully charged battery, depending on temperature of course. That 12.4 reading after a couple days is down a bit. But, an 8 or 9 year old battery? Not that bad. How many cranking amps does that battery push after sitting for a week is more important.
Isn't there a auto parts store there that can analyze the charging system, Like O'Reillys or Autozone here?
I have a Foxwell BT-705 Analyzer...
To check the condition of your charging system, battery must be in the car, you can preform a out of car test but that just checks the condition of battery.
4 of 4 shows the charging system with No Load and Loaded, Lights on HVAC fan speed High, Stereo & Amps mid volume...
I don't have many high AMP draw Accessories
Currently I have a 80amp alternator installed. The original alternator is 63amps...
From your description I would guess that your alternator should be up-sized to a 80-100 amp alternator. If your AGM battery is really 9 years old then you might start looking for a replacement. That is pretty impressive of a life for an AGM battery and very similar to what I have experienced with my Ford RV, it's V10 with an AGM battery. When they fail it happens kind of fast from my prior experiences with AGM products
When changing the alternator you have to disconnect the external voltage regulator (if you have one) and rewire the alternator. I replaced the alternator's output wire with a #6 Marine cable which is made up of small copper wires and is much more flexible than standard automotive wire. The alternator's output goes to the battery Positive terminal on the starter motor which sends the current to the battery.
I have used both quality one-wire alternators and some cheap ones. The quality alternators have a charging connect at low rpm's, others wait until the engine revs up before charging. Like 4-vettes suggested they are available in one wire of the standard three wire. I have converted one-wire alternators to a three wire system when they exhibit questionable behavior. The aftermarket alternators are pretty nice today. I don't understand why someone would want to put a 150 amp alternator on a 100 amp battery.
My 100 amp Tuff Stuff alternator is more than able to handle my: Sniper EFI with electric fuel pump, MSD Ignition, 2 SPAL electric cooling fans and water/methanol injection system.
great advice..
if it were me
- replace battery (seems it has served well) but of course do a load test..
- leave the rest alone and see if it slow cranks again.
- OEM alternator working is a stout alternator compared to the replacements..
riverracer au
I wouldn't mess around with half measures. If you can find a DR44G (they're all over around here) then go for that. They're good for 145 amps and for 20-30 bucks worth of parts (a voltage converter and a PCM controller) you have some voltage control. I did have to fabricate a bracket to bolt it in but it is wonderful.
I went from a 63 amp 10 DN, to a 94 amp 12si, to a 140 amp CS144, and now to this 145-amp DR44G...... I'd suggest you just skip all that and go straight to the top.
Here is the page showing where I finished installing it..... but you can read the thread for more info.
Alternator or Battery going Bad
