Team Camaro Tech banner
1 - 16 of 16 Posts

·
Registered
Joined
·
305 Posts
Discussion Starter · #1 ·
Optima Red top, 3 years old with nothing on voltmeter says 12.17 volts. Start turning things on I get these various readings:

Ign on, but don't start - 12.10
Fuel Pump - 11.93
Water pump - 11.75
Fuel and Water - 11.40
Fuel, water, try to start - 6.99, let off attempting to start goes back to 11.00..... It cranked very slowly, then just clicked. Now immediately afterwards I shut off fuel pump and water pump tried to start again, cranked very slow again, but then after about 10 sec of holding key in start position it turned over enough to start. Would this be a battery issue?

For power I am running from trunk - 1 ott welding cable to starter, 1 ott welding cable for ground, grounded in 2 places, battery to frame and battery to body. I then ran 4 gauge from the frame ground to the front clip. Another from front clip to motor, and a ground strap from alternator mount to frame. I would think this is good for grounds, right? I am also running from starter to alternator a 4 gauge wire..... Should I get a new battery?
 

·
Registered
Joined
·
305 Posts
Discussion Starter · #4 ·
I am about to do the 3 wire conversion and get a CS alternator. I currently have a Summit 1 wire 100 amp setup. I have read about the 1 wire problems, hence that's why I am in the process of changing it. So you guys think this is a charging problem....

With headlights on and car running it is at 10.6, at 1500 rpm it is closer to 13.2.......
 

·
Premium Member
Joined
·
22,122 Posts
If those voltage readings were taken AT the battery, then it is weak, and needs charging or replacement.
If they were taken at the front end of those cables, you need to retest at the battery, could be loss thru the cables.

edit: could also be too much timing, worth cranking her over with the pos coil wire disconnected to test.
 

·
Registered
Joined
·
3,064 Posts
Try putting a charge on the battery to bring it up to at least 12.6 volts. The battery should hold there providing that your charging system is okay. If your alternator is only putting out 13.2 volts at 1500 RPM's......then I would say your charging system is the problem. The alternator should be charging around 14.5 volts if working correctly.
 

·
Registered
Joined
·
305 Posts
Discussion Starter · #7 ·
Jim those readings were taken at the battery not the cables. I never thought of the timing issue, I have initial @ 12 and full @ 36... Atleast I think my timing is set there..... Better double check.

Dave, the alternator is putting out 14.5 on the back of the alternator but the battery is only showing the 13.2......

I charged it on my trickle charger overnight came out said it was full charge with charger on and hooked up to my battery I got 13.2, once I unplugged the charger it dropped to 12.6 and stopped around there. 1 hour later still read 12.6......
 

·
Registered
Joined
·
1,913 Posts
I think you have charge problems. You should not have a 1.3V drop from the back of the alternator to the battery. It should be a single piece of gauge wire with good termination on each end. 10 or even 8 gauge. It should have less than a .1V drop.
 

·
Registered
Joined
·
305 Posts
Discussion Starter · #9 ·
Took it to Autozone, checked it out, they put a load on it, failed the test, recharged it there tested again, failed...

17 days out of replacement battery period... Had to call Optima because store would not replace it because it is out of warranty. Winded up talking to a real nice guy at Optima that was able to get it approved to get me a new battery, they are shipping it out to me on Monday!!
 

·
Premium Member
Joined
·
22,122 Posts
yeah!!!!

Trunk mounts are tough, there is just so much wire.

Can you get a voltage drop reading across that cable?
Maybe use some sort of extension cables so one end of the meter is connected to the pos battery cable, the other to the end on the starter, see how much it's really dropping when cranking, should be as near zero as possible.

That one wire has to go for sure.
 

·
Registered
Joined
·
5,277 Posts
Your readings don't seem unreasonable for a battery that has been sitting for some time without a charge. 12.17 is not out of the ball-park for a battery that has been sitting. Ditto on charging. Your starter will want to see at least 8 volts if not 10 during crank. That means the battery voltage would be slightly more than that due to a voltage drop in the cables.

On another note, there is no reason to run your water pump or fans while cranking. Heck, if you're carberated, you might even get by without running the fuel pump. Just a thought to lighten the load by a few amps during crank.
 

·
Super Moderator
Joined
·
33,294 Posts
I agree with dnult. Those readings are good, 14.5 at the alt and 13.2 at the battery are good with an external regulator. Another help is to swap the alternator for a 55 amp or 61 amp as they use the same ext reg. And a step further is to replace the ext reg with a Wells VR715 reg, electronic.

The battery is in a low charge state, the alt is working hard to replenish. Also, there will be a low reading at the battery posts in the trunk.

One thing to help having a higher charge voltage at the battery is to have the terminals soldered onto the cables at all places. A solder pot is an excellent tool to use to tin the cable, and tin the terminal, then finish by soldering them together.Then slid over a length of shrink sleeve to protect from the elements. You did put on the length of shrink?

After you get the battery charged, you might attempt to up the voltage setting at the regulator by removing the cover and lengthening the spring to increase voltage. It doesn't much to increase. Or better yet, take your reg & alt to alternator shop and have them adjust it for you, say to 14.8 under full load.

After changing to an internal reg alternator, charging will be better, but the battery measurement would rpobably be low due to cable losses. As cable heats up with current losses, available voltage goes down, hence the warm/hot cable showing a voltage drop, part of physics occurring.
 

·
Registered
Joined
·
5,277 Posts
Since your battery is trunk mounted, you might be interested in using remote sensing to help with the long path to the battery. Take a look at http://www.camaros.net/techref/electrical/dnult_alt/. Get a good 130 or 140Amp 5 wire (3 wires used) alternator. Run the charge wire to the battery in the trunk. Connect the remote sense to the horn relay. This will give your battery a little more voltage than the electrical system and help keep it charged. Also the newer alternators put out a heck of a lot more at idle than any of the other varieties.
 

·
Registered
Joined
·
1,163 Posts
in addition, a bad starter will draw a ton more current than a properly working starter...not that thats your problem, but i have seen bad starters melt the cables right off a new battery that a customers "boyfriend" just installed...turned it over hard until it started smoking...lmao...if it werent for guys like biff though, where would guys like me be???
 

·
Registered
Joined
·
5,277 Posts
It would be worthwhile to pull the plugs and do the crank test again as well. To borrow someone elses words it should spin like a singer sewing machine. Also, your voltage drop should be significantly less. I'd expect you to see more like 10 volts.

I bring this up because my step brother's GM pickup was drawing 900Amps from the battery during crank. Turned out the problem was a bearing siezure after some teenage oil changer put antifreeze in the oil pan. I doubt you're having a severe problem like this, but it wouldn't be a bad idea to rule out mechanical drag issues before throwing money at it.
 

·
Registered
Joined
·
305 Posts
Discussion Starter · #16 ·
Good points guys, once I get it running and convert to the CS Alternator I will recheck some of these things just to be in the safe side.
 
1 - 16 of 16 Posts
Top