For the electromechanic's GURUS

[vizail]

This apply for a 1982/ 911SC 3.0L

I notice that after a few days the batery loose some cranking power.
The alternator is working fine and the output is from 13.5 to 14.3 Volts. I see that I have a 600 amp Batery and have to give it a quick charge everyother day.
Can I put one of this New Gell Batery's , with 850. to 1000. amp?
I'm considering the instalation of two electric fans for the rear A/C Condenser
All imput will be greatly appreciated..!
Cordially

Vic

[Fritz Peyerl]

Vic, how old is the battery? can you check how much current draw you have when the car is switched off. This will show you if you have some stray current.
Also check your battery cables and the grounding strip from body to starter or transmission. Corrosion on the connectors can give low power.

[vizail]

The Batery is about 2 years old and the car is not used that often. I've clean and change almost all the cables on this car. I disasembled this car for RESTO and I'm in the final stages .
I wanted to know if I can put one of this new high amp Batery's (850 to
1000 amp. for the new Condenser fan Istalation since I will need more power. The starter is new

Current draw... You mean having the Voltimeter on when running and then turn it off and see the Voltage reading?

Cordially

Vic

[DW SD]

Originally Posted by vizail

The Batery is about 2 years old and the car is not used that often. I've clean and change almost all the cables on this car. I disasembled this car for RESTO and I'm in the final stages .
I wanted to know if I can put one of this new high amp Batery's (850 to
1000 amp. for the new Condenser fan Istalation since I will need more power. The starter is new

Current draw... You mean having the Voltimeter on when running and then turn it off and see the Voltage reading?

Cordially

Vic

Vic,
Voltage is analagous to water pressure. Current is analagous to volumetric flow of water per unit of time. Typically, you need an inductive apparatus to measure current flow.

Isolating current drains is not simple, but a good first step would be to test your battery. If it is bad, replace. If it is good, then you will need to find current draw source. Clock is a known source for cars used very infrequently. I use a battery shut-off switch. Clock would take weeks to drain, not days.

Here's a simple exercise that might shed light:
What is your battery's voltage after two days of sitting (can you check once or twice a day and plot battry voltage vs. time - when the battery is hooked up to the car? What happens to the battery voltage vs. time if you leave it disconnected from the car? If there is a big difference, I'd suspect a voltage drain somwhere.

Doug

[vizail]

Doug

Very nice exercise. I will start taking readings tomorow. The clock..! I know will draw some power . I will plot Voltage and time laps.
But how about a powerfull new Gell Batery or a biger, more amp capacity batery, let say a 875amp instead of a 600 amp?

Cordially

Vc

[DW SD]

Originally Posted by vizail

Doug

Very nice exercise. I will start taking readings tomorow. The clock..! I know will draw some power . I will plot Voltage and time laps.
But how about a powerfull new Gell Batery or a biger, more amp capacity batery, let say a 875amp instead of a 600 amp?

Cordially

Vc

Vic,
I have a 450 CCA battery in mine with the 3.6 - it is the smallest car battery that costco sells. I don't think more current capacity is necessary, unless you drive in very cold weather.

Doug

[brendon]

A higher amp battery will really only give you more cranking power. If you need to be able to handle more power when the car is running (e.g. extra electric fans on your condensor), a higher-amp alternator may be necessary.

I forget what our alternators are rated for, but there really isn't a lot of current draw in our cars. Very few electronic devices compared to newer cars where everything has a computer attached. Unless you plan on doing a big stereo as well, your stock alternator will probably be able to handle the extra fans.

[Kaliv]

Just curious, is there a way to check how well your alternator is working without finding out that your battery won't start your car after a few days of driving?

[911pcars]

IMHO, it sounds like electricity is leaking out.

Connect an ammeter to the neg. battery post/cable and measure for current leak with ign. OFF.

You can have the highest capacity battery, but if it discharges between use, it will be useless.

Sherwood

[vizail]

No No you guys didn't get it . The batery lose some cranking power in about a week or so.
I want more cranking power and reservior of amp.
The question is simple .
Can I put a bigger capasity batery without afecting the system?

Cordially

Vic

[MURF]

Do You Have A Battery Drain??remove Negative Terminal And Connect Test Light Between Terminal And Post..if Light Lights Up..you Have A Draw.pull Fuses And Disconnect Consumers To Locate Culpret..usually Stereo Installation

[DW SD]

Vic,
Murf and Sherwood offered nice test ideas, which will work.
Think of your battery as a bucket of water. If water is pi$$ing out of the bucket (current drain), using a larger bucket is still going to end with an empty bucket (no current to crank your car). It just might take a day or too longer with the larger battery.

Doug

[3.2 CAB]

In car battery terms, HIGHER AMPS, OR CCA = longer time to run down when not in use. You could put a number of batteries in the trunk, but if you don't fix a voltage drain, those batteries will run down in time. I had a voltage drain problem before, do a search. It was my old tired stereo causing the drain. Good luck!! Tony.

[vizail]

MURF

I put the test light from the negative(-) post to the car body and no light.
Took and log a Voltage reading the batery today 12.6 V. So far so good.

I'm beginning to suspect that the stereo and the clock might be the culprit.

Will keep you Informed.

Cordially

Vic

[vizail]

Second Batery Votage reading 24 hour's later 12.5 V.

I disconect the negative terminal and put a test light from the negative Post in the batery to the body and the test light didn't came on.
I still think I need a batery with more cranking power 900 CA

Cordialy

Vic

[911pcars]

With all due respects, I still think you don't. Try using an ammeter instead of a test light.

But it's your dime.

Sherwood

[vizail]

Sherwood

Thank's for the input, and in IMHO I don't know how to use it, I just take Voltage reding's in the appropiate DC range, and take continuity check's wiht the test light.
Can you show me how to set the Ammeter and take the reading's?
Here is what I have..


I'll really apreciate The Help.

Cordially

Vic

[dshepp806]

METER SET TO: 200mA scale, 12:30 PM position, just below and to the left of the symbol showing "A", with the horizontal lines (dashed and solid,..as this will be measuring DC (NOT AC) amps)). (Assuming you have no more current magnitude to measure than 200 mA DC, that is..if so, you may use the 10 AMP connection point on the meter, although +/- tolerance will be less precise..)

Move the multimeter connection (red cable) (FROM THE PRESENTLY ILLUSTRATED VOLT POSITION) to the 200 mA connector point on the meter,..ground (black) stays where it is....now the meter's ready to measure DC current. (Doesn't really matter about current flow direction polarity), just hook one meter lead to disconnected neg. battery cable and the other to the battery terminal post. You will then read the current draw on the battery in milli amps...

Understand that your meter is fused internally for it's current metering circuits, should you blow a fuse on the meter or something, you can replace the meter's fuse (although I don't think it will happen).

Don't frikin do it if you're not clear on the procedure..

Best,

[dshepp806]

Leak, ...

...bad/weak battery.............

....connections,.............


...weak alt?....


could be many things,....

Drain is first!!


Best

[porcupine911]

to complement doyle's written instructions...