bet

I have had the battery tested twice in the last week. Each time it says good battery. The p-car mechanic says that he has not had good luck with the dry cell technology in 993's. He suggested I get an Interstate and a battery acid pad. Hmmm. I find that difficult to swallow having spent $110 on the Optima and I can't prove it is bad. I guess I will see what he figures out today.

Thanks for the suggestions.

WillyC4S

Brian,

I had the same problem w/ my C4S last year and posted on this board some of my results. I ended up leaving out 2 fuses for the interior lighting and it seems to have fixed the problem. It was an intermittent issue.

The 993 at rest should read about 20mA current draw. No-load reading.

With the fuses pulled, I could let the car sit for over a week and it would start up. Could not do that before when having the current leak.

I also noticed that my LED's in the door would be flashing slow immediately after I activated the Immobilizer. This is not the correct sequence. It should be flashing fast for 10 seconds and then settle down to a slow flash after that. If it enters the slow flash mode immediately there is a fault somewhere in the system. Could not find this fault as all the pin switches (including the one in the glove compartment, did you know about that one?) were fully functional. Manual discusses these flash modes under the alarm section.

Pull the fuses and see if that helps. If it does, then at least you have a temporary solution. For me it works, but I live w/o interior lighting at night since I don't drive my C4S daily.

Careful w/ the current measurements. Putting a meter in line with the current can be dangerous as the entire load of the car goes through the meter. If you start the car w/ the meter in line you'll have to get a new fuse for the meter (minimum) and maybe a new meter.

Good luck and let me know if you have questions.

*****

Ben in Plano, TX

Brian,

While it could be your specific Optima (quality control?) and/or the application of the Optima with a '96 I can tell you my red top has been flawless for about a year now in my '97S. I also have a friend with a '96 C4 with the same experience.

Ben

bet

*****,

Thanks for the comments. I have read your thread extensively. I actually printed it out and gave it to my mechanic. I have only been able to reproduce the flashing LED's once, and that was when I set of the alarm while pulling the fuses.

I could get my reading down to .02 with #38 (radio boster) and # 29 (interior lights I think). However even with those in I could not get a reading higher than .04 (it went to than when the LED flashed). This doesn't seem like enough to completely flatten a battery in 5 days.

Thoughts?

Ben,

I am with you. I don't buy the Optima doesn't work with the 993 argument the mechanic said. Too many people use them. Now whether or not mine is good is another question that I am not completely sold on. I am going to take it to a different battery store to have it tested.

WillyC4S

Brian,

I didn't think people ever read those deep technical posts!

I'm not sure what you mean by "only been able to reproduce the flashing LED's once". Everytime you activate the Immobilizer to lock the car, the LED's should start flashing. The question is whether it's a slow flash or a fast flash for the first 10 seconds after initially locking the car. A car without any electrical faults should exhibit fast LED flashing for the 1st 10 seconds after locking the car. If it flashes slow immediately, that means you've got a door open, the glove compartment isn't closed, the front trunk is open or the rear engine hood is open. Of course, anything that opens the circuit along the wiring harness originating from those pin switches will produce the same effect as a floating switch (open pin switch).

Why don't you pull the 2 fuses out and let the car sit. However, make sure that your Optima battery is fully charged beforehand; that way you've eliminated the Optima battery as a variable in the test.

My guess is that with a fully charged battery (and assuming you have a good battery) and those fuses pulled out, you'll go more than a week and still be able to start the vehicle. This should be the case.

If the vehicle doesn't start then it is a bad battery since you've eliminated (most likely) the current drain and the battery is fully charged to start with. The only logical reason for a flat battery at that point would be a defective battery which won't hold a charge. If that is the case, then you'll have another can of worms to deal with in getting a replacement for an Optima. They aren't very good about doing things like that.

BTW, I had my ammeter hooked in series to the battery when the car was sitting idle for a week. I had the meter on top of the front trunk so I could easily see what the current consumption is at a quick glance. This way you'll know for sure that you're only chewing up 20-30mA during your experiment.

Let me know how this goes!

Good luck.

*****

mike cap

bet,

Just read these recent posts.

You're going around in circles with this. You know the charging system voltage is ok and the alternator does't "collapse" under load. You know the ma draw at rest is minimal. 20ma, 40ma, 60ma - immaterial. Still won't kill the battery in a month, let alone a week.

You have a bad battery. Follow your mechanic's advise and replace it with a lead acid maintenenace free battery. You're problems will be over. Well, one of them anyway....

bet

Mike,

No circles here. I just wasn't comfortable with my use of a multimeter nor the store's testing of the alternator, so I had the mechanic check. End result...the mechanic verified my multimeter readings (24-25 ma) readings and strong alternator. I agree it is the battery. Now I just have to decide what to do about it. Go fight with the store for another (it would be my third in 6 months) new Optima or eat the Optima and get an Interstate.

Related battery question...my mechanic says that the dry (gel) cell technology used in the Optima can be difficult to deal with. Specifically he indicated that a strong alternator can cause problems over time and cause the battery not hold a charge properly. Anyone else heard this?

Randall G.

I would be hesitant to blame the Optima technology (as opposed to having bad luck with one battery). Besides many people on the 964/993 boards having good success with them, a similar battery (made by Panasonic) was OEM on '90-97 Miatas. Apparently, Mazda didn't want to use standard lead-acid due to the battery's installation in the trunk. I still have the original battery in my '96 Miata (almost 8 years old), and it cranks stronger than the 2 year old lead-acid in my P-car. Over on miata.net, many (many) raves about how long their OEM battery has lasted--up to 12 years.

Good luck finding your problem!

mike cap

bet,

Glad to hear you're not chasing your tail.

I investigated the dry cells that are available for my piston aircraft a few years ago. I wanted to get away from the 1/2 hour chore every month or so of getting to ther battery case and unscrewing the dozen caps (24 vdc), etc.

I'm not slamming the Optima at all - a lot of thes guys seem to be very happy with them - but the same technology for the aviation side was frowned upon by the techs and owners in the field. I was told that the gell batteries were sensitive to taking a full charge if the voltage wasn't right on and weren't very forgiving for an aircraft that sits a lot, as most of our GA planes tend to do.

That's why I just bought a Diehard lead acid, maintenance free this spring when I replaced the battery in my '97 C2. Six years on the OEM battery I thought was pretty good and it was really still ok. I load tested it and it was fine. One of my guys probably has it in his boat.

No maintenance with the Diehard and just vent it through the trunk floor for safety's sake.

Randall G.

Hey Mike,

I have heard rumor that a flattened Optima cannot be charged with a home charger, and must be taken to a parts store for charging. But, I don't know this for fact (for example, I've never flattened my Miata battery). Some FAQ's for Optima batteries:

http://www.optimabatteries.com/faq.asp

Doesn't your maintenance-free DieHard still have caps/plugs for adding water/checking water level? I know that the "maintenance-free" Excide battery in my P-car has a threaded plug for each cell. One of those plugs leaked a tiny bit, even though I had never removed it. Snugged it up (for some reason it was loose?), and it hasn't leaked since. Anyway, I think the main motivation for buying an Optima (outside of it lasting longer) is to get rid of the lead acid spill hazard in your trunk. And, of course, no need to worry about venting hydrogen. For these reasons, and because of my excellent experience with the Miata, I'll be installing an Optima when the Excide dies.

mike cap

Randall,

You can pry the Diehard's caps off if you were so inclined, but it is maintenence free design and you should never have to. Any evaporation or boiling from an overcharge is recirculated and refills the cell.

As long as the vent tube is connected and exits (in my case under the car), you would never vent acid and gas into the trunk. It is very easy to re-route the vent tube to the front trunk drain nipple.

bet

I read the FAQ on the Optima. The very last paragraph raises a concern. I have the red top. I don't have an after market alarm but is the amp draw similar to the 993's 25ma draw? The fact that my car has sat this year for weeks at a time caused problems? This is my 2nd red top that has failed in 6 months. Maybe the red top is not for me at this point because I do not drive the car daily. Thoughts?

WillyC4S

Brian,

I went for the yellow top Optima because of the issue you mentioned, deep discharge for a SLI (starting, lights, ignition) battery isn't well tolerated; the yellow top is a deep discharge battery so can be recharged after multiple cycles of discharge (i.e. car sitting w/o a trickle charger).

*****

914und993

*****'s rationale for using a deep discharge battery is a good one. Modern cars have a much higher resting draw than older cars, and that takes a toll on ultimate battery life. What you give up with a deep discharge battery, compared to a "starting" battery of the same size/weight, is raw cranking amperage. The trade-off may be well worth it if the battery is regularly discharged more than a few percent of its total capacity (e.g. goes a week or more between drives). This applies to "wet" lead acid batteries too, not just the Optima.

Seems like the Optima red tops have had some quality control issues over some period this year (even the Bentley team at Le Mans had a bad one). That isn't necessarily a reflection on the technology of absorbed glass mat batteries.

Chip

OldGuy

there is a thread on the 964 board about a ccu fan draw
draining a batt. which a mechanic replied it is common
to 964 and 993's

https://rennlist.com/forums/showthre...threadid=89314

Hope I did that right