Optima battery charge current is high
 

After starting the engine (new cobra - not driven yet) the amp meter reads between 10 and 25 amps depending on the state of charge of the battery. I've checked everywhere for low resistance to ground, etc. (thanks, Blas for your help) and everything looks right. The alternator is putting out 14.8 volts (perfect). I checked the amp meter and it is reading correctly. I've pretty much narrowed the problem (if it is a problem) to the Optima Red Top battery. Has anyone had this problem or is it normal?

Even I'm looking forward to this one to be resolved.
You might also note for everyone that you duplicated the high AMP meter readings on two different gauges. And that all your grounds have been checked, as were cable crimps, etc.
You could just try a different battery from another car maybe, that would be a fast and easy way to tell if the Optima battery is bad...Perhaps a shorted cell or sulfiding from sitting unused? What's the date on the battery? RED top right?
Maybe a call to Optima or where you purchased the original battery for a test or replacement battery?
Fly me out to Calif from cold Chicagoland, even if it takes 3 weeks to resolve the problem, or until Chicago get warm....

The alternater will only produce enough amps to get the job done. If the battery is fresh and there's no other load, the alternater will only produce 10-20A. As lon as the volts are good, don't worry about the amps until you start putting a bigger load on the system.

Blas,

Yes I DID run a second ammeter in series with the amp meter and, when turning a fan on, got the same reading on both meters - so, the amp meter seems to be working fine. Given the record with short life for the Optima batteries I'll probably buy a second battery (not Optima) and try it. Any recommendations for a non-Optima battery??? Meanwhile - it will take me a week or so to get to this - Erick Voss has my car right now for the clutch and other (brakes, etc.) problems. I'll post results for everyone's benefit.

Highest CCA you can find in your size
 

mattpatt Matt unless the batterys is mount other that trminal side upAny battery will do. There are only a couple of battery companies making all the batterys sold. Opti I believe builds their own. If you can find a 750 CCA or higher, this should be fine. Check the warrentty for coverage. First year is free replacement and after that pro rated. Some have a free replacment for 5 years. This battery also cost double the price. I do know that Opti batterys charge higher voltage that other normal ones. This is hard on the Alt and charging system. Would recomend you have a master fuse to protect if a short happens in the car. I have a 95 amp setup and run a volt meter. I run 14.21 volts. I don't worry about amps, they are there. If you can isolate the battery with some hard foam and still have it not move around, this may help extend the life of the battery. I also run a trickel charger. Check batterys at Sears, Pepboys, Auto zone, O'Reillys, NAPA, for prices and warrenttys. Good luck Rick L.

I can't see your problem.

If you have say 12.5 volts, then fire up the engine, the battery volts drops to say 10 volts cranking, if you then have a charge rate of 14+ volts, then there must be current flow of some figure.

I think you're chasing a problem that's not a problem.

Does the battery start the engine ok in all conditions?

Does the charge rate have acceptable tolerance to load condition? eg: lights, wipers, ignition system etc.

Blas,

Didn't answer all your questions. The battery is a Red Top dated 4/11 (I think) - it's at Erick Voss's right now.

I may try a different battery just to know once and for all.

Who knows - maybe there's no problem and this is normal - but I'd hate to be on a long ride and have it go belly up on me.

Thanks, guys

If this is a new car, then the battery is presumed to be new and in need of a full charge. The high charge amp doesn't surprise me. Before you run out and buy a new battery, throw a charger on it overnight and then check your amp gauge. I bet your battery just needs a good, solid charge after sitting idle.

DD

I'm thinking once the car is started,running your ignition system (MSD or otherwise) and an electric fan, 10+ amp draw would be normal, depending on what else electrical you have on at the time, 25 amp draw is not out of the question......You may not have a problem... before you go buying another battery, pull the one off your daily driver and try it and compare the results.......
As bob said, once started, an alternator only produces the amps needed to maintain the draw on the battery..

David

That amperage draw is not unreasonable. You're running the ignition (I assume you don't have a magneto), you're overcoming the resistance of the wires, the battery just cranked the engine, so it can take some charge, and the battery probably wasn't fully charged when you cranked the engine (they really never are unless a charger just finished running on it).
I think the problem is:
A. You have an Ammeter.
and
B. You're looking at it.
:-)

Ammeters are nostalgic and period correct, but just about everything else about them is a bad idea. Running the entire electrical load (independent of the starter) of a vehicle (especially a modern one) through a little instrument in the dash is antiquated. Even if it works you need a voltmeter to get the whole picture of what's really happening.
What is the range of the ammeter and what is the maximum output of the alternator? Lot's of people run alternators that exceed the capacity of most ammeters.

new charger
 

i just changed batteries (red top) and learned that the opti battery require a unique charger. New battey may need a charge to top it off. Our amp meter was pegged until I ran the charger through its full cycle, been fine ever since. Check out the opti web sight and look at charging requirements. hope that helps.

I'm sure the high early charging current is associated with the battery. Everything else checks out OK. In running the engine a bit longer (a 12 mile drive) the current drops from an initial ~20 amps to ~9 amps. So, the battery is charging. A std battery would charge much faster. Maybe this is normal for AMG batteries? I'll drive it a bit more and then, probably, take it out and do a full charge/rest and have it checked. Maybe it's normal????

As DD says, an overnight sleepover with a battery charger should clear its head-cold, if not then a replacement may be in order. -- You may want to swap it out for a new optima, blue top.

Steve

I've contacted Optima and.on their advice, will doo a charge, rest and test process to determine if the battery is "ok". I'll let everyone know the results.

Final info on this "problem" for those that may find it helpful.

I swapped in the battery from my regular car (advice from Blas) and, after starting, the charge current spiked and dropped to ~4-5 amps within ~30 seconds (the Optima was leveling off at ~9 amps best case). So, the Optima was drawing more current than I expected.

With the engine off I ran a few loads (wipers, 2 light settings, etc.) with a digital ammeter in series with the amp meter. Looks like the amp meter reads 2 - 3 amps high (at lease on the discharging side or the meter). So, with the regular battery the actual charging current was 2-3 amps which I expect (MSD ignition - is read by the amp meter the way I have my wiring done).

Per Optima's instructions I charged it completely, let it rest a few days and had it tested on an automatic tester (Pep Boys). Results - a good battery.

In reading up on AGM batteries (like the Optima) I've learned that they have very low internal resistance compared to conventional batteries. This is probably why the high charging current even when fully charged. I could not find any details about the resistance value and if it applies during charging, though.

Bottom line - I put the Optima back in the Cobra and am not worried - seems to be normal. Like Jim said, my problem was that I have an amp meter and was looking at it.
<{:>)))

By the way - after re-installing the Optime the charging current is now lower (5 - 6 amps). Maybe a new battery just needs to settle in?

Thanks everyone.

Matt