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I just had my second Optima die without warning a few weeks ago. My car is equipped with a kill switch and power was shut off from the battery. I had purchased two Optimas several years ago, and installed one in the car. It worked really well, but when the car was in the shop last year the battery died without any warning. Figuring that they might have left the radio on, I brought out the other battery and all was fine. The car sat in the garage for most of last year waiting for the wheels to come back, and this spring, once I got them mounted, the car started right up. I took the car to a local car show and everything was fine, and then a couple of weeks later, took it out to a suburban car show and drove the car 80 miles on a hot day. Car performed very well, got home, and got it home in the garage. Went out to go to the Father’s Day show at Oakbrook Center, and the battery was totally dead, not even dim lights. I checked and the cut off switch was off, and I tried to charge the battery. I only got some dim headlights and not enough juice to turn the starter. Tried several more times to charge the battery and nothing.
The ammeter on the car is working, and shows a good charge coming out of the generator. Does anyone have any ideas?
My experience is that if an Optima discharges below, perhaps, 5.9 volts, that conventional charging of that battery alone will not bring it back. What usually works for me is to wire the discharged Optima in parallel with another 6V battery (which can be wet cell) that has at least 6.1V, then slow charge. By slow charge, I mean 4-6 amps, for perhaps four hours. Give it a rest and do it a couple of more times. When the discharged Optima will hold 6.1 or 6.2 overnight, then you can top off the charge with that battery alone.
While the Optima(s) are coming back, suggest you hunt for whatever is pulling them down. This is much easier on cars which have fuse blocks–i.e., not 1929-forward Pierces. Use a volt-ohmmeter (VOM) but with the meter set to accommodate 10 amps. With a good 6V battery in place, disconnect the ground cable and connect one lead of the VOM to the battery ground post and the other to the detached ground cable, checking for amp (current) draw. There should be NONE. With a fuse block system, you would remove one fuse at a time until you get the desired zero reading; but with Pierce’s circuit breaker system you have to disconnect one electrical item at a time.
Wild guesses:
1. With battery disconnected, test the master shut off switch both open and closed and look for a short and/or resistance. Then check the cutout.
2. For your car, the clock would be the first power-consuming item I’d disconnect.
Please keep us posted on what you find.
As a point of reference, I recently purchased a ‘41 Cadillac (sorry, my P-A is undergoing open heart surgery) that had two Optimas in parallel. While in transit from Seattle, the transport company left the cut-off switch +ON+ and the glove box door open. The light in the glove box killed the Optimas. I was able to get them to successfully accept a full a charge, but under load, while cranking the engine, they were toast. I put them on a load tester and indeed, even though they came up to resting voltage OK, as starting batteries, they were useless.
Adam, I’m sorry to hear of your misfortune. Yes, Optimas cannot tolerate a really deep discharge. If you haven’t tried the method above (charge in parallel with a decently charged other 6V battery), you just might be able to salvage them.
I did try the method you suggested and the batteries came up to voltage. In terms of cranking ability, not so much. #history
I use Optima batteries for most of our 6 volt cars and in the P-A Museum. I have a couple in use dating to 2013 and 2015 without any issues. I love them for many applications and almost all vintage car use. But be aware that there are two issues that will harm Optima batteries.
1) Constant small draw to discharge as described above. I went through two new 12 Volt Optimas in two weeks on our 1988 Cadillac with the car garaged. After replacing the second one, the dealer called Optima and they advised that the slow constant draw from the integral computer would kill an Optima. Conversely our use in the Museum on earlier cars results in holding a virtually full charge in storage for over a year without issue.
2) Charging an Optima with a conventional battery charger quickly destroys their capacity to retain cranking power. You must use an “AGM” battery charger exclusively .if you want long life from an Optima
@David – this slow draw business with the glove box light is exactly what clobbered the Optimas I discussed. My go-to chargers are +NoCo Genius+ I have several. These are super versatile as they’ll handle standard lead-acid, AGM and LiFePo4 (Lithium Iron Phosphate) types. I’ve had batteries that that were given up for dead, recovered by these chargers. Alas, these Optimas were too far gone for hope of satisfactory revival.