Bad (Optima) Battery ??

[JimsGems]

Batteries are funny things, as you know. If you charged the battery and you were able to load test it accurately and it's pulling down to 11.5 when 13.8 to 14.4 optimal you are loosing to a 2.3v drop under load, I’d say… "your battery is toast!"

I manage Uninterruptible Power Systems (UPS’s) with 600 batteries (typical per location) including distribution and related inverters and I loose approximately 8% (48 batteries) a year on average, and they are under constant load. Batteries used or unused fail! (These batteries are about $600 each) The new batteries (Gel-Cells, like the Optima requires no maintenance once activated) are much better and more stable than lead-acid batteries of the past.

Once activated you can plan on a four year life cycle (under use or sitting on a shelf), batteries will usually work better if they are used and prevented from being "deep cycling" (run down and fully recharged). There are trickle chargers designed and available, I strongly suggest once you install a battery in a Cobra or…? And it may sit through a winter or during a two year build, keeping a trickle charge on the battery will assure a good chance to get optimum life out of your battery.

Batteries also like moderate temperatures without getting real cold or real hot, that another reason to keep the battery behind a seat or in the trunk. Ideal (I said Ideal) is 68 to 74 degrees. Cold batteries can’t make enough power and hot batteries have a shorter life cycle. Don’t let batteries freeze and don’t set or store them on a concrete floor. This is just a basic rule & there are always exceptions.