91 brg that I only get to drive occasionally, and have had problems with batteries.
I bought a new WestCo battery last year and put one of those priority start auto disconnect devices.
The battery discharged to a level that even with the priority start didnt preserve enough juice to start it.
So I took off the priority start and was able to jump start it.
Now it is so dead that I can't even jump it.
I had one of those emergency battery jump start kits that also has a cigarette lighter dc source.
I plugged it into the cigarette lighter and then the warning lights would come on, but still I wasn't able to jump start it.
I am not very savvy with electrical stuff- so can anyone give me some advice? Did I fry something (Alternator?) and how to best check it. Would replacing my battery help? Any help greatly appreciated.
The first thing to do is to disconnect the battery, and try charging it a a low rate (about 1-1/2 to 2 amp charge rate) for at least 24 hours. The Miata battery requires a low charge rate to charge properly. It may not be fully charged after 24 hours, but should have enough charge to function. Next, There is a question as to the condition of the battery. This generally requires a "load test" by a battery shop that is honest and knows what they are doing. Places like "Auto Zone" can do this also, but you always wonder if they know what they are doing. Once the battery is charged and "known good", then it's reasonable to see if the Alternator is functioning. With a good charged battery and alternator, the running voltage should be above 14 VDC and usually slightly less than or equal to 15 VDC. Below 14 VDC usually indicates a problem, unless there is a very heavy electrical load present, or the battery is low or malfunctioning.
It is possible to "load test" the alternator with the proper equipment on or off the car. Again this should only be done by someone that knows what they are doing.
Given that you have a 91 model, it's not unreasonable to suspect alternator problems, esp. since you have replaced the battery and still have trouble. Since you drive the car only occasionally, a trickle charger is likely a must have to maintain the battery. Without considering such things as radio codes and the like, a battery disconnect switch might be appropriate.
My 99 has had a history of battery replacement. The OEM battery was bad when I bought the car. A review of the port inspection records showed that the battery failed port inspection, was charged, and passed by a few hundredths of a volt. The battery was replaced with a Westco within the first mounth of ownership (Warrenty Replacement) The Westco failed load testing in 2005, and was replaced, likely as a result of odd starting problems related to a bad Cam Sensor. I do notice that only occasional use can result in a slower than normal cranking speed. Using a trickle charger now and then seems to be the answer, and is really appropriate in cold weather.
If the battery voltage is too low, my 99 will crank slower than normal, and may not start. Seems the ECU or something related to the ignition will not allow the ignition to fire when the battery voltage while cranking is below some value.
Take a look at the Battery Tender (preferrably the Plus model, with the Miata or other AGM batteries...)
formatting link
That way, you keep it plugged in, and it only charges when needed... No worries about destroying anything or overcharging. I use them on my motorcycles when they're sitting - works great..
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.