Hey guys.

I have a 93 RX7 that I don't drive much, just 25k miles total.

This has caused battery issues, so my general solution has been to use a trickle charger while it sits.

However a few months ago I went to start it, seemed to have power inside the car (power door locks, lights, etc), but when I turned the key, nothing. No sounds, no attempts to start, nothing.

I could JUMP the car and it would start... so I did that, left it running for like 30 mins or more, then turned it off. Then when I turned the key, again nothing.

So I replaced the battery a few months ago, got a decent priced one. Turned the key... fired right up. Cool.

Now every week or two if I hadn't been driving it I'd make sure to start the car... let it run for a bit, turn it off. Fine. Now a few days ago went to do that... and same as before, power in the car, turn the key, nothing.

Trickle charger has a green light indicating it's fully charged.

Any thoughts on what's likely causing this and how I might avoid this problem?

And once fixed, should I go through the effort of just disconnecting the battery in the future every time I park the car? How long should a car be able to sit without the battery draining if everything is working as-expected?

Thanks for any thoughts.

 

Do you have or can you get a digital multimeter (DMM) or analog voltmeter? You'll need one to do some quick troubleshooting. First thing is to just hook up your DMM/voltmeter across the battery's terminals and measure the voltage. Do this with the engine not running, and then again after you get the engine started and running at idle speed - report back with your voltage readings. If your battery is good and fully charged, you should be seeing about 12.4 ~ 12.6 volts with the engine off. With the engine idling, you should be seeing between 13.8 ~ 14.5 volts at the battery terminals, which tells you the alternator is good and charging the battery.

If the battery is good, and the alternator is charging it correctly, then you have a parasitic current drain that is draining your battery when the car is just sitting. Could be something simple & stupid - does the dome light go off with the doors closed? Glove box or hatch light on? If not one of those, then you'll need to start hunting for the circuit that is drawing the current. But before we go there, post up the voltage readings.

 

The trickle charger would not be affected by the parasitic drain and would keep the battery charged.

Might be an issue with high resistance in the ignition switch. Try to listen when you turn the ignition switch and see if you hear a “click” but no start. Try to bypass the switch to test. You can undo the plastic around the column and unplug the harness.

 

Well that would really depend on how much current the parasitic drain is pulling, and on the trickle charger's design. Most trickle chargers limit charging current, so it's entirely possible that the charging current will just be consumed by the parasitic load, and the battery won't be fully charged - even if the indicator light on the charger says it is.