Maybe we shouldn’t have let the Miata sit so long

Ah - very timly as mine wasn't able to start after sitting without a trickle for a few weeks.

Right off I've driven my 92 NA once a month or so through the winter, keep it on a trickle charger when I remember.

Been trying this week but haven't been able to bring it back trying to trickle charge while jumpered to a "good" battery also.

Last batteries I've bought were were all the 8AMU1R :

RockAuto - DEKA 8AMU1R - 11/2/2023 - $137 - Dead last week call it 1.5 years

Battery Mart - MAR-8AM-U1R "Miata" - $114 - 02/19/2019  - 11/2/2023 - 4.7 years

Battery Mart - MAR-8AM-U1R "Miata" - $N/A - 11/19/2015 - 02/19/2019 - 3.25 years

So average a little over 3 years life on those.

Might have to grab the diehard silver ($200) another battery mart one ($160)

Get one of these: Link

It actually works. I couldn't find the key to the Miata. I finally check the ignition. Yes, there it is, turned to accessory. Talk about dead!

Neither my car charger or my motorcycle charger would "see" it. That red box thingy sure did, and in about 8 hours brought it back full strength.

YMMV, but it worked for me. Sure, it's no replacement for a new battery, but you might be able to get a few more years out of your old one.

P.S. Two days later I left the fog lights on at work. Same routine. Brought it back again!

Edit: The Miata battery is 3 or 4 years old. I think 4. And yes, it's been dead several times before this episode.  

In reply to Shadeux :

Might have to try that - I just have a harbor freight trickle charger but borrowed my neighber's Schumacher unit also (has an AGM mode).

It never told me the battery was bad, but the light would come on green, say 100% charge, and then it wouldn't start. In the "start mode" it would just start like normal.

Throughout the past week I've kept messing with it, it'll charge enough to just barely turn the engine over then clicks.

I took it for like an hour drive after just jumping it and when I parked and tried to restart, the same.

I learned this lesson with the Datsun. I now have the cars and bikes on battery tenders.

In reply to Tom1200 :

I've learned this lesson too. Then I learned it again. And again....

The Miata sits on a Ctek charger. All of the lights were green, too.....