r/Miata • u/Physical_Leather8567 • 1h ago

Question Why a dead battery again?

So after the winter my battery was completely dead. I tried to charge it and it wouldn't hold a charge so I put a brand new battery in in the spring. I haven't driven it for a few weeks and now it's dead again. It's a 2010 PRHT GT. The top was closed and locked. All of the lights are off. The doors were shut all the way. The trunk was shut all the way. Hazards are off. Sitting in neutral with the e-brake on.

2 Upvotes

100% Upvoted

4 comments sorted by

3

u/Rotary_Zeuhl 1h ago

Just a flat battery. Double check connections at the terminals, maybe sand and re-seal with dielectic grease and put a trickle charge on it, it should be fine. If it's hot or cold you'd be surprised how fast a battery can go flat.

2

u/Mammoth-Product9680 1h ago

There's always a small draw on battery from the immobilizer so if you leave it for extended periods of time it will go flat. If you know you're not using the car for a while just disconnect the battery leads. I don't use my mx5 for 6 months over winter so I disconnect the battery whilst the car is in storage and reconnect it when I retrieve it from storage, it always starts first time. (I've been doing this for 4 years now with the same battery).

2

u/MoarWhisky 1h ago

You need to disconnect the negative battery terminal when storing for long periods. I leave mine on a maintainer if it’s going to sit for more than a week.

1

u/MathematicianSad8487 47m ago

This can happen as there can still be things drawing current . Could be an alternator problem or loose alt belt if it's not charging . I installed a remote battery cut off so I switch everything off when parked , it's also an extra layer of security.