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1999–2005 Mazda MX-5 Miata Battery FAQ's

Please read our FAQs page to find out more.

Where is the NB battery and what size fits best?

The battery sits in the trunk. A Group 51R or Miata‑specific AGM fits well; lightweight AGM or lithium options reduce weight and sharpen response while preserving balance.

Do I need a vent tube on the NB Miata battery?

Yes for flooded/AGM units—use the factory vent routing to keep the trunk fume‑free. Lithium batteries don’t vent gas but still require a secure tie‑down.

Should I use a maintainer on a weekend NB?

Yes—ECUs and alarms draw a small current. A smart maintainer prevents low‑voltage starts and extends battery life during storage.