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Battery Sizing
How much Ah you need for engine-off playback.
Inputs
W
min
Results
Fill in the inputs and tap Calculate to see results.
From the Catalog
Real products with verified specs. Tap one for the full data sheet.
Gear for this build
In stock at our partner shops — real prices, shipped from people who run this stuff.
JS Alternators
JS Alternators High-Output Alternator
250A–400A+ hand-built in the USA. Find the fit for your year/make/model.
From $649JS Alternators
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Sundown Audio
Sundown SA150-975L Super-Cap Battery
What a capacitor pretends to do — real stored energy for voltage sag.
$299.99JS Ultimate Sounds
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Stealth Energy
American Bass Stealth ST-750 75Ah AGM
75Ah AGM — deep reserve for high-draw audio and dual-battery setups.
$434.28JS Ultimate Sounds
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Stealth Energy
Stealth Energy ABLT-40 13.8V LTO 40Ah
Lithium titanate — huge current, light weight, holds voltage under load.
$620.72JS Ultimate Sounds
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JS Ultimate Sounds and JS Alternators are run by the ShowUp team — buying there supports the site. Prices as listed at the shop.