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A dead battery bank at dusk in a cabin, an RV bay with a tray that looks a size too small, a boat box that needs a fresh bank before the season starts: each one turns on the same question, and that question is the 8d battery size. It is a size class, not a single battery: the listings in this guide share a long, low footprint, while voltage, capacity, weight and height vary by chemistry and maker. The steps below show how to read the size, match it to the tray and the bank, and check the figures that matter before you buy.
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What the 8d battery size means
Group 8D covers large deep cycle and starting batteries built on a shared footprint: most listings here give 20.47 to 20.51 inches long and 10.55 to 10.59 inches wide, with heights from 8.66 to 9.5 inches. The LiTime and Redodo listings give 20.47 x 10.55 x 8.66 inches, the Mighty Max lists 20.47 x 10.59 x 8.86 inches, and the Odyssey lists 20.4 x 10.8 x 9.5 inches. The NPP listing gives 20.51 x 8.66 x 8.82 inches in the bullets and 20.51 x 10.59 inches x 8.82 inches in the spec table, so allow the wider figure when you measure. The same footprint holds both 12V and 24V batteries, so voltage comes from the label, not from the size.
Step 1: Measure the tray, the height and the terminals
Measure the tray length, width and height with a tape, and leave room for the cables and the hold-down. Compare each figure with the listing: the LiTime and Redodo listings give 20.47 x 10.55 x 8.66 inches, and the Mighty Max lists 20.47 x 10.59 x 8.86 inches, so a tray that fits one of those footprints may still need more height for the taller battery. Check the terminal style too: the Odyssey lists SAE top terminals, and the Mighty Max lists an internal thread terminal, so the cables and lugs must match the posts on the battery you pick. See the types of battery terminal connectors for the common styles.
Step 2: Read the size chart
The chart below gathers the figures the listings state for each battery in this guide. Read across a row for one battery, and read down a column to compare the same figure across the listings.
| Battery | Dimensions (inches) | Weight (lb) | Capacity | Voltage |
|---|---|---|---|---|
| LiTime 24V 230Ah | 20.47 x 10.55 x 8.66 | 84.1 | 230Ah, 5888Wh | 24 |
| Redodo 24V 200Ah | 20.47 x 10.55 x 8.66 | 82.67 | 200Ah, 5120Wh | 24 |
| NPP 12V 250Ah | 20.51 x 8.66 x 8.82 | 164.2 (2-pack) | 250Ah, 3000Wh | 12 |
| Mighty Max ML8D 12V 250Ah | 20.47 x 10.59 x 8.86 | 149.0 | 250Ah | 12 |
| Odyssey ODPAGM8DT 12V | 20.4 x 10.8 x 9.5 | Not stated | 1450 CCA | 12 |
The chart shows why the size label alone does not pick the battery: the LiTime and Redodo share the same 20.47 x 10.55 x 8.66 inch footprint, yet the LiTime lists 230Ah and 5888Wh while the Redodo lists 200Ah and 5120Wh. The NPP lists 250Ah and 3000Wh in the same class, and the Odyssey lists 1450 CCA for starting use. Use the chart to shortlist by footprint first, then by voltage and capacity.
Step 3: Match the voltage to the bank
The footprint does not set the voltage: the listings here hold 12V and 24V batteries in the same size class. The Odyssey, NPP and Mighty Max listings give 12V, while the LiTime lists 24V and the Redodo bullets give 25.6V for its 200Ah battery. Match the battery voltage to the bank voltage and to the charger and inverter the bank already uses. The NPP listing says its 12V 250Ah batteries can build 24V, 36V and 48V banks, and the LiTime and Redodo listings give Max 4P2S for larger banks. See the 12V vs 24V deep cycle battery guide for the trade-offs.
Step 4: Match capacity to the load
Capacity is listed in amp-hours and watt-hours, and the listings state both figures for most batteries here: the LiTime lists 230Ah and 5888Wh, the Redodo lists 200Ah and 5120Wh, and the NPP lists 250Ah and 3000Wh. The Mighty Max lists 250Ah with no watt-hour figure stated, and the Odyssey lists 1450 CCA instead, since it is built for starting. Compare the listed figures directly and do not convert between amp-hours and watt-hours, since the listings give each figure as stated. For a longer run time, look for the higher listed capacity in the same voltage, and check the cycle figures: the LiTime lists 4,000+ cycles at 100% DOD, 6000 cycles at 80% DOD and 15000 cycles at 60% DOD, while the Redodo lists over 4000 cycles at 100% DOD and up to 15000 cycles.
Step 5: Check weight, protection and warranty
An 8D battery is heavy, so check the listed weight and the path the battery must travel to the tray: the Redodo lists 82.67 lb, the LiTime lists 84.1 lb, the Mighty Max lists 149.0 lb, and the NPP lists 164.2 lb for the 2-pack. The Odyssey lists no weight, so check the label before you plan the lift. The LiTime and Redodo listings state IP65, and the Mighty Max listing states UL Certified, so match the stated protection to where the battery will sit. Warranties run from 1 year on the Mighty Max to 2 years on the NPP and Odyssey and 5 years on the LiTime and Redodo, as listed.
Ways to check fit before you buy
- Measure the tray in length, width and height, and compare each figure with the listing before you order.
- Confirm the voltage on the label matches the bank: 12V and 24V batteries share the 8D footprint.
- Check the terminal style against the cables: SAE top terminals on the Odyssey, internal thread on the Mighty Max.
- Weigh the lift: the listed weights run from 82.67 lb to 164.2 lb, so plan the path and the hold-down.
For more options, see our batteries guides.
FAQ: power away from the grid
How big is a group 8D battery?
The listings here give 20.47 to 20.51 inches long, 10.55 to 10.59 inches wide, and 8.66 to 9.5 inches high. The Odyssey lists 20.4 x 10.8 x 9.5 inches, the tallest of the listings here.
Is a group 8D battery 12V or 24V?
Both. The Odyssey, NPP and Mighty Max listings give 12V, while the LiTime lists 24V and the Redodo bullets give 25.6V. Match the voltage to the bank, since the footprint alone does not set it.
How much does an 8D battery weigh?
Listed weights run from 82.67 lb for the Redodo 24V 200Ah (on Amazon) to 149.0 lb for the Mighty Max 12V 250Ah. The NPP lists 164.2 lb for its 2-pack, and the Odyssey lists no weight.
What is the difference between the LiTime and Redodo 8D batteries?
Both list the same 20.47 x 10.55 x 8.66 inch footprint and a 200A BMS with IP65 stated. The LiTime lists 230Ah and 5888Wh at 24V, while the Redodo lists 200Ah and 5120Wh at 25.6V.
Can an 8D battery start a vehicle?
The Odyssey lists 1450 CCA for starting, while the LiTime listing says it is not for starting vehicles, golf carts, or jacks. Check the listing for the use you need: a deep cycle listing and a starting listing serve different jobs.
Related solar guides
See the lithium battery size, the deep cycle battery for a boat, the LiFePO4 battery life and the single vs dual battery tray guides.
