JMI Battery Pack Holder XL for Wheeley Bars

Product Overview

The JMI Battery Pack Holder XL is an oversized steel cradle that carries a field power supply on the frame of an HD Medium or HD Large Universal Wheeley Bar. It accepts packs up to 15¾″ × 11¾″ — a far larger footprint than the standard Battery Pack Holder, which tops out at 5½″ × 10″. The tray is heavy-duty steel with a corrosion-resistant finish and a rimmed edge that keeps the pack seated while the dolly is moving. It bolts to the Wheeley Bar frame using the bar’s existing hardware, so no drilling is involved, and the first installation typically runs about five minutes. Shipping weight is 7.4 lb. Made in the USA by JMI, part of the CXB Astro family.

Who It's For

This is a good match if you run an HD Medium or HD Large Wheeley Bar and your power source is larger than the 5½″ × 10″ footprint the standard holder accepts — a Group 24 or Group 27 marine battery, a Pelican-case style power box, a twin-cell LiFePO4 pack, or a full power-distribution box with its own fuse panel and outputs. It also suits you if you would rather carry one large pack in a single rimmed cradle than split the load across two smaller holders.

Key Features & Design

• 15¾″ × 11¾″ capacity: Takes large marine batteries, Pelican-case power boxes, dual-cell LiFePO4 setups, and full astronomy power-distribution boxes.
• Heavy-duty steel cradle: Welded steel with a corrosion-resistant finish, sized for the weight of a Group 27 battery.
• Rimmed edge: The raised lip around the tray holds the pack in position while the dolly rolls over seams and uneven ground.
• Existing-hardware mounting: Bolts to the Wheeley Bar frame with the fasteners already on the bar — no drilling and no additional fasteners.
• 7.4 lb shipping weight: Light enough to leave installed permanently without meaningfully changing how the bar handles.
• Made in the USA by JMI, part of the CXB Astro family.

Recommended Uses

• Carrying a Group 24 or Group 27 marine battery on an HD Large Wheeley Bar for all-night imaging runs.
• Mounting a single power-distribution box with fuse panel and multiple outputs so mount, camera, dew heaters, and focuser all draw from one place on the dolly.
• Rolling a fully powered rig from a garage or observatory to an observing pad without lifting the battery separately.
• Consolidating a twin-cell LiFePO4 setup into one cradle instead of two standard holders.

Compatibility and Accessory Notes

The XL holder is designed for the JMI HD Medium and HD Large Universal Wheeley Bars, and it needs the tripod legs extended above their minimum setting for the wider tray to clear the frame. It does not fit the Standard Medium Wheeley Bar, the HD Shorty, the AP Pier Mount bar, the Triangle Style bar, or the Sky Trekker series — the Standard Medium frame in particular is narrower and has no mounting room for the XL footprint. On those bars, and on HD bars running near minimum leg extension, the standard Battery Pack Holder (5½″ × 10″) clears the frame, and two of them can be mounted side by side for two separate packs. The battery pack itself is supplied separately. Tell us which Wheeley Bar you own and how far your legs typically sit from minimum, and we will confirm the fit before you order.

Good to Know Before You Order

• HD Medium and HD Large only. The Standard Medium, HD Shorty, AP Pier Mount, Triangle Style, and Sky Trekker bars all fall outside the XL’s fitment.
• Leg extension affects clearance. With the tripod legs near minimum extension, the XL’s footprint can interfere with frame clearance even on an HD bar. Extending the legs further, or fitting two standard holders, both resolve it.
• The battery pack is not included. The holder is the cradle and its mounting hardware only.
• Capacity is a footprint limit, not a weight rating. The published figure of 15¾″ × 11¾″ describes the tray opening.
• Two smaller packs in one XL tray is possible but less secure than two standard holders, where each pack sits in its own rimmed cradle.

Frequently Asked Questions

Is it difficult to install?

No. The XL bolts to the Wheeley Bar frame using the hardware already on the bar. There is no drilling and no extra fastener to source, and most owners finish the first installation in about five minutes.

Why does the XL not fit the Standard Medium Wheeley Bar?

The 15¾″ × 11¾″ footprint needs the wider frame span of the HD Medium or HD Large bar to mount cleanly. The Standard Medium frame is narrower and does not offer that mounting room.

What happens if my tripod legs sit near minimum extension?

At that setting the XL tray can run into frame clearance on an HD bar. Extending the legs somewhat further usually clears it; otherwise two standard Battery Pack Holders fit at any leg extension.

Can I carry two battery packs on one XL holder?

If both packs fit inside the 15¾″ × 11¾″ opening, yes. Two standard holders keep each pack in its own rimmed cradle, which travels more securely.

What size packs does it actually take?

Up to 15¾″ × 11¾″ — Group 24 and Group 27 marine footprints, Pelican-case style power boxes, dual-cell or twin LiFePO4 setups, and power-distribution boxes with built-in fuse panels.

Bottom Line

In short: the Battery Pack Holder XL takes a 15¾″ × 11¾″ power pack, bolts to an HD Medium or HD Large Wheeley Bar frame with the hardware already on the bar, and keeps a full-size field battery riding with the scope instead of carried separately.