Batteries

Powering a Rig Through a Cold Night

Capacity, chemistry and voltage stability all matter, and the last one causes the most mysterious failures.

• Capacity in amp-hours: Total your loads — mount, cameras, dew heaters, focuser, hub — and multiply by session length, then add substantial margin for cold.
• Lithium iron phosphate: Holds voltage steadily through most of its discharge and tolerates cold better than lead-acid, which is why it has largely replaced it for field use.
• Lead-acid and AGM: Inexpensive and heavy, with capacity falling sharply below freezing and voltage dropping steadily as they discharge.
• Voltage stability: Mounts are sensitive to voltage sag. A battery that still shows charge but drops below the mount's tolerance under load will cause stalls that look like mechanical faults.
• Cable gauge and length: A thin or long power lead drops voltage under load, and this is a frequent cause of cold-weather problems that batteries get blamed for.
• Charging in cold: Many lithium chemistries should not be charged below freezing. Bring the battery indoors to charge rather than leaving it on a charger in a shed.

Why Choose David Astro for Batteries

We size power for Canadian winter operation, which is a different calculation from a summer specification.

• Full load totalled: We add every device including dew heaters, which are frequently forgotten and often draw as much as the mount.
• Cold derating applied: We size with margin for capacity loss at low temperature rather than to the nameplate figure.
• Cable specified with the battery: We recommend adequate gauge and the shortest practical run, since voltage drop in the cable causes faults blamed on the battery.
• Authorized dealer: Genuine products with manufacturer warranty, in Canadian stock.
• Ships from Canada: No duties or brokerage fees for Canadian buyers.

Batteries in Canada — Frequently Asked Questions

How big a battery do I need?

Total your loads in amps, multiply by session hours, then add at least 50% margin for cold-weather capacity loss. A typical imaging rig with dew heaters draws far more than people expect.

Why does my mount stall when the battery still shows charge?

Voltage sag under load. Mounts have a minimum operating voltage, and a battery near the end of its useful range, or a thin cable, can drop below it briefly during a slew.

Which chemistry for winter?

Lithium iron phosphate holds voltage better and tolerates cold better than lead-acid. Note that many lithium batteries should not be charged below freezing, so charge indoors.

Does cable thickness matter?

Considerably. A long thin lead can drop enough voltage under load to cause stalls, and it is a much cheaper fix than a larger battery. Keep runs short and gauge generous.

Powering an all-night session?

Tell us every device on your rig and we will size the battery and cable. Full warranty, shipped from Canada.