The Celestron 17 amp-hour Power Tank is a multi-function 12V DC power supply for operating your telescope and power-hungry accessories in the field. This rechargeable sealed lead-acid battery works with all telescopes that can be powered by a 12V DC external power supply. It is particularly useful for simultaneously operating a telescope and a power-hungry CCD camera and/or a dew heater system. The 17 amp-hour Power Tank is substantial in size and weight, in addition to being substantial in power capacity. It weighs 17 pounds, 2.4 ounces with a shipping weight of 21 pounds, and measures 13.5” long x 5.25” wide x 14” tall.
The 17 amp-hour Power Tank has all of these features:
- a large 17 amp-hour capacity rechargeable battery (with somewhat less capacity when used in temperatures below 32 degrees F), which is enough power for several nights of observing with most telescope and accessory combinations
- two 12 VDC cigarette lighter plug outputs for powering scopes and dew heaters, with sliding covers to keep them dirt- and debris-free when not in use
- two built in 5V/1.5A USB ports for charging portable devices (such as a Smart Phone, iPad, or tablet) in the field
- a separate 8’ long DC power cord (the left-hand cord labeled C in the feature image below), with a cigarette lighter plug on one end for connecting to one of the cigarette lighter plug outputs on the Power Tank and a female 5.5mm pin jack plug for connecting to the 12V DC input on a Celestron telescope on the other end
- a very, very bright 800,000 candle power built-in spotlight for scope setup/breakdown and for finding your way across a dark field (definitely not for use at star parties if you want to preserve your dark-adapted vision . . . and that of other observers)
- a bright built-in red lens lamp for scope setup and takedown (too bright for reading star charts; a variable brightness LED flashlight is still best for that); the lamp can be removed from the Power Tank, although still connected by a power cord, and attached to any convenient metal surface by means of a magnet on its back
- separate on/off switches for scope power, red lens lamp, and spotlight
- battery indicator lights that show the status of the battery – ON/ready to use; needs charging; charging; or OFF/fully charged
- an AM-FM radio with built-in speaker to keep you company when observing alone (it’s best to use a separate CD player or iPod and headphones while at a star party, in case your choice of music doesn’t agree with the other observers nearby)
- an external 110V AC recharger for replenishing the Power Tank’s battery charge as many as 100 times or more; the two parts of the adapter for U. S. and Canadian use are labeled A in the feature image below (since Celestron products are sold world-wide, the Power Tank also includes three other AC adapter plugs for use in Europe and Asia, which are labeled B in the feature image below); the AC adapter can be used with any 100 to 240 volt 50/60 Hz AC power supply
- automobile jump-starting capability (requires user-supplied jumper cables) for starting your car in an emergency (250 amp cranking capacity for 5 seconds when fully charged), and
- a molded-in carrying handle.
In addition to powering Celestron scopes, the 17 amp-hour Power Tank can also be used with 12V Meade scopes, including current LX200 models. However, a Meade #607 DC cord is needed to connect the Power Tank to a Meade 12V scope due to the difference between the sizes of the 12V DC input plug center posts on Meade and Celestron scopes. Because the Power Tank has a 12-volt DC output, it cannot be used with older Meade non-GPS LX200 scopes that require an 18V DC external power supply.
As with any rechargeable battery, the Power Tank will operate at full power until approximately 40% of its charge is left. The output voltage will then start to drop relatively quickly past this point. At 30%-35% of its full charge, the Power Tank may not have enough output voltage to successfully operate your various electronic components. The maximum true full power output capacity of the 17 amp-hour Power Tank is therefore in the neighborhood of about 10.5 to 12 amp-hours.
To calculate how long the 17 amp-hour Power Tank will operate your particular complement of equipment, add up the maximum amperage ratings of your telescope and your telescope accessories. Divide 10.5 by the total amperage draw of all your components to find the worse case number of hours that this Power Tank will operate your system. Keep in mind that accessories will usually not operate continuously at their full rated amperage. A dew heater might be rated at a 1-amp draw, but that is when it is turned up to maximum power. Seldom are dew heaters turned on full and left at that setting. Operating at only 1/4 to 1/3 of the rated power is usually more typical. The actual operating time of the Power Tank on a single charge can therefore often be two to three times the length of the worst-case scenario calculated above. Your operating time will depend on the ambient temperature and the particular combination of components you are using.
A note on assembling the AC adapter: The AC adapter has five parts, the adapter itself, and four different prong assemblies that snap into the adapter and plug into your household AC wall socket. Choose the prong assembly that matches the configuration of your AC wall socket. Do not attempt to slide the prong assembly straight into the adapter! This will cause damage to the adapter that is not covered by warranty.
Refer to the feature images below for proper assembly. Note that the metal prongs of the prong assembly are placed at the opposite end of the adapter from the end with the cord connected to it. The prong assembly is placed on top of the AC adapter so that tabs on the prong assembly can drop into small slots in the sides of the long and wide slot of the AC adapter. When the tabs drop into the slots and the top of the prong assembly is flush with the top of the AC adapter, slide the prong assembly into the AC adapter in the direction of the arrow in the image until the prong assembly clicks into place.
You should not have to remove the prong assembly unless you move overseas and need to connect your Power Tank to a different type of AC outlet. The prong assembly can be removed from the adapter by using a pencil to push down on the tab in that adapter that locks the prong assembly in place.
The battery instructions caution against using the charger continuously for more than 24 hours to avoid overcharging the battery and possibly damaging it. In addition, the instructions suggest recharging the battery occasionally to maintain its performance if it is not going to be used for several months at a time.
Printed instructions are supplied with the Power Tank. If all else fails, read the instructions!