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My astronomy project:
Lithium Battery power


  1. Astroserver and powerbox, ver 1.0
  2. Astroserver and powerbox, ver 2.0
  3. Balcony outdoor outlets
  4. Lithium Battery power
    1. Lithium Battery power
    2. DC/DC converter
    3. To be continued

I take no responsibility or liability for what are written here, you use the information on your own risk!

Page IV.1: Lithium Battery power

When living in a very light polluted area as I do, Bortle Class 9, it's important to have the opportunity bring the equipment out to a dark place. Then the equipment needs to be compact and not too heavy. One of the bigger problem is how to power the equipment. Now with computer controlled equipment, mount, guide camera, camera, dew heaters, GPS, USB Hub, motor focus etc it needs a lot of power and it needs to last about ten hours out in a cold climate. My latest setup is built to have a low power consumption, it only takes 20 Watt which make it a lot easier.

I have earlier used Lead Acid car batteries, the capacity of them could only be used to 50% or you destroy them and in the coldness they only has half the capacity. I have now destroyed two of my batteries because I have discharged them too deep, and the weight of my 45 Amph battery is 14 kg and the bigger 72 Amph is 20 kg, not a good solution. I have a friend who bring a motor generator to solve the problem, but big and heavy. Nowadays we use Lithium batteries to power almost everything, even cars. There are Lithium batteries that are made for astro equipment. It had been easy to buy one of them, the capacity isn't very high but you can have two of them or more. Now I try to do my own solution for it.

Please only read about this and don't try to built something by your own, it can be dangerous and you can destroy your expensive equipment if something goes wrong.

I take no responsibility or liability for what are written here, you use the information on your own risk!

At Celestron I found a guide about batteries for telescope:

Astroequipment powered by Lithium Battery

To build your own battery from battery cells isn't a good idea, the components are expensive and it must be safe also. I bought a battery made for E-bikes. It's not 12 Volts but 24 Volts, that make it a little bit more complicated. This one has 12 Ah capacity, at 24 Volts that is 288 Wh. Less than my car battery but I can use more of its energy, don't know yet how the battery will last when it's cold. There are other batteries of this kind but with higher energy, then it's 36 or 48 Volts which make it even more difficult because you must convert it down to 12 Volt.

At the image, what I got, the battery, a cassette that hold the battery and a battery charger. The enclosure of the battery is very stable which is good and the battery has built in electronic safety devices. The battery weight is about 3 kg, big difference compare to my lead acid batteries.

A battery like this has a lot of energy stored and should be handle with care, read the battery's included instruction carefully.

Astroequipment powered by Lithium Battery

First I examine what Voltage the battery deliver. In this case the built in switch is in OFF position, still there are 23.2 Volts. I haven't investigate it yet, but I think it can't deliver any power when in OFF position, more like some leakage of current.

Astroequipment powered by Lithium Battery

With the switch in ON position I have 25.8 Volts.

Astroequipment powered by Lithium Battery

When the battery charger is connected the Voltage increase to 26.1 Volt. All these figures are important to know, the later DC/DC converter must handle much more than 24 Volt as input voltage.

Astroequipment powered by Lithium Battery

At the top end of the battery there is an energy meter, it came fully charged.

Astroequipment powered by Lithium Battery

The battery charger deliver 29.4 Volt and 2 Amp capacity, I think it will take 5 to 6 hours to charge the battery.

Astroequipment powered by Lithium Battery

The cassette, you can even lock the battery in this cassette with a key. At this end of the cassette I will 3D-Print an enclosure for the DC/DC converter.

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