Lithium ion Power Bank to power goto scope

[Flyingfuzz]

A quick review of using a Lithium power bank to power a Skywatcher Star Discovery 150p goto scope.

I wanted to use an external power bank to power my goto and was looking at the 7Ah Skywatcher (in the UK these are around the £60.00 mark) when I chanced upon the new Lithium type of power bank (paid £35.00). Now these appear perfect, small size and large capacity - infact they appear too perfect. Multiple outputs for 12v, 16v and 19v at 2A, 2 - 2.1A USB's LED torch and it could start you car if you wish. My mount needs 12-15V at 1A so the 12V output was just right.

I purchased a 50800mah version (50.8Ah - now thats a big lead acid battery) I thought if it does not work at least I have a large capacity charger for tablets and phones.

Having checked the polarity of the pins and plugged in the handset it happily began its initialisation phase, this was a test in the daytime so guestimating where the stars would be. However the power bank shut down before I could complete the alignment phase, this happened every time I initialised the scope. It would appear these devices are a bit cleaver and if no current drain is detected they shut down to save power and i guess the initialisation phase does not draw enough current. A bit of testing later and if you simply switch on the LED torch during the alignment phase the device stays powered on, once aligned switch off the torch and the "tracking" of the mount draws enough current to keep the device powered on. I simulated a 2.5 hour session by selecting objects to view for about every 15 mins and it stayed powered on all the time and stilled had all 4 capacity leds lit, so a minimum of 75% of the power remaining.

The device came in its own case but it is small enough to slip into a large pocket for easy transporting. A bit of red filter over the LED torch and ready to go. Only time will tell if it stands the test of regular use.

[Destix]

Where did you buy it from, what's the model/name of the unit?

Sent from my SM-G920F using Tapatalk

[pete_l]

Where did you buy it from, what's the model/name of the unit?

Sent from my SM-G920F using Tapatalk

It looks like one of these: Virgo 50800mAh Car Jump Starter

Though to describe it as a "jump starter" sounds just a leeeetle optimistic.

When looking at the quoted capacity of these devices in general, it does appear that the mAh value advertised is that of the internal 3.7 Volt cell(s). So divide that value by the ratio of the output voltage to the cell voltage (in this case: 12 / 3.7 = 3.2) - then knock off a bit for the internal 3.7->12V inverter's efficiency: call it 10% and you end up with about 14 Amp-Hours as 12V. Still pretty impressive for the size and weight.

[Flyingfuzz]

It looks like one of these: Virgo 50800mAh Car Jump Starter

Though to describe it as a "jump starter" sounds just a leeeetle optimistic.

When looking at the quoted capacity of these devices in general, it does appear that the mAh value advertised is that of the internal 3.7 Volt cell(s). So divide that value by the ratio of the output voltage to the cell voltage (in this case: 12 / 3.7 = 3.2) - then knock off a bit for the internal 3.7->12V inverter's efficiency: call it 10% and you end up with about 14 Amp-Hours as 12V. Still pretty impressive for the size and weight.

Agreed, I dont believe its 50800mah at 12v either more like you said 25% of the capacity still 12-14mah is not bad, still should last a nights viewing and so much more portable than a 17Ah power tank.

Its a non branded model number G-PW6008 (made in China) off a well know auction site from a UK supplier.

[Flyingfuzz]

Learned another point when viewing last night, if you cancel a goto command and stop the slewing the scope stops tracking and hence drawing power which allows the power bank to shut down. So don't stop a goto command and all is OK.

[Frangipane]

Hi I just wanted to ask if your unbranded Lithium Power bank lived up to expectations?

I am wondering if it's the way to go instead of dropping 100 notes for a celestron one... it's to power the AZ GTI mount I have

Thanks