Portable power for Sky-Watcher Synscan GOTO 8" Dobsonian

[chellaxy (Chelle)]

Hi everyone,

Apologies for another post about portable power but I didn't seem to find what I was looking for on other threads so thought I would ask here:

I have Sky-Watcher synscan on a Dobsonian that requires 12V but I'm not super electrically minded. Would a 12V car jumpstarter work? Why/why not?/Any additional components or modifications necessary?
I just really don't want to have to spend hundreds just on a powerpack!

Specifically considering this model: Repco 12V 800A Sealed AGM Battery Jump Starter - RCJS800.

Thank you in advance for any insight!

[OzEclipse (Joe Cali)]

Jump starter batteries are designed to supply a lot of current for a very short time. You would be better with a deep cycle AGM or lithium ion. If you really want to use a jump starter, someone in this thread describes using a 1200A model.
https://www.iceinspace.com.au/forum/.../t-147334.html

[chellaxy (Chelle)]

Thank you!

[Leo.G (Leo)]

As Joe said, jump starters will run the things for a while with the high capacity things being the exception but for the dollars they cost you can get a nice portable power station such as Bluetti and numerous other companies sell (that's the name I know but there are lots of them). You get a dedicated supply which will run so much more than just the mount and not a great deal dearer than a good jump starter and probably lighter too using the LiFePo4 batteries.

[OzEclipse (Joe Cali)]

You pay a lot to have everything packaged in a nice neat box like a Bluetti. Inside something that costs a few hundred dollars, a pretty small $30-$40 battery frequently resides.

One of these:
https://www.jaycar.com.au/12v-7-2ah-...m-ufb/p/SB2486

With one of these:
https://www.jaycar.com.au/cigarette-...clips/p/PP2007

And a charger:
https://www.jaycar.com.au/6-12vdc-1-...arger/p/MB3900
This charger is compatible with all battery types.

I have some very old 12v 7AH SLA batteries that have been recharged more times than I can count. They still run my scope (EM200 - an EQ6 clone) for more than half of a night. If I don't intend to do an all-nighter, I often run my scope off these rather than using my big 120AH Li Ion.

If your power consumption requirements increase later, eg you add a cooled astrocamera, dew heaters, you can either buy extra batteries and put them in parallel or (better) you can buy a different bigger battery and the charger will work with a wide range of battery capacities and types.

[Leo.G (Leo)]

I've seen some of the Bluetti units on special (older models) at good prices.
For me the difference is a LiFePo4 battery vs SLA, the SLA is heavy in comparison albeit extremely cheap in comparison. I picked up a dep cycle SLA at Aldi one day, 30KG, thinking it was supposed to be the LiFePo4 but that was the next week. The equivalent LiFePo4 was 12 KG,, a huge difference. To be fair that was a high capacity battery, not a little thing like you've shown Joe.
I've used a 1200Amp jump starter in the past when I've taken my gear up to a local lookout but it was quite heavy when thrown in with the EQ5 Pro mount (inc weights) and 152mm Skywatcher refractor, along with the 80mm Megrez added as a finder, camera, laptop (plus small gas stove and some food and water (for coffee) and pans because my son and I hadn't had dinner and it was going to be a very late night).
All up it was quite a slug up a big hill carrying way too much for someone who had a major heart attack only 2 months prior. I had my son run back down the hill to get my heart medication from the car when I was only half way up (no vehicle access in that spot) and spent half an hour or more just sitting before I was game to continue up the hill.
I must make an electric carry buggy with small off road tyres one day and a cable remote to control it. Then I won't need a power supply, the cart will be the power supply.


I've searched LiFePo4 batteries to make my own rig, I have the battery box with fuses and meters and outlets already built in but the LiFePo4 are far from a cheap battery but extremely light in comparison to SLA.
That is however a much dearer option.