Portable power for Sky-Watcher Synscan GOTO 8" Dobsonian
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!
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,494
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
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.
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,494
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.
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.
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.
If like me, you worship at the alter of Ryobi 18v power tools and already have numerous batteries, google up Ryobi 18V 120W ONE+ Battery Power Source R18BT12V which is an absolutely awesome add on for a hundred bucks and supplies 12V and usb power with whatever sized batteries you already have.
I run my portable scope off one with a 4Ah battery and its good for a few hours.
I have a 100Ah lithium in a decent battery box for the heavy sessions, but if you just fancy a couple of hours under the stars with an eyepiece ...
These are the Ducks Nuts for the GoTo dobs and the likes, fellas }
12V 20Ah Lithium Battery LiFePO4 Rechargeable Deep Cycle BMS Solar Boat Camping,
They have the hex F2 bolt Terminals aswell
Dimensions - 185-L x 167-H x 82mm-W
Weighing in at 2.05Kg's
They have the options for the smaller 8Ah with the Spade terminals,,, 12Ah, the 20Ah and a 50Ah then onto the larger sizes -- some sizes currently Out-Of-Stock
Thanks Bob that's quite an affordable solution for a light weight LiFePo4 battery. Sorry, Lithium battery.
Any idea what sort of run time with a normal EQ skywatcher mount (EQ5 pro, laptop computer and minimal draw camera?
I have some new 8-AH lithium Aldi 20 volt packs I could run through a buck converter to get the required voltages, not sure how long it would drive my gear but I have a couple of new units and it would be worth me looking into, already having the battery packs, I could wire a couple up in parallel in my dedicated battery box I bought new and have never populated.
Plus I could try them in the yard where I have AC power available as a back up. I'd have to fit a 19 volt outlet for the laptop, a 12 volt regulated output for the mount and 5 volt for the camera but it works straight off USB I believe. It's minimal work to set it all up and try it.
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,494
Quote:
Originally Posted by Leo.G
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.
The charger I recommended is both Li ion and SLA compatible. Then Chelle can upgrade to Lithium or stay with lead acid. I have a 120AH Lithium in my 4wd, solar charged that powers my car fridge and provides camping power for charging all my devices. I installed it isolated from the main car battery to avoid accidental discharge. It's easily removed for powering my astro activities. It weighs 15kg, about 1/2 to 1/3 of it's lead acid equivalent. Expensive but cheap compared to the cost of a few visits to the physio to fix the back.
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!
Lots of different options around. I have the same scope as you, and have been using one of these for several years with no issues. I think I got mine off ebay or from Jaycar.
Very light - it sits on the dob base and lasts at least 2-3 nights of reasonable observing time before requiring a recharge. I also occasionally plug in a secondary mirror heater and heated filter holder, although they do drain the battery a bit faster. I used to use the jump-starter battery pack, but it was a pain having to move it around as the scope slewed, and its power diminished after only a few years.
Thanks Bob that's quite an affordable solution for a light weight LiFePo4 battery. Sorry, Lithium battery.
Any idea what sort of run time with a normal EQ skywatcher mount (EQ5 pro, laptop computer and minimal draw camera?
I have some new 8-AH lithium Aldi 20 volt packs I could run through a buck converter to get the required voltages, not sure how long it would drive my gear but I have a couple of new units and it would be worth me looking into, already having the battery packs, I could wire a couple up in parallel in my dedicated battery box I bought new and have never populated.
Plus I could try them in the yard where I have AC power available as a back up. I'd have to fit a 19 volt outlet for the laptop, a 12 volt regulated output for the mount and 5 volt for the camera but it works straight off USB I believe. It's minimal work to set it all up and try it.
Sounds you have it all pretty much sorted Leo, , Who'd ever thought of using power tool batteries and the likes with a step down buck converter, your a genius mate,, super light and portable, bit of sorting with connections initially but wow, great going for initiative.
bit of a diverge but I have a lady friend who uses one of them AA, AAA, rechargeable battery stations, funny thing is she has been using the non rechargeable batteries in them, EVEREADY's and cheap $2 shop bulk pack non rechargeable types, never had a problem with em, great for small torches, remotes and older typical household items, I was surprised but there you go, sorry I digress Lol
But yes, quite lightweight is the 20Ah LiFeP04 @ close to 2Kg,, the 8Ah is approx 1/2 the size weighing only 0.95Kg & the 12Ah is only 1.4Kg.
How long would the 20Ah last, well, the Eq5 draw approx 1Ah while tracking and can draw 3-4Ah when slewing but that is only for a few minutes at a time,, but if your slewing a lot then that adds up..
The good thing about Lithium's compared to AGM's is you can access about 85-90% of the batterie capacity, say 20ah in this instance, so you should be confident in running the EQ5 for 15hrs,, But a 20ah AGM can only access 45-50% of its capacity and would only run the same EQ5 mount for closer to 7-8hrs..
Mind you with any battery operating in the cold 'as we astronomers do & speshly in winter' you could easily deduct another 10-20% from the run time
Now adding the Laptop to this battery I would have a stab-in-the-dark, no pun intended, Lol, while using a 12V to 17V inverter supply, I estimate the laptop would draw approx 2 maybe 3Ah, depending on size and power of the processer and how much work it is doing ?
All said, If your Laptop is fully charged before starting your astro session, (By the way - the camera uses very little power, only milliamps, like 0.1 or 0.2 of 1amp, so no worry there) I would have fair confidence this 20Ah would last a night of 5-6 hours
Sounds you have it all pretty much sorted Leo, , Who'd ever thought of using power tool batteries and the likes with a step down buck converter, your a genius mate,, super light and portable, bit of sorting with connections initially but wow, great going for initiative.
That's the easy part, I have a twin charger system the batteries plug into and I'll just strip it and use it for my purposes, the chargers are cheap and regularly on sale at Aldi (I also have other chargers for them).
I also have a range of their 20 volt power tools and a somewhat large collection of the batteries in 4Amp
EDIT: Caveat, this is only a valid option if you already have the battery packs, the 2 new 8-AH batteries I have sitting around for a project for my son cost $100 each. The 4-AH I have plenty of for power tools.
