DIY Power tank thoughts

[MG01]

I'm starting to plan a powertank project and after some thoughts on battery type and capacity.

I want to be able to run my imaging rig off grid but I'm concerned that infrequent use could be a problem for batteries.

I think i'll need to power the following:

Atik 383 and Lodestar, filterwheel, Eq6, mele quieter miniPC, pegasus UPBv2 and 5" dewband.

Does 6Amps seem reasonable as an estimation of current load?  In which case maybe a 40Ahr battery would provide enough juice for a winters evening?

Would Lipo batteries be the best bet?  I use small ones for RC cars but have no experience of the larger capacity type.  What voltages can I expect?  I know my CCD likes it a little higher than 12v and am a little concerned about voltage drop over a session...especially since loosing a mount board to undervoltage from my old powersupply.

Any thoughts?

[iantaylor2uk]

If you're looking at 6 amps, delivered at 12 volts, then that's 72 watts. If you want it to last 6 hours then that is around 430 Wh. You can get a Jackery 240 Wh battery which I've found is good, and there is also a 518 Wh version. I don't think the mount will take much current when tracking. I think the mini PC, the camera cooling and the dew strips will be the power hogs. The other thing to remember is that batteries don't like extreme cold (less than -5C) in my experience.

[MG01]

Thanks Ian, that looks like a solid choice for an off the shelf solution.

Ideally though I'm looking to put something together myself so am looking maybe at golf buggy batteries?  There just seems quite a range and I've no real understanding of what to look for.

[teoria_del_big_bang]

HERE is an old thread that may help and has links within it to other similar threads.

As you will see I built on a couple of years ago and works a treat using a large(ish) leisure battery.
Only real downsides are it is very heavy and needs putting on trickle charge every few weeks even if not used to keep battery healthy and do not run the battery right down when in use so buy a battery bigger than anything you think you may need in a night.

Steve
 

[MG01]

26 minutes ago, teoria_del_big_bang said:

HERE is an old thread that may help and has links within it to other similar threads.

As you will see I built on a couple of years ago and works a treat using a large(ish) leisure battery.
Only real downsides are it is very heavy and needs putting on trickle charge every few weeks even if not used to keep battery healthy and do not run the battery right down when in use so buy a battery bigger than anything you think you may need in a night.

Steve
 

Thanks Steve, I'll have a read through those threads

[Horwig]

Here's my attempt, some years old by now, but still working faultlessly, even after sitting idle for VERY long periods

 

[kbrown]

I used a 42Ah car battery successfully for a while. But since it was just an ordinary lead acid battery, it didn't like to be discharged periodically so much, As a result it started sulfating and it's capacity dropped and dropped over time. So make sure you get at least a deep cycle battery. Also keep it topped up when not in use.

Edited January 12, 2023 by kbrown

[MG01]

4 hours ago, kbrown said:

I used a 42Ah car battery successfully for a while. But since it was just an ordinary lead acid battery, it didn't like to be discharged periodically so much, As a result it started sulfating and it's capacity dropped and dropped over time. So make sure you get at least a deep cycle battery. Also keep it topped up when not in use.

I think having looked into it I'm going to wait until LiPo batteries are a little more affordable.  I'm going to build a field box with a PSU inside and with a long lead for hookups that I can adapt to take batteries when I can afford them.  For now I mainly go where there's power anyway.

[TyWilliams]

I'm a bit scared as I haven't taken my setup out yet, but I have a pretty good power bank. Its a Kia EV6, an electric car that has 240v out to power my laptop and EQ5 pro mount. Skywatcher 200 newtonian with EQ5 pro goto mount, and bits and bobs to try to get into this fascinating pastime.

[doublevodka]

On 04/01/2023 at 22:58, MG01 said:

I'm starting to plan a powertank project and after some thoughts on battery type and capacity.

I want to be able to run my imaging rig off grid but I'm concerned that infrequent use could be a problem for batteries.

I think i'll need to power the following:

Atik 383 and Lodestar, filterwheel, Eq6, mele quieter miniPC, pegasus UPBv2 and 5" dewband.

Does 6Amps seem reasonable as an estimation of current load?  In which case maybe a 40Ahr battery would provide enough juice for a winters evening?

Would Lipo batteries be the best bet?  I use small ones for RC cars but have no experience of the larger capacity type.  What voltages can I expect?  I know my CCD likes it a little higher than 12v and am a little concerned about voltage drop over a session...especially since loosing a mount board to undervoltage from my old powersupply.

Any thoughts?

Have a look at Lithium Iron Phosphate batteries, appear more resilient than lead acid and normal Lithium and as I understand it can go for long periods without charging. Most of the commercially made powertanks now use these, and as a bonus they are much lighter than lead acid

2 hours ago, TyWilliams said:

I'm a bit scared as I haven't taken my setup out yet, but I have a pretty good power bank. Its a Kia EV6, an electric car that has 240v out to power my laptop and EQ5 pro mount. Skywatcher 200 newtonian with EQ5 pro goto mount, and bits and bobs to try to get into this fascinating pastime.

I think you win the prize for the biggest astro powertank 😂

[MG01]

On 13/01/2023 at 14:00, TyWilliams said:

I'm a bit scared as I haven't taken my setup out yet, but I have a pretty good power bank. Its a Kia EV6, an electric car that has 240v out to power my laptop and EQ5 pro mount. Skywatcher 200 newtonian with EQ5 pro goto mount, and bits and bobs to try to get into this fascinating pastime.

I think as elec vehicles grow in popularity we'll see a few used as powertanks...just make sure you don't get yourself stuck without any juice!!

It's an awesome hobby and you're definitely in the right place to find help with your setup if needed....have fun out there! 

[MG01]

On 13/01/2023 at 16:35, doublevodka said:

Have a look at Lithium Iron Phosphate batteries, appear more resilient than lead acid and normal Lithium and as I understand it can go for long periods without charging. Most of the commercially made powertanks now use these, and as a bonus they are much lighter than lead acid

I did but the price put me off a bit.  I was looking at 'golf buggy' batteries and to get anywhere need a 40/50Amp hour at 12v they were getting very expensive.

IN the end I've decided that since I have mains at the sites I use I'm going down the 'protected' mains supply route.  A 30Amp Powersupply in a rugged case (cheaper version of a peli case)

[kbrown]

2 hours ago, MG01 said:

I did but the price put me off a bit.  I was looking at 'golf buggy' batteries and to get anywhere need a 40/50Amp hour at 12v they were getting very expensive.

IN the end I've decided that since I have mains at the sites I use I'm going down the 'protected' mains supply route.  A 30Amp Powersupply in a rugged case (cheaper version of a peli case)

I used to drive to dark(er) sky sites with my rig hence my car battery approach. But as I said over time it became less and less effective. These days I just use my rig in our back garden where I have mains available. Instead of shelling out for a mains powered power supply I simply just keep my CTEK battery charger on the battery all the time. Works well and I didn't have to buy anything new...