More power... LiFePo4...

[GeordieStew]

Good afternoon.

I own a Bluetti AC70 at the moment. 1000W 768Wh for my astro setup (mount, cooled camera, guide camera, mini pc, dew heaters, flat panel). I'm going to start car camping too with my astro gear so I can get to darker skies. I'd like power for two nights imaging and living (charging phone/tablet/hand warmer only... cooking on gas). 

The AC70 does ok, but I imagine it'll die on night two.

I have a couple of choices.

1) Buy another AC70 (768Wh) for about £400

2) Buy an AC180 (1152Wh) for about £500

3) Buy a standalone 12V 100Ah LiFePo4 (1000+Wh), charger, "stuff" and a box. Probably about £350-400 (like this https://uk.eco-worthy.com/products/lifepo4-12v-100ah-lithium-iron-phosphate-battery)

My gear will be running through a Pocket Powerbox Advance Gen2 where possible.

Options 1 and 2 only really have cigarette socket and 1 or 2 USB-C 100W PD outputs (plus AC).

Could I build option 3 to only have either Anderson (with cables) or DC5521 sockets? I have other charging options for phone etc.

What other "stuff" would I need for option 3? Distribution, some kind of monitor for utilisation/capacity, switch? 14AWG cable? 

Could anything blow up? Do I need any regulation of anything? Considering all of my astro gear is 12V anyway (between 0-5A typically).

Cheers (latest threads on this seem to be from 2023)

[JeremyS]

I’m no expert but I’ve tried several makes and wished I’d started with Tracer LiFePo’s

[900SL]

I don't use Lifebouy sorry LifePo, titter ye not, but I do use a 12.6V AGM in an insulated battery box. I have a 30A fuse immediately downstream and use Anderson powerpoles to connect to a 12V fused busbar on my tripod, which feeds a Pegasus powerbox on the rig. This provides 12V to camera, AsiAir etc and 5.5V to a local TPLink repeater. I power the mount by a separate supply

These are great:

 

 

 

Edited 21 hours ago by 900SL

[GeordieStew]

4 minutes ago, 900SL said:

I don't use Lifebouy sorry LifePo, titter ye not, but I do use a 12.6V AGM in an insulated battery box. I have a 30A fuse immediately downstream and use Anderson powerpoles to connect to a 12V fused busbar on my tripod, which feeds a Pegasus powerbox on the rig. This provides 12V to camera, AsiAir etc and 5.5V to a local TPLink repeater. I power the mount by a separate supply

These are great:

 

Thanks for that. Is it this one? https://www.aliexpress.com/i/33006131825.html ish?

[900SL]

7 minutes ago, GeordieStew said:

Thanks for that. Is it this one? https://www.aliexpress.com/i/33006131825.html ish?

Yep, thats the one F1005

They also do a smaller one, 5 port, without the fuses. Useful if you have an in line fuse and don't need the fused terminals

[Elp]

Do you actually know what your power draw is at any one time, or better yet under maximum load? This approach will be better to determine the way forward. You may also get more mileage if you power dew control separately from the main rig as it can draw a lot of power if it's not running on low. What scope are you using?

[GeordieStew]

7 minutes ago, Elp said:

Do you actually know what your power draw is at any one time, or better yet under maximum load? This approach will be better to determine the way forward. You may also get more mileage if you power dew control separately from the main rig as it can draw a lot of power if it's not running on low. What scope are you using?

Askar 71f

SW Wave 150i

MeLe Quieter 4C

ToupTek ATR2600C

ZWO ASI290MM Mini

30cm Dew Heater Strap - 6.4W 0.53A

20cm Dew Heater Strap - 4.3W 0.36A

Pocket Powerbox Advance Gen2

Deep Sky Dad FP2 Flat Panel (not here yet)

 

I could boot everything up, cooling the camera indoors isn't really a fair comparison. And slewing uses a bit of power.

[Elp]

If you slew in Dec and Ra you'll get the max possible draw reading so probably advisable.

A way of prolonging batteries is to also cool to zero degrees rather than minus figures.

[Elp]

1 hour ago, GeordieStew said:

Do I need any regulation of anything?

If DIY building you'll need a voltage regulator, those DIY LiFePo4 batteries drop voltage like a brick within minutes without one.

[GeordieStew]

Just plugged everything in. Bluetti says maximum 55W. Dew Heaters on full, camera cooling, mount on the move. 

Does that sound about right?

[Elp]

Maybe... It's a bit high if it is. What you can also do is eliminate bits one by one to see how much it drops, then you'll know roughly what each item draws.

Based on 55W, you divide any batteries Wh battery capacity by that figure to work out roughly how many hours it'll run, you can also factor in a 10-20 percent inefficiency reduction but I've found the division calculation only quite reliable with my batteries.

[Elp]

By the way how is the Bluetti, I've been thinking about getting the smaller EB3A as it has 12v dc plug outputs. You get a bit of an inefficiency factor if you use a mains plug with such a power source.

[GeordieStew]

6 minutes ago, Elp said:

By the way how is the Bluetti, I've been thinking about getting the smaller EB3A as it has 12v dc plug outputs. You get a bit of an inefficiency factor if you use a mains plug with such a power source.

It's been spot on so far. Mine doesn't have the DC plugs unfortunately. And the cigarette lighter (need a new name for these) on everything are always dodgy... loose and not confidence inspiring. But it lasts well, it's not too noisy. Lights are bright. Easy to use. Not too heavy. Just works!

[GeordieStew]

13 minutes ago, Elp said:

Maybe... It's a bit high if it is. What you can also do is eliminate bits one by one to see how much it drops, then you'll know roughly what each item draws.

Based on 55W, you divide any batteries Wh battery capacity by that figure to work out roughly how many hours it'll run, you can also factor in a 10-20 percent inefficiency reduction but I've found the division calculation only quite reliable with my batteries.

Mini PC seems to be about 18W. Dew straps 20W ish on full whack, may drop off when to temperature.

Hard to judge the rest. 

[Elp]

To put it into some sort of perspective, that dew heater draw alone is nearly as high as one of my whole rigs (hem15, 183mm pro cooled to minus 10, GC, asiair mini). This rig runs consistently for just over four hours on a 100Wh battery so I'm guessing it's close to 25W when in use.

Edited 19 hours ago by Elp

[adyj1]

3 hours ago, Elp said:

If DIY building you'll need a voltage regulator, those DIY LiFePo4 batteries drop voltage like a brick within minutes without one.

I thought lifepo4 batteries had a battery management system built in, and that was one of the advantages? Certainly the the 8ah batteries I bought from amazon do... How DIY are we talking? 

[Elp]

29 minutes ago, adyj1 said:

I thought lifepo4 batteries had a battery management system built in, and that was one of the advantages? Certainly the the 8ah batteries I bought from amazon do... How DIY are we talking? 

As per option 3 above. I had two similar ones from the same brand and when trialling it with a custom rig, a fully charged battery dropped its voltage from around 12.8V down to less than 11 within around 5 minutes.

Pre built batteries/power stations like their Bluetti will have the BMS built in.

Edited 13 hours ago by Elp

[GeordieStew]

Most of the LiFePo4 batteries I've looked at come with BMS. They're about £200 and 100A. 

Then a charger is £60ish. Then a distribution block is £60ish. Connectors, wiring, box, some additional fuses.

Just been checking out the new Delta 3/3 Plus from ecoflow due out in UK in December. May wait for that. 

[Elp]

Looking into it I believe a BMS is designed to monitor the battery voltage so it doesn't damage the battery via excessive charging or discharging as that can damage the internal chemistry. A voltage regulator is different in that it ensures a stable voltage output which is required when powering your mount for example which typically needs over 12v consistent input. In my above trial example I wasn't using a voltage regulator hence the voltage just tanked and became unusable for the application. A complete power pack/station will likely have both built in otherwise they'd be no use.

Edited 4 hours ago by Elp