Battery Recomendations

[groberts]

I've recently acquired a ZWO AM5 mount which I hope (a) will be better for my back than the excllent but very heavy AZ-EQ6  GT I've been using for years and (b) provide greater flexibility, in particular going to sites darker than my Bortle-6  in Surrey!

I'm sure many of you already do this and would be grateful for any recomendations for a good / reliable portable battery I could use to run my astrophotography rig for a decent night's session.

The basic electric power demands are: AM5 mount + ASIair plus, ASI294MM pro camera, x8 EFW, x3 dew straps for main scope (81mm & 102mm) Guidescope (50mm).

Graham   

[Elp]

You need to know what your power draw in watts is, in the absence of putting an in line meter between the battery and your rigs you can use the figures within the asiair whilst it's running. Then look at the Wh capacity of batteries, a lot of people state add in a power conversion efficiency reduction (say rate the stated Wh at 80pc or something), then divide the battery Wh by the W your rig draws. I've found this calculation pretty reliable to figuring how long the battery will last. The other rating you need to look at is Amps of the 12V power supply, 5A I'd say is too low, needs to be at least 10A.

I know from experience the batteries I've used fine with my hem15 setup aren't sufficient for the am3, it has a low voltage warning beep you can't switch off so it'll constantly beep whilst slewing and even when tracking. This is from a LiFePo4 battery that runs at around 12.6V, the rig will continue to run but the beeping will continue. So I suspect it needs over 13V with a higher Amp rating, but such a thing is difficult to judge without others contributing their experience as to how it'll run your rig.

So look towards those power station type supplies. I've looked at the Jackery, Ecoflow, Anker and Bluetti though haven't bought one yet. I currently use Talentcells because they fall under typical airline threshold of 100Wh capacity in case I wish to take them abroad.

Edited September 23 by Elp

[AstroKeith]

First split the dew heaters off - they dont need a regulated supply and can be swapped mid session anyway without losing alignment or data.

The mount is power hungry, especially when slewing. Thick cables are a must otherwise you will lose 1 or 2 volts while slewing and goto.

I'd look for batteries with regulated 12V output. Those with cigarette lighter sockets are unregulated and likely to dip under load. An alternative is to get a dc-dc converter from Amazon (9to30Vin 12Vout).

As Elp says, get some measurements and then scale up for the number of hours you want.

[RafalT73]

Hi, below please look at attached screenshot- that’s the power consumption during night session - about 50W. The heaters are off (in that moment there was no need to turn it on) but they both draw no more than 1.5A (1.5A x 12V = 18W). So, totally 70W would be the typical power consumption for most of the gears. If you want operate your telescope for let say 8 hour as max then 70W x 8h = 560W with no reserve. In real life such capacity would be enough for 6 h in Winter time and much more in Summer. Based on that you can look for some battery. The best ones are LiFePO4 or Ion-lithium battery 

[RafalT73]

By the way, I built such a battery myself. You can find the project detail here https://moje-nocne-niebo.pl/en/portable-power-supply-for-astrophotography/

[Tony Acorn]

There's "always more than one way to skin a cat" as they say. I have the ZWO AM3, two ZWO ASi non-cooled cameras, a ZWO EAF focuser and two dew heaters.

I have an older SkyWatcher PowerTank and a new Beaudens LiPO4 166Wh unit. I use the Beaudens to power the mount, focuser and cameras. I use the PowerTank to supply the dew heaters via the USB outputs and I've had over 5 hours without an issue so far.
As winter draws on (and if clouds leave us) I hope to run for longer. I also bought a 100-240V primary / 13.5V DC 5A secondary SMPS from e-bay (<£9) because my HEQ-5 Pro seemed to be struggling with power. This PSU could be mains powered at home or, using an inverter (I have a 300W one), could be run from the direct battery output terminals on the PowerTank for field use. That would give me the option to run the Cameras and focuser from the Beaudens and the AM3 from the PowerTank with the 13.5V 5A PSU whilst the dew heaters would also be from the PowerTank's USB sockets.

HTH 

Tony

[groberts]

Thanks everyone, I obviously need to do some homework, and will.  However, I was rather hoping that somebody with a similar set-up might have some specific recommendations?

Graham

[Elp]

It depends how long you want to run for, no point recommending a 10+ hour battery if you're not going to reap the whole 10 hour runtime regardless of recharging, increased capacity costs more, batteries also drop down in longevity during cold weather too so best to get slightly more than you need.

Plug it all in, have everything running including your mount slewing in both Ra and Dec, then report back on the power the asiair is reporting.

I've seen the Jackery's and Ecoflow's recommended lots of times. Make sure it's a lithium iron phosphate (LiFePo4) chemical makeup as I believe they're more modern, retain life better.

Edited September 23 by Elp

[Carbon Brush]

If you are buying lithium batteries, think about lifetime.
If not used very often (UK weather) they may outlive you🤔
They tend to last some hundreds of charge/discharge cycles, gradually losing capacity on the way. The calendar does not matter.
Typical quoted figures are 500 cycles and you have 70% left.
Reduction in performance in UK cold is not that bad.
The charger and management circuits with lithium packs are very good for protecting against abuse and damage.
Caveat. This does assume proper charging and storage.

If you choose lead acid, the battery degrades from the day it is built.
Loss of capacity is temperature dependent. Leave it in a cold shed during cloudy weather - not an airing cupboard.
However, if you are going to use it on a cold night, let have some indoor time first.
Performance tends to fall off when cold - they are inferior to lithium in this respect.
It is generally your responsibility to ensure proper charging - and if left unused top up charge is more frequent than lithium.

Before lithium packs were generally available a lot of people used to buy 80Ah or 100Ah leisure batteries.
The idea was that despite a combination of age degradation and cold poor performance there was quite enough left for a full night.
You do though need good muscles to throw a 100Ah battery about😁

If I was setting up a new battery powered package, it would be lithium without a doubt.
However, look carefully. The online videos of of ebikes exploding are a usually a consequence of of manufacturers (incorrectly) saving money on manufacture.

There is some very good advice from Tracer...
 

8 Steps to Charge Lithium Batteries Safely   Li-ion | Li-Po | LiFePO4 Lithium batteries, when used correctly, offer a safe and efficient way to power a wide range of devices. However, it’s essential to understand and adhere to specific charging practices to ensure both optimal battery performance and user safety. Follow these 8 steps to charge your battery safely:

 

Use the Correct Charger Always use the correct Tracer supplied charger & follow the Safety Precaution Instructions.

 

Don't Leave Unattended Always supervise your battery charging.

 

Never Charge Overnight Always supervise your battery charging.

 

Avoid Extreme Temperatures Only charge between 0~45°C ambient temperature.  (LiFePO4 max ambient charging temp 40°C)

 

Don't Overcharge Once the battery reaches its full charge, unplug it promptly.

 

Charge in a Safe Location Charge in a well-ventilated & fire-resistant area.

 

Avoid Deep Discharges Be extra vigilant when charging a fully discharged battery.

 

Inspect for Damage IMPORTANT! Never charge a damaged battery. Check for swelling or any damage before every charge.

[RafalT73]

20 hours ago, groberts said:

Thanks everyone, I obviously need to do some homework, and will.  However, I was rather hoping that somebody with a similar set-up might have some specific recommendations?

Graham

Anker power station (an example 512Wh power station cost 450£)

The above link lead you to Anker website. It’s rather suggestion than recommendation - final decision is on you. Please keep in mind, that output voltage on the station is 12V so you need to yake in to consideration additional voltage drop over the cable. Finally you can have 11.5V on your end equipment (in some cases it could be problematic).

[CraigT82]

I have the Anker 521 and it gives out 13.5v via the cigar socket. Was the same reading at 100% charge too. I will check what the output voltage is as it discharges further and relay that back here. 

[RafalT73]

1 minute ago, CraigT82 said:

I have the Anker 521 and it gives out 13.5v via the cigar socket. Was the same reading at 100% charge too. I will check what the output voltage is as it discharges further and relay that back here. 

Ohh! I didn’t expect. That’s really good!! If so, that could be a really good choice

[AstroKeith]

3 minutes ago, RafalT73 said:

Ohh! I didn’t expect. That’s really good!! If so, that could be a really good choice

Hold on!

First it must be measured on load - the similar load you are using. It will immediately drop by about a volt.

Then watch the discharge curve, at the load you are using. It will remain relatively high for most of the time, and then dive. How much useable voltage/time you get depends on the current being drawn.

If you need a good voltage, then consider a dc-dc converter. supplier link this will give you that 13.8V constant until the battery output shuts down.

[CraigT82]

Right well I discharged the Anker 521 down to 15% using a small fan and the no load voltage across the pins is still 13.48v

I then hooked up a 4 watt dew heater strap to the cigar socket ( I've already bared the ends of the strap wire as I'm shortening the cable) and measured that load voltage at 13.37v

(4w is a small load but it is what my mount uses when tracking so quite useful for me.)

Would be good to test the load voltage at higher load but I don't have anything to hand with a higher draw that I can use to test that.

The OP wishes to power a lot more than just a mount though so would need a pretty hefty power pack, certainly much larger than the 521.

Edited September 24 by CraigT82

[Elp]

I'm just wondering how many of these power stations people use hold a plus 13V DC output. My LiFePo4 Talentcell full charge outputs around 12.8V that drops to around 12.6 through most of the session. Once the asiair reports around 11V I know it's nearly flat. It runs my hem15 autoguided setup for around 4 hours ATM (will be less when its colder out), but an am5 will beep because of the low voltage, my am3 did when I tried the same power configuration, you can't turn the beeping off as far as I know.

[AstroKeith]

Mounts that have stepper motors need to be well supplied.

An ordinary meter won't tell the whole story. The stepper motors are driven by very short pulses, at many times what a meter will show the average current to be. Harmonic Strain drive mounts in particular draw higher pulse currents.

These pulses can cause at least a volt drop down the cable, maybe two. The mount needs to be fed by a short stout cable directly from the battery/power source. 

Beware of non-brand power cables. About a year ago I bought a dozen various 1m cables from Am**on. With one exception they were rubbish. On dissection, two of them had just four 0.1mm stands of copper, yet they were sold as 6A cables. At 6A continuous load, initially they dropped 3 volts, but after a few minutes the copper gave out and they went open circuit.

[Elp]

This is one of the reasons I suggest to have the mount slewing in both RA and Dec, it'll give you a higher power draw to work within.

[groberts]

Thanks everyone, to be honest my eyes glaze over when I start looking at electricty stuff, just doesn't agree with me 🤪

Anyhow, taking on board the advice I'm drawn to Anker, who generally seem to get very good reviews.  In particular either the 555 - my favourite but a bit put off by it's weight or the 521.  

I curretly (no pun intended) run all my AM5 & related needs directly from 240V mains via a DC powers adapter straight into the AM5 and onwards to the ASIair plus and all the other equipment (see image below for spec).  Am I right in thinking the power adapter would plug directly into either of the Anker Powerhouse mentioned using a standard UK x3 pin plug and then just work the same as off the mains, or am I missing something?

Graham   

[Elp]

It should work okay, but you need to check if the amperage is sufficient I think to match that of the output of the adaptor. Or use the DC out port.

I was looking at the 521, but might wait for the Bluetti EB3A to come back in stock next month as it has 2 off 12v out ports.

Edited September 24 by Elp

[AstroKeith]

If you plug that adapter into the 3 pin mains socket on the Anker, you will lose capacity in the inverter. You are taking dc from the battery cells, the inverter is producing 240Va, and then your adapter is converting back down to 12Vdc. You are probably going to lose 50% capacity.

Did you try that link I posted above https://www.amazon.co.uk/HOMELYLIFE-Automatic-10A-Waterproof-Transformer/dp/B07WFMG11F/ref=sr_1_1_sspa?crid=9Z5OFZ3C2DP8&dib=eyJ2IjoiMSJ9.PvkmenU9z0q22gENn7KTqYCTZfWVX3qMcmx1pz5LgsUCgwkZLBFM9-hMCdRCP0586xevs9Mg-WYnyccZtktdhC2unZvHwS3Hx5fI6GtE1qDj6cPEl65RiVhKvFxxlAO4ekpKdZjxKGp51YZ2JeH9tSqpP4v5AGnmqwVPFLfh4m7sKYosqfcY1t6Dnpp4TCt49e89GSuL_UtzsyoG6MhVg7w2pcbVhcwcGd3M-E8C5sBoE_4uN3_S8y-horE_VTg7bzotoyOphOpub1IcQVZMLJmFLGTTp4v6Yqjvg2PQE1o.X9NMHV6AeOWrZ2kl7WMQkd7k2slebkyW5jIZ2KpicqU&dib_tag=se&keywords=dc-dc+13.8+converter&nsdOptOutParam=true&qid=1727184799&sprefix=dc-dc+13.8+converter%2Caps%2C69&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

These are about 95% efficient.

[Elp]

11 minutes ago, AstroKeith said:

If you plug that adapter into the 3 pin mains socket on the Anker, you will lose capacity in the inverter

So if you use a direct 12v output connection, do you avoid this? Looking at some of the models I've seen its a "feature" of the more expensive models to have 12v outs (5.5 x 2.1mm type connections).

[groberts]

51 minutes ago, AstroKeith said:

If you plug that adapter into the 3 pin mains socket on the Anker, you will lose capacity in the inverter. You are taking dc from the battery cells, the inverter is producing 240Va, and then your adapter is converting back down to 12Vdc. You are probably going to lose 50% capacity.

Did you try that link I posted above https://www.amazon.co.uk/HOMELYLIFE-Automatic-10A-Waterproof-Transformer/dp/B07WFMG11F/ref=sr_1_1_sspa?crid=9Z5OFZ3C2DP8&dib=eyJ2IjoiMSJ9.PvkmenU9z0q22gENn7KTqYCTZfWVX3qMcmx1pz5LgsUCgwkZLBFM9-hMCdRCP0586xevs9Mg-WYnyccZtktdhC2unZvHwS3Hx5fI6GtE1qDj6cPEl65RiVhKvFxxlAO4ekpKdZjxKGp51YZ2JeH9tSqpP4v5AGnmqwVPFLfh4m7sKYosqfcY1t6Dnpp4TCt49e89GSuL_UtzsyoG6MhVg7w2pcbVhcwcGd3M-E8C5sBoE_4uN3_S8y-horE_VTg7bzotoyOphOpub1IcQVZMLJmFLGTTp4v6Yqjvg2PQE1o.X9NMHV6AeOWrZ2kl7WMQkd7k2slebkyW5jIZ2KpicqU&dib_tag=se&keywords=dc-dc+13.8+converter&nsdOptOutParam=true&qid=1727184799&sprefix=dc-dc+13.8+converter%2Caps%2C69&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

These are about 95% efficient.

OK, I think I get your drift here (just) Keith, which is obviously not good but I did look at your link and do not understand how I would therefore use the converter you've suggested - please explain?

+ Presumably the Anker power packs will work fine - the question is, if using the adaptor is very inefficient (which is what I think you're saying?), what is a better way of connecting the said power packs to the AM5 and thence onto the rest of the equipment?

Thanks for all your help and everyone else.     

[AstroKeith]

13 hours ago, groberts said:

OK, I think I get your drift here (just) Keith, which is obviously not good but I did look at your link and do not understand how I would therefore use the converter you've suggested - please explain?

+ Presumably the Anker power packs will work fine - the question is, if using the adaptor is very inefficient (which is what I think you're saying?), what is a better way of connecting the said power packs to the AM5 and thence onto the rest of the equipment?

Thanks for all your help and everyone else.     

OK, the input to the converter goes to the cigarette lighter socket on the Anker. No matter what voltage the Anker puts out, the converter will supply a clean 13.8V on its output. Connect the converter output to your rig.

[woldsman]

17 hours ago, CraigT82 said:

Right well I discharged the Anker 521 down to 15% using a small fan and the no load voltage across the pins is still 13.48v

I then hooked up a 4 watt dew heater strap to the cigar socket ( I've already bared the ends of the strap wire as I'm shortening the cable) and measured that load voltage at 13.37v

(4w is a small load but it is what my mount uses when tracking so quite useful for me.)

Would be good to test the load voltage at higher load but I don't have anything to hand with a higher draw that I can use to test that.

The OP wishes to power a lot more than just a mount though so would need a pretty hefty power pack, certainly much larger than the 521.

+1 for the Anker 521 with the caveat that I’ve not used it during winter (yet). It’s it a regulated supply? At (say) -10 degrees voltage could drop a couple of points. Otherwise a well-built portable unit for the price point.

[Carbon Brush]

Simple tests. No rocket science.
Grab a few car bulbs and a multimeter. A few bits of wire and tools/materials to prepare & hold the kit.

Measure the off load voltage with the pack fully charged. That is the highest voltage the electronics will have to withstand.
Generally mounts will handle 16V/17V. But an old mount?
Read the mount manufacturer specification.

Load up the pack using a car side light or similar bulb. sort of 5W/6W or about 0.5A load.
This is similar constant current to an active (tracking) mount that uses DC servos. Steppers are a different situation.
Measure the voltage at the pack.

Load up the pack using a headlamp bulb. These take sort of 4.5Amps. Or an off balance mount slewing.
Measure the voltage at the pack. Then measure at the end of the lead you propose to use for powering the mount.
If there is a significant difference (voltage drop on the led) then find another lead.

Finally. Starting with a 100% charged pack, connect the headlamp bulb and monitor voltage vs time.
How does the voltage vary as the pack discharges? Will this cause problems - again read the mount specification for minimum operating voltage.
Is there a definite shut off as the battery reaches the recommended discharge limit - there should be. If not send the pack back for refund.

All of the above can be done in daylight, in a warm place, when it is cloudy.
No loss of observing/imaging time🙂. And a high level of confidence having shown that the kit is fit for purpose.