Power Tanks

[noah4x4]

One other point..."50 Ah" is a bit deceptive. The MaxOak is built of 3.5v cells (like vacuum cleaner batteries) and that rating applies only at 3.5V. What is far more important is that it churns out 12v and 2.5A but a whopping 185 watt hours.  It's enough to completely recharge a laptop computer!

[noah4x4]

It will be plenty to embrace Celestron accessories including Starsense, GPS, Sky Portal wireless accessory (I have all of these running with my SE4 and MaxOak).  

You will possibly be OK with a modest camera too. My caution is from my Atik Horizon camera demanding two Amps just on its own (thirsty beast, but it does exceed 4k UHD). 

[RayD]

3 minutes ago, noah4x4 said:

One other point..."50 Ah" is a bit deceptive. The MaxOak is built of 3.5v cells (like vacuum cleaner batteries) and that rating applies only at 3.5V. What is far more important is that it churns out 12v and 2.5A but a whopping 185 watt hours.  It's enough to completely recharge a laptop computer!

Spooky, I was just about to reply noting the same thing about the Ah rating.

These little units are really good.  I use one indoors for when I am testing kit or doing a video, and for just running a mount they are good, but are pretty well all limited to the 2.5A output, which a lot of mounts will push whilst slewing, and can lead to overheating.

Limit the slewing, or reduce the slew speed to slow, and these are good little solutions.

[johninderby]

The cheaper batteries are OK if you don’t ask too much of them and will do for uses that don’t require a lot of amps. 

The Tracers that I bought for a more demanding use will put out 30A continuous and 90A short term and are a bit of overkill just for running a mount etc.

[noah4x4]

15 minutes ago, RayD said:

Spooky, I was just about to reply noting the same thing about the Ah rating.

These little units are really good.  I use one indoors for when I am testing kit or doing a video, and for just running a mount they are good, but are pretty well all limited to the 2.5A output, which a lot of mounts will push whilst slewing, and can lead to overheating.

Limit the slewing, or reduce the slew speed to slow, and these are good little solutions.

Absolutely RayD. 

I have also used mine to power an Intel NUC with Iris Plus 640 graphics that demands 19v, 3A and a peak of 45 watts. However, the MaxOaks 185 watt hour rating will keep that going for around 6 hours and although the claimed output is 20v/3A it is actually 19.3v so within the + or - 10% tolerance for that minicomputer. 

All that users need to remember is to check the total Amps required by their equipment. If more that 2.5A then use multiple MaxOaks. I use one for my mount (etc) and another battery (my original 8Ah Tracer) for my camera that as I said requires 2A on its own. But to merely run an SE and it's limited accessories it will be fine. The Tracer at 8AH wasn't enough for both mount and camera and a second Tracer (notably much higher Ah) was silly money compared to the MaxOak.

 

[RayD]

12 minutes ago, johninderby said:

The cheaper batteries are OK if you don’t ask too much of them and will do for uses that don’t require a lot of amps. 

The Tracers that I bought for a more demanding use will put out 30A continuous and 90A short term and are a bit of overkill just for running a mount etc.

You're spot on.  They are not necessarily intended for this application, so are perhaps a bit OTT, but they are indeed good.

I think they were really originally intended for applications where weight was key, such as transportation systems, but work perfectly well for astro work of course.  If weight bothered me I would have one, but I use a 33Ah AGM for my field stuff, which whilst 11Kg is not a lightweight, it's not so chunky as to be problematic.

[johninderby]

The Tracers are built to a standard with full certification so useful for applications that require certified components.

My Tracers in the place they were bought for. An Armortek 1:6 Tiger 1 tank. A 170kg beast when finished. They are just small enough to drop through the engine hatch.

[JimothyC]

56 minutes ago, noah4x4 said:

I have also used mine to power an Intel NUC with Iris Plus 640 graphics that demands 19v, 3A and a peak of 45 watts. However, the MaxOaks 185 watt hour rating will keep that going for around 6 hours and although the claimed output is 20v/3A it is actually 19.3v so within the + or - 10% tolerance for that minicomputer. 

Most of the Intel NUCs will run off of 12-20v, so can feed them 12v if that's all you've got. 

[RayD]

9 minutes ago, johninderby said:

The Tracers are built to a standard with full certification so useful for applications that require certified components.

My Tracers in the place they were bought for. An Armortek 1:6 Tiger 1 tank. A 170kg beast when finished. They are just small enough to drop through the engine hatch.

Ah that explains the wheels (tyres) that I saw in the background in your earlier picture.  Perfect for that, light with plenty of power.

[rhw1967]

As an extension of this, how do people keep their Powertanks dry and dew free when out and about using their telescopes ? 

Was thinking of getting one of these that are on sale now and just using the box as a portable carrier ...... https://www.screwfix.com/p/masterplug-weatherproof-box-kit/46169?_requestid=580110

[johninderby]

Never had a problem with dew on a battery so just let it sit on the ground. Some of the powertanks with USB ports etc might want to be kept off the ground but otherwise don’t need protecting from dew.

BTW here’s the Celestron Powertank manual.

https://celestron-site-support-files.s3.amazonaws.com/support_files/18771_PowerTank_Lithium_Manual_5Lang_F.pdf

[Carbon Brush]

May I throw another item into the discussion?

When you look at a 12V lead acid battery, you are given figures for voltage and capacity (amp hours).
For example 12V and 20Ah.
The total energy available is 12V x 20Ah = 240Wh (watt hours).

When you buy a Tracer (or similar) pack you are told the power delivery in the same way.
So a 12V 22Ah pack will deliver 12V X 22Ah = 264Wh.

However, the chinese sellers on Amazon and ebay  sometimes play specmanship, or cheat, or omit detail. Take your choice on the interpretation.

You will have seen power packs to provide 5V for phone charging, etc. These use a 3.7V single lithium cell and a circuit to stup up the voltage to 5V.
The advert states it gives 5V and is (for example) 10Ah capacity.
You might then expect it to provide 5V x 10Ah = 50Wh.
But they are referring to the capacity of the 3.7V cell.
This means in reality you have 3.7V x 10Ah = 37Wh available, less the step up convertor efficiency.
The actual power from the pack is going to be more like 30Wh.
If you don't follow the maths, don't worry. Just send me £50 and I will send you £30 in return.

A similar trick is played with the 12V output packs used for car jump starting.
A pack comprising 4 cells each 10Ah is described as 40Ah.
You actually have a 12V 10Ah battery pack as the cells are series connected for use!
 

Check the specification carefully. The bargain battery may not be as good as it seems.
Especially when you consider the risk of the chinese stuff not being properly constructed in the first place.

If a manufacturer is going to lie about the specification, can you trust anything else about the product?

Yes I have a few horror stories about lithium batteries.
Including a 'Segway' copy battery pack (approx 720Wh) failing and replacements that were not UN38 certified being sent by air freight.
Fortunately no aircraft caught fire and crashed, this time.

 

 

[johninderby]

Hence the old saying you get what you pay for.  ?

[noah4x4]

5 hours ago, JimothyC said:

Most of the Intel NUCs will run off of 12-20v, so can feed them 12v if that's all you've got. 

We have drifted off topic, but it might assist those now considering buying the MaxOak powervunit in answer to the OP.

It is is true that low budget NUCs like an i3 with regular HD graphics can be run at 12v. But I have a i5 NUC with Iris Plus UHD Graphics that demands close to 50 watts at peak load and in my experience it doesn't particularly like "12v" unless backed up with plenty of available Amps albeit the quoted Intel NUC range is "between 12v and 19v + or - 10%".

I think that the issue here is that many "12v" external power units output merely 11+ volts and the more powerful NUCs do want a minimum of a true 12v. At the other end of the scale I was concerned about power cells that claim to output 20v when the NUC wants only 19v. However, most of these output (say) merely 19.3v so within the +10% tolerance (note that a 10% tolerance at the lower 12v end is more tight).  There was much debate about this in Cloudy Nights and Intel NUC Forums before people concluded the MaxOak is a great buy. Final conclusion was  it's probably best to run a NUC at 19v/20v. Frankly, I have moved mine indoors as I use USB3 and Thunderbolt display cable to a 4K UHD monitor (much more reliable than wireless) and I now use the regular Intel mains electricity adapter. 

[noah4x4]

3 hours ago, Carbon Brush said:

May I throw another item into the discussion?

When you look at a 12V lead acid battery, you are given figures for voltage and capacity (amp hours).
For example 12V and 20Ah.
The total energy available is 12V x 20Ah = 240Wh (watt hours).

When you buy a Tracer (or similar) pack you are told the power delivery in the same way.
So a 12V 22Ah pack will deliver 12V X 22Ah = 264Wh.

However, the chinese sellers on Amazon and ebay  sometimes play specmanship, or cheat, or omit detail. Take your choice on the interpretation.

You will have seen power packs to provide 5V for phone charging, etc. These use a 3.7V single lithium cell and a circuit to stup up the voltage to 5V.
The advert states it gives 5V and is (for example) 10Ah capacity.
You might then expect it to provide 5V x 10Ah = 50Wh.
But they are referring to the capacity of the 3.7V cell.
This means in reality you have 3.7V x 10Ah = 37Wh available, less the step up convertor efficiency.
The actual power from the pack is going to be more like 30Wh.
If you don't follow the maths, don't worry. Just send me £50 and I will send you £30 in return.

A similar trick is played with the 12V output packs used for car jump starting.
A pack comprising 4 cells each 10Ah is described as 40Ah.
You actually have a 12V 10Ah battery pack as the cells are series connected for use!
 

Check the specification carefully. The bargain battery may not be as good as it seems.
Especially when you consider the risk of the chinese stuff not being properly constructed in the first place.

If a manufacturer is going to lie about the specification, can you trust anything else about the product?

Yes I have a few horror stories about lithium batteries.
Including a 'Segway' copy battery pack (approx 720Wh) failing and replacements that were not UN38 certified being sent by air freight.
Fortunately no aircraft caught fire and crashed, this time.

 

 

I covered this ground earlier and confirmed that the MaxOak claims of 50000mAh are at 3.7v. However, it does genuinely offer 185 watt hours and as regards Wh per $ it's probably unbeatable. I have had mine for over a year and I know of three others with similar good experience. Look too at the positive reviews on both UK and USA Amazon. 

As regards carriage on commercial paasenger aircraft, the limit is now strictly 100 watt hours. So anything bigger than an 8Ah x 12v Tracer is illegal. Well worth bearing in mind if intending to fly. 

[rhw1967]

For me, I think the MaxOak is spot on. I won't be running a lot of things from it, just my scope and the WIFI or GPS  attachments.  You've said how long it will last, again which is perfect for me. Am new to Astronomy so right now just want to observe the night skies, have no interest in photography at the present time.

I think the MaxOak sounds perfect for giving me a long night's observing (as long as the clouds stay away that is... haha) 

[RayD]

1 minute ago, rhw1967 said:

as long as the clouds stay away that is... haha

Ah, now then......That's the hard bit ?

[Astro-Geek]

This has been a very interesting and informed discussion, but I'd hazard a guess that the majority of Astronomers are far more interested in gazing upwards into infinity than the mathematics and science of their batteries.  ?

 

Lithium has far more efficiency in power to weight and longevity, but the average very low power consumption needed for scopes still makes lead acid still a viable proposition IMHO.

I'll keep using my cheapo DIY lunchbox SLA powertank for my scopes, but I'm well sold on Lithium for my bikes and RC aircraft, where the choice is much more clear-cut energy wise.

 

[JimothyC]

8 hours ago, noah4x4 said:

We have drifted off topic, but it might assist those now considering buying the MaxOak powervunit in answer to the OP.

It is is true that low budget NUCs like an i3 with regular HD graphics can be run at 12v. But I have a i5 NUC with Iris Plus UHD Graphics that demands close to 50 watts at peak load and in my experience it doesn't particularly like "12v" unless backed up with plenty of available Amps albeit the quoted Intel NUC range is "between 12v and 19v + or - 10%".

I think that the issue here is that many "12v" external power units output merely 11+ volts and the more powerful NUCs do want a minimum of a true 12v. At the other end of the scale I was concerned about power cells that claim to output 20v when the NUC wants only 19v. However, most of these output (say) merely 19.3v so within the +10% tolerance (note that a 10% tolerance at the lower 12v end is more tight).  There was much debate about this in Cloudy Nights and Intel NUC Forums before people concluded the MaxOak is a great buy. Final conclusion was  it's probably best to run a NUC at 19v/20v. Frankly, I have moved mine indoors as I use USB3 and Thunderbolt display cable to a 4K UHD monitor (much more reliable than wireless) and I now use the regular Intel mains electricity adapter. 

I’m running an 8th gen i5 with Iris 655 happily on 12v. One of the advantages of a Lifepo4 battery is that the voltage is very stable and stays above 12v for 99% of the run time of the battery. 

My total power consumption for an iOptron CEM25P, 2 Dew heaters, a Nikon D7500, Pegasus FocusCube and the PC is around 30w. This gives me about 9 hours run time with my setup from a 22ah lifepo4 golf trolley battery. Just enough for an evening’s session.  

I’m a setup and breakdown every evening user and the lack of wires running across the garden is a real improvement. It also means I can keep the same setup if I head off to a dark site. I looked at 12v power supply or even a feed from the leisure battery in my camper van. But the voltage drop you get on a long cable run means using pretty heavy gauge wire to get good efficiency. Having the power source and the pc at the mount makes things a lot simpler for me. 

[noah4x4]

Where this topic becomes highly material is with regard to wireless remote controlled EAA rigs where typically extra power is required at the scope for camera and mini-computer but supplied from a lightweight power source that can be affixed above the mounts point of rotation to avoid cordwrap. Something like the MaxOak or a Tracer is then ideal.

EDIT

I think Jimothyc and I are actually agreeing in that you do need a stable 12v - 19v for most NUCs. 11.5v isn't enough.  I have found the MaxOak outputting 19.3v (albeit rated 20v) more reliable than using my older Tracer 12v 8Ah and/or another charger type unit that I had claiming to output 16v which lasted about an hour! 

[Geoff Lister]

I measured the current consumption of my mounts:-

The Skymax, Cosmos & Skyprodigy mounts have similar basic mechanical construction, motors, and motor control. These are my mount power sources:-

I tend to use the mains supply for the Dob, as it is in easy reach of house power. The other sources will fit in the little satchel, supplied with the Skymax, and I have added stick-on hooks to the mounts so that the satchel can hang from the rotating section, and avoid cord-wrap. The 6V, 2600mAh NiMH packs are "borrowed" from radio-controlled model sailing yachts, and tend to be the preferred option for a good evening's portable observing. I found the 10-cell battery holder gave unreliable operation unless the contacts are kept very clean. I have also added little clips on each of the mounts, to act as a strain-relief for the power jack, when using the plug-top supply's lead, to avoid the power jack being pulled out as the mount rotates.

Geoff

[Astro-Geek]

I'm a newcomer to this forum and I confess I didn't realise how sophisticated some of the user's setups are.

I should admit that most of my thoughts on here were based on the assumption of just a simple motorised scope with a dew heater.

You Guys (and Gals maybe) are way ahead of me......   ?

[rhw1967]

Just now, Astro-Geek said:

I'm a newcomer to this forum and I confess I didn't realise how sophisticated some of the uer's setups are.

I should admit that most of my thoughts on here were based on the assumption of just a simple motorised scope with a dew heater.

You Guys (and Gals maybe) are way ahead of me......   ?

I am in the same boat bud, hence me asking tons of questions. Everyone on the forums have been super helpful and friendly.