Power Tanks, batteries and other wizardry...

[teoria_del_big_bang]

21 minutes ago, Shimrod said:

I have one of these as well (it can be picked up for £214 from picstop) and it is both lightweight and has all the power connectors I need. You don't have to worry about keeping it charged (like lead acid or Li-on) batteries, and the battery technology (LiFe-Po) is much safer than Li-on when it comes to possibly knocks or damage to the battery. It beats lugging the equivalent 20kg lead acid battery around and it will last for years. It is the battery technology rather than the brand that makes this expensive - have a look at tracer batteries which use the same technology and cost similar amounts.

That is actually a great price and although sounds expensive would probably work out cheaper in the long run.

The W/Hrs is about the same as the two supplies from Amazon and Maplin mentioned above at 158.4 W/Hrs. But:-

• You will get somewhere near all of that out of it if fully charged, I doubt you will from the others.
• It will last longer (i.e. more years) without having to be really careful to keep it charged, the others are liable to holding less power as it ages and maybe even failing altogether if not charged regularly.

However, not sure how you would power your laptop without some extra device such as 12V Laptop Charger

Steve

 

Edited December 20, 2020 by teoria_del_big_bang

[nephilim]

1 hour ago, Shimrod said:

I have one of these as well (it can be picked up for £214 from picstop) and it is both lightweight and has all the power connectors I need. You don't have to worry about keeping it charged (like lead acid or Li-on) batteries, and the battery technology (LiFe-Po) is much safer than Li-on when it comes to possibly knocks or damage to the battery. It beats lugging the equivalent 20kg lead acid battery around and it will last for years. It is the battery technology rather than the brand that makes this expensive - have a look at tracer batteries which use the same technology and cost similar amounts.

I bought this for all the reasons you've listed. Imo its definitely worth it & much less hassle than lead acid or trying to mess around trying to bodge something together. I wanted something that would work straight out of the box & be as convenient as possible & this fitted the bill perfectly.

[Shimrod]

1 hour ago, teoria_del_big_bang said:

That is actually a great price and although sounds expensive would probably work out cheaper in the long run.

The W/Hrs is about the same as the two supplies from Amazon and Maplin mentioned above at 158.4 W/Hrs. But:-

• You will get somewhere near all of that out of it if fully charged, I doubt you will from the others.
• It will last longer (i.e. more years) without having to be really careful to keep it charged, the others are liable to holding less power as it ages and maybe even failing altogether if not charged regularly.

However, not sure how you would power your laptop without some extra device such as 12V Laptop Charger

Steve

 

In my case I use a low power laptop - an HP spectre x2. The biggest power draw is the screen, the processor has a TDP of 15w. The laptop will go about 4 hours in the cold, and I use a cheap 20ah powertank (£30) which plugs into the usb-c port and keeps it topped up.

The other thing in favour of the LiFe-Po battery is the consistent power delivery as the battery discharges - no drops in voltage as you might find on other batteries.

[teoria_del_big_bang]

Just now, Shimrod said:

In my case I use a low power laptop - an HP spectre x2. The biggest power draw is the screen, the processor has a TDP of 15w. The laptop will go about 4 hours in the cold, and I use a cheap 20ah powertank (£30) which plugs into the usb-c port and keeps it topped up.

The other thing in favour of the LiFe-Po battery is the consistent power delivery as the battery discharges - no drops in voltage as you might find on other batteries.

Ah well yes it is certainly true that many laptops use less power than my brick and probably many of the newer models are far more lowered powered than mine. 

Steve

[SMF]

Andy, not sure about the stats but I looked at the Maplins chart that shows expected rating in various usage examples. Didn’t look that much to me. I might be wrong.

I’ve spent a few weeks debating this subject and after Ships and Star’s suggestion have just ordered the below:

https://www.fishingmad.co.uk/31508-bison-battery-box-carrier-with-usb-charger-led-meter-breaker-and-12v-socket-.html
and

https://www.batterymegastore.co.uk/product/hankook-xv27-leisure-battery/
 

Gives me 90AH for £135.00 which I recon will last six nights and more. The bigger Celestron Powertank is 17AH and that lasts more than a night for most people.

I’m fortunate to live right on the beach and plan to use this for leisure next summer as well.

Edited December 20, 2020 by SMF

[teoria_del_big_bang]

10 minutes ago, SMF said:

Andy, not sure about the stats but I looked at the Maplins chart that shows expected rating in various usage examples. Didn’t look that much to me. I might be wrong.

I’ve spent a few weeks debating this subject and after Ships and Star’s suggestion have just ordered the below:

https://www.fishingmad.co.uk/31508-bison-battery-box-carrier-with-usb-charger-led-meter-breaker-and-12v-socket-.html
and

https://www.batterymegastore.co.uk/product/hankook-xv27-leisure-battery/
 

Gives me 90AH for £135.00 which I recon will last six nights and more. The bigger Celestron Powertank is 17AH and that lasts more than a night for most people.

I’m fortunate to live right on the beach and plan to use this for leisure next summer as well.

I really like that battery holder.

That should be great and give you plenty of power, just make sure you do not totally drain the battery and keep it charged, re-charging regularly if not used for a while as it will discharge slowly on the shelf. But even if the battery goes down after a few years you only have to buy a new battery and still have that great holder.

Steve

[SMF]

14 minutes ago, teoria_del_big_bang said:

I really like that battery holder.

That should be great and give you plenty of power, just make sure you do not totally drain the battery and keep it charged, re-charging regularly if not used for a while as it will discharge slowly on the shelf. But even if the battery goes down after a few years you only have to buy a new battery and still have that great holder.

Steve

That’s what I liked about this battery box, with the external connections I can connect my battery trickle charger/conditioner without taking the box apart. The battery selected is sealed, maintenance free, heavy duty deep cycle as well. Place back on charge between uses in a corner of the workshop and I recon it’ll last years. The likely hood of getting through 80AH in any one use, Astro or beach, is highly unlikely.

I’ve already got a charger but they are only about £15 if anyone hasn’t. 

One down side, not very good for hiking, it’s gonna be heavy. About 24kg with battery and box but I recon it’ll only be carried over short distances anyway.

[Newforestgimp]

2 hours ago, teoria_del_big_bang said:

Some interesting finds and I am also particular interested how good either the Amazon one or the Maplin one is (I guess Mapling have remained an on line company as sadly I thought they went bust a while ago)

Amazon

Maplin

Both claim to be about 150W/Hrs which for a smallish imaging rig sounds good. One thing I would say is that whatever power they claim they can deliver in practice it will always will be less and in some cases maybe only half (that is a guess I cannot say for sure and sometimes you only find these things out by trying them). Many things contribute to lack of performance such as temperature, efficiency of the circuitry when creating all the different voltages.

If it was just a HEq5 size mount and a dew band drawing an average total of 1 to 2 amps at 12V throughout the night that is an average of 24 Watts so in theory would last 150 / 24 = 6.25 hours. But I would think if I were buying this I would only bargain on getting 4 to 5 hours. 

Now it may well be you actually only draw around 1A on average with this setup so long as you are not slewing from target to target every few minutes as it is the fast slewing to target that draws a high current (on HEQ5 I think it states around 2A). When tracking it will only be drawing about 0.5 A.
A dew band probably takes 0.5 to 1A depending on size, so a 100 mm dia scope probably about 0.5A but a bigger one on 200mm or bigger diameter may be 1A or a little more.
That's why I suggested maybe 2A average. But if a small scope and you are not doing a lot of slewing you may keep to around 1A to 1.5A so may get 8 hours or more, very difficult to say without knowing  exactly the current draw of each item and the efficiency of the supply.

One thing I haven't mentioned is the laptop. If use on an inverter then this will very quickly run down your battery and no actually idea how long it will last with the laptop as well. In fact it is impossible because many older laptops have woefully poor battery life so would be on mains power nearly all night. Most laptops have power supplies around 50 to 80W (I think - mine is 65W at 20V). This will be a maximum it can provide and so the laptop may not take this amount to charge or run. But lets say it takes 40W at 20V that means that with 150W/Hrs available (if it were 100% efficient - which it will not be) then the laptop alone will only run for 3.75 hrs (150 / 40).
Also the inverter will be nowhere near 100% efficient and my guess is in reality you will get only 2 to 2.5 hours running the laptop + of course what ever the battery can provide. 

So as I said very difficult without all the info of power used by each item and also how efficient the supply is with a small mount, small dew band and laptop with good battery my best  guess is you might get 2 to 3 hours from these at best.

There are things you can do to extend this life all of which are to draw less current:

• Use dew band at a lower voltage than 12V so it does its job but not over warm the scope.
• Use a low power tablet instead of laptop.
• If you use laptop then get a good battery, maybe two and hot swap them when one runs low (I do not know how feasable this is as I have never tried) but even one good battery means you can run only on battery for 2 to 3 hours before plugging into invertor.
• Do not use the invertor to run laptop but get a seperate 12V to Laptop Voltage supply (Like This) that will probably be more efficient and run it from the 12V, also only plug into supply for a short while and run most of night from battery (or ideally batteries).
• Dim screen right down and let it automatically turn off altogether when not being used.
• Install  a solid state drive rather than conventional HDD.

On a last note I think the Watt/Hrs is a better indicator of battery life than A/Hrs or mA/Hrs.
mA/Hrs is really the same as A/Hrs but rated in 1/1000's of an Amp rather than Amps. So if you divide mA/Hrs by 1000 you get A/Hrs.
If it is stated in A/Hrs or mA/Hrs then really it should state at what voltage. Some scrupulous sellers quote the A/Hrs as a ridiculous figure that makes it seem really powerful but they are quoting it from what is on the batteries which will be 3.6V for lithium-ion. But at 12V the figure will be 3.33 less than this quoted figure.

Steve

Thank you for a very comprehensive explanation, it has helped me understand much better.

[teoria_del_big_bang]

3 minutes ago, SMF said:

One down side, not very good for hiking, it’s gonna be heavy. About 24kg with battery and box but I recon it’ll only be carried over short distances anyway.

Always one drawback, but if you are not walking for miles then not an issue. Might even be able to hang it below the mount to make it more stable as well. 

Steve

[M40]

As far as electrikery goes, why don't you just get two of the 7AH skywatcher/celestron power tanks? https://www.firstlightoptics.com/batteries-powerpacks/skywatcher-powertank-7ah.html

Use one for the mount and one for all else. You could always up the second to the 17AH if you felt it necessary. 

[Newforestgimp]

3 hours ago, M40 said:

As far as electrikery goes, why don't you just get two of the 7AH skywatcher/celestron power tanks? https://www.firstlightoptics.com/batteries-powerpacks/skywatcher-powertank-7ah.html

Use one for the mount and one for all else. You could always up the second to the 17AH if you felt it necessary. 

That is actually a really good idea 👍

[SMF]

Went for this:

Got a little carried away changing things, happily I’m electrical for work so had most of the sundries.

Added two extra 12V ports, switches and a natty little USB 3A double with volt meter from Amazon.

Then I took the inverter from the truck and tacked it on the side.

90AH, 240V at 600W, three 12V sockets, one at 20A, two at 5A and three USB, and bonus of running a trolling motor for fishing.

Two hobbies in one sorted.

Quite pleased with it.

[SMF]

Just need the boat now. 🤣

[nephilim]

1 hour ago, SMF said:

Went for this:

Got a little carried away changing things, happily I’m electrical for work so had most of the sundries.

Added two extra 12V ports, switches and a natty little USB 3A double with volt meter from Amazon.

Then I took the inverter from the truck and tacked it on the side.

90AH, 240V at 600W, three 12V sockets, one at 20A, two at 5A and three USB, and bonus of running a trolling motor for fishing.

Two hobbies in one sorted.

Quite pleased with it.

Looks very tidy, an extra 12v will be a bonus. Both my mount & upcoming dedicated cooled camera utilize 12v

[Newforestgimp]

On 24/12/2020 at 15:20, SMF said:

Went for this:

Got a little carried away changing things, happily I’m electrical for work so had most of the sundries.

Added two extra 12V ports, switches and a natty little USB 3A double with volt meter from Amazon.

Then I took the inverter from the truck and tacked it on the side.

90AH, 240V at 600W, three 12V sockets, one at 20A, two at 5A and three USB, and bonus of running a trolling motor for fishing.

Two hobbies in one sorted.

Quite pleased with it.

Wow !! This is what I need, it would be perfect for paddle boarding and kayaking !!!

[bsshog40]

On 20/12/2020 at 04:47, Shimrod said:

I have one of these as well (it can be picked up for £214 from picstop) and it is both lightweight and has all the power connectors I need. You don't have to worry about keeping it charged (like lead acid or Li-on) batteries, and the battery technology (LiFe-Po) is much safer than Li-on when it comes to possibly knocks or damage to the battery. It beats lugging the equivalent 20kg lead acid battery around and it will last for years. It is the battery technology rather than the brand that makes this expensive - have a look at tracer batteries which use the same technology and cost similar amounts.

I just bought one of these power tanks. I didn't get the pro though as all I need it for is to power my cpc800. It seemed to have good reviews. I just hate dragging an extension cord out. Thought this would be the perfect thing.