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halli

Help with 12V Laptop power !

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Hi All 

I currently image in my back garden and use an AC extension lead to power everything.  I want to move to a battery source and have bought a 88Ah leisure battery for this purpose so that i can go mobile  and get to some dark skies!

To solve the laptop power issue I bought a 12V car power adapter for laptops from Clas Ohlson which worked ok. In my case I need 19V for my laptop input.

However I found that whenever I used it strange things happened to my NEQ6 mount !  The mount is driven by an EQMOD direct connection and was powered from the same battery as the laptop supply.  The EQMOD screen would occasionally lose track of where it was and think it was in the parked position. Not sue what was causing this but it appears to be repeatable ans was very frustrating.  My though might be that the power supply was very noisy and it may have been noise injected into the battery connections or even the laptop that were affecting the mount electronics in some way.

I have another battery so I guess i could power the laptop from this to see if I can isolate the problem.

Has any one any experience of this ?  Also what do other people use to provide  laptop power from 12V ?

Any information would be appreciated

Thanks

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Thanks - yes I guess that would mean I can use my normal laptop charger.  They look relatively inexpensive £20 plus -  not sure about the efficiency.

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2 types pure or mod pure is more money   as the volts flow as a wave , mod volts come in block some things do not like mod but my laptop and tv work ok ,ps if you loooking at useing 150v get one that do 300v so on.

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I use one battery purely to power the NEQ6 as I have found that when too many things are plugged in-dew bands, laptop etc draw too much power and causes problems on the NEQ6.

A separate battery with one of these for my laptop

http://www.amazon.co.uk/gp/product/B00D06JY30?psc=1&redirect=true&ref_=oh_aui_detailpage_o09_s00

(mine is a toshiba hence that cable-others are available) saves inverting and creating an inefficient method of providing power

or buy a higher capacity laptop battery

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Thanks m.tweedy it may be the same thing thats happening to me and may be due to a dip in Volts to the NEQ6 when the power consumption is high and not noise !

I have a car battery as well as a leisure battery so I have the option of using a single battery for the NEQ6 although it may mean lugging another battery around.

The car adaptor you use is quite similar to mine although its for more general use.

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sadly i have to use 2 batteries as well.

my 85 ah one tends to be the one for starparties and 2 x 50 ah (a LOT lighter in weight) for normal dark sky and public observing tese wer given to me by a mobility scooter repairer after they came out of mobility scooters that were being scrapped (sadly he has closed so that source has gone)

the laptop adaptor is specific to my model and is designed to provide the correct power input. slighly more expensive but worth it in my eyes.

i also got a battery that is double the capacity of the supplied one and can get 5 hours plus from it. (more when i convert to a SSD) 

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another tip is to put the batteries in something similar to this

http://www.tesco.com/direct/insulated-cool-box-24l/210-0965.prd?pageLevel=&skuId=210-0965

helps protect the battery from draining too quick on freezing ground and air and has the additional benefit of hiding the bright lights from the sockets that the equipment is plugged into

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I use a couple of 20Ah gel cell batteries.

The 12V-19v convertor on one for the laptop - when it decides to charge the internal battery it can pull a lot of current.

The other does the NEQ6/ EQmod etc.

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Stay with a 12-19 converter!!! The 240 ones may or may not produce adequate waveform and may or may not work with your original adapter. Just make sure you leave the ferrite beads on the 12-19V cables as they reduce the interference.

Make sure that power availability is adequate - some laptops will want up to 100W!

I use three setups with 12-19 adapters and all work perfectly well. 

/per

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Thanks for all your input, I guess in retrospect two smaller batteries would have been better than buying one big one !  

I will do further testing with my DC/DC converter to try and isolate the issue.  I was thinking about some sort of noise filter and the mention of ferrite beads has reminded me of  a simple solution so thanks for that idea.  Hopefully I can get these from Maplins

Cheers

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How about using a netbook rather than a laptop and run it off it's own battery?  I can get 8 hours running time from mine.  You don't need much processing power for image capture and guiding etc.  Just a thought :)

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Hi There , Merry Xmas , where your problem lies is, when the very capable 88ah battery is under load , the initial fully charged battery voltage drops a small amount , this is just enough to dip below the happy voltage point for a NEQ6 (if I remember my problems from a couple of years back about 12.6V ) the way you can cure this and have 8hrs+ un-interrupted battery use ,is , getting a cigar plug DC to DC converter with the correct wattage rating , this fools the mount into thinking it is getting a constant 12.5 / 13V even while late into a session when the battery starts edging towards 11.8V and downwards, I find it a good idea to have the laptop fully charged before going out so that it is not using extra power to charge up & operate , here is my old post about modding a converter...

http://stargazerslounge.com/topic/165173-neq6-flashing-led-resulting-bad-tracking/

Hope you get it fixed and get back out again .

Dave.

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Hey guys and gals!

Apart from Merry Christmas, let me just point out that a lead-acid battery drawn down to 11.8 "and downwards" is being ruined. The only battery type that will come out of a discharge like that alive and well is AGM. Gel and free liquid ones suffer permanent damage if discharged below 11.9V.

Here's the table for discharge:

post-9361-0-57337400-1419514862.png

Clearly, we all have to be careful with the batteries!

My tips for when you buy batteries are:

  • Bring a voltmeter! Make sure the battery, as delivered from the shelf, has at least 75% charge (12.4V or higher)
  • Try to stick with AGM or modern GEL - much better resilience
  • Don't even think of a standard free liquid battery - they get sulfur clogged electrodes very easily if discharged

/per

Edited by perfrej

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Yes , exactly why I chose a 90Ah AGM after exhaustive research before buying a big battery , sorry  I got the discharge volts wrong , I was in a hurry this morning to attend a full roast dinner ;) .

When I was ironing out my set up problems, I noticed one of the things also to take into account is the cold temp. the battery is exposed to at a remote site, often sitting on frozen ground in winter in the -degC numbers , this really affects battery performance , to fix that , I built a cosy insulated carry case for the AGM battery, with a long DIY dew strip wrapped round the battery to keep it snug.

For the past few years the 90Ah AGM running a 12V dc to dc converter for my NEQ6 / a 12V dc to dc converter for my already charged laptop / 4 dew heaters( objective / finder guider / DSLR on tripod doing timelapse / battery snug belt)  , this set up has been working fantastic, when the weather behaves :)

Dave.

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Hi guys  - Merry Xmas and thanks for the info - it is all very interesting.  There's a lot of food for thought here and the previous thread was very informative !

I am now aware of the NEQ6 voltage tolerance issues which explain a lot.  I started experiencing them when I connected my laptop via a DC/DC converter very much like the one you pointed out Dave !  The NEQ6 would experience poor tracking. and behave erratically when performing a go to etc. I had also experienced power drop outs which were very frustrating  to such an extent I contacted the vendor of the stand who sent me another input board to replace the one I had.  I suspected the connector at the time but I guess it may have been the plug on the end of the power cable.   The design is pretty poor which is a shame for such a critical function.

Any how -  back to the battery -  It seems like a good idea to use a DC/DC converter for the stand to keep the volts up.  The minimum on mine is 15 v -  i'm not sure if this will affect the performance of the mount or not - any views on this ?

I have 2 batteries but it would be a shame if I cant use just the 88Ah one that I have recently forked out for.  I will try this suitably insulated and using a DC/DC converter for the mount as well as the laptop.  I had thought about buying a netbook or something similar with a  longer battery life but that would mean even more expense !

My battery is :

http://www.batterymegastore.co.uk/product/XV24/

not sure if it is an AGM battery but hopefully it will tolerate the NEQ6,  Laptop and a dew heater reliably - I tend to use foam tubes these days to prevent dew anyway.  Interesting to note the discharge voltages of the batteries and the need to monitor this to ensure a longer lifetime.  I guess its best to trickle charge the battery after every use

Cheers

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Hi , yes the battery will do fine, it is a flooded lead acid  Leisure battery in the specs on the link you posted, if you were ever to replace it at all , I would recommend getting an AGM (more discharge cycles, etc )  , but you already have this battery, so use it :) .

A common discharge level of these batteries we use , is about 50% (many battery pdf technical documents state an increase in battery life if mainly used to 50%)  , on Per's posted table above which relates to flooded lead acid deep cycle batteries, you can see your battery 50% voltage is 12.2V  , at this voltage a dc to dc converter for the mount will still be running fine , but an EQ6 running direct at that voltage would be quite impossible to tolerate :) .

AGM have a tolerance that allows them to occasionally be run down to 30% / 40% discharge , but 50% is a good mark to aim for

batt_cht.gif

A smart charger is always recommended for marine / leisure batteries , C-tek is a very popular choice for a lot of astro folk , I use a http://www.ringautomotive.co.uk/uk/products/Cars/Battery+Care/SmartCharge-plus-/RSC512  and It does a grand job.

At 50% battery level , when out at a site,  you don't need to immediately switch everything off , but be conscious that the battery has reached half way :)

Dave.

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