Please help me understand the Ah of a power pack

[BGazing]

Now, a default powerpack for my Synscan are 8 AA (non-rechargeable) batteries. How many Ah do they produce at 12V?

This will help me compare them against the @12V figure of the powerpacks on offer, but I have no yardstick of comparison...

[Bizibilder]

Amp-Hours are quite straightforward.  If you draw a current from a battery of one Amp for one hour you have used "1 Amp-hour".  Some smaller batteries are rated as, say 800 mAh (eight hundred milli-amp-hour) this meands they can run a load of 0.8 Amps for one hour before expiring (or being recharged).  The Ah value is independent from the voltage of the battery.

[Mick J]

Interesting question,  a quick google produces this from 2006 and this undated.  Possibly the batteries you are using now are listed ?  hope this is helpful.

I think that if one battery is producing say 1.5 volts at say 800 mAh, then 8 would give 12 volts at 800 mAh.

[BGazing]

So basically the entire battery pack is giving me around say 1.5 Ah at 12V...interesting.

Thanks!

[brantuk]

8xAA 1.5v batteries won't last on even an average night - your observing session will end very quickly. Better to get a 12v 17ah power pack which will drive tracking all night with a couple dozen goto slews. You also need to factor in dew control which draws a lot of amps for the controller and dew bands.

Most serious observers and imagers will use a leisure battery (85ah or 110ah) which will provide most power requirements to run all their gear (goto, dew control, cameras, guiding, etc)  all night on the coldest of nights. But for just Sysncan goto I have used a 17ah power pack for over 12hrs with no sign of dropping off on a warm autumn night. Hth

[BGazing]

8xAA 1.5v batteries won't last on even an average night - your observing session will end very quickly. Better to get a 12v 17ah power pack which will drive tracking all night with a couple dozen goto slews. You also need to factor in dew control which draws a lot of amps for the controller and dew bands.

Most serious observers and imagers will use a leisure battery (85ah or 110ah) which will provide most power requirements to run all their gear (goto, dew control, cameras, guiding, etc) all night on the coldest of nights. But for just Sysncan goto I have used a 17ah power pack for over 12hrs with no sign of dropping off on a warm autumn night. Hth

Many thanks! If I buy a strong LiPo it will have only one 12V output, I guess I would have to use a splitter of sorts to connect both the goto and thr dew controller, right? How does that device look like, sorry to ask?

Also, how much would a dew heater draw at around zero degrees Celsius per hour? I really do not intend to pull all nighters, especially in the wInter LOL

[spaceman_spiff]

I second Brantuk's comment but also add that you should try to get a battery that has at least twice the Ah capacity as you plan to use when observing. Batteries really don't like being completely drained so it makes sense to get a larger capacity battery that is only partly drained.

I use a 12V 17Ah lead acid gel battery that drives the mount (which draws about 0.7A) for observing sessions lasting up to 8 hours. So 17Ah is OK for my needs but I may need a larger battery if I want to add other gizmos.

Hope that helps.

   

[damnut]

Once you have a power unit capable of giving at least a good nights viewing, is where the diy sets in. There are many threads on SGL with projects to distribute power. This is one I did for a friend, with an integrated four dewstrip controller an inverter for a laptop, usb pass through and two more 12v outputs.

[nigelbeaumont]

Also bear in mind that the Ah of a battery is normally rated as the current that it can maintain for 10 hours, eg a 24 Ah battery can supply a current of 2.4A for 10 hours - however the capacity is less for larger currents, so it won't supply 6A for 4 hours, it will probably only maintain this current less than 3 hours. It's all due to the internal resistance of the battery, as more energy / capacity is wasted in overcoming this at higher currents

[cuivenion]

I always thought you totalled the Ah and the voltage, so if you had 10 x AA rechargables at 1.2v and 1Ah each that would mean you have a 12v output with 10Ah capacity. Is this not right?

[Thalestris24]

I always thought you totalled the Ah and the voltage, so if you had 10 x AA rechargables at 1.2v and 1Ah each that would mean you have a 12v output with 10Ah capacity. Is this not right?

Hi

No - I think it depends on whether you connect them in series or parallel. To get 12v from 10 x 1.2V batteries you would have to connect them in series but the overall capacity will still only be 1AH. On the other hand, you could connect them in parallel and get an output of 1.2V for 10 x 1AH.

Louise

[cuivenion]

Hi

No - I think it depends on whether you connect them in series or parallel. To get 12v from 10 x 1.2V batteries you would have to connect them in series but the overall capacity will still only be 1AH. On the other hand, you could connect them in parallel and get an output of 1.2V for 10 x 1AH.

Louise

 Thanks that's cleared up a few things for me.

[BGazing]

Once you have a power unit capable of giving at least a good nights viewing, is where the diy sets in. There are many threads on SGL with projects to distribute power. This is one I did for a friend, with an integrated four dewstrip controller an inverter for a laptop, usb pass through and two more 12v outputs.

Box2_2.jpg

Box4_2.jpg

Looks neat! Any solution for us non-DIY guys...? I.e., any prefab solution for those who buy their way out of trouble?