Topics

Running Mach2 from battery at 24v


Steve Armen
 
Edited

Hello,

Preparing for a mach2 in the future, would anybody care to recommend (AP staff included) a good quality DC2DC boost converter for 12V to 24V? Reading the specs, it seems the mount may like to operate at 24V instead of 12V. In the case of operating from 12V batteries, looking at options. 

Looking at this one: https://www.amazon.com/DROK-Conversion-Efficiency-Waterproof-Transformer/dp/B081RFN1VJ

It's nice with much overhead for the current load /power required, good efficiency. Not that I'm planning on slewing at 1800x running from batteries :-) 

thanks,

Steve


uncarollo2 <chris1011@aol.com>
 

If you are doing nothing but slewing, then it's nice to have 1800x. However, the mount runs just peachy with only 12 volts. In fact it will even run nicely at 10 volts. When you are tracking or guiding, etc, it doesn't matter what voltage you use, 12v, 18v, 24v. All works just the same.

Rolando



-----Original Message-----
From: Steve Armen <st5.armen@...>
To: main@ap-gto.groups.io
Sent: Fri, Sep 11, 2020 4:30 pm
Subject: [ap-gto] Running Mach2 from battery at 24v

Hello,

Preparing for a mach2 in the future, would anybody care to recommend (AP staff included) a good quality DC2DC boost converter for 12V to 24V? Reading the specs, it seems the mount may like to operate at 24V instead of 12V. In the case of running from batteries.

Looking at this one: https://www.amazon.com/DROK-Conversion-Efficiency-Waterproof-Transformer/dp/B081RFN1VJ

It's nice with much overhead for the current load /power required, good efficiency. Not that I'm planning on slewing at 1800x running from batteries :-) 

thanks,
Steve


Dean Jacobsen
 

Hi Steve, I have been running my Mach2 on 12 v since I got it.  Actually, I have the power supply set to 13.5 v but a couple of times I forgot to turn the PS on and ran all night on the backup battery.  It works fine although I don’t slew any faster than 900x (for mapping runs) and I generally run the mount at 600x.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Steve Armen
 

Thank you for the advice,

It will be cleaner to power direct from 12V battery, when imaging where AC is not available. 

Steve


Frank Widmann
 

When I run 24 volt stepper motors from a battery, I just wire two twelve volt batteries in series to get 24 volts. Motor scooter and wheel chair batteries are reasonably priced and durable.


Seb@stro
 

Hi Steve,

If you don’t need to slew at high speed, you might not find a great advantage in boosting your battery voltage to 24V.

While it might seem appealing to get room as far as power is concerned, be aware that a dc-dc boost converter won’t give you much than what your battery can already provide. In fact, any voltage conversion (buck or boost) will result in loss of power in the system. Your load (the mount in your case) will consume about the same amount of power (more voltage and less current at 24V than 12V) but the inefficiencies (as small as they can be, say 5% like in the model you are considering) will be totally lost, resulting in a lost of autonomy of your battery-powered system.

Also keep in mind that some dc-dc converter designs require a minimum load to work (or start working) and perform at their nominal specified efficiency... So depending on what else you plan to power from 24V oversizing might not be your friend...

Clear sky!

Sébastien 

Le 11 sept. 2020 à 17:32, Steve Armen <st5.armen@...> a écrit :



[Edited Message Follows]

Hello,

Preparing for a mach2 in the future, would anybody care to recommend (AP staff included) a good quality DC2DC boost converter for 12V to 24V? Reading the specs, it seems the mount may like to operate at 24V instead of 12V. In the case of operating from 12V batteries, looking at options. 

Looking at this one: https://www.amazon.com/DROK-Conversion-Efficiency-Waterproof-Transformer/dp/B081RFN1VJ

It's nice with much overhead for the current load /power required, good efficiency. Not that I'm planning on slewing at 1800x running from batteries :-) 

thanks,

Steve


Steve Armen
 

Hello Sebastien,

All good points. That 5% loss in the boost converter would most likely turn into heat. In any case, if there are no benefits for normal tracking and guiding for imaging at 24V, there would be no point operating at that voltage. 


Seb@stro
 

Right, heat as well as vibrations or even EMI/RFI (ElectroMagnetic / RF Interference). Some poorly designed dc-dc converter can even be harmful to sensitive precision electronics and/or disrupt nearby wireless (or wired, though that is less common) communication links.

The reason being that high efficiency in modern power supplies (or dc converters) rely on switching components (varying frequency) for voltage regulation which in turn creates unwanted electric noise and RF emissions. If those are not filtered correctly by the product designer, they may end up messing with your system. And these problems are often intermittent and hard to troubleshoot.

There’s another thread where folks complain about wifi connection problems with their Mach2. Power supply would be the first thing I’d check and replace with a known clean voltage. And as such, nothing comes cleaner than a pure battery voltage.

Heck, even if I have easily access to mains 120Vac from my backyard, I always power my mount from a 28A-h 12V battery.

My general advice would be to never cheap out on power supply (or converter), especially when the application requires high precision.

As the AP adage says “the mount is the single most important thing in an imaging system”, we could add “and so is the voltage that powers it...”

Sébastien