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Re: Choosing the right battery

T.K
 

On Sun, Oct 6, 2019 at 06:34 PM, Howard Dutton wrote:
Lets say about 6.5 watts/motor so 13 watts.
Thanks
My knowledge about electricity is very basic. So go easy on me.
Can you teach me how you estimated 6.5 watts for each motor?

My mount is an AltAz dobsonian, so both motors should be running. Maybe in the future I'll try astrophotography (with lv8729 or tmc2130). So I will need a derotator and maybe a focuser.
12Ah lead acid batteries are realy bulky. 12Ah lead acid batteries are really bulky. I have to decide on using multiple smaller batteries that I can replace them with each other. Lithium-ion battery packs are probably the better solution.


On Sun, Oct 6, 2019 at 09:12 PM, Peter Dulowsky wrote:
I have miniPCB + Teensy 3.2, ESP32 SHC, 2x NEMA17 on EQ5. The Dec axis is set to power off. The setup is powered from a small diy battery pack that conists of 4x 18650 Li-Ion cells rated 1500mAh. These come from an old laptop battery so the real capacity is lower - i guess maybe 75% of what they used to be new. My observing sessions are 3 hours max and the battery is perfectly capable to last that long. I charge the cells to 4.05V. The voltage after ~3 hours is about 14.2V - thats about 3.5V per cell so there is still some juice left.  
How do you connect the batteries? It has 14.2 V which means you have assembled them in series and the final current should still be 1.5Ah. Am I right?


Re: OnStep v3: Cannot flash ESP8266

Khalid Baheyeldin
 

Oh ...

I remember this board.

For the STM32 PCB, we relied on the D1 Mini having a microUSB port and simplified the pinmap based on that.

Thinking out loud ...

If we used another STM32 with more pins (e.g. a 96 pin density), then we would have added ESP flashing, as well as other things (home switch, 2nd focuser, ...etc.). Examples are STM32F103RCT6 series. But these are 72MHz still, so no compelling reason to go through all the design process again.


Re: Choosing the right battery

Peter Dulowsky <peter.dulowsky@...>
 

I have miniPCB + Teensy 3.2, ESP32 SHC, 2x NEMA17 on EQ5. The Dec axis is set to power off. The setup is powered from a small diy battery pack that conists of 4x 18650 Li-Ion cells rated 1500mAh. These come from an old laptop battery so the real capacity is lower - i guess maybe 75% of what they used to be new. My observing sessions are 3 hours max and the battery is perfectly capable to last that long. I charge the cells to 4.05V. The voltage after ~3 hours is about 14.2V - thats about 3.5V per cell so there is still some juice left.  


Re: Choosing the right battery

Howard Dutton
 

On Sun, Oct 6, 2019 at 03:20 AM, T.K wrote:
Can anyone help how much Ah capacity for an OnStep controller (Mega 2560, two 1.3A motors and esp8266 for WiFi) is enough to tracking for at least 4 hours?
This isn't really enough information (the same old mistake, current Amp != power Watts) but assuming NEMA17 motors...

This is assuming just Axis1/2 motors are the primary current draw.  Depending on setup other motors might be powered up active for focuser/rotator (I always go for low power motors and/or power them down when not moving.)

Lets say about 6.5 watts/motor so 13 watts.  The RAMPS/ESP8266 shouldn't draw much relative to the motors.

P=I*V.  13 watts = I * 12V;  so I = a bit over 1A.  Lets say 1.5A and you're covered for the Mega2560, etc. and for running a focuser/etc. now and then.

So 4 hours at 1.5A is 6Ah.  It's a good idea to not abuse lead-acid batteries so < 50% depth of discharge and you want a 12Ah battery.

If you use the option to turn off the Dec axis motor when not moving (if this is a Eq mount) average power is much less (about half.)

You also might not run the motors "very warm" at 6.5 watts but rather 5 watts or so in which case you'll probably end up using ~1A @ 12V or 0.6A with Dec powered off.


Re: New Dob Owner

John K.
 
Edited

You made very weak azimuth setup.

The biggest pulley I could print on my 3D printer is 347 teeth, so I went with 320. 

I am going to have to go with it, and see what happens.  It does seem sturdy enough, and the Az spins quite freely with the lazy susan bearing.

If it doesn't work, I'm going to have to buy a bigger printer.  :)


Re: MaxESP2 and BME280 not working due to Wire.h?

Howard Dutton
 

Read this, and use the latest master branch on GitHub.


Choosing the right battery

T.K
 

Hello
I want to use a sealed acid battery as power supply.
Can anyone help how much Ah capacity for an OnStep controller (Mega 2560, two 1.3A motors and esp8266 for WiFi) is enough to tracking for at least 4 hours?


Re: New Dob Owner

T.K
 

On Sun, Oct 6, 2019 at 09:39 AM, How Eee wrote:
You made very weak azimuth setup.
I tried so. Then i rebuild it.
Here are my 1st and 3rd versions. And i think it will be a not last one.
What makes it weak?
Almost no force acts on Az axis. There is just the friction of two disks and it negates by the bearing between them.
The other problem would be angular momentum of telescope which don't seems to be an issue because of nearly symmetric design of the telescope. It is worst when the OTA is horizontal. but with a balanced tube, it is negligible too.
 
Do you mean it's insufficient (small in diameter) for torque transmission?


Re: OnStep v3: Cannot flash ESP8266

Murat Isik
 

I am using my self designed monolithic PCB that has these traces in place. (See attached)

So as I say, it works perfectly for v2.x and I have done it several times.

Unfortunately Howard, the old code segment fails as well.

What I have to check is to test with a second PCB that I have as a backup to make sure there are no hardware failures on my equipment.
I'll let you know.

Thanks.


Re: New Dob Owner

How Eee
 

You made very weak azimuth setup.
I tried so. Then i rebuild it.
Here are my 1st and 3rd versions. And i think it will be a not last one.


вс, 6 окт. 2019 г., 6:57 tj_slice via Groups.Io <tj_slice=yahoo.com@groups.io>:

I installed the new pulley, and it clears the optical tube this time.

Next up are the stepper mounts.  Does anyone know how hot the planetary gears will get?


Re: "Align" button greyed out

Khalid Baheyeldin
 

For the record: my tests were done with the latest OnStep, but with the
D1 Mini flashed with an old version of WiFi-Bluetooth (2.22 or so).


Re: "Align" button greyed out

Drew 🔭📷🚴‍♂️
 
Edited

No, bluetooth. But I will give error correction a try. The problem seems to be in the recent versions though. I will try to see if there are any observable factors that come into play.

I agree with the long press, I just didn't think of it. Maybe a line of text at the bottom of the screen? "Long Press button (> 1 second)  to accept alignment"


Re: New Dob Owner

John K.
 

I installed the new pulley, and it clears the optical tube this time.

Next up are the stepper mounts.  Does anyone know how hot the planetary gears will get?


Re: Classic byers mount on Astromart for a great price..

John Scherer
 

That is indeed, too bad.. I didn't know that about those mounts.


Re: Classic byers mount on Astromart for a great price..

Khalid Baheyeldin
 

I saw this on the Canadian AstroBuySell web site.

Anytime I hear Byers, I listen carefully.

That is until I saw this part: "Sector gear design provides 2 hours of continuous tracking and instant push button reset".

And if you read here (and subsequent comments), you see that indeed it needs to be reset every so often, which makes it less than ideal for a Goto mount.

Bummer ..


Classic byers mount on Astromart for a great price..

John Scherer
 

I'm not the current owner of this or in any way affiliated with him but, if anyone is looking for a great mount for conversion to Onstep, this Byers 812 mount would be a fantastic candidate.  I wish I had $1500!


Re: "Align" button greyed out

Howard Dutton
 
Edited

On Sat, Oct 5, 2019 at 02:22 PM, Drew 🔭📷🚴‍♂️ wrote:

Attached is a pic of the screen. The "Align", "RevNS" and RevEW" buttons have the grey lettering. It doesn't show well in the pictures. The button reverses work (some of the time) Also the North and West button can hang and keep the motor running until you push another button.
In the Connection activity where you enter the IP check the "error correction" box, see if that improves things. (assuming WiFi?)


Re: "Align" button greyed out

Khalid Baheyeldin
 

Yeah, a long press is not obvious, but it is safer on those pesky touch screens.

But greyed out has nothing to do with long or short press. When the slew ends (beeeep) all buttons that can be used are red.


Re: "Align" button greyed out

Drew 🔭📷🚴‍♂️
 

Thnx, I don't think I would have ever guessed the long press in this case.


Re: "Align" button greyed out

Drew 🔭📷🚴‍♂️
 

New info and possible workaround for now. For fun I went into the main "guide/focus" screen. The one where the buttons fill the screen. I unchecked the "Lock" checkbox and the align button turned red (the mini guide screen in the alignment menu is always red, locked or not). I clicked it and got a "alignment success" The button then turned to a "Sync" button.