|
Hi guys,
I have troubles with my actual battery, so I'm trying to get how amps this mount consume on a large night (7-8h).
I'm going to made a battery only for the mount. The rest of the components have other battery.
A 45Ah battery would work doing only 2 or 3 GoTo for autoguide aligment and night object without pass the 50% discharge, or I'll need a 60-70Ah battery?
The manual says you need at least 3Ah, I think for the GoTo commands to work. In tracking with guiding pulses how many consumes?
Greetings, Enol.
|
Dear Enol,
When properly balanced, and gears are not jammed, the G11 typically uses 0.20 to 0.25 amps in sidereal tracking.? If autoguiding, maybe 0.25 to 0.3 amps.? If fast slewing (brief times) expect 0.35 amps per motor.? This is using a 17V DC power supply, which gives 42% more torque than 12VDC only.??
I find it very useful to employ a power supply with voltage booster circuit, and with output ammeter and voltmeter.? The ammeter tells me if I have the axes balanced, and his much current my motors and Gemini are using.? The output voltmeter also tells if the input battery supply is drooping which will show up as output voltage drop.??
I make these supply units for Gemini-1 and -2.? Let me know if interested...!? Here are some photos...
All the best? Michael
Hi guys,
I have troubles with my actual battery, so I'm trying to get how amps this mount consume on a large night (7-8h).
I'm going to made a battery only for the mount. The rest of the components have other battery.
A 45Ah battery would work doing only 2 or 3 GoTo for autoguide aligment and night object without pass the 50% discharge, or I'll need a 60-70Ah battery?
The manual says you need at least 3Ah, I think for the GoTo commands to work. In tracking with guiding pulses how many consumes?
Greetings, Enol.
|
Hi,
I'm interested, but shipping and taxes probably will cost more than the box itself. El you have a wiring and component diagram to made one??
Greetings, Enol.?
El lun., 10 may. 2021 3:44 a. m., Michael Herman < mherman346@...> escribi¨®: Dear Enol,
When properly balanced, and gears are not jammed, the G11 typically uses 0.20 to 0.25 amps in sidereal tracking.? If autoguiding, maybe 0.25 to 0.3 amps.? If fast slewing (brief times) expect 0.35 amps per motor.? This is using a 17V DC power supply, which gives 42% more torque than 12VDC only.??
I find it very useful to employ a power supply with voltage booster circuit, and with output ammeter and voltmeter.? The ammeter tells me if I have the axes balanced, and his much current my motors and Gemini are using.? The output voltmeter also tells if the input battery supply is drooping which will show up as output voltage drop.??
I make these supply units for Gemini-1 and -2.? Let me know if interested...!? Here are some photos...
All the best? Michael
Hi guys,
I have troubles with my actual battery, so I'm trying to get how amps this mount consume on a large night (7-8h).
I'm going to made a battery only for the mount. The rest of the components have other battery.
A 45Ah battery would work doing only 2 or 3 GoTo for autoguide aligment and night object without pass the 50% discharge, or I'll need a 60-70Ah battery?
The manual says you need at least 3Ah, I think for the GoTo commands to work. In tracking with guiding pulses how many consumes?
Greetings, Enol.
|
Enol . ?Boost converter. ?There are a lot of Chinese knockoffs on fleabay which have been known to fail. ?Best you make your own. ?The Ti data sheets and app notes are sufficient to build one but do use star ground return? ive been thinking of doing one....just to try it. ?I had the opportunity to test one. ?It was excellent. I could hear the difference in the motors. ?
Cheers
--
Brendan
|
Brendan, one question. The manual of the G11 says you need at least 3 Amps to work propertly. I think this is for GoTo commands to work. With your information, a GoTo only need 0.35 Amps at 17v, so 0.6 Amps at 12v. Something seems to be incorrect.
My actual battery supply 2.1 Amps max. With guiding, tracking, or one motor slew it work perfectly, but with a GoTo command at 800 velocity it start to move and suddenly stop.
Greetings, Enol.
Enol
.? Boost converter.? There are a lot of Chinese knockoffs on fleabay which have been known to fail.? Best you make your own.? The Ti data sheets and app notes are sufficient to build one but do use star ground return?
ive been thinking of doing one....just to try it.? I had the opportunity to test one.? It was excellent. I could hear the difference in the motors. ?
Cheers
--
Brendan
|
On 5/10/2021 9:00 AM, Boreack wrote: Brendan, one question.
The manual of the G11 says you need at least 3 Amps to work propertly. I think this is for GoTo commands to work.
With your information, a GoTo only need 0.35 Amps at 17v, so 0.6 Amps at 12v. Something seems to be incorrect.
My actual battery supply 2.1 Amps max. With guiding, tracking, or one motor slew it work perfectly, but with a GoTo command at 800 velocity it start to move and suddenly stop.
Greetings, Enol. Just to add a data point.... I run my mount, two cameras and mini-PC all from the same 12V 5A power supply. I do not recall individual current draws but with everything running (and the imaging camera cooling), I never saw more than a total of 3A with the mount slewing. I know the recommendation is to use 17VDC but A) I don't see any need for more torque with everything balanced and B) running a brushed motor at higher applied voltage (and correspondingly lower PWM values to achieve the same speed) is harder on the brushes. Since slewing at full speed draws very little current (well under 2A in my case) I don't see the need for higher voltage. Paul -- Paul Goelz Rochester Hills, MI USA pgoelz@... www.pgoelz.com
|
Yeah peak is a bit overrated mostly why¡¯d 200-250ma (if not less) at sidereal rate to 600ma slew?
but take into account both axes at this does so 1.2A peak. ?It¡¯s hard to tell with digital readouts?
I run 3A @18vdc on a lab supply and it¡¯s perfect But also allow some variation for ¡°not all power supplies are equal¡±!
devices like the boost converter can handle 5A peak with good dissipation you can even parallel them
--
Brendan
|
Hi gang,
As a simple temendy for Enol, just reduce the maximum slew rate.? There is a digital setting for that.?
If Enol's system runs out of current as the counterweight shaft moves toward horizontal, the problem is it is unbalanced.
________
An ammeter on the Gemini input is very useful.?
Without it you cannot determine the cause of the high current draw.? It could be one or more of:
a. Imbalanced scope load
b. Jammed worm gear
c. Bad wornout motor
d. Un-lubed worm or needle bearings need cleaning and re-lube
Best regards, and good luck, Michael
Yeah peak is a bit overrated mostly why¡¯d 200-250ma (if not less) at sidereal rate to 600ma slew?
but take into account both axes at this does so 1.2A peak.? It¡¯s hard to tell with digital readouts?
I run 3A @18vdc on a lab supply and it¡¯s perfect But also allow some variation for ¡°not all power supplies are equal¡±!
devices like the boost converter can handle 5A peak with good dissipation you can even parallel them
--
Brendan
|
I certainly can see the benefits of monitoring current and volts for the Gemini?
--
Brendan
|
Hi Michael. The fail was in all positions, always doing a GoTo command or a Park command.? Every command that use 2 axis will fail after 1 sec of start or less. Is like instantaneously. Manual move of the axis throw the Gemini Windows controller work Ok in all 3 velocities.
Greetings, Enol.
I certainly can see the benefits of monitoring current and volts for the Gemini?
--
Brendan
|
Brendan
I went to TI and used their web designer. The good : 2587 comes in to 220 package. The bad : limited to 1 amp at 18v. I'm not sure the current limit would be a problem but.....
Chuck On Monday, May 10, 2021, 03:39:51 AM PDT, Brendan Smith <brenatlilydale@...> wrote:
Enol . ?Boost converter. ?There are a lot of Chinese knockoffs on fleabay which have been known to fail. ?Best you make your own. ?The Ti data sheets and app notes are sufficient to build one but do use star ground return? ive been thinking of doing one....just to try it. ?I had the opportunity to test one. ?It was excellent. I could hear the difference in the motors. ? Cheers
--
Brendan
|
Chuck.....I've seen one operating on a Gemini no problems.?
Look at fig 19 "Boost" control.?? You probably saw the flyback control design versions.?? But in boost,,,,no problems running a Gemini with some overhead current available.
You can soft start it its internally protected and referenced and designed to open cct if fault. (many fleabay Copies do not do this).
You can parallel devices, but one one is sufficient.?? You can buy the appropriate inductive coil, Bournes PM2102 series.? It will cost around $20~25 USD to make (not incl PCB) design layout is paramount, use a star earth and follow design app notes, TI SNVA731,
If you want to parallel devices, look at TI app note SNVA552.? A single device is enough maybe use a DPACK and solder it to the PCB and use a large PCB PAD as heat dissipation.? The LM2588 is pretty much the same device.
I did design one of these "LM2578 Boost 12-18VDC"? PCBs in EaglePCB (a 60mm x 50mm PCB...should be able to squeeze it to a 50x50mm PCB) but haven't made it yet.?? Its single sided but would rather double side it...so usually send to PCB fab house.
As fro Enol.....as Michael said the system failing on both axes sounds like a Power supply problem...2.1 Amps may be too low as initial start peak may be quite a bit higher.?? Lowering the slew to 600X is a good idea and many users do this.? You will never see this initial current spike on a digital meter as their refresh rate is 2~3 times per second at best.
Another thing about many 12V DC power supplies is that they droop in voltage when loaded with higher current.? I was measuring a 7.5A 12V PSU the other day at 3A (with a Digital active load) and its drooped to 11.1V DC 3A out!?? Wow.... .......!? This is too low way too low.
A question for Enol........is your system shutting down when it doe this....like does the HC "LED" stop???? I'm wondering if your PCB needs Fuse F2 replacement.
Cheers
Brendan
--
Brendan
|
I don't think It power off. The conexi¨®n with the PC continues. The mount only stop the slew and continue with the tracking. I don't remember if the mount buzzer sound, but I think don't.
Greetings, Enol.?
Chuck.....I've seen one operating on a Gemini no problems.?
Look at fig 19 "Boost" control.?? You probably saw the flyback control design versions.?? But in boost,,,,no problems running a Gemini with some overhead current available.
You can soft start it its internally protected and referenced and designed to open cct if fault. (many fleabay Copies do not do this).
You can parallel devices, but one one is sufficient.?? You can buy the appropriate inductive coil, Bournes PM2102 series.? It will cost around $20~25 USD to make (not incl PCB) design layout is paramount, use a star earth and follow design app notes, TI SNVA731,
If you want to parallel devices, look at TI app note SNVA552.? A single device is enough maybe use a DPACK and solder it to the PCB and use a large PCB PAD as heat dissipation.? The LM2588 is pretty much the same device.
I did design one of these "LM2578 Boost 12-18VDC"? PCBs in EaglePCB (a 60mm x 50mm PCB...should be able to squeeze it to a 50x50mm PCB) but haven't made it yet.?? Its single sided but would rather double side it...so usually send to PCB fab house.
As fro Enol.....as Michael said the system failing on both axes sounds like a Power supply problem...2.1 Amps may be too low as initial start peak may be quite a bit higher.?? Lowering the slew to 600X is a good idea and many users do this.? You will never see this initial current spike on a digital meter as their refresh rate is 2~3 times per second at best.
Another thing about many 12V DC power supplies is that they droop in voltage when loaded with higher current.? I was measuring a 7.5A 12V PSU the other day at 3A (with a Digital active load) and its drooped to 11.1V DC 3A out!?? Wow.... .......!? This is too low way too low.
A question for Enol........is your system shutting down when it doe this....like does the HC "LED" stop???? I'm wondering if your PCB needs Fuse F2 replacement.
Cheers
Brendan
--
Brendan
|
Enol
You can take the motors off and Gemini set it up on a bench to test!?? Of course the motors are not loaded with inertia but never the less its a good way of testing and narrowing down issues.
--
Brendan
|
Hi, Finally I could test it with a new battery, and works perfect with the equipment at 1200 slew rate. The problem was Tha output and cables of the old battery, that couldn't supply enough amperes.
Greetings, Enol.?
Enol
You can take the motors off and Gemini set it up on a bench to test!?? Of course the motors are not loaded with inertia but never the less its a good way of testing and narrowing down issues.
--
Brendan
|
Michael Herman