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Portable Li power for Gemini1-G11?

 

Is anyone using a Lithium portable power bank for a G11-Gemini1? If so, are you providing 18V as well as 12V and if so, how?
 

Depends on what power bank you get. I got a bluetti type a while ago to deal with frequent power outages at home and have yet to try it with my mount. Those types come with AC outlets, 12V car lighter outlets, as well as USB. In my case I would use one of the AC outlets for the power brick that feeds 16V to the mount and the other would be for my laptop. The car adapter would be for the camera and other 12V accessories.
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If your power bank only has 12V you can still use it with the Gemini and everything else, except a laptop maybe. If you have a mini PC or the AAir then you¡¯re set.
?
Jonathan
 

Thanks for the reply.
?
The reason I ask is that when I first got my G11 (20 years ago!) the goto performance of the servos using 12V was awful -- many stalls. 18V fixed that.
So I want either (a) a power bank that supplies 12V and 18V, or (b) a recommendation for a solid 12-18V converter. ?Converting DC to AC and back to DC seems terribly inefficient. ?The SLA battery in my current power pack is spent which is why I'm looking for a replacement, preferably a lot lighter, but in the worst case I would just replace that battery.
I don't image away from home so I don't need to power a laptop or camera, but I do need power for dew heaters as well as the mount.
?
?
 

I use the next one:
BEAUDENS Generador Solar Portable ?


El jue, 18 jul 2024, 2:53, Mario Wolczko via <mario=[email protected]> escribi¨®:
Is anyone using a Lithium portable power bank for a G11-Gemini1?? If so, are you providing 18V as well as 12V and if so, how?
 

On Wed, Jul 17, 2024 at 05:53 PM, Mario Wolczko wrote:
Is anyone using a Lithium portable power bank for a G11-Gemini1? If so, are you providing 18V as well as 12V and if so, how?
I went the DIY route several years ago with a $15 heavy duty Craftsman tool box loaded up with a 28ah AGM battery, a smart charger that allowed the battery to supply power while plugged into utility power and when the site power failed continue to supply power to the Gemini 2 and imaging gear seamlessly. The old AGM battery output was wired to a pair of 10A DC-DC converters set to output 13.5VDC and 18VDC as well as a few USB ports with integrated voltmeters.
?
Last year when the second AGM battery pooped out and the cost of the LiFePO4 chemistry batteries got cheap I reworked the same $15 Craftsman heavy duty tool box with a 30ah LiFePO4 battery with integrated battery management controller, swapped the old lead acid smart charger for a new LiFePO4 smart charger with a higher charge rate and removed the 12V DC-DC converter to improve efficiency slightly and because the voltage output of LiFePO4 is a flat 12.5V for 90%+ of battery capacity.??
?
But be sure to do your due diligence as some brands like the popular Talent Cell do not continuously deliver 12.5V for the full capacity of the battery! Read the battery specs carefully or you may be surprised that the battery only delivers 12VDC for half the battery capacity just like a standard lead chemistry SLA or AGM battery! It is all about the number of cells in the battery, how they are wired and how the BMS is programed.?
?
If you read the specs carefully the DIY path is MUCH MUCH less expensive per AH and works like a charm. Also unlike lead acid chemistry batteries - which can only be discharged at MAX 60% of rated capacity without significantly reduced charge/discharge cycles - you can get 90-100% of the rated capacity without reducing the life cycle of the battery.??
?
As I said do you homework before buying any batteries or power packs!??
?
--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric - South Pasadena?
 

¿ªÔÆÌåÓý

Chip,
Thanks ¡ª this looks like a great approach. ?Was there a particular brand of DC-DC converter you used?
-Mario

On Jul 18, 2024, at 10:51?AM, Chip Louie <chiplouie@...> wrote:

On Wed, Jul 17, 2024 at 05:53 PM, Mario Wolczko wrote:
Is anyone using a Lithium portable power bank for a G11-Gemini1? If so, are you providing 18V as well as 12V and if so, how?
I went the DIY route several years ago with a $15 heavy duty Craftsman tool box loaded up with a 28ah AGM battery, a smart charger that allowed the battery to supply power while plugged into utility power and when the site power failed continue to supply power to the Gemini 2 and imaging gear seamlessly. The old AGM battery output was wired to a pair of 10A DC-DC converters set to output 13.5VDC and 18VDC as well as a few USB ports with integrated voltmeters.
?
Last year when the second AGM battery pooped out and the cost of the LiFePO4 chemistry batteries got cheap I reworked the same $15 Craftsman heavy duty tool box with a 30ah LiFePO4 battery with integrated battery management controller, swapped the old lead acid smart charger for a new LiFePO4 smart charger with a higher charge rate and removed the 12V DC-DC converter to improve efficiency slightly and because the voltage output of LiFePO4 is a flat 12.5V for 90%+ of battery capacity.??
?
But be sure to do your due diligence as some brands like the popular Talent Cell do not continuously deliver 12.5V for the full capacity of the battery! Read the battery specs carefully or you may be surprised that the battery only delivers 12VDC for half the battery capacity just like a standard lead chemistry SLA or AGM battery! It is all about the number of cells in the battery, how they are wired and how the BMS is programed.?
?
If you read the specs carefully the DIY path is MUCH MUCH less expensive per AH and works like a charm. Also unlike lead acid chemistry batteries - which can only be discharged at MAX 60% of rated capacity without significantly reduced charge/discharge cycles - you can get 90-100% of the rated capacity without reducing the life cycle of the battery.??
?
As I said do you homework before buying any batteries or power packs!??
?
--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric - South Pasadena?
Glenn S
 

I¡¯m using a DIY custom battery box from Amazon with a 12v 100ah LifePo. ?You can run a 12-19v step-up.?

<img src="https://i.ibb.co/sJ1JFWq/IMG-4667.jpg" alt="IMG-4667" border="0">
?
<img src="https://i.ibb.co/Gx1YtYL/0479-BEAB-B80-C-413-E-AC20-68-EEE2-AD065-A.jpg" alt="0479-BEAB-B80-C-413-E-AC20-68-EEE2-AD065-A" border="0">
?
https://a.co/d/i4jcEbw
https://a.co/d/duwwNLf
 

¿ªÔÆÌåÓý

Glenn,
Excellent, thank you! ?I was eyeing that converter but had not seen the battery box. ?And the battery is on sale!
-Mario

On Jul 18, 2024, at 3:46?PM, Glenn S <glennsmooth@...> wrote:

I¡¯m using a DIY custom battery box from Amazon with a 12v 100ah LifePo. ?You can run a 12-19v step-up.?

<img src="https://i.ibb.co/sJ1JFWq/IMG-4667.jpg" alt="IMG-4667" border="0">
?
<img src="https://i.ibb.co/Gx1YtYL/0479-BEAB-B80-C-413-E-AC20-68-EEE2-AD065-A.jpg" alt="0479-BEAB-B80-C-413-E-AC20-68-EEE2-AD065-A" border="0">
?
https://a.co/d/i4jcEbw
https://a.co/d/duwwNLf
 

West Mountain Radio sells battery boxes that can be customized with various switches and meters. You might find something useful there. I believe they also offer batteries but please don¡¯t hold my feet to the fire if I am mistaken!
anyone who believes the bureau of alcohol tobacco and firearms is a convenience store can't be all bad.
 

The DC-DC converters are effectively a small switching power supply.? Back in the day Meade supplied a small DC-DV boost converter when the LX200 called out 18vdc.? The AC power supply was unregulated crap. But those DC boosters were solid. It was also an easy DIY for electronics geeks. It gave a nice motor performance boost.?
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All these systems were designed around Lead Acid batteries which are actually 13.8v at full charge and shouldn't be drained below 12v under load to prevent cell damage. (About 50% of charge). Operating Gemini 1 below12v also NOT recommended.
So if you were using a regulated 12v AC adapter from a laptops you were underpowered a bit from the 13.8v battery based design to start. AGMs tend to have voltage fall off faster than a marine type L-A but have their advantages too. LiFePo have a much flatter curve and are a good voltage match to LA You can get 80% rather than 50% of the rating before recharge, so not only lighter,? but you can lower the AH spec compared to L-A
?
These days DC boost converters are ubiquitous and many can be set for Constant Current (charger) or Constant Voltage, (PSU) the mode you want for use as a power supply.?
The benefit of the higher voltage is only for the sake of the motors, which are the only devices that see the full supply voltage rail.
It improves torque, so may help with guiding as well as slew.
It will cause motors and voltage regulators to run hotter though, so for longevity sake you might want to not run at the max slew rates and always take care to balance loads carefully or you will strain and possibly overheat the motors.?
The simplest DIY is LiFePo, a with a boost converter for the Gemini.?
Add automotive 12v jacks? and tap the battery direct for a 12v dew heater controller and USB automotive chargers for USB devices unless you're running a power distribution box which then needs just a single 12v battery box connection.?
An AC charger for automotive batteries that is safe/ has a setting for LiFEPo completes the project.
If you have LiPo or Lithium batteries as a DIY? I'd recommend designing a 24v (6x? cell) battery pack,? appropriate BMS,? then use 2 DC-DC Buck converters for the 18vdc and 13.8vdc dc outputs.?
For AC recharging, use a 30 vdc power supply and let the BMS manage the charge level since the fully charged float level is about 28v. (6 cells).
The only thing to be careful about is ground loops if you're connecting a laptop that is running on its own AC adapter plugged in some distance away.
That's a different subject entirely.
?
 

Many thanks for all the comments!

I¡¯ve obtained a LiFePo battery and charger and rebuilt my battery box so I¡¯m back in business. Grateful to not have to lug a massive SLA around.

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