I use one 100Ah Li battery and a couple of 100W panels. I put my battery into a modified trolling motor battery case. My rig consumes about 50-60% of the battery capacity in 10-12 hours. I would recharge the battery completely the next day with the panels.

One last consideration should you choose the LiFePO4 route: these batteries can't be recharged below 32 degrees F if I recall correctly. The better brands will have built in BMS (battery monitoring system) to prevent just that. Our family has been Rvers for decades. Many in our "circle" have gone from AGM to LiFePO4 and discussions abound about this aspect of them. So, if you want to be out for several nights and it's cold.....
Ken

These recommendations are consistent with what I've been using for dispersed camping dark site trips for a good many years.

I started with AGM glass mat batteries from West Marine for their deep cycle capabilities, and have more recently switched to LiFePO4
units because they're so much lighter.? Originally I went with an 80 Ah AGM, but switched to two 55 Ah units in deference to my aching back.
Now I use a Jackery 550 purchased on sale from Harbor Freight: .

I purchased a small gas generator to do recharging on really long trips, but regretted it.? The fumes from having it and a container of gas inside my Suburban were unacceptable.? I just ended up getting a second battery and not worrying about recharging.? If I were to do it again, I would get a generator which would run on propane and use the same cannisters that I use on my camp stove.? Solar panels are attractive because they're quiet, but I haven't tried them.

Will be interested to follow along and see what you end up selecting.?? Enjoy!

On Wed, Nov 29, 2023 at 08:01 AM, James Richards wrote:

Hi!? I would like to take my Losmandy mount to dark sky locations where there is no power.? I'd appreciate any suggestions from the community for a good, basic portable power supply that works with Gemini 2.? ?Thanks!!

Hi James,

If you are only going to use the battery pack to power a Gemini 2 for GOTOs and visual tracking your capacity needs will be minimal. You can as others have said reliably count on about 1Ah @ 12V even if you use a 16V converter to give your servo motors a little speed boost. Using the 1Ah you probably can consume about 12Ah on a very long summer night and expect to need the same for winter nights where the battery will have a lower capacity and output due to the cold.?

If the battery pack must support a full imaging system that 100Ah @ 12V is also a very good number and will last at least one full night from sun down to sun up. That said it also depends on your rig controller's power use and things like how hot you need to run the dew strips to keep dew at bay. For an imager it is important to tally up you device usage and then give yourself a 50% margin so the battery retains enough capacity to carry your current needs as the battery ages.?

Speaking of aging the best AGM lead Acid batteries only have about 1,000 charge discharge cycles in them and that is only if you discharge down to 40% of rated capacity or 12.1-12.2V.?

Now you need to make a decision on battery chemistry. For most people there are basically two battery chemistry choices that stand out, conventional lead acid we are all familiar with as automotive type batteries. These include car batteries, golf cart batteries, motorcycle batteries etc. and the deep cycle, SLA, AGM etc. makes no difference they are all lead axis chemistry and none will last very long if you discharge even the best type AGM battery to less than 50%-60% of their rated capacity.?

In other words if your really need 50 Ah of capacity for one or two nights and you want to get the actual maximum battery lifespan of about 5-7 years you really need to buy 2 to 5 100Ah conventional lead acid type batteries depending on your tolerance for buying new batteries that's a lot of 100Ah batteries.?

The other currently viable battery chemistry is LiFePo4. These batteries can be discharged much deeper and still get maximum battery life out of them. The better LiFePo4 batteries will include a battery management system - BMS - to manage the battery discharge cut off voltage and recharge shutoff voltage. To maximize the usable capacity of these batteries you will need a LiFePo4 specific type battery charger as they need a higher charge voltage than lead acid batteries can tolerate.?
?
The standard BMS cut off voltage is 10V which basically gives you the full capacity of the battery. But a safer cutoff is 12.9V which is 80% of rated capacity and will yield the maximum number of charge discharge cycles typically given as 3,000 cycles. Even at a 10V cutoff you should see about 2,000 charge discharge cycles but in practice there is not a.lot of power left below 12.7V as the voltage drops off sharply.?

So if you really need 50Ah as above if you buy a 50Ah LiFePo4 battery you only really need a 50Ah rated battery but to be sure buy a 60Ah and expect to see all 3,000 charge discharge cycles at the full 50Ah cutoff.?

I know it is a lot to read but you need to read it to understand the problem. It was only in the last couple years that the LeFePo4 batteries have stabilized and standard BMS is mostly available at prices that made them competitive with AGM batteries.

Do the math and you will save a lot of money and toxic waste. The numbers say LiFePo4 battery and a home made or semi home made pack is the way to go. I bought a heavy duty plastic tool box and used off the shelf DC-DC step up/down converters to build a stable dual voltage 13.8V and 18V output in my home made 40Ah LiFePo4 pack. This work very nicely and requires only the simplest of handiwork with a soldering gun or crimping tool.?
?
--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric Weather for Imagers - Click on my sig!

Yeah these guys have good suggestions. ?Few heater PWM can reduce per usage as with PWM camera TECs. ? ? But also good idea to keep camera power away from dew heaters as they induce switching noise. ?Tends to permeate switching noises thru all power it’s connected to FWIW ?

Always get more capacity than you need ?ie you might add a laptop or 12v water coffee heater (luxury) And capacity does drop off with batteries?

Funny enough the Gemini et el uses the least power. I like the solar charger idea. ?Especially if you do a few days These days the suggestion is to aim ~100Ahrs and if needed ensure you ?have enough solar or others recharge facility.?

Good ideas from David Bob, James & Paul?

FWIW good topic?
--
Brendan

On Wed, Nov 29, 2023 at 08:01 AM, James Richards wrote:

Hi!? I would like to take my Losmandy mount to dark sky locations where there is no power.? I'd appreciate any suggestions from the community for a good, basic portable power supply that works with Gemini 2.? ?Thanks!!

I use one of these with my G-11 and Gemini 1. Hooked up to Michael Hermann's power boster.

开云体育

Hi!? I would like to take my Losmandy mount to dark sky locations where there is no power.? I'd appreciate any suggestions from the community for a good, basic portable power supply that works with Gemini 2.? ?Thanks!!

Hi everyone,

so far I have been using APT (Astro Photography Tool) for automating taking frames, but I failed to promt a meridian flip.

Has anybody actually managed to do this using APT and Gemini 2 Level 5 ?

Would be great to have confirmation that it works in principle before I invest even more time to get it done. Otherwise I will switch to NINA, which has a proven record for this.

Thanks a lot,

Joerg

Hi Bill,

In the case of SkySafari or other 3rd-party software that talks to the mount directly, the question needs to be asked from the developer of that software. I really don't know how SkySafari handles Sync/Align. I do know how any ASCOM-based software would do it, since ASCOM protocol doesn't support an "Align" or "Additional Align" function and that's implemented in the driver.

As far as time adjustment after the first sync, this is done using the stars position, and not any external clock source. The HA Index is what corrects for any time differences between earth position and Gemini clock.

Regards,

? ?-Paul

Paul,

So I'm wondering what would happen if I used a 3rd party software program to build the model (like SkySafari) and it only sends an Align on the first command? ?I have done this many times and it seems like it works fine. ?It may be that SkySafari actually sends a Sync the first time, but I'm not sure. ?Not sure how Synchronize synchronizes the time when invoking it with the HC. ?I thought it was the mount, not the HC that knew the time.

Bill

On Mon, Nov 20, 2023 at 03:06 PM, Bill Tschumy wrote:

Anyway, why does the first star need Synchronize? ?I haven't run into other mounts that make a similar distinction.?

And that's how it works now, with Gemini-II. Gemini-I used Synchronize for the first star, as that is exactly what it does (synchronizes time and HA/DEC indexes). Since the user really doesn't need to know such details, Gemini-II changed it to Align.

Regards,

? ?-Paul

Bill,

As I recall with Gemini 1 you only do ALIGN when model building. Each Navigational star you ALIGN on adds a data point offset visible in the model table. Sync is used to make small adjustments after a GOTO but doesn't update the model table as I recall.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric Weather for Imagers - Click on my sig!

More info re: requirements for ASIAIR v2.x



--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric Weather for Imagers - Click on my sig!

On Tue, Nov 21, 2023 at 11:18 AM, k.weilding2@... wrote:

Hi Chip

Thank you that’s great information, so the cable which I use to connect my Gemini one to my laptop can be used to connect the ASIAIR? to the mount.?

I don't know, do you have a newer laptop with a regular Type-A USB port and is the laptop talking to the Gemin 1 now? If yes then probably that cable will work fine. Other USB to RS232 converters work I just do not know which ones exactly other than the ATEN product used with Losmandy sourced or equivalently pinned Gemini 1 RS232 cable.?

?

My Gemini has been updated to EPROM L4 v1.05.

Perfect!

?

Do you know if you can use a inexpensive tablet (?150) or do you have to have a expensive IPad or Galaxy tablet. I read you need 8GB RAM to get the best out of the tablet.?

There was a minimum hardware requirements list that ZWO posted on the FB group ()?some time ago, nearly a year ago in anticipation of the new release of the V2.x ASIAIR app for Andriod and iOS. If you are an Android user you really need a minimum of a 4GB RAM not 8GB RAM and 64GB internal storage for a tablet but more RAM and storage lets the app run much faster. This makes the tablets a lot more expensive but the large screen is a lot prettier to look at when previewing or using the ASIAIR for EAA. I just use my Google 7 Pro phone as it has more RAM than needed. BUT for imaging use and EAA sharing at public outreach events the bigger screen produces more oos and ahhs.?
??

?

Thank you once again for your advice it is much appreciated.

Regards

Ken

?

Happy to help!

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric Weather for Imagers - Click on my sig!

开云体育