Battery for Mach2 in the field
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Shailesh Trivedi
I have looked far and wide in this forum. There is a lot of discussions about the Pegasus power boxes, but is there no recommendation for a battery for a Mach2GTO in the field under far away dark skies. I am considering a LiFePO4 12v. At the risk of CP5 resetting due to low voltage, I want to purchase a 100Ah battery so I can run the mount, camera and my laptop.
I also have a heavy-duty inverter which I have used with lead-acid marine batteries in the past. Is that an option to AC power the Mach2 through the LiFePO4 and split DC using one of the Pegasus power boxes for the other accessories? Is 100Ah overkill or will 50Ah suffice? Any thoughts or recommendations? Shailesh
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Roland Christen
At the risk of CP5 resetting due to low voltage, Rolando
-----Original Message-----
From: Shailesh Trivedi <shailesh.trivedi@...> To: main@ap-gto.groups.io Sent: Sun, Feb 27, 2022 12:52 pm Subject: [ap-gto] Battery for Mach2 in the field I have looked far and wide in this forum. There is a lot of discussions about the Pegasus power boxes, but is there no recommendation for a battery for a Mach2GTO in the field under far away dark skies. I am considering a LiFePO4 12v. At the risk of CP5 resetting due to low voltage, I want to purchase a 100Ah battery so I can run the mount, camera and my laptop.
I also have a heavy-duty inverter which I have used with lead-acid marine batteries in the past. Is that an option to AC power the Mach2 through the LiFePO4 and split DC using one of the Pegasus power boxes for the other accessories? Is 100Ah overkill or will 50Ah suffice? Any thoughts or recommendations? Shailesh -- Roland Christen Astro-Physics
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Jeffc
That is kinda what I do. However I would split out the 12v power to the inverter at the battery. I would not run the inverter off the Pegasus power box.
It depends on the camera and laptop. What about dew heaters? 50ah will suffice probably for a most of the night. (Cold temperatures may also shorten the runtime. I know you can’t charge them below 32F. The fix is easy - put the battery in a cooler. ) The 12v is pretty consistent out of the 1500x. Based on my experience, I would go with the 100ah. Also… I previously powered the mach2 with the 1500x at 12v, and using a heavy load. 12” SCT, camera etc. I had mixed results with slews (some oscillation after the slew was done.) Using the 24v AP power brick solved the problem. The Yeti has a pretty clean built in AC inverter (in theory) , so I can just use the power brick on AC. I do have a 12v->24v step up converter, but I’ve not used it with the mount. -jeff
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Terri Zittritsch
On Sun, Feb 27, 2022 at 05:52 PM, Shailesh Trivedi wrote:
I have looked far and wide in this forum. There is a lot of discussions about the Pegasus power boxes, but is there no recommendation for a battery for a Mach2GTO in the field under far away dark skies. I am considering a LiFePO4 12v. At the risk of CP5 resetting due to low voltage, I want to purchase a 100Ah battery so I can run the mount, camera and my laptop.Shailesh, I use a 55ah mighty max lead acid battery and it works for imaging all night when at a star party, then I recharge during the day. The mount doesn't use much power when not slewing. Most of the power for my setup is used by the camera cooler then dew heaters. My laptop is also very power efficient and has an oversized battery. Terri
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Richard
I have 12V, 40 Ah LiFePO4 battery system that I built and have used in remote locations for a few years now. I have recently been using this to power my Mach 2 and cameras (SBIG-8300 without cooling and auto guider). I can get a night's imaging from this setup and I recharge the battery during the day using a solar array. For the laptop and if I cool the camera, I use a separate battery. I would suggest a battery >100 Ah rating if I were to start over today.
Rick
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Shailesh Trivedi
Thank you, Jeff, Terry, Richard and Rolando. I now have sufficient experiential data to make a decision.
Thanks again everyone for your time. Shailesh
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A LIpo battery is the way to go, available on Amazon. I put mine in a Homedepot plastic tool box, and made Powerwerx outlets for it.
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Richard Hennig
I am using Jackery Li-ion batteries. I have two of them, 500W and 300W. Either lasts all night for running the mount, camera, ASIAir Pro, and dew heaters. In the daytime, I am using a 100W Jackery solar cell to recharge them.
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Stone, Jack G
Currently Costco has these on sale for both the 1200W and lower wattage systems. I was eyeing this yesterday!! Compact and complete – just plug and play. I only search Amazon, and it did not have the setup equipment.
From: main@ap-gto.groups.io <main@ap-gto.groups.io>
On Behalf Of Richard Hennig
Sent: Tuesday, March 01, 2022 1:21 PM To: main@ap-gto.groups.io; Peter Bresler via groups.io <PABresler@...> Subject: Re: [ap-gto] Battery for Mach2 in the field
I am using Jackery Li-ion batteries. I have two of them, 500W and 300W. Either lasts all night for running the mount, camera, ASIAir Pro, and dew heaters. In the daytime, I am using a 100W Jackery solar cell to recharge them.
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ap@CaptivePhotons.com
Keep in mind if you do not need the inverter, and do not need a solar panel connection, it is much cheaper to simply buy a LiFePO4 battery - they come in about 1/3 the cost or less. Just add a charger and cables.
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+1 on that meter super easy to put it inline and know how many amps i was pulling for a night and then size appropriately Brian
On Tue, Mar 1, 2022 at 2:50 PM ap@... <ap@...> wrote:
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Luke Dodd
I agree with Linwood.
Dew heaters , coolers on CCD, mount, PC etc if imaging for 6 hours even at a conservative 5amp total draw is 30aH. The most important thing is most batteries don’t like a deep discharge ie below 50% of capacity, and a total discharge will usually destroy the battery. I would choose a battery with aH capacity twice what I expect to use.
I have been thinking about a battery supply for my mount, but its not a high priority atm, I may make my own out of commercial grade LiIon packs.
So if you want decent cycle life only plan to draw 50% capacity. The only way to accurately measure is to hook up a power meter inline with your system and actually measure the current draw. This will help. Also battery performance drops off as temp falls. In cold climes insulate your battery.
LiIon , LiFEPO4 have a higher nominal voltage 13.8V compared top SLA. Most of your gear will work better at the slightly higher V. Also Voltage drop under load needs to be considered.
I would not recommend LiPos unless you have very good monitors and cell balance chargers. I use them in my RC planes drawing 150amps peak, these babies can catch fire if mishandled. But their weight and energy density are hard to beat.
Luke
Sent from Mail for Windows
From: ap@...
Sent: Wednesday, 2 March 2022 8:50 AM To: main@ap-gto.groups.io Subject: Re: [ap-gto] Battery for Mach2 in the field
Keep in mind if you do not need the inverter, and do not need a solar panel connection, it is much cheaper to simply buy a LiFePO4 battery - they come in about 1/3 the cost or less. Just add a charger and cables.
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Greg McCall
Re "
LiFePO4 but conventional LiON batteries" Basically, any battery with Lithium in it is a Lithium-Ion battery so LiON also includes Lithium Iron Phosphate. The battery chemistry often used in cameras, mobiles etc. (such as Jackery) are Lithium Cobalt based batteries (normally NMC or Lithium Nickel Manganese Cobalt) NMC (or even LNMC) are the explosive types that the airlines etc are worried about. Their voltage also doesn't roughly match the lead-acid types so they need regulators to have the output around 12v. People often think the regulator is an advantage but it's really an extra point of failure and needed to get the nominal 12v LiFePO4 'roughly' matches the lead acid voltage of the 'nominal' 12v battery. It has a flatter discharge curve, is about 1/3rd the weight, and can have way more charge / discharge cycles than lead-acid. NMC batteries are a lot more likely to catch fire than the safer LiFePO4 but they are both Lithium Ion batteries. (also different construction methods with all these batteries) All in one boxes typically have a compromise somewhere. I've seen undersized chargers, small or not pure sinewave inverters and solar chargers that are not MPPT or only handle low voltage solar panels. I would suggest better to buy just the components you need at the quality level you want. Due to the flat discharge curve of LiFePO4, a voltmeter is almost useless in displaying it's state of charge (SOC) Some batteries have built-in SOC with WiFi access in their Battery Management System (BMS) inside the battery case. If not, you can get something like a Victron BMV 712 battery monitor but then you have to figure out where to mount the current shunt and meter etc. Alternately, just err on the larger size battery and make sure it's fully charged before each time you use it. Greg
On Wed, Mar 2, 2022 at 9:50 AM ap@... <ap@...> wrote:
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ap@CaptivePhotons.com
On Tue, Mar 1, 2022 at 06:13 PM, Greg McCall wrote:
Also, LiFePO4 batteries can be safely discharged far more than 50% and still have really good life, unlike Lead Acid. Sorry if my "conventional" LiON was ambiguous, thanks for clarifying. There are two flavors of DIY. You can buy cells (at various levels) and wire them up into a battery, adding a battery management system. That will save you the most money, but does have some quirks that I found advice conflicts badly, e.g. whether or not physical compression was relevant for certain types. I found for not much more money you can buy a pre-packaged battery such as the below (which is a bit of a monster at 200ah, i.e. equivalent roughly to a 2500-3000w Jackery's capacity). On top I attached a "Smart Shunt" from Victron which has no meter, but has a blue tooth connection (it's expensive though). This monitors charge/discharge and provides a state of charge you can check from a cell phone. With their charger you can also monitor it via bluetooth. I found meters at dark site to be a bit problematic, the readable ones tend to be blue and bright and annoy people, the subtle, non-intrusive ones are hard to see at a distance. This one I can just look at my phone to check, I don't even need to get out of the car. Important: Most pre-made LiFePO4's sold on amazon and the like do NOT have low temperature charge disable. You will destroy a LiFePO4 charging it below freezing, at least without a heater. You can discharge much colder, but not charge, you need to let it warm up thoroughly first to be above freezing throughout. Some higher end batteries have a thermistor inside and will actively prevent charging, most of these inexpensive ones you are on your own not to do so. This also means (absent heaters) that in cold areas with solar panels you may not be able to recharge them either. For a "do one night at a dark site" this is fine - -bring it home, warm it up, and charge before your next outing. In the below the heavy connector has a split to two #10 powerpole connections which replace my two 30a AC power supplies normally. Above it in my closet storage I have a charger with a powerpole, so I can connect and charge before taking it to a dark site. I decided there was no point in a battery box, while there is a bit of "stuff" on top that might be better sealed away, this was just fine, it a carrying handle on either side. This all took about 10 minutes to put together, except the copper bus bar which took a bit of work to figure out how to bend to the right shape. Linwood 
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Greg McCall
Re battery charging below freezing (that gets around me saying 0degC), many also don't like discharging below -20C None of these temperatures would be expected in Sydney, Australia so it's not something I watch out for. For USA people, Will Prowse seems to review a lot of battery brands available in the US In addition, the LiFePO4 can be charged at much hight rates compared to Lead-Acid and don't need that staged charge rate which also slows down the charge. (although you need a charger with a lithium profile - usually means LiFePO4 profile) It's also best fusing as close to the battery terminal as possible. Remember that fuses protect the downstream wiring and not the downstream device. (ie. fuse goes before wire burns in a short) I've seen posts re separate batteries for dew control etc. I really think these issues are due to too small batteries being used as well as too thin on the wires with motors causing voltage drop spikes because of larger resistance in thin wires. If worried, use thicker wires and run a separate feed from your motor to the battery. Also, avoid the cigarette lighter connectors as they provide a poor connection, can easily come loose and it's hard to get thicker wires into the connector. I recorded once a zoom meeting (at the start of the pandemic) that talked about batteries for anyone interested. If still bored and want another zoom meeting, I talked about voltage drop on cables another time I hope this helps cheers Greg
On Wed, Mar 2, 2022 at 10:50 AM ap@... <ap@...> wrote:
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Shailesh Trivedi
Thank you Linwood, Greg, Luke, and Brian.
What is your recommendation between the powerole meter here https://powerwerx.com/watt-meter-analyzer-inline-dc-powerpole and the Victron here battery meter BMV 712 listed on Amazon here https://www.amazon.com/Victron-Energy-MONITOR-VTBMV-S-BMV-712-Battery/dp/B075RTSTKS/ref=sr_1_1_sspa?crid=38XK8JNMUU7KX&keywords=victron%2Bbattery%2Bmonitor&qid=1646341648&sprefix=Victron%2Caps%2C282&sr=8-1-spons&smid=ACEM1DTDODKXX&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFZVDFZRkxNWUpVNkMmZW5jcnlwdGVkSWQ9QTEwMjE4OTZERVYyRENVWTVITjgmZW5jcnlwdGVkQWRJZD1BMDY1ODg2NFQzSjA0UUpQN0xXViZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1 Shailesh
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Hi Sheilesh the powerpole meter (first link) is very simple. you plug it in, and it has readouts for amp usage, w/h, watts, volts, etc. when you unplug it, it forgets everything. My goal was to run a system for a night and measure the amperage, and this was ideal for that I don't have any experience with the second item, but it looks a lot fancier, has bluetooth, etc. It would probably be better for longer term analysis/usage, but i'm just guessing here
On Thu, Mar 3, 2022 at 1:08 PM Shailesh Trivedi <shailesh.trivedi@...> wrote: Thank you Linwood, Greg, Luke, and Brian. --
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Shailesh Trivedi
Brian,
I am new to the concept of an inline battery meter. What do you do with the current and power information? Is there a cut off function beyond a programmable function?
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Wenhan Chang
Hi all,
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I don't use it all the time I use it to measure the total amps used during a night, and then i can size a battery for example, i ran everything on my rig (camera, computer, mount, etc.) and found i used about 18 amp hours of power. so I sized a battery around 25ah for cushion, and I know it will last the night. I also know if i add additional things (such as power hungry dew heaters) i will need to run with the meter to see what are the new results and if I need to upgrade battery capacity this is how I use it. I'm sure others use it differently
On Thu, Mar 3, 2022 at 1:24 PM Shailesh Trivedi <shailesh.trivedi@...> wrote: Brian, --
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