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battery pack for g11 gemini 2

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#1 asesino

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Posted 21 March 2011 - 10:14 PM

I am waiting delivery on a G11 Gemini2, in the meantime I am trying to find a battery pack for it , the concensus seems to be that a deep cycle battery is the best option, but they are 12v and the mount seems to work better at 18v, the only one that I can find is the Kendrick one but it is pricey. Does any one have any suggestions for a battery or a setup that will work and that it is not $350 plus? :question:

#2 Jovian

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Posted 22 March 2011 - 01:24 PM

I have the same equipment on order, and have been using (2) 12VDC batteries connected in parallel for a CGEM. So I certainly hope the G2 works properly on 12VDC. The owner's manual states that the Gemini 2 operates on 12-18VDC. I don't think there would be a problem, but would be interested in other opinions.

#3 Billydee

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Posted 22 March 2011 - 01:57 PM

I understand that the 18 volt power plug on the Kendrick does not hook up to the new Gemini 2. You need to check. You can get a DC to DC converter that can step up the 12v to 18v and it keeps the voltage at 18v as your 12v is discharged. They usually run about $150 in the 4amp output range. That is the way the Kendrick works. I think it is listed on their web page and other people make them, also.

Luck, Bill

#4 asesino

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Posted 22 March 2011 - 10:57 PM

I guess we are on the same boat, I checked the dc to dc converter and it is 150 bucks, it will work with a deep cycle battery 100 more or less, plus clamps oh I don't know 20 bucks, plus charger,plus whatever else is needed fuses and the like, more and more it seems that the Kendrick is the way to go. Oh well, I spent 3700 on the mount, might as well go the whole nine yards. :foreheadslap:

#5 Billydee

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Posted 23 March 2011 - 01:51 PM

Asesino,

Like I said, I understand the 18 volt power cord does not match the plug in on the new Gemini 2 (the Kendrick cord is different so you won't plug in any true 12 volt equipment into it). I am sure that Kendrick will supply the proper power cord once they know what it is and how to make it. Kendrick is a great company. Don't know what country you are in but if you buy while in the USA Kendrick has a warehouse in upper NY state and buying from it saves the duty from Canada to the US.

Luck, Bill

#6 rsbfoto

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Posted 23 March 2011 - 03:00 PM

Hi,

This guys have a good priced capable DC/DC converter

http://www.batterysp...romcarplug.aspx

I have one of those working since 3 years in my Observatory and 0 problems.

#7 Billydee

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Posted 23 March 2011 - 09:08 PM

The new Gemini 2 system on a GM-11 can draw 5.6 amps total (2.8 amps for each of the two tracking motors). The above listed DC/DC converter is a 3.5 amp max unit. It should handle a normal load but might not be able to handle a max load. It also does not have an adapter for the new Gemini 2 coax power connector.

From Yahoo:

Hey guys,
I was setting up to plug in my Gemini 2 for the first time this morning and noticed something that is likely everyone here already knows... The Gemini 1 and Gemini 2 power connectors are different apparently.

I wanted to run my system off of 18 volts. I'd read that it was better but the exact reason escapes me. Anyhow, I purchased a very nice Kendrick battery and a cable for the Gemini 1. I though to myself "why would they change that..."... well it is totally different. Indeed so much that I'm concerned. The Kendrick power cable has 4 pins and is pretty beefy. Additionally there is no way I could accidentally plug that into one of my MANY other 12 volt accessories I have as the plug is not in any way a standard power plug. The new Gemini 2 seems to use a normal power plug like any other powered device, only it is labeled 12-18 volts (and apparently likes 18!) I don't really want an 18 volt plug laying around that could plug into my CCD, computer, fans, or video setup.

Luck, Bill

#8 asesino

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Posted 23 March 2011 - 10:06 PM

Asesino,

Like I said, I understand the 18 volt power cord does not match the plug in on the new Gemini 2 (the Kendrick cord is different so you won't plug in any true 12 volt equipment into it). I am sure that Kendrick will supply the proper power cord once they know what it is and how to make it. Kendrick is a great company. Don't know what country you are in but if you buy while in the USA Kendrick has a warehouse in upper NY state and buying from it saves the duty from Canada to the US.

Luck, Bill


Thank's Bill, I will get the kendrick quad pack he does have the special 18v cable already, it is really nice. :) It is also good that he has that warehouse in New York, that will save me a few bucks.

#9 rsbfoto

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Posted 24 March 2011 - 10:34 AM

The new Gemini 2 system on a GM-11 can draw 5.6 amps total (2.8 amps for each of the two tracking motors). The above listed DC/DC converter is a 3.5 amp max unit. It should handle a normal load but might not be able to handle a max load. It also does not have an adapter for the new Gemini 2 coax power connector.

From Yahoo:

Hey guys,
I was setting up to plug in my Gemini 2 for the first time this morning and noticed something that is likely everyone here already knows... The Gemini 1 and Gemini 2 power connectors are different apparently.

I wanted to run my system off of 18 volts. I'd read that it was better but the exact reason escapes me. Anyhow, I purchased a very nice Kendrick battery and a cable for the Gemini 1. I though to myself "why would they change that..."... well it is totally different. Indeed so much that I'm concerned. The Kendrick power cable has 4 pins and is pretty beefy. Additionally there is no way I could accidentally plug that into one of my MANY other 12 volt accessories I have as the plug is not in any way a standard power plug. The new Gemini 2 seems to use a normal power plug like any other powered device, only it is labeled 12-18 volts (and apparently likes 18!) I don't really want an 18 volt plug laying around that could plug into my CCD, computer, fans, or video setup.

Luck, Bill


Hi,

You might be right but I am using Maxon motor, have both of my G11 loaded with nearly 70 pounds and the DC/DC converter listed above is doing his job, but OK if you want to be on the safe side get a bigger one which is a fraction of the cost of a fried Gemini II unit.

One thing is the maximum load you can get through the Gemini II and the other thing is what load are you really using with a well balanced G11 mount.

I am slewing with both mounts at 640x which are 2.7° per second.

As already explained in the moment you use 18V instead of 12V your current goes down by aprox 33% which menas that if at 12V you draw 5.6 amps in total with 18V you will only draw 3.8 ampere ...

Just my 2 cents to this ...

#10 Billydee

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Posted 24 March 2011 - 12:23 PM

Rsbfoto,

You are correct on the current draw at 18v. I did not mean the DC/DC converter you use is bad (it is a great unit at a very good price). I just wanted to point out the new Gemini 2 appears to pass more current through the board than the Gemini 1 (not sure why, motors are motors) and that the power connection is different (make sure the converter has that connector).

Thanks, Bill

#11 Jovian

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Posted 24 March 2011 - 04:02 PM

This whole discussion has been really informative. Thanks guys.

I spoke with the guy over at Kendrick's. I didn't catch his name - probably Mr. Kendrick - but he was very helpful.

The 12V-18V inverter, part no. 2085-INV ($139.95) will work with the G11/Gemini 2 combination. He fuses it for 7A for the Gemini 2. The cord - not yet listed on the website - would be described as part no. 2086LC12 w/XLR connector for the Gemini 2 ($39.95).

#12 rsbfoto

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Posted 24 March 2011 - 04:21 PM

Rsbfoto,

You are correct on the current draw at 18v. I did not mean the DC/DC converter you use is bad (it is a great unit at a very good price). I just wanted to point out the new Gemini 2 appears to pass more current through the board than the Gemini 1 (not sure why, motors are motors) and that the power connection is different (make sure the converter has that connector).

Thanks, Bill


No problem, but I guess you misunderstood what was said in the Gemini II group.

The 2.8 ampere is related to the fact that, that is the maximum amperage the board supports and not pulls from anywhere.

The servo motor pull the current and that is what goes through the Gemini board, So if by any means a motor would draw more then 2.8 ampere you would fry that controller ...






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