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Old 21-05-2017, 01:56 PM
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RobF (Rob)
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Too much voltage?

I seem to have an issue with my Mount Hub pro not wanting to connect with a bank of AGM batteries, after they been on solar charge for an extended period. My best guess is the batteries are so "full" they're putting out just a bit more voltage than the Mount Hub Pro is comfortable with.

This theory seems confirmed by fact the MHP will happily run off a separate battery initially, then later in the night (after my laptop and various toys have been running off the battery bank for a few hours) the MHP is ok running off the battery bank power.

I don't want to have to power down and do a power swap halfway through the night though. Is there anyway to better regulate the volts and power coming off the battery bank initially? Battery bank is trickle charged by a good quality solar regular and single small solar panel.

Appreciate any thoughts from those with much more electronics nouse then I?
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Old 21-05-2017, 02:22 PM
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Slawomir (Suavi)
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Hi Rob,

I checked the manual and it states that Plug the cigar plug into a suitable output which delivers 12-15v DC Centre Positive.

Perhaps you could check voltage of your fully charge battery bank with a voltmeter?
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Old 21-05-2017, 02:36 PM
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Marke (Mark)
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Do you have them in parallel or in series I asume they are in Parallel ?
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Old 21-05-2017, 03:30 PM
raymo
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A fully charged conventional 12v battery will not exceed about 13.8v, so if your device should accept 12-15v something must be wrong with the device.
If your laptop and other devices run o.k. off the battery bank, they are obviously not connected in series.
raymo
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Old 21-05-2017, 04:45 PM
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Thanks guys. The batteries are definitely all in parallel, and voltmeter later in the night was reading about 12.7 volts - I forget to check earlier when MHP wouldn't connect - it refuses to establish its USB connection, which makes life pretty difficult. I'm so addicted to a single USB and power connection now I don't think I could go back to plugging everything in separately any more.

Really surprised it would be fussy about voltage, considering the amount of current it happily disperses to dew heaters etc.

I wonder if its also a sign of problems with a device I have plugged into it. I have no probs running the whole rig off 240V with Jaycar 12V switched power supply I should add - which is the normal mode of operation.
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Old 21-05-2017, 09:39 PM
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OzEclipse (Joe Cali)
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It sounds like it is some other issue not volts. Earth loop? noise?

If you want to obtain a constant output voltage, use a DC DC up down buck converter like this one

http://tinyurl.com/mayvd8a

This up down converter will transform down if the input is over 12.7 and up if it is under 12.7 (or any voltage) You can set a wide range of output voltage from a wide range of input voltage. Note current is limited to around 3A.

Input Range:3.8V ~ 32V
Output Range:1.25V ~ 35V
Input Current:3A ( max )
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Old 22-05-2017, 07:46 AM
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Hey Rob, I add some issues with mine and that was resolved when I used a separate dedicated power supply for the hub. The dew heaters were interfering with the guiding. I probably was drawing a little too much power for my C11 corrector plate with a "homebrew" heating system. So now I'm aware of that I separate the mount power and the hub power and anything that might draw more amps. Normal "reasonable" heating for my refractor I keep through the hub though.
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Old 22-05-2017, 11:34 AM
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Does the USB hub work OK on the "charged" batteries if it is the only device connected and powered by the batteries? If so, the problem points to noise introduced on your DC power line. The noise can be introduced by your other devices such as laptop which incorporate switch mode power supplies. One of frequency of the frequencies of your equipment switch rates must be similar to that of your hub. Since the problem goes away after a period, I'd guess that the laptop is the main protagonist since it uses more power. At some arbitrary frequency, the switch modes will effectively use an on-off switching ratio determined by the input voltage and power drain. As the battery voltage droops, the on-off ratio adjusts to provide a constant rate of power to the laptop. This also alters the switching frequency slightly as it does so. (Or at least the complex components generated in the switching process) When the system haseen on for a while, the generated noise spikes on you DC supply do not upset the hubs operation.
The cure can require RF filtering of your DC feeds to the various devices. This includes maybe ferrite inductors placed over the cables (both positive and negative) and by putting capacitors across the + and - lines near each device. There should be two layers of capacitance used. One set that has some thousands of microfarads in value (to smooth out larger bumps in the levels) and some smaller values say 100 picofarads as well. These will smooth out the shorter RF spikes that the bigger value caps cannot.
Another aid in the noise reduction is to run your devices in a "star" feed from the battery. Each device to have its own direct feed to the battery. This should minimise noise gernerated by other devices getting on to the sensitive ones.
HTH
Brian
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Old 22-05-2017, 11:29 PM
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Many thanks guys, you've given me a few strategies there to try out next time. Up until recently I was trying to run the rig off 3 daisy chained cigarette connector lines, with all that coming of a "triple adaptor". I assumed it was just bad connections. However last time out I installed dedicated high amp cable with Anderson connectors and a single cig connection at the end for MHP - and STILL had same issues.

Quote:
Originally Posted by OzEclipse View Post
It sounds like it is some other issue not volts. Earth loop? noise?

If you want to obtain a constant output voltage, use a DC DC up down buck converter like this one

http://tinyurl.com/mayvd8a

This up down converter will transform down if the input is over 12.7 and up if it is under 12.7 (or any voltage) You can set a wide range of output voltage from a wide range of input voltage. Note current is limited to around 3A.

Input Range:3.8V ~ 32V
Output Range:1.25V ~ 35V
Input Current:3A ( max )
Many thanks Joe - that's EXACTLY the sort of thing I was looking for, with thought of putting between between female and male cig connectors (or Anderson plugs). But only if I can pin down for sure the MHP really is upset at a higher voltage.

Quote:
Originally Posted by multiweb View Post
Hey Rob, I add some issues with mine and that was resolved when I used a separate dedicated power supply for the hub. The dew heaters were interfering with the guiding. I probably was drawing a little too much power for my C11 corrector plate with a "homebrew" heating system. So now I'm aware of that I separate the mount power and the hub power and anything that might draw more amps. Normal "reasonable" heating for my refractor I keep through the hub though.
Yes Marc, I was thinking the first thing I'd take off the hub would be the dew heater - run it off a separate controller and power line. I'm just so addicted to it all being together. Logical thing to try for troubleshooting though. The funny this is it runs so reliably off 240V switchmode supply, or a single AGM battery (until it drains significantly). I really wasn't expecting big batteries in parallel to be such a pain.

Quote:
Originally Posted by tempestwizz View Post
Does the USB hub work OK on the "charged" batteries if it is the only device connected and powered by the batteries? If so, the problem points to noise introduced on your DC power line. The noise can be introduced by your other devices such as laptop which incorporate switch mode power supplies. One of frequency of the frequencies of your equipment switch rates must be similar to that of your hub. Since the problem goes away after a period, I'd guess that the laptop is the main protagonist since it uses more power. At some arbitrary frequency, the switch modes will effectively use an on-off switching ratio determined by the input voltage and power drain. As the battery voltage droops, the on-off ratio adjusts to provide a constant rate of power to the laptop. This also alters the switching frequency slightly as it does so. (Or at least the complex components generated in the switching process) When the system haseen on for a while, the generated noise spikes on you DC supply do not upset the hubs operation.
The cure can require RF filtering of your DC feeds to the various devices. This includes maybe ferrite inductors placed over the cables (both positive and negative) and by putting capacitors across the + and - lines near each device. There should be two layers of capacitance used. One set that has some thousands of microfarads in value (to smooth out larger bumps in the levels) and some smaller values say 100 picofarads as well. These will smooth out the shorter RF spikes that the bigger value caps cannot.
Another aid in the noise reduction is to run your devices in a "star" feed from the battery. Each device to have its own direct feed to the battery. This should minimise noise gernerated by other devices getting on to the sensitive ones.
HTH
Brian
Lots to think about there Brian. I haven't been able to get the MHP to connect via USB off the fully charged battery bank, however I have previously also had a DC/DC convertor running the laptop off the batteries too. I might next time try connecting the MHP with the laptop running only on batteries. Another thought is to put an opto-isolator on the USB line I suppose. I've got a couple of decent ones here somewhere - will have to add to my travelling kit.


Should also add - this is the DC/DC convertor my laptop is running off (the only other thing pulling power off the battery bank):
https://www.jaycar.com.au/60w-regula...aptor/p/MP3478
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