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Battery goes flat/or needs changing over in the middle of imaging session the middle

alcol620

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alcol620

alcol620

Posted
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Hi Folks

Advice required.

On a couple of occasions my battery has run out, without warning in middle of an imaging session. The mount is therefore unable to be returned to the home position. I assume that the mount has to be returned to the home position marks manually and all the setting have to be put back into the Synscan controller and a goto star alignment carried out again?

Would this also be the case if a battery was changed over during the course of an imaging session?

Any enlightenment would be appreciated.

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jgs001

jgs001

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Yep, that's correct, whenever you lose power for whatever reason, you must start again. Changing the battery mid session would cause a loss of power, and the system will need to be setup again.

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faulksy

faulksy

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probabl best getting a larger capacity battery a/hr and maybe a gauge such as a digital volt meter so you can monitor it during use, something like this

http://www.ebay.co.uk/itm/DC-3-30V-0-36-2-Wire-LED-Digital-Panel-Volt-Meter-Voltage-Voltmeter-Car-Motor-/351026520215?pt=LH_DefaultDomain_3&var=&hash=item51bacfa097

hope this helps

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Physopto

Physopto

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Hi,

Once power goes all sync is lost you have to restart from scratch. In other words any break in power to the mount will loose positioning. This applies to EQ5,6, etc. mounts same with Celestron 5 that I have anyway. Best if possible, to leave power charger on the battery at all times. Then the battery acts as a smoothing circuit and backup reservoir. Not tried it with the EQ8 but that has encoders, so should not matter.

Use the biggest battery you can. If using a lead acid battery as most of us do remember you will only get about 50 to 70% of its rated output. It depends upon the length of cable and csa of the cable (larger better) from the battery to the mount. Cable resistance will cause voltage drop and more of it the longer the cable. If using a battery charger use  an Intelligent type charger. Some allow a 13.6 volt maintenance or float state. But beware of the float state as this is not short circuit protected usually. I use CTEK chargers. A charger of 10% battery capacity is recommended for Lead Acid batteries. So 110 Ah requires about 10 amp charger. Anything less is OK. But will need to be able to keep up with the usage rate.

By the way a cheap volt meter will tell you what state the battery is in if just checked every so often during the nights usage. Not sure at what voltage the Celestron shuts down but I suggest you do not go below 11 volts at the mount.

Hope this helps.

Derek

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Skipper Billy

Skipper Billy

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I have found this device to be really useful

http://www.ebay.co.uk/itm/Red-Blue-LED-DC-4-5-30V-0-100A-Dual-Digital-Voltmeter-Panel-Ammeter-Voltage-Amp/390806011207?rt=nc

Voltage tells part of the story - amps drawn completes the picture.

For instance I now know that with everything turned on and in action the max amp draw is 5 amps - the average is 3 amps.  Taking the average I can expect my 80ah battery to last about 20 hours. IE way more than one session.

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stevend

stevend

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Not so far as I know, the AAs will only get used if the ext supply stops. I used to do this until I gained confidence in how long my power supply would last. I once accidentally unplugged the ext PS and everything carried on as it should.

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meddyliol

meddyliol

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I have found this device to be really useful

http://www.ebay.co.uk/itm/Red-Blue-LED-DC-4-5-30V-0-100A-Dual-Digital-Voltmeter-Panel-Ammeter-Voltage-Amp/390806011207?rt=nc

Voltage tells part of the story - amps drawn completes the picture.

For instance I now know that with everything turned on and in action the max amp draw is 5 amps - the average is 3 amps.  Taking the average I can expect my 80ah battery to last about 20 hours. IE way more than one session.

Excellent, just ordered one.

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Physopto

Physopto

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You can always have two DC power supplies in parallel with two (power) diodes connected to the positive input of the mount. The diodes ensure only the higher of the two power supplies is drained by the mount. The moment this supply drops below the other, that one takes over.

Hi Michael,

I've done this before, but it has to be remembered that the diodes will drop the forwards voltage by ~0.5 volts. So  a  fully charged battery at 12.8 volts will only pass on 12.3 volts after the diode. Doesn't matter for the most part if normally on a ac/dc charger. But if on a long supply cable it can drop the voltage below the EQ5 cut out level if a power failure occurs.

If the battery is close to the mount it won't matter at all.

Derek

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