Suitable power tank

[seiko]

I'm looking for a cheap Powertank alternative and my local Makro had a 12v JumpStarter 300mah at £19.99. Will this be adequate for a 5i noting my observation sessions don't last more than an or two at the very most? The only reason I'm thinking of this is my scope is due to arrive today and I wanted to get going.

Thanks in advance.

[arad85]

As long as it has a 12V output and you have a 12V -> Nexstar 5i cable, then it shoud do. Beware, the 6SE I had didn't come with a cable to connect it to a powertank.

[MeerkatinBKK]

I wouldn't think 300mA hours would cut it. I don't know about the 5i, but the 5SE mount is rated at 750mA, so 300 would last less than an hour.

Nick

[arad85]

I don't think he means mAh... You wouldn't be able to jump start a bumblebee with 300mAh

[MeerkatinBKK]

I was puzzling over the 300mah bit, but thought it wise to warn just in case. I had visions of trying to jumpstart the wheels with a couple of AAs!

Nick

[seiko]

Hmmm, thought it was a 300mAh to be honest with the packaging suggesting you simply connected to your car battery and leave it for 15 minutes before trying to start? it was very small compared with my old powertank. They had a 900mAh too but that was over £40 and for a little more I could easily have a Powertank. Perhaps I've simply misinterpreted the digits?

Also and more importantly, I have a 12v adapter lead, what precautions must I take before plugging in?

[arad85]

Sounds like that is a battery CHARGER not powertank.... If it is a charger and you're asking if it would power the scope - then no it won't...

HTH

[seiko]

Nope, definately a jump starter.

also, probably a silly question but how do I check if my cable is center tip positive?

[MeerkatinBKK]

Hmm I'd recommend re-checking those numbers in that case. Most people seem to use 7Ah and up and as Arad says above, 300mAh isn't really going to help in jumpstarting a car battery.

SE mounts (and I think all other Celestron ones) need a cable with centre-tip positive. It should be marked on the mount and in the back of the manual. Check first as the mounts don't as a rule have a polarity safety thingy to stop them getting fried.

You're not near Birmingham are you? New telescope owner would explain the lack of cricket at Edgebaston today!

Nick

[arad85]

Nope, definately a jump starter.

also, probably a silly question but how do I check if my cable is center tip positive?

Jump starters have current capabilities in the hundreds of Amps. You sure that wasn't 300A cranking power You need to look for the capacity on the battery - most are either 7 or 17Ah....

Don't forget dew heaters too - you have an SCT now

[seiko]

Agh, that makes sense. I'll take another look on the way home. Nervous about that center positive though. And no, not Birmingham based, cloudy Suffolk