Quote:
Originally Posted by glend
In my experience, the car jump start units do not last very long. They may handle your load but they designed for high amp output in short bursts and not long sustained deep cycling. If you let them sit they will lose their charge, and once that happens they cannot recover. I won't use them anymore, preferring deep cycle batteries for dark site work. I use a 44ah for mount power and have a 100ah for dew heaters, laptop inverter, camera cooling, etc. Does not take long to recharge next morning with a solar panel, and they have lasted for years with no sign of deteriouration. They are heavy buggers, especially the 100ah, but they last. I must admit they do double duty, at home they sit in the observatory on float.
Read the fine print on thise car jump start packs, most of them have batteries with less than 20ah inside.
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I have a Repco 44AH battery pack......inside is an AGM battery......I have used it for running my fans, EM400 Mount and power to IPAD for 3-4 nights without needing to recharge.
Yes if you let them sit for ages ( I'm talking a fairly long time) they might die.....but for regular scope use thats not usually the case.
Deep Cycle batteries can also suffer the same problem .....but generally not to the same degree so you will get better life but you are definitely not immune.
Now days the best thing to do is as Matt has done and buy a good quality LiFePO4 battery and wire it up yourself.
Or if you don't want to wire it up yourself buy one of these.....
http://www.arkcorp.com.au/c/37/arkpak-portable-power