What's a good battery?

Just got a steal of a deal on a Nexstar 8, but need to power it.

sometimes maybe a laptop too.

Live in pacific northwest, so probably a dew shield will be enough (?) but I'm not sure if I also need a dew heater (no experience with SCTs, just dobs).

There are lots of different kinds out there, but my local big store has a 19 amp-hour one for $40. It also has 7 Ah ones for cheaper ($30 or so), and those tend to have some spiffy add ons such as a bright light which would help when you are breaking it all down for the night. Some even have compressors. I think having it jumper cable ready is more important as a secondary emergency feature (or can you use ANY such battery as a car booster by connecting 2 male cig. plugs -- one to battery, one to your cars cig lighter, then crank? it needs big amperage to be sure, but I think that's what that bigger battery is all about).

In short, should I just by this 19aH plain rechargable sealed lead-acid with jumpers built in and a single 12v cig jack with no lights or compressors for $40, or should I try to find one that has it all: long Ah life, light, dual 12v jack, jumpers and compressor? Is there such a thing -- the battery to end all batteries? or anything along the way? This $40 one looks featureless, but strong and that may be enough.

Thoughts?

TomL

For one that has it all, Celestron now puts their name on a Power Tank (I think both ATWB & Astronomics carries it). A bit expensive but a very nice unit. Has terminals for jumper cables & everything.

I would get two batteries - one 10 Ah or better to power only the scope ... Nexstars are sensitive to voltage fluctuations and turning other equipment on and off isn't going to help that. I have a 7Ah for a NX11, and it just barely doesn't last the whole night dusk to dawn ... so that's why 10Ah or better

And, one bigger one (like the 19Ah or even more) to run the laptop and dew heater and whatever else off. This one is nice with more than one plugin. A 19Ah will run just a laptop about 8 to 10 hours.

If one of those batteries has lights and other gizmos, that's nice but not necessary. Both of my batteries are jump-start packs containing sealed lead acid batteries and do have lights, and I usually use the red light to clean up. I doubt I'll ever use them to jump my car though

The only issue with using jump-start or lawn mower batteries is that they are made with thin plates inside and are designed (like car batteries) to provide relatively high amperage but only discharge ~5-10%. Running these types of batteries down can cause them to lose capacity in a relatively small number of discharge cycles. I had a 17 AH battery of this type drop to only taking a 50 percent charge in a scant four cycles. Gel cell batteries are supposed to be better at resisting this-- but the one I killed (or at least crippled) was a gel unit.

Marine/deep cycle batteries, OTOH, are designed to be run down and recharge fully-- although you can still do harm to one of these if you run it to full discharge. (Evidently some type of electrolytic scale can form on the plate.)

Marine batteries are certainly heavier, but make up for it by being virtually unkillable in my experience.

Jim

Most of these come with a "wall wart" transformer which will overcharge and damage the battery if left on too long. A very few of the jumpstart type batteries have a built-in charger which will switch itself off when the battery is fully charged. The only ones I have seen like this are sold by Harbor Freight Tools and I strongly recommend them. There;s a 17 amp-hour one with this feature on sale in the stores now for $40.

John