Solar, Generator or ?

[icanon]

Next year I am planning a few days of 'off grid' camping to do some astronomy. Usually I go to star parties with full hook-up but planning on doing some solo in some nat'l parks.

My question is what is a cost effective way to recharge my battery while I'm off grid? Should I go solar, generator or just add another battery? I will need a minimal of power to run the detectors, propane fridge and an hour per day of water pump all of this will be off grid for 4 days max.

So what would you do? Remember I am planning to do this once or twice per summer.

Thanks.

[icanon]

MEXICOWANDERER wrote:


But Kudos with a capital K on your lens grinding. That impresses me to no end. Who did the coating if I do may be rude to ask?

A friend of mine who has a coating business in Sudbury Ontario Canada called MOONWARD Vacuum Coatings. I did the grinding all by hand I must say, it took me nearly two years on and off then drove 8 hours for him to do the testing and coating.

[MEXICOWANDERER]

My knees are knocking and I'm whimpering.

Crystal Skies To You Amigo.

(now to figure out a way to use fiber optics and a laptop for control and image capture...) My warranty has run out so your treasure has to remain on the perpetual wishlist.

But Kudos with a capital K on your lens grinding. That impresses me to no end. Who did the coating if I do may be rude to ask?

[icanon]

Here's a photo of me with my 16in f/6 telescope

[MEXICOWANDERER]

Chew and spit time.
Refer to the BatteryMINDER sale in the forum list. Buy one. You can sure use one no matter what.

Cheapest RV battery. Costco, Sams, Wal-Mart. Connect a cheap set of jumper cables from new battery to existing battery.

Have a ball on your outing.

When you get home, charge to the eyeballs then stuff the extra battery in a corner, plug in and connect the batteryMINDER, then forget about it until the next outing. Do check water in between times, though.

When your existing battery dies, you have a battery ready to rock n roll. A coddled unworked RV battery will last 7-10 years or even longer. Coddled means batteryMinder or Battery Tender maintained.

Smart money does not work 3 days a year. Smart money either works or stays ready to work. A four year old worked RV battery isn't exactly a spring chicken.

[SoundGuy]

icanon wrote:
My battery is two years old will be three next summer, willing to change for two batteries. Deciding on which and what batteries to go with? Keep in mind this is a 3 - 4 day adventure and for minimum TT use as I don't need much.

Since your requirements are minimal, as are mine, there's no need to replace your "just fine" current battery at all ... keep it, buy a second of your choice, and operate them sequentially, running the first one 'til it's ~ 50% drawn down then switch to the second. JMO, but too many here on the forums tend to exaggerate the need for battery reserve in large quantity ... fine for those who dry camp a lot, expect to run a lot of devices each day, and have invested a considerable sum in a solar setup for recharging those batteries but for the rest of us this approach can often lead to unnecessary expenditure. For just a couple of trips a year, each trip just 3 - 4 days duration, it sounds to me like you're the ideal candidate for K.I.S.S. 😉

[MEXICOWANDERER]

Also, I have a 16” Dobson telescope that I made myself, yes mirror and all.

IMPRESSIVE! Jealous as all get-out!

[icanon]

Thanks for all the replies. It's been really helpful.

[Gjac]

Double post

[Gjac]

korbe wrote:
We have 2 Trojan 6-volt total 225 amp hour batteries. When my wife and I boondock in the summer months, and in conserve mode, we can enjoy our time using about 20 amps per day, about 10%. After about 6 days, it's time to recharge the batteries, dump the tanks and refill the fresh water tank.

This is my experience also. After 7 days batteries are at 50%,60 gals of water is gone unless I use backpacker tricks, and laundry needs to be done. For 4 days and minimal battery use as you described I would just use what you have and when it is time to replace buy two 6v GC batteries.

[icanon]

pianotuna wrote:
Hi icanon,

There's the rub. Unless the existing battery is nearly new, then adding an additional one may be a problem. That means replacing both.

For small capacity battery banks 1.5 watts of solar per amp-hour of storage would be a good point to aim at.

icanon wrote:
Doug, adding another battery sounds good to me, could you suggest make and model?

Thanks pianotuna

My battery is two years old will be three next summer, willing to change for two batteries. Deciding on which and what batteries to go with? Keep in mind this is a 3 - 4 day adventure and for minimum TT use as I don't need much.

[pianotuna]

Hi icanon,

There's the rub. Unless the existing battery is nearly new, then adding an additional one may be a problem. That means replacing both.

For small capacity battery banks 1.5 watts of solar per amp-hour of storage would be a good point to aim at.

icanon wrote:
Doug, adding another battery sounds good to me, could you suggest make and model?

[dclark1946]

If you do consider solar make sure your camp sites have direct sun available. Where we dry camp the trees are over 100 ft tall and very dense and more than likely it will be raining off and on half the time we are there. There is very little direct sunlight and the rest of the time it is deep shade. I use solar here in sunny TX when the trailer is being stored at home for battery maintenance. For us, a small (1000 W) quiet generator is a good solution with a single Gr27 115AH deep cycle 12V battery.

What is extremely important is that you make sure that your battery(s)have been well maintained and are in good condition so that you are getting the energy storage you expect.

Dick

[doughere]

icanon wrote:
Thanks everyone for the replies.

Fred, I have two portable power packs for my celestron cpc telescope, so I'm good for a few nights. Also, I have a 16” Dobson telescope that I made myself, yes mirror and all, so minimun of power there, just power pack to run dew heaters.
Since I already have a 75w solar panel I think I'll add another 75w that will give me a total of 150 watts. Should be fine?

Doug, adding another battery sounds good to me, could you suggest make and model?

I think any pair of 6 volt GC's will do fine. I'd look around for the lowest price you can find. Mine are no-name 7 or 8 years old and still doing fine (they'll last me 4 days without sun). I think any will do fine; but I'm sure there are going to be plenty of this brand / that brand opinions.

Doug

[Golden_HVAC]

icanon wrote:
Thanks everyone for the replies.

Fred, I have two portable power packs for my celestron cpc telescope, so I'm good for a few nights. Also, I have a 16” Dobson telescope that I made myself, yes mirror and all, so minimun of power there, just power pack to run dew heaters.
Since I already have a 75w solar panel I think I'll add another 75w that will give me a total of 150 watts. Should be fine?

Doug, adding another battery sounds good to me, could you suggest make and model?

Hi,

My E-meter shows exactly how many amps are going out of the batteries at once. It shows 0.8 amps X 24 hours a day, and 1.1 amps while the refrigerator gas valve is on, so that could be 6-18 hours out of that total. That is why I am estimating about 35 AH daily just to run the RV - including some pump usage, but not the lights or furnace.

Of course TV and any inverter usage is beyond what I can estimate for you.

I would recommend a minimum of 150 watts, but rather would say to get a 140 - 200 watt panel from SunElec.com They are pretty cheap, you would be investing less than a couple of tanks of gas into the solar system upgrade. I would not really recommend a 75 watt panel (though I have one, that I bought in 1996 for some $375) Smaller panels require to many mounts per 1,000 watts of total capacity. Yet I also do not recommend any panels larger than about 200 watts, due to their size, and the ability to catch way to much air per panel.

First thing to check is how much space the panel will require, and where it can be located on your roof. No sense in buying a 200 watt panel that is 45" wide and 75" long if it will not fit anyplace on the roof.

Good luck,

Fred.