Jump to content

SkySurveyBanner.jpg.21855908fce40597655603b6c9af720d.jpg

I need a bigger battery...

Andymarrison

Recommended Posts

Andymarrison

Andymarrison

Posted
Posted

Now that it's winter, and I'm running my scope and two dew heater strips off one power pack (one for the corrector plate of the SCT; one for the eyepiece), I'm running out of power after only a couple of hours. What power setups do other people use to get as much observing time as possible?

Link to comment
Share on other sites
  • Replies 39
  • Created
  • Last Reply
perfrej

perfrej

Posted
Posted

Anything with at least 40-50 Ah in it, preferably AGM batteries as they can take a full discharge without damage and charges in less than half the time of normal lead-acid or gel batteries. Also, lead-acid and gel are more or less destroyed the second you take them below 10V.

/per

Link to comment
Share on other sites
Teslar

Teslar

Posted
Posted

If you can afford it go for a >50Ahr leisure batter for caravans or boats. These are designed for constant load. The marlin units and others are designed for short burst jump starting and not will not perform as well as a leisure battery

Link to comment
Share on other sites
m.tweedy

m.tweedy

Posted
Posted

I use 2 x 50 AH. One for the mount so it has constant power when in use and have no worries about the dew bands as they are on a separate battery. They are lighter to carry than one BIG battery, mount has it's own dedicated supply so no worries about slewing, if the dew bands draw a lot of power I can afford to switch them off and continue the session for quite a while longer.

Link to comment
Share on other sites
Andymarrison

Andymarrison

Posted
  • Author
Posted

Thanks guys - I like the idea of having two medium rated packs, Michael, not least because the high Ah rated packs seem to way an awful lot! I might start with one 50Ah pack for the strips and keep the 20Ah one for the mount (which seems to need very little power over a typical session).

keeping the pack warm sounds like a good idea - how do I do that safely?

Link to comment
Share on other sites
Bizibilder

Bizibilder

Posted
Posted

First tot up the Amps you need - 2A for the mount, 2 each for the dew heaters and add 3.5 for the lappy you may use as well! Total = 9.5A. Call it 10A needed. An observing session may be 5 hours? So you need 10x5 Amp Hours = 50 Amp Hours. Double the answer - so you don't discharge the battery more than 50%. Total is now 100Ah.

I would suggest a leisure battery of between 80-100Ah capacity. Don't forget you will need a good charger/conditioner (good = Expensive I'm afraid!!). The upside is that it will last you for years and will save you money over time.

To keep the battery "warm" mine lives in a plastic battery case surrounded with 15mm of expanded polystyrene. When not in use it stays on its charger at room temperature. I suspect it stays pretty warm outside as its own chemical reaction when in use will generate a little heat.

Link to comment
Share on other sites
Antscope

Antscope

Posted
Posted

The temperature will greatly affect the output of the battery, just insulating it and keeping it at 25c preserves its performance, also try not to discharge it to 11.5 volts if its a lead acid battery, when it does need charging go with 2amps or lower charge rate in a charger, an intelligent one is best as you can leave it unattended.

Makes sense that your mount won't consume much power even though it has servo's but as is mentioned your scopes objective heating strip would pull a lot of power, you could streamline that power usage by using a dew shield with the heating strip. Go with a duty-cycle heating controller, this will save you lots of power/battery weight etc, most controllers use resistance to control heat output meaning the strip is "on" the whole time using power.

You'd be surprised what little heating you can get away with as the aim is to keep the glass just above ambient.

I use a 18ah battery but I have a smaller scope and a different mount, though soon I'll be observing in sub zero temperatures for the next 4 months.

Link to comment
Share on other sites
omahaastro

omahaastro

Posted
Posted

If I'm not at a star party where folks find the noise irritating (although these units only run 55 decibels, so they're not too bad)... I run a Honda EU2000 generator and a converter. Otherwise, I dispense with the cute little jump starter/'power tanks' and run a 100 Ah marine battery.

Link to comment
Share on other sites
Andymarrison

Andymarrison

Posted
  • Author
Posted

Ok chaps - just went ahead and ordered a 100 Ah leisure battery with a smart charger (you were right - those little things are expensive!). I'll give that a go first, then will probably switch to a more efficient dew heater control (the one I've got is just a set of variable resistors, I think). Battery should arrive tomorrow, then I've got to rig up a little fused 12V distribution box (Kenny who I met at PSP kindly gave me the instructions for that), then I'll report back on how much time I'm getting with the new set up. Thanks everyone!

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.