Deep Cycle Battery Woes

[solissydney]

Hi.
In Feb 2009 I purchased a Century 12V 47 AH Deep Cycle battery.
That battery has now had it.
I worked out that, because of the problems with my old mount, and because of the
bad weather since my purchase, the battery would have been in use for about 150 hours in total. It has been charged on an intelligent charger, one Projecta 4300. It has cost me app. $100.00 a year. I am considering looking into buying a new battery from NRMA with a 3 year warranty.
Any other suggestions?

[Marke]

Just get one online , I can get a 150Ah for $350 2yr warranty free shipping . Try here http://www.aussiebatteries.com.au/eShopDirect/index.cgi?cat=0 45Ah AGM for $159 free delivery , forget NRMA .

Mark

[solissydney]

Yes, you are right about where it is best to buy a battery.
Thanks for the tip
Ken

[bmitchell82]

Thats a bit shot. 150 hrs total out of a battery with a microprocessor charger. They should last a damn long time if your not flattening them completely (be aware that you really shouldn't discharge it much past 50% for maximum life, and if you go deep, don't go past about 80% capacity or you will kill the battery).

Also be aware not all batterys chargers are made equal, some are specifically designed for charging specific types of batteries. Thats why I like my CTEK charger as it is able to do a whole range of them.

here (http://brendanmitchell.net/?p=465) is my setup for remote power and soon I will be adding a solar power aspect.

I purchased a 105 A-H battery from my local store for 240 rods. The thing is rock solid, and my other imaging friend has had the same battery for 2 and a bit years now and its still going strong.

[solissydney]

I am about to place an order for one 45AH AGM for $159.00 from Aussie Batteries
This will replace my 50 AH one. I never come near to over-use the battery, usually use it only 2 - 4 hours at any one time.
I looked into chargers for the AGM batt. I was assured by Aussie Batt. that my Projecta 4300 charger was OK to use for the new battery. I am about to get a second opinion on that.
Sounds OK?

[Marke]

That 150Ah is to run the Obs including lights its not for portable. It has 15A C-Tek with supply mode connected to it - the 15A does upto 300Ah batteries.

Mark

[loc46south]

Hi - I run my observatory on Solar Power and have found out the hard way that not all batteries are created equal - I suspect you have discharged your battery beyond it's safe point and killed the cell. You shouldn't discharge your battery lower than 11 volts (if you want it to last).

Geof Wingham

[Marke]

That should be fine it doesnt take much to charge a small battery and the Projecta will handle it , most chargers do AGMs now .

[bmitchell82]

I think you mis read my reply Mark, i was talking in relation to he only got 150 hours total out of his last battery. not your 150 AH batter. :)

[Marke]

Doh! yeah 150 Hr not much :)

[xstream]

30% DOD is the usual rule of thumb, which relates to about 12.60V in a AGM, go any lower before fully recharging your battery and you are greatly reducing it's life cycle.

The main thing you need to consider is how many Ah are you using and purchase the size of your battery accordingly.

[acropolite]

Battery life is, as John has implied, a function of depth of discharge.

Discharge fully and you'll get less cycles before the battery is worn out, lighter discharge will result in a longer service life.

The single most important thing is to fully charge the battery immediately (within a day or so) after any discharge and don't pump high current in to the battery if it's in a low state of charge. Equally important is to maintain the correct electrolyte level, if the level falls below the top of the plates due to overcharging the life of the battery will suffer.


If you leave the battery in a discharged state for any longer than a couple of days the sulphate formed from the discharge process will harden and recovery is difficult if not impossible.

Another factor not usually considered is the care that the battery has had before your purchase, self discharge on deep cycle batteries is around 5% per month, a new battery left on the shelf for months could be in a sulphated state before you even buy it.

Another misconception regarding stat of charge is battery voltage, as a rough guide 12 volts with no load represents 50% discharged, 11 volts is pretty well dead flat.

[naskies]

Sorry to hear about your battery woes, Ken.

I placed an online order for a 100 Ah battery and 8A charger from Aussie Batteries yesterday morning... it arrived on my doorstep this morning. The 100 Ah is a heavy beast - in retrospect, I probably would have preferred a 45 Ah battery.

[solissydney]

Yes, there is quite a gap between the two. I would have considered going for something in between 45 and the 100 AH. My images last night under a dark sky had elongated stars due to the near dead flat battery. The light on my EQ6 mount was flashing for most of the time I was exposing.

[solissydney]

Received my new UP-45 AH deep cycle battery today,.
Where my previous battery was charged to 12 and a fraction Volts. The new one was charger up to 13.25V. One must not deplete the battery below 10V. pity it does not have a carry handle. I did order a carry case at extra cost thinking it had a carry handle, but it just came with 2 grips. Rather useless I think.
Anyone wants the carry case can pick it up in Castle hill.
The battery is (labeled as 40ah 10hr) What does that mean? 4 amps an hour over 10 hours???

[naskies]

Internal resistance of the battery... if you drain it at different currents, you'll get different capacities out of it. The 10 hour figure is the capacity if you were to drain it over 10 hours, i.e. you'll probably get less capacity over 5 hours and more capacity over 20 hours.

[GrampianStars]

A battery rated at 40a hrs. for 10 hours means that if you divide 40 into 10 the battery can be discharged at 4 amperes continuously for 10 hours.
So if you use the battery for 5 hours @ 4amps it will be 50% discharged :(

Likewise, if the rating was at 5 hours (average night) then divide 5 into 40. This would mean that the battery could discharge 8 amperes continuously for 5 hours.
So if you use the battery for 2. 5 hours @ 8amps it will be 50% discharged :(

IMO 40ah is very limited and the discharge is too great.
A 100ah /20 hrs should have been your minimum ( So if you use the battery for 10 hours @ 10amps it will be 50% discharged

[xstream]

Batteries are the same as your scope or mount, you get what you pay for.

"A penny wise a pound foolish". :)

[solissydney]

I only use the battery for powering my mount and auto guider

[marki]

Buy a honda or yamaha genset and save yourself from the battery woes. At least half the weight of a deep cycle battery if not more and it only takes a minute to refill and its off again. Mine is running right now, can you hear it? Thought not :P:D.

Mark

[bmitchell82]

Im with you there Mark, only issue is some people cry if they hear a mosquito farting 300m away on dark sky camps........ I know they are quiet but yeah ive been stung before! Genny during the day, battery by night plenty of redundancy if all goes to pot :D

[solissydney]

On the contrary, I did hear the noise from your noisy generator.
It kept me awake last night

[hotspur]

Very well articulated Paul.

Batteries and charging etc,is a very important topic,that one has to try an gain some knowledge on.Many of these outdoor hobbies such as camping,hunting,and astronomy are so much more enjoyable when good battery gear and charging gear is bought,and most importantly looked after properly.As has been mentioned-you get what you pay for.\

Go to a dedicated battery shop,such as 'battery world' or similar,and find a proper sales person who knows what they are talking about.I have been lucky and found a very helpful person in kingaroy battery world (he's keen on astronomy-so picked my brains to buy gear,so this has helped alot).

Buy a proper battery charger,not some crap thing from cheap auto shops.Spend between $200-$300 on one,either Ctek,or projecta.

I bought a $250 Projecta one-it has screen you can toggle through see what's going on.Also talk to dumpies,occasionally they get batteries in the might be reasonable-I got this 97amp deep cycle battery from tip,looked clean and not old,had it tested,the battery guy said it was in very good order-I've used it to power my engal for camping and dew heaters.However,on long term trips,I'll spend the money on a 120amp hour AGM.

A good AGM 120 amp battery will cost $320 along with a good charger $200 plus-worth the money.

Maybe IIS should have a battery 'sticky' Pauls advice is very good,over on hunting/fishing forums they have battery/power sticky.I've noticed some here think they can get get out off power supply issues cheaply-it just does not work.I've done a lot of research into it,and its paying off in my field trips

Even the cable in image here cost $50-proper socket for fridge.fuse,all heavy duty.If you spend $1000 plus on a fridge/mount whatever,spend a proportional amount on fittings.

[GrampianStars]

NEQ6 Pro Mount about 2ah. SG-4 needs about 200 mi.ah. (2.02ah)

So if you use the 40ah/10hr battery for 10 hours @ 2.02amps it will be 50.5 % discharged :(

Therefore if you use the battery for an average 5 hours a night 5 hours @ 2.02amps it will be 25.25% discharged
That should only be your Maximum usage ever! :thumbsup:

[Marke]

Thats a lot of current draw ? I have a meter to monitor battery use , mount uses about .5A tracking , All up with camera ,mount , focuser and fans every thing going I draw about 3A tops. Even laptop only uses 0.9 after boot up I total 5Ah use after 7hr running the laptop.
AGM will discharged lower than 50% as well . The spec sheet for mine say good for >1400 dischages to 10v , they are designed to go much lower than your normal battery , thats what you are paying the extra for.
Mark

[MrB]

Yep, I used to take a genny camping and it never really bothered me.... I would let the tank run dry thru the night and then it was just me, the campfire and the stars... that was when I began to appreciate the total lack of noise.
Hence my move to a solar setup. No power issues and zero noise. Was cheaper than a genny too, for me anyway ;)

[RobF]

Sounds like you've purchased wisely Ken. A mount and guider shouldn't draw more than 1amp, unless you're slewing all of the place continuously (which usually isn't the case for imagers).

Max discharge down to 33% gives you 26ah, which should give you at least 2 very long nights of imaging. Recharge as soon as you can, and trickle top up from time to time. Sounds like you already have a good charger which is very important.

I've bought from Aussie Batteries before with no probs at all. You can always buy an extra >100ah 2nd battery in the future if you start running dew heaters, laptops and other juice hungry beasts!

[Barrykgerdes]

As an example of battery powering a telescope I have a LX200 classic that I use for school nights and other displays. The telescope operates in alt/azm mode. Sessions usually run between 2 and 3 hours.

I have used a 12v 18 AH battery that was discarded from my golf buggy due to poor capacity 4 years ago after two years use. It gets charged up when I want to use it. It has never failed to last the distance for this use.

Barry

[PeterM]

Great thread and input from everyone. Very timely for me.
I'll be heading out to Leyburn again each month after several years hiatus. I have equipped myself with a 2nd 12inch LX200, spare SXVHR9 and all the other bits I needed to do my SN search once a month from there - ok an extravagance, but like government policy why pay for one when for twice the price you can have 2, at least that way the home observatory stays intact.
I have bought a new Full River 85amphr/20hrs deep cycle battery and a Jaycar 600w full Sine wave inverter. This will power the LX200, The Starlight camera and my Toshiba laptop. The dew zappers will run directly 12v from a 55 amphr battery.
Can someone confirm that the LX200 will use about 1amphr (doing say 300+multiple short slews). The SXVHR9 is rated at 1amphr or less and the lappy about 6.5 amphr. So over say 7 hours that would be 8.5amp draw per hour so I should get a night out of it without draining the battery too low. Then when I get home within a few days fully recharge the battery and this will prolong its service life.
Thanks

[Barrykgerdes]

Hi Peter

The LX200 will probably work OK directly from the 12volts without the inverter and AC supply. All the ones I have worked with do. This may save a few watts. Try it first. They do slew a little slower on 12volts but that is not usually a problem.

Barry

[RobF]

You really need to stick an ammeter or multimeter in the circuit to see what you're drawing Peter. I did experiments with my laptop in all sorts of states, imaging, slewing etc before buying an extra battery to get my by 2 nights at Leyburn. Camera draw depends a lot on how hard you're pushing cooling too of course. I don't routinely run dew heaters - they can be hungry for juice and pretty essential for an SCT.

[xstream]

Peter the using of a 600w inverter is a very inefficient way of powering it all it won't take too long to kill an 85Ah battery with a 600w inverter, it's overkill for what you're powering. I would of gone down the DC to DC route a far more efficient means.

BTW the Full River AGM is an intelligent buy, one of the best AGM's out there. Deep Cycle batteries aren't all equal. :thumbsup:

[hotspur]

Good luck with the search Peter-you might meet up with David Trappet-he use to come up here.

As mentioned going with the sine wave inverter will really chew you battery,a DC option would be good.

Yes,quite a useful thread,its one of the major topics on camping and outdoor forums,I am surprised we have not had a thread like this here,its a good one.

What's did the 'full river' battery cost Peter-looking at buying a 120 amp AGM soon,looking at different options.

cheers C

[marki]

Thats easily fixed Brenden, tell them to get stuffed :D. Bet they will be around in the morning wanting to get batteries recharged.


Mark

[PeterM]

Thanks John and Chris.
I guess my ignorance of DC had me concerned when I read somehwhere about potential problems for the laptop from having multiple DC connected to the battery. The DC is an option as I have cables and input for dc to the battery.
Chris have sent you pm re the Full River.
John wont the scope etc only draw what it needs from the inverter, I am ignorant on how it will flatten the battery quicker.
Peter

[bmitchell82]

Thats the issue. :P they aren't astrophotographers :D stay up till 1am max and then pike! :D anyhow i have a big battery now and another one should be on its way within a month. :)