Dual Battery, choice of model for the auxiliary?

Greetings all,
My auxiliary battery is getting a little old and I need to replace it for our upcoming Kimberly trip.
I have a 75 series Troopy 4.2 D…I run a 12 V fridge and a 12v TV. And have a 600w inverter that we sometimes use for additional lighting laptop and charging small batteries etc..
The question is… do I buy a similar battery to the main one....Heavy duty good cranking power etc… or do I buy a deep cycle battery designed for long use etc???

Cheers!

Dust
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Reply By: Member - Rick P (NT) - Wednesday, Mar 04, 2009 at 23:36

Wednesday, Mar 04, 2009 at 23:36
What a lot of the battery places are saying is to get two of the same batteries and buy them at the same time. As far as the Deep Cycle goes they just take to long to recharge infact they can take days, and you haven't always got that time. We run the Centery Marine Pro 600 in our vehicles and all the tour mobs doing Kakadu are getting 3-4 years out of them. That is pretty good in this heat.
AnswerID: 352241

Follow Up By: Member - Mike DID - Thursday, Mar 05, 2009 at 09:30

Thursday, Mar 05, 2009 at 09:30
- "What a lot of the battery places are saying is to get two of the same batteries and buy them at the same time."

Gee, would that be because they want to make twice as much profit ???

When two batteries are wired in parallel, it's important to have identical batteries.

But when you use a battery ISOLATOR, you no longer have two batteries wired in parallel - the whole point is to NOT discharge the Starting battery while discharging the Aux battery.

One battery should be optimised for starting and the other should be optimised for deep cycle !

MAYBE it's a case of applying some useful information in the wrong situation ??? . . . . nah, I'll remain cynical, they're just trying to double their sales.
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Follow Up By: Maîneÿ [wa] - Thursday, Mar 05, 2009 at 10:25

Thursday, Mar 05, 2009 at 10:25
Yes,
I agree with Mike R

I would suggest to get AGM DEEP CYCLE batteries *designed* to run a fridge
NOT a battery that's specified as a Cranking battery !!

Sure some Cranking batteries may be capable of running a fridge periodically
But - AGM DC's will do it far better because they are specifically designed for the job and they will re-charge much faster too.

My last Deep Cycle batteries lasted six (6) years and were replaced only when my cranking battery died out bush and I had to replace it with one of the DC's, I later fitted the present AGM DC's, so I can speak from experience!

Mainey . . .
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Follow Up By: Member - Phil G (SA) - Thursday, Mar 05, 2009 at 16:32

Thursday, Mar 05, 2009 at 16:32
It gets pretty hot in teh limited space under the bonnet of a 75series in the Northern Territory. Thats why Rick's recommendation has credibility. AGMs don't last in that environment.
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Follow Up By: Maîneÿ [wa] - Thursday, Mar 05, 2009 at 17:38

Thursday, Mar 05, 2009 at 17:38
Rick has posted: "As far as the Deep Cycle goes they just take to long to recharge in fact they can take days, and you haven't always got that time"

The information above is what most of the replies here have been about, I had two wetcell DC'c and I know they did not take long to recharge!

Ummm, maybe the charging regime is at fault - not the battery !!

Mainey . . .
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Follow Up By: stephen looking - Thursday, Mar 05, 2009 at 19:45

Thursday, Mar 05, 2009 at 19:45
Agree with Phil, it does get hot under the bonnet, if you can put a AGM in the back of the Troopy(use bloody big wire), or go a wet cell DC, or hybrid under the bonnet.

If it was me i would go a hybrid type.

Regards........Stephen
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Reply By: Patrol22 - Wednesday, Mar 04, 2009 at 23:39

Wednesday, Mar 04, 2009 at 23:39
Dust - there are probably dozens of threads in the archieves on dual batteries but there is always something new or different that others are trying out. I've just recently installed a dual battery system in my D40 Navara and aside from the cranking battery that came with the vehicle, I've installed 2 x 105AH Supercharger All Rounder batteries with a redarc isolator to provide my aux power. Have I done the right thing? Hey it's anybodies guess but I did some math etc and figured this was the best arrangement to power up my winch if ever required and the other bits and pieces including my fridge. I will post a 'report' once I've had the opportunity to evaluate the set up over 6-8 months.
AnswerID: 352244

Reply By: RV Powerstream P/L - Thursday, Mar 05, 2009 at 09:19

Thursday, Mar 05, 2009 at 09:19
If you travel everyday like a tour vehicle then you can do what has been stated above in this thread.
If you intend to camp up for extended periods then it is worth looking at something different .
The old idea that deep cycle batteries take too long to charge is old hat as smart charging equipment although considered expensive by some can overcome that idea.
The bigger batteries as for winch use is also a good plan as long as you have the capacity to recharge them.
Your cranking battery recovers from starting the vehicle in about five minutes of running so then you have your drive time to recover your auxiliary and the smarter the charging and the higher the voltage the quicker you recover your charge.
The type of battery you use can also restrict your capacity to recharge and to recover quickly you need a high recombination battery to extract charge in the shortest time frame.
So High voltage,High recombination and smart charging can definately pay dividends.
Ian
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Reply By: Member - Ingo57 (NSW) - Thursday, Mar 05, 2009 at 10:01

Thursday, Mar 05, 2009 at 10:01
Gday Dust

I am no sparky and no great wiz with electrics but I have run an Aux AGM battery for the past 4 years and love it. The beauty of them is they will take as many amps as you can throw at them which gives them a quick recharge rate, they are sealed and you can easily bring them back to life on the car alternator very quickly if they are discharged.

When touring Im moving every day so the battery doesnt even get looked at but Easter long weekend is the longest I will stay in the one spot and is when it gets a real workout
Mine is a 95Ah or 105Ah (cant remember) but it will run my fridge
two versa lights and Inverter to charge camera battery only for 3 days.
On the 3rd evening I usually start and run the engine (Idle) 15 - 20 mins and that keeps everything going until we pack up after lunch on the 4th day.

For my needs I wont buy deep cycle again when/If this one eventually dies.

Cheers Ingo
AnswerID: 352281

Follow Up By: Maîneÿ [wa] - Thursday, Mar 05, 2009 at 17:08

Thursday, Mar 05, 2009 at 17:08
You suggest your AGM is NOT a Deep Cycle battery
"For my needs I wont buy deep cycle again when/If this one eventually dies"

So obviously it's rated as a Cranking battery, along with the relevant CCA numbers not with *AH* numbers ??

But you say "is a 95Ah or 105Ah (cant remember) "

Maybe it's just a 'compromise' battery - with both sets (AH & CCA) numbers ??

What brand/type is it ??

Mainey . .
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Follow Up By: Member - Ingo57 (NSW) - Thursday, Mar 05, 2009 at 21:47

Thursday, Mar 05, 2009 at 21:47
No Mainey Its not a cranking battery its AUX in the back of my Rig
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"95Ah or 105Ah cant remember" It was 4 years ago mate!.........but If its eatin you out Mainey,, Give Derek Bester from ABR sidewinder a call and ask what AGM's he was using in his battery packs 4 years ago and Im sure he can let you know. I use it as a dual battery.

And lastly for my comments "For my needs I wont buy deep cycle again when/If this one eventually dies"

Let me re-word it for you. I have used Deep cycle battery's in previous 4wd's and wont buy another deep cycle again after using AN AGM FOR THE PAST 4 YEARS when/If this one eventually dies.

Hope this makes more sense for you!!!

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Follow Up By: Maîneÿ [wa] - Friday, Mar 06, 2009 at 09:10

Friday, Mar 06, 2009 at 09:10
Ingo,
Nope, it's not "eatin me out" at all, as you said your no sparky and no great wiz with electrics, I've only asked you what "type" of battery you have?
I thought the question "" What brand/type is it "" was realistic

I believe it's a *DEEP CYCLE* battery you have in your battery box.

Mainey . . .
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Follow Up By: Member - Ingo57 (NSW) - Friday, Mar 06, 2009 at 09:35

Friday, Mar 06, 2009 at 09:35
Mainey

Thanks for clearing that up mate!!!!!

Nope, me not being a "battery nerd" its not realistic that Im going to remove the child seats to access then open up the box, unclamp the battery mounts and pull it out just to let you know what brand it is??
Wouldnt have a clue and dont care, but its an AGM

Now that Ive been politically corrected, I will reword again for you
The AGM "DEEPCYCLE" battery I now use Is far superior to my previous "DEEP CYCLE" which was not an AGM.

Hope this is acceptable for you and hope you sleep better tonight! Lol

Ingo
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Follow Up By: Maîneÿ [wa] - Friday, Mar 06, 2009 at 09:45

Friday, Mar 06, 2009 at 09:45
Ingo,
as I stated above, it's an AGM "Deep Cycle" battery.

you really can't get any better than that !!

Mainey . . .
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Follow Up By: Member - Ingo57 (NSW) - Friday, Mar 06, 2009 at 10:03

Friday, Mar 06, 2009 at 10:03
Mainey,

"you really can't get any better than that"

I know!! Thats why I thought I would post my experience to Dust!!
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Reply By: Sigmund - Thursday, Mar 05, 2009 at 10:43

Thursday, Mar 05, 2009 at 10:43
My CT has 2 x 97 amp lead/calcium batteries wired in parallel. From a 40% charge the car alternator will recharge them in about 90 minutes.
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Follow Up By: Member - Phil G (SA) - Thursday, Mar 05, 2009 at 16:34

Thursday, Mar 05, 2009 at 16:34
Sigmund,
How do you know they are charged?
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Follow Up By: Sigmund - Thursday, Mar 05, 2009 at 18:50

Thursday, Mar 05, 2009 at 18:50
The red light on the Redarc in the car goes off.
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Follow Up By: Member - Phil G (SA) - Thursday, Mar 05, 2009 at 19:06

Thursday, Mar 05, 2009 at 19:06
Gday Sigmund,
You're suggestion that you can get 120Ah back into the Camper Trailer in 90minutes from an alternator is not possible. I'm not sure what "Redarc" you are have, but measuring voltage somewhere in the car won't tell you what's happening at the battery terminals in the campertrailer.

If you were reading 14.7volts at the CT battery terminals, with less than 1 amp going into each battery, I'd say they were pretty much charged.
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Follow Up By: Maîneÿ [wa] - Thursday, Mar 05, 2009 at 19:27

Thursday, Mar 05, 2009 at 19:27
The (State of Charge) 40% charged is equivalent to only ~11.9v, so I would think it's probable to fully charge them in 90 mins from an Alternator, however, he would be probably testing the 'surface charge' only anyway.

If the reading was 14.7 volts at the CT battery terminals, with < 1 amp going into each battery, I would suggest they were 'still' being charged as no amps would be going into any battery if not being charged!

Mainey . . .
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Follow Up By: Member - Phil G (SA) - Thursday, Mar 05, 2009 at 20:04

Thursday, Mar 05, 2009 at 20:04
Mainey,

With all due respect, please check your facts before you post.

At 14.7V, there will always be charge going into a lead acid battery. When its mostly charged (>90%) it will start gassing, and giving off heat. Most smart chargers come off the absorption stage when current has dropped below 1% of capacity (C/100) which is about 1amp for a 100Ah battery. During float (usually 13.8V) , current is usually less than C/100 .

I measure charging with an in-line digital ammeter that measures to 2 decimal points. i don't make it up. If you want to read more about it, I suggest you have another read of Bill Darden's FAQ:
http://jgdarden.com/batteryfaq/carfaq9.htm#stages

95% of alternators never provides more than a float charge voltage. An alternator will never fully charge lead/calcium batteries in a campertrailer.

Cheers
Phil
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Follow Up By: Maîneÿ [wa] - Thursday, Mar 05, 2009 at 22:45

Thursday, Mar 05, 2009 at 22:45
Phil,
I've read and reread the posts concerned, I can't see where you say anything different to what I've posted?

Other than your added thought, "an alternator will never fully charge lead/calcium batteries in a campertrailer"

My two Calcium DC's lasted 6 years with very heavy use, maybe my little 55 amp alternator COULD maintain them fully charged after all.

Mainey . . .
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Reply By: oldtrack123 - Thursday, Mar 05, 2009 at 15:35

Thursday, Mar 05, 2009 at 15:35
Hi Dust
IF you intend to travel every day ,a cranker could be ok.
If you are going to be camped for a few days depending on how many amphrs of battery power you use,you could quickly stuff a standard wet cell cranker. You need to calculate your expected daily use to determine size of battery req.
The watts shown on each devise x hrs expected to be used daily, all added up will give you total watthrs for the day, divide by 12 will give you your amphrs daily use.
A deep cycle battery is specially designed to meet this service & give long life .
Wet cell lead acid d/c are cheaper than agms & no problem parallelling with your existing wet cell lead acid.
You should have a dual battery system or some other form of isolating them from each other when engine is not running.
Agms really require a slightly differant charging regime to standard wet cells both crank & deep cycle to get max performance from them.
NOTE :- wet cells should only be discharged to about 50% of their capacity for long life, agms can be more heavily discharged.
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Reply By: Sand Man (SA) - Thursday, Mar 05, 2009 at 21:21

Thursday, Mar 05, 2009 at 21:21
Cranking batteries are not designed for prolonged current draw, such as running a fridge.

That is what a deep cycle battery is designed for.
There are different types of deep cycle batteries.
The cheapest is a "wet cell" deep cycle and may have caps where you need to check the electrolyte and top up with distilled water from time to time.
Then there is a sealed "wet cell" deep cycle battery, classed as "maintainance free"

The best form of deep cycle battery is an AGM style, giving faster and more complete charging, does not produce dangerous gasses during charging and therefore does not need venting. They can be tipped over without spilling and are the only type that should be considered, if installing in the back of a vehicle.
They are also more expensive, heavier and take a larger "footprint" for a given Amp Hour rating.

I do not support the theory that they should not be installed in an engine bay. They will come to no harm if common "heat barrier" practice is followed. This may be nothing more that adequate space from an exhaust manifold or turbo charger.

A deep cycle battery is what you need, the type determined by how much you are prepared to spend.

Bill


Bill


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Reply By: Dust - Friday, Mar 06, 2009 at 21:13

Friday, Mar 06, 2009 at 21:13
Thanks for all you suggestions,it is very much appreciated!

Dust
AnswerID: 352642

Follow Up By: Member - Rick P (NT) - Saturday, Mar 07, 2009 at 05:56

Saturday, Mar 07, 2009 at 05:56
See what you started here Dust, now that's it's all over I should explain a bit more on my ideas. Firstly I picked the Century Marine Pro 600 because the battery plates are fixed top and bottom, great for those corrugated roads we sometimes go on and that is what Battery world recommended. Although they are nort a deep cycle they don't mind being treated as one. The reason I stated that we don't like Deep Cycle is in the past we have also found them hard to recharge and they can take a long time, but that could all have changed with smart charge technology but I was always under the impression they will only take a small charge anyway, you would have to look into that. Also there is big diffrence between going bush up here as to doing the High Country in Victoria. There have been times when we have gone bush and my Waeco would hardly swich off. Mainly because it was 36-38c and 85% humidity. Than your best bet is to have a EU10 on hand because no battery is going to last any time in that situation. Just on the same batteries and getting them at the same time I was always led to beleive if one battery was not up to speed it would effect the other one. Good luck but I still think talking to somone like Battery World will always give you the best advice because they deal in it every day.
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Follow Up By: Maîneÿ [wa] - Saturday, Mar 07, 2009 at 10:33

Saturday, Mar 07, 2009 at 10:33
Rick
using your own "idea" it makes sense to use a 620 CCA Exide Extreme, they (as do many batteries) have their plates 'locked' at top and bottom too. They have an excellent 2 year warranty, but this drops to only 6 months when used as a 'cycling' battery, reason being they as also your 600 CCA Marine cranking battery are not designed for the heavy use associated with running a fridge, the plates are different as is the chemical compound.

As you say you have posted "your ideas" however I would suggest there would not be one *qualified* person or company that will recommend in writing, using a Cranking battery over a Deep Cycle battery to power a high drain product like a fridge on a long term basis as when on a holiday.
Yes, for sure on the weekend away, where the vehicle is constantly used it will work, because the battery will be constantly charged, cranking batteries won't take being discharged as low as DC's will,
when the owner takes his vehicle away for a few weeks holiday and does not drive it for most of the time, he will be facing ruining a good cranking battery simply because of sulphation of the plates due to the constant low discharge by the fridge.

Yes a battery cut-out device will disconnect the fridge from the battery when it gets to this position so the battery is not constantly damaged, but the food is spoiled because the battery is disconnected from the fridge.

I've previously searched and can't find any battery retailer/manufacturer website that recommends Cranking batteries over DC's for running high drain products like a fridge on long term basis!
If I've missed one somewhere, I expect it will show up here and I will stand corrected.

Mainey . . .
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Follow Up By: Member - Rick P (NT) - Saturday, Mar 07, 2009 at 10:51

Saturday, Mar 07, 2009 at 10:51
I'm all ears and always prepared to learn a bit more. In my case I run my fridge 24/7 as I use my truck for work as well. So when I come home I charge the battery with my Ctec 2500 and let it figure things out for for itself. Haven't had any problems since I started using it. Also when we go bush and sit around for a few days we do the same thing mainly as I said before it's too bloody hot to do anything else.
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