Conflicting views on battery type for dual battery set up

[Antiquesman Junior Member Find all posts View Profile Close Antiquesman]

Today I purchased a Redarc BCDC1220 from someone on ebay and went to his warehouse to collect it.
I asked him what deep cycle battery he recommended and explained I would mainly use it to run a fridge and maybe some lights. His response was "deep cycle batteries are smoke and mirrors".
There was also another gentleman there and they both informed me that one does not need a deep cycle battery for a dual battery set up but suggested I would be better off purchasing a cheap $65 battery and replacing it ever year rather than buying an expensive deep cycle that would only last 2-3 years anyway.
As this is the first time I have heard someone recommend a standard battery as the auxilliary battery, I would like to get others opinions on this subject.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

Deep cycle batteries are not smoke and mirrors. They have different plate thicknesses and in the case of AGM are a different construction. I'm no battery expert but there are many different designs for different functions.

Whether they are worthwhile for the auxiliary is a different matter. In my case I wanted something that could handle deeper discharge and be used for very occasionally starting. I wouldn't go over the top of with the battery but you want something decent.

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[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Deep cycle batteries as written above are designed for cyclic use, as to whether there worth
the extra though depends on what you want to do.

ALso deepends on if your a cashed up grey head nomad prepared to swallow all the sales hype

Deep cycle batteries do have there place, they need to be looked after though for
maximum life.

Most discuusion you hear on these forums are about proper charging and how much
extra life you'll get out of a deep cylce in cyclic use. The issue that never gets raised is
that in most battery failures are caused by the physical abuse a battery receives rather
than the electrical abuse. So even if you really look after a AGM the pounding it will
receive in a car enviroment will shorten its life unless you only travel on smooth tarmac
all the time.

I'm happy using a century marine type battery myself, they have a cyclic capability and
and designed to withstand the pound from waves their subjected too in a boat.

I use mine in cyclic operation to run my fridge and cycle it from full to 20% SOC with no issues.

Battery is now 4 years old and will still run my freezer for 3 days without a problem and was a
hell of a lot cheaper than an AGM so I'm well ahead.

I also use this battery for winching.

Cheers
LeighW

[Antiquesman Junior Member Find all posts View Profile Close Antiquesman]

Deep cycle batteries as written above are designed for cyclic use, as to whether there worth
the extra though depends on what you want to do.

ALso deepends on if your a cashed up grey head nomad prepared to swallow all the sales hype

Deep cycle batteries do have there place, they need to be looked after though for
maximum life.

Most discuusion you hear on these forums are about proper charging and how much
extra life you'll get out of a deep cylce in cyclic use. The issue that never gets raised is
that in most battery failures are caused by the physical abuse a battery receives rather
than the electrical abuse. So even if you really look after a AGM the pounding it will
receive in a car enviroment will shorten its life unless you only travel on smooth tarmac
all the time.

I'm happy using a century marine type battery myself, they have a cyclic capability and
and designed to withstand the pound from waves their subjected too in a boat.

I use mine in cyclic operation to run my fridge and cycle it from full to 20% SOC with no issues.

Battery is now 4 years old and will still run my freezer for 3 days without a problem and was a
hell of a lot cheaper than an AGM so I'm well ahead.

I also usde this battery for winching.

Cheers
LeighW

Leigh are you able to tell me the model /size/amps that the century marine battery you are using is? Running a freezer for 3 days sounds like the ideal battery for me.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

It is a MarinePro 720, N70ZM.

Capacity 100AH

As above, this will run my waeco 40Ltr for approx three days.

Cheers
LeighW

[barryswanson Senior Member Find all posts View Profile Close barryswanson]

Have you considered a calcium battery such as the Delkor? They are a hybrid sealed type that withstand vibration really well and are suitable for deep cycle and cranking applications. Myself and many friends I know have them and haven't had any trouble with them yet using them for running fridges and winching.

[frederick Member Find all posts View Profile Close frederick]

Gidday Guys, i recently went through the same dilemma and after dozens of conflicting views regarding this battery is better than that battery etc i decided to go down to battery world and showed the guys my dual battery setup and told them i would be running my waeco fridge plus maybe charging a mobile or similar (no winching) from rear 12 volt plug that runs off auxillary battery when camping and they recommended the "all rounder" @ $224.00. As they said "we can sell you a more expensive battery but the all rounder is the most popular one they sell with the least come backs" So the moral of the story is maybe go to a battery place and seek some professional advice, at least then if you have a problem you can go back to them and get it fixed. Most larger battery stores are in every city or large town in Australia so no need to go back to where you purchased it just go to the nearest town so long as you have your receipt.
Merry christmas to all.

Wazza (frederick)

[eatlovelearn Junior Member Find all posts View Profile Close eatlovelearn]

solar power collection stations like the one at yuendamu in the NT only use agm deep cycle batteries to store their power , and that is a multi million dollar installation . they obviously know what they are doing .

[eatlovelearn Junior Member Find all posts View Profile Close eatlovelearn]

Have you considered a calcium battery such as the Delkor? They are a hybrid sealed type that withstand vibration really well and are suitable for deep cycle and cranking applications. Myself and many friends I know have them and haven't had any trouble with them yet using them for running fridges and winching.

the only problem i think with calcium batteries is that they need around 15 volts to fully charge though i may be wrong

[Pedro Advanced Member Find all posts View Profile Close Pedro]

I would suggest you use an AGM battery for your fridge.
I buy my gear from Fridge and Solar and here is a link to details of why you should use an AGM
http://www.fridge-and-solar.net/agm.htm

Any questions send him an email.
I am a satisfied customer and feel free to mention my name (Pedro )

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

I use an All Rounder. As others have said, pick a battery that can handle engine bay heat and vibration.

I have an insulation wrap on both my batteries to reduce radiant heat.

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[barajak Senior Member Find all posts View Profile Close barajak]

As well said on this post there are many battery types and the best one depends on your requirements. With a nominal 12v input battery charger like the BCDC1220 you can use a deep cycle as an auxilary battery as this unit sets the auxillary battery up as a separate curcuit. That said I would not because they take to long to charge up. If your requirment is to use most of your stored charge and then drive all day to the next location, it could be the ideal battery for you. For best battery life, you should avoid having two different batteries on the same circuit as the battery with the least resistance will take the most charge (and cook). By different I mean dissimilar batteries or identical batteries at a different state of discharge. I use the ABR isolator and a good GP battery. This works well for me as the ABR unit keeps both batteries together on the circuit down to 12.3 volts. This is enough power to run the Engel for 36 hours in normal conditions and still have the same voltage in both batteries. This type of isolator allows more current to flow to the aux battery than a charger unit so the aux battery will recover faster. So a BCDC1220 with a big deep cycle will be good to power up the fridge and camp for the long weekend fishing trip and take the rest of the week to get back to a state of full charge and a setup like mine is better when you are on an extended trip with say only a couple of hours drive time between camps.

[Nifty07 Junior Member Find all posts View Profile Close Nifty07]

I am an electrical engineer and have been dealing with remote communications sites for over 30 years. These sites have battery banks where the footprint is about the size of some cars. (eg 48 volt and 5,000amp/hr)

The issue of aux batteries is very confusing because of miss information but simple to resolve.

The so called 'heavy duty deep cycle' car batteries are generally designed with a CCA rating. This is the ability of the battery to supply high currents for a short time measured in seconds. A battery rated at the 'C20' rate means the battery will supply a twentieth of of the stated current for 20 hours. eg 100ah @ C20 means 5 amps for 20 hours (5*20=100). There is no correlation between (for example) a battery with a 850 amps CCA rating and a battery with a C20 rating of 100ah. Essentially batteries manufactured for high CCA ratings (high current for shot time) use plates with many holes and physically look like a fishing net whereas a marine battery (designed for low current for longer times) has solid lead plates.

When considering what type of aux battery is for your application you need to work out what you want. Do you want to supply 850 amps for 30 seconds or 5 amps for 20 hours. If you want the 850 amps then go for a 'heavy duty deep cycle' battery and if you want to run a fridge then go for a marine battery. Ohh dear, the car battery dealers will have fun with this one because many dont know the difference.

Essentially the difference is in the plate construction. The heavy duty deep cycle battery has plates with lots of holes which gives heaps of current for a short time and the marine battery has solid plates to give a lower current for a longer time.

I fitted a heavy duty deep cycle for the primary battery as it is for cranking the motor over (high currents for short time) and a marine battery for the aux battery (fridge draws a few amps for a long time). I then fitted an AGM battery in my camper because it has other properties such as charges quicker and holds a higher voltage. The issue with AGM batteries is that they dont like the heat so you should not put them under the bonnet.

If you do your research you can get technical papers with lots of ho-hub but when these papers talk of heavy duty batteries they are speaking of batteries specifically designed for that purpose. These batteries cost about $10,000(+) per bank and their performance cannot be compared to a car battery.

All my batteries are wired together in the Prado. I use 35mm cable between the primary and secondary batteries (via an isolator) and 16mm from the secondary battery to the trailer battery. I dont have any problems because the wire offers a small resistance and thus does not 'boil' the primary. Should one of the batteries fail this would trip the breaker (fuse) and if a battery goes open circuit it wont affect the others.

I find the primary battery charges first, then the secondary then the trailer. This is because of the internal resistance of the wire and is the reason I use different sized wiring.

On a technical perspective lead acid batteries display a higher plate resistance as they near full charge. This means it is harder to get the charge into them using a constant voltage charger as they approach full charge. The voltage regulator for most alternators is built into the alternator and so the battery should not be able to 'boil' unless there is a fault. I modified the Prado to give me 14.1 volts (factory was 13.6v) so that my batteries would get a full charge. Even at that the trailer battery will not ever get a full charge due to the losses in the cable.

I agree you should not use different types of batteries in a system but when you engineer the system (fancy way of saying using different sized cables and propr charging techniques) then you wont have any problems in your car.

Trust this explanation helps. The next issue will be with 'which is the best charger' but not tonight as I am sure there will be some reaction/questions to this post.

Nifty

[shaun2k Lurker Find all posts View Profile Close shaun2k]

Excellent post Nifty that cleared some things up for me - much appreciated.

[tassie tiger Advanced Member Find all posts View Profile Close tassie tiger]

We use a 100ah deep cycle with the camper trailer to run the Waeco. But when we bought the waeco they had a package deal and part of it was one of the Waeco RAPS 36ah battery pack;

http://www.waeco.com.au/products5.as...Id=78&catId=77

Its been great. The portability is fantastic and we tend to use it when on bbqs etc. Normally get around two full days on the waeco if you keep the kids away from opening it all the time.

Recently we hooked up a mates RAPS 36 to mine and got a full long weekend and was still going strong till home.

You dont need a seperate charging system for them and you can just plug it into 240v to charge. Has a digital readout for charge level etc. Wont suit all applications but for a fridge and some lights they are great, particularly the portability. Have seen them for as low as $230.00

Another hint is to use LED lights for low power use and the other thing I do is when the kids 12v toys break I snaffle the battery out of them. One of those little batteries can keep our four LONG led light strips going for a week or more.

Here is the Waeco blurb;

RAPS 36 Battery Pack
Price $335.00
Dimensions W230 x H245 x D227 mm
Weight 13.6 kg approx.
Capacity 36 amp hours
Voltage Heavy duty 12 volts
Performance Genuine deep-cycle AGM battery cells
Warranty 1 year warranty
Other
Cigarette and hella
output sockets.

Digital volts display.

Battery condition
LED's/test button.

Secure screw connection charging socket.

1.5 m charging lead.

Maximum charging
current: 14.4 amps