Thread: start v deep cycle battery running engle - test

From: http://auto.howstuffworks.com/question219.htm

People who have recreational vehicles (RVs) and boats are familiar with deep cycle batteries. These batteries are also common in golf carts and large solar power systems (the sun produces power during the day and the batteries store some of the power for use at night). If you have read the article How Emergency Power Systems Work, then you also know that an alternative to gasoline-powered generators is an inverter powered by one or more deep cycle batteries.

Both car batteries and deep cycle batteries are lead-acid batteries that use exactly the same chemistry for their operation (see How Batteries Work for more information). The difference is in the way that the batteries optimize their design:

* A car's battery is designed to provide a very large amount of current for a short period of time. This surge of current is needed to turn the engine over during starting. Once the engine starts, the alternator provides all the power that the car needs, so a car battery may go through its entire life without ever being drained more than 20 percent of its total capacity. Used in this way, a car battery can last a number of years. To achieve a large amount of current, a car battery uses thin plates in order to increase its surface area.

* A deep cycle battery is designed to provide a steady amount of current over a long period of time. A deep cycle battery can provide a surge when needed, but nothing like the surge a car battery can. A deep cycle battery is also designed to be deeply discharged over and over again (something that would ruin a car battery very quickly). To accomplish this, a deep cycle battery uses thicker plates.

A car battery typically has two ratings:

* CCA (Cold Cranking Amps) - The number of amps that the battery can produce at 32 degrees F (0 degrees C) for 30 seconds
* RC (Reserve Capacity) - The number of minutes that the battery can deliver 25 amps while keeping its voltage above 10.5 volts

Typically, a deep cycle battery will have two or three times the RC of a car battery, but will deliver one-half or three-quarters the CCAs. In addition, a deep cycle battery can withstand several hundred total discharge/recharge cycles, while a car battery is not designed to be totally discharged.

You could always get yourself some Exide Orbitals. Built for Deep Cycling, but providing 750CCA, can accept recharging at a much higher rate than ordinary lead acid batteries, can be mounted at almost any angle, doesn't need ventilation...only $225 ea from your local Marshall batteries place. :wink:

Paul

Hi weeds, Zook pretty well covered the actual use and Omaroo covered the theoretical side of it.

As you have cranking batteries available at no cost, use them but I would like to clear up a few thing.

The use of the term deep cycle can be misleading. Originally and unless specifically naming the type of deep cycle battery IE, an AGM, when the term is used by itself, a deep cycle battery is a wet cell battery that has plugs on top of it to allow the battery’s water to be topped up and this is the type of battery you are talking about and the type I will be referring to.

Next deep cycle batteries should not be take down bellow 10.5 volts at any time and even taking them to 10.5 volts, the soon you can start recharging them the better, even if it’s slowly with your solar panel.

Deep cycle batteries can happily be used to start a vehicle but only now and then. If you use a deep cycle battery as your starting battery, you will be replacing it in a very short time.

You can use a cranking battery as you second battery but the continuos deep discharging may shorten it’s life and you don’t get the same stored capacity as a deep cycle of roughly the same size because the deep cycle can go to lower voltages on a regular basis and still have a long operating life.

Now this one you should consider when it comes time to replace the back up batteries. Deep cycle batteries tend to last longer that cranking batteries do, when left unused for long periods.

Last but not least, you say your plans are to be driving around during the day and then connect the back up batteries to the vehicle battery.

I’m not quite sure what you mean, but if you have an auxiliary battery in your 4x4, heres and idea that will allow you to charge your camp batteries quicker and to a higher state than your vehicle battery.

When you come back to your camp site at the day, if you have an inverter and a battery charger, you can hook the inverter up to the auxiliary battery in the vehicle and run an extension cord over to the camp batteries, to power the battery charger and charge the camp batteries over night.

One more point, I would be very surprised if you could get 4 amps for anywhere near 6 hours from your solar panel. No matter what size the panel is, as it gets hot during the day, the current output drops to at best, only about 2/3 of it max.

Cheers

Very interesting thread.

What is the impact (on the life expectancy of both deep and cranking batteries) of having no discharge.

I was always under the impression that when not using your deep cycle (ie with fridges, etc), you should try and have at least something draining it to preserve its life expectancy. Is this not correct? :?

Thanks

I run 2 starter batteries in my Stage 1, and have done for 18 yrs. I used to use a 3 way but last year bought an Engel. Have done 3 tests, admittedly not in Summer ( too bloody hot for camping), and have managed over 70 hours on 1 battery each time and still been able to start vehicle. I have fridge cycling between 1 and 4 degrees. This is not a scientific test but vehicle parked alongside camper with fridge in the car. The 2 batteries are Supercharge 700 CCA. Different batteries and conditions will of course give varying results, but this is my experience. Will be testing this to the max in July/August on an extended desert trip.
One day I will advance to a solar backup as well.
Perry

Originally posted by Noddy
What is the impact (on the life expectancy of both deep and cranking batteries) of having no discharge.

Hi Nobby, this is one of those things that is a little hard to verify but according to those who work with batteries in a research capacity, all seem to say the sulphration starts to degenerate wet cell battery’s capacity to be fully recharged the longer it is left in a no-charge, no-discharge state.

Applying some form of load periodically is supposed to reduce or even stop sulphation occurring.

As to what size load for how long and how often, I do not know.

Cheers and not much help there.

firstly an update

test abandaned at 4pm today - we have had full cloud cover all day and when i checked the batteries i only had 11.8V, bloody clouds. although the fridge was still running i hooked him back up to 240V. the temp in the van a 4pm today was 30 degrees so i guessing the engle would have been cycling on more than off throughout the day

outcome - i got 36hrs out of two start batteries with solar panel fitted, must check my solar panel is producing an output on a sunny day

Originally posted by drivesafe

1. Last but not least, you say your plans are to be driving around during the day and then connect the back up batteries to the vehicle battery.

I’m not quite sure what you mean,

2. One more point, I would be very surprised if you could get 4 amps for anywhere near 6 hours from your solar panel. No matter what size the panel is, as it gets hot during the day, the current output drops to at best, only about 2/3 of it max.

Cheers

ok i will try to clear some things up

in the defender i have 1 x start battery and 2 x deep cycle. this will always be my setup as i am happy with it. in the van short term i have 2 x start batteries

re: 1.
my plan was that when ever i was back at the campsite i would connect the fender and van together i.e via an anderson plug so that the two fridges (one in the van and one in the fender) draw from the four batteries ( two x deep cycle in the fender and two x start in the van). when i'm away from the campsite the alternator will look after the fender batteries and the solar panel will look after the batteries in the van.

re: 2.
i have been playing with my setup on the fender for eight months or so which the solar panel fitted. i would think its quite reasonable that i get 4amps/hr for 4-6 hours a day. most of the time the solar panel is in float mode as there is no load on the batteries. i have an amp gauge fitted between the regulator and the batteries. when the batteries have a load on them and the fender is parked to the north and its a clear sunny day my panel is always reading around the 4amp mark thoughout most of the day. i plan to record some readings from the amp gauge over the next couple of weeks

Originally posted by Captain_Rightfoot+--><div class='quotetop'>QUOTE(Captain_Rightfoot)</div><div class='quotemain'><!--QuoteBegin-cewilson
I have run a Waeco 80 litre off of a starting battery, but honestly not with much success. It worked great during the day whilst driving, and kept up quite easily. But when I stopped at night, it would drain the battery quite easily. (the battery is 830CCA).

After around 5 days on the road, I was waking up to a flat battery every morning - which gets really bloody annoying!

Personally, I would always recommend a deep cycle for running of accessories such as a fridge, whilst I recommend the opposite for winches!

Cheers
Chris

I have run our 40l Engel off our defender battery quite a few times without problems. I'm not sure if it is a deep cycle or not (it is what came with the car) but it has never looked like going flat. Something is fish here [/b][/quote]


I can run a 40litre Engel easy too with no problems. Try an 80litre and see what happens :wink:

Nah seriously, the draw from this unit is quite impressive compared to my old Engel 40 litre. If I didn't need the extra room, I'd definetely go back to a smaller fridge.

But the missus gave me the ultimation of having warm alcohol, or buying a bigger fridge. Sorry guys, but warm rum and beer really sucks!