Alternative to Dual Battery system - Concept

[ivand]

Hi All,

I have an idea that I wanted to share with the community about an alternative to a dual battery system. The purpose of this setup is to:

• Provide power to front Auxiliary sockets while ignition off - charge mobile/gps etc.
• Allow fridge to run off the back auxiliary port while ignition off - accept that I would need to charge the battery within 24 hour period - will need to calculate this once system is functioning.
• Allow LED lights to be controlled via remote controlled relay while car is powered off
• prevent the battery from discharging so as to not damage battery/still able to start car.
• The installation of kit to be reversible and removable.

I understand that a second battery is the ideal situation, however I did not want to run a battery in the boot/under seat and have not found any other suitable alternative location.
In time, I imagine i would get a larger main battery that has more AmpHour rating to better support this setup.


Ref1: Isolator looking at using is Low Voltage Battery Isolator - Jaycar Electronics
Ref2: Fusebox possibility - Automotive Fuse Box - 6 Blades - Jaycar Electronics however its limited to 15A per circuit.
10 Way Blade Fuse Block with LED Indicators - Jaycar Electronics can support 30A but its somewhat larger to mounts under engine bay.
Ref3:Want to add simple form of dimming as LED's can be too bright sometimes. Preferably a simple potentiometer however it depends on the type of LED strip and i need to test this.
Ref4:LED strips were purchased from BuyInCoins.com - Shopping with Unbeatable Price, Just Buy in Coins and appear to work well. They do dim with lower voltage so should be easy.
Ref5: Need to find a 4 channel wireless relay controller, that preferably can support more than 5Amp per relay. Alternatives to this welcome. 4-Channel Remote Control Relay with 2 Key Fobs - Jaycar Electronics

Comments/feedback/questions welcome.

Kind Regards,
Ivan

[DBO]

Nothing wrong with the idea. I initially had similar thoughts but have to admit that after looking at potential power usage (i.e. length of time I could run fridge etc), the 2nd battery was the way to go. If you're going for something like this, perhaps think about installing a bigger battery (e.g. Optima Yellow top) because the stock battery isn't all that great.

[dkguffe]

Hi Ivan.

Are you aware that most fridges already have built in under voltage turn off? All the major brands cut out at 11V already.

For LED dimming, I would suggest to build a PWM. It can be done very simple, and all from stock components from Jaycar or Altronics. I can help you with a schematic if you want. Then you can have the pot to turn the lights up and down.

[chief]

I would prefer something like the "ark pak" ...

Greetings from Germany

[ivand]

Hey dkguffe,

Thanks for the reply. Aware the fridge has cutout but its mainly for things like led lights, auxiliary charger that I want to cut out - purely for the piece of mind. I will look at an updated battery once this one gets a bit older.
Regarding the PWM, I have had a bit of a read on them but have not quite found a simple enough diagram that was proven to work. Help would be appreciated here if you don't mind.

Thanks all for your comments.

Cheers, ivan

[whereswes]

Think we're all trying to help.

Another option might be to go for a cheap low voltage cutout kit like 12V Low Voltage Cutout Kits for Cars and Boats (K4328) | Techtronics Australia.

You can buy these already assembled (think Arrid might have one) but would expect to pay considerably more.

With either option, will need to re-route your accessories outlets via the low voltage cutout controller.

A really good source for advice with 12v controllers is The 12 Volt Shop. Found them over the years to be very helpful and not pushing any particular brands, just the best component for the job.

Cheers
Wes

[ivand]

Well I have finally completed my setup (stage one, without the wireless remote) and am very satisfied with the setup.
I am still using the OEM battery supplied by Suzuki and my fridge works for approximately 18 hours before running low and cutting out. The fridge used is a Waeco CF25 (WAECO mobile solutions) and is generally opened about 8-10 times a day.

Ideally it does not run long enough and to solve this I will replace the battery.
The battery I found to suit the demands is this one.
Century Batteries Australia
It has 720 cold cranking amps and 100 amp hours which is unique in a battery (that I can tell)

Next steps:

• Upgrade battery
• Install flashing LED indicating isolator cutout
• Wireless remote controller
• Two additional remote lights with 5-10 meters of extension lead

Cheers
Ivan

[fordem]

Just so that you are aware of it, and especially because I didn't see it mentioned before - battery construction is different based on the intended use.

A battery designed for engine starting will have a reduced service life if subjected to repeated deep discharges such as those that occur when used to power a fridge and a battery designed for deep cycle service will have a reduced service lift when subjected to the high amperage current draw required to crank an engine.

Either way, you can expect reduced battery life if you opt for a single battery.

[ivand]

Originally Posted by fordem

Just so that you are aware of it, and especially because I didn't see it mentioned before - battery construction is different based on the intended use.

A battery designed for engine starting will have a reduced service life if subjected to repeated deep discharges such as those that occur when used to power a fridge and a battery designed for deep cycle service will have a reduced service lift when subjected to the high amperage current draw required to crank an engine.

Either way, you can expect reduced battery life if you opt for a single battery.

Hi Fordem,
Thanks for the reply. I agree that a battery is usually designed for one or the other, however this battery claims (and has had some good reviews on it) that it is capable of achieving both within reason. Based on the documentation they have given and my small understanding of batteries it seems as though it may just be what im after (a compromise to keep only 1 battery but still use it for what i want).

Having a read of the following document (http://www.centurybatteries.com.au/i...arine-category) is the following paragraphs:

Car batteries vs Marine batteries
Car batteries
To understand why you should use a marine battery for boating
applications, we can compare a marine battery with a standard
car battery.
Cars require batteries that provide a high burst of power
for a short time, just long enough to start the car’s engine. Only a
small portion of the battery’s power is used, and this
is restored over time by the car’s alternator.
Standard car batteries have thinner lead plates and porous
active material (lead oxide based paste coated onto the battery
grids) to maximise the surface area of the plate exposed to the
acid.
Maximizing the surface area provides higher current delivery
and as a result, greater starting power. However, because car
batteries have thinner plates they are not reliable in providing
longer periods of power while the engine is turned off and the
alternator is not charging.
Marine batteries
The main requirement of a marine battery on a boat is
to start the boat’s engine. However, unlike car batteries, marine
batteries are also commonly required to deliver constant power
draw when the engine is switched off.
Generally when a car engine is turned off, the vehicle’s electrical
accessories are no longer in use, or are used
for a very short time only. On a boat, when the engine is turned
off there is usually a number of on-board accessories operating
at once, for extended periods of time.
Standard car batteries have as many thin and porous plates as
possible to maximise surface area and provide a high cranking
current. A deep cycle battery is built with thick plates and a
denser active material designed to withstand deep discharges
but at a lower current flow rate. Standard car batteries with thin
plates will be damaged by deep cycle use and are not reliable
in applications requiring sustained discharge, such as on-board
accessories.

Also looking at their brochure here (http://www.centurybatteries.com.au/i...arine-brochure) I see that the Marine Pro 720 is recommended for deep cycle applications as well as starting.

Looking at this page here (Battery Charging), it appears that their batteries are 100% discharged at 11.9v, which would be their safe rating and what my isolator kicks out at. I have had my isolator kick in about 10 times now and the battery has started the car without hesitation.

I suspect the battery will give me the best possible outcome when running a single battery system as designed in the diagram in first post, with understanding that it is a compromise compared to a dedicated deep cycle battery for auxiliary systems.

Happy to hear of any alternative batteries that i may be able to use.

Cheers,
Ivan