PDA

View Full Version : Simplest Dual Battery Setup



yannpiat
23rd May 2013, 10:18 AM
I have looked at previous posts, and am now completely confused on what to do. I have 96 discovery, soon to carry a winch and already has a fridge. I am wondering what is the simplest and most beneficial dual battery system? What wiring kits are needed, and battery type/brand is recommended? Will the fridge be on the same battery as the winch, How do I connect it, does it run to the alternator also? will my alternator need to be upgraded?

Very new to the dual battery world, and help would be appreciated.

Thanks

roverrescue
23rd May 2013, 10:26 AM
1/ Install second battery.
2/ -ve terminal to a good chassis earthpoint.
3/ +ve terminal to Primary battery +ve with heavy cable.

Use a multimeter to monitor battery vs fridge run time.

voila

simple and probably best for winching too...

S

austastar
23rd May 2013, 10:31 AM
Hi,
Get a deep cycle battery for your winch/fridge/camping needs so you won't ever accidently discharge your starting battery.
The deep cycle battery can be directly connected to your starting battery through a device like

https://www.aulro.com/afvb/images/imported/2013/05/334.jpg

Traxide (http://www.traxide.com.au/trax1sc80_2.html) sell these, and are a good crew to deal with.
I bought a kit from them to put in my second battery and found them very helpful indeed when I ran into a problem of my own making.

usual disclaimers here - just a happy customer

cheers

numpty
23rd May 2013, 11:19 AM
Install second battery, same as starter and connect both through a 3 way marine switch. Cheap and effective.

Works for me. ;)

Ivan
23rd May 2013, 12:12 PM
I fitted a dual battery to my old D1. I used a heavy duty solenoid to connect the positive leads and a chasis earth. The solenoid was activated by the alternator charge light. This meant the solenoid would not engage until the engine was running. If your main battery goes flat just run a lead from the second battery to the solenoid terminal to connect the two together.

HTH

Ivan

tangus89
23rd May 2013, 01:43 PM
I fitted a dual battery to my old D1. I used a heavy duty solenoid to connect the positive leads and a chasis earth. The solenoid was activated by the alternator charge light. This meant the solenoid would not engage until the engine was running. If your main battery goes flat just run a lead from the second battery to the solenoid terminal to connect the two together.

HTH

Ivan


I have a similar thing on my classic, except I have a relay that connects the two positives together when the ignition is on. Run my fridge and other auxiliaries off the second battery (which runs them all the time) and all the normal stuff (cd player lights etc.) runs off the original battery. it cost about 50 bucks for wiring, relay, connectors and cig plugs, plus a secondary battery.

Judo
23rd May 2013, 01:59 PM
Keep in mind:

fridge = deep cycle battery (low current / long time)
winch = cranking battery (high current / short time)

A marine type battery can do both. If your second battery will be powering both winch and fridge, I would recommend a marine type battery.

lokka
23rd May 2013, 11:15 PM
I run a SLA 100AH battery in the back alongside the fridge it has a set of cables connected to the main via a 60Amp relay which is locked on once the ignition is on it only runs the fridge and i have an extra socket for other bits if needed in the back its a non perm set up and when im not using the fridge the battery and fridge are removed and the cable that conects the battery tucked away and the fuse down at the relay end is removed so line to back is neutral when not in use .
I am yet to fit a second batt up front but it will happen soon enough and i will probably just use a similar set up to what i have now tho go for a 200Amp relay to join the 2 batts up front

Vern
24th May 2013, 06:08 AM
Just buy the TRAXIDE US 160(?), great kit, will run your winch, Australian made, and great to deal with. Plus Tim is a member on here.

Bushie
24th May 2013, 07:40 AM
Pair of batteries (don't necessarily need to be the same) connected with a marine isolator.
The reason I say don't need to be same is that in my situation I don't think I have ever run them in parallel.
Have had this system installed for the last 30 years without a failure.

https://www.aulro.com/afvb/images/imported/2013/05/314.jpg



Martyn

Sitec
24th May 2013, 06:32 PM
Here's what I'm using. It's a Redarc Smartstart dual battery relay. You turn the ignition on, start your engine and 15 sec +/- this little box clicks and links your start battery to your second battery. The supply lead to the second battery has a large inline auto reset fuse at each end in case of any shorts. It was under $150 too. I'd be running your winch on your start battery, but having a matching brand and size of battery as your leisure battery as its basically running as though it was side by side. (We've had issues with trucks and tractors when different batteries are paired.. Don't ask me why tho!!) They will run a fridge fine, and then they are both there on demand for the winching..... Just my thoughts. Keep it simple what ever you do. Running a matching pair of batteries instantly gives you a spare starting battery when out bush!

Keithy P38
25th May 2013, 07:50 PM
I'm running a Traxide SC80 and two "Supercharge 'all-rounder' batteries". They are dual purpose (105ah and 760cca) so will happily start your car as much as they would run a fridge.

I have circuit breakers at either end and an Anderson plug at the aux battery which I disconnect from the main once at camp and plug solar directly into.

All up my kit cost about $200 from memory. Without the solar panels I get nearly 3 days out of my aux battery running an 80L ARB fridge and camp lights before I need to recharge.

My setup is switchable so I can also isolate the two batteries that way.

Cheers
Keithy

shane_vor
28th May 2013, 03:28 PM
Plus 1 for the simple relay for me as well. I was a bit adverse to the flash ones with circuits for delaying the connection of the two batteries and other things. I've never had one but was concerned about the robustness of the circuits in the bush. So I opted for a heavy duty relay which is switched to on when the ignition is on. Both batteries have heavy duty circuit breakers (easy to reset). Both batteries are the same size 70a/h if I recall. When going away I throw a 100a/h into the shelves in the back and the whole set up is maintained by a solar panel on the roof. Simple is best I reckon.

BDB
28th May 2013, 07:28 PM
look at the Ark Pack alternative to hard wired 2nd batteries .

There are threads in the D3/4/RRS forums

Tombie
28th May 2013, 07:45 PM
Robustness in the bush?! :lol:

On an Aux battery system?

Don't even consider the diodes, relays, rectifier pack, wiring connectors, fuses, fusible links, suspended lead plates, oil pressure switch, or other myriads of items that are just as vulnerable to failure which can render the vehicle Dead..

Or simple relays which can fuse in the latched position, draining both batteries...

Good to see Luddites are alive and well in the modern world :D :)

Keithy P38
28th May 2013, 08:20 PM
It's funny you mention Ark Packs BDB, I am using an Ark Pack (the older one, not the new expensive one) as my battery box as my aux battery lives in the back of my P38.

I like it because regardless of what your vehicle does during the week, you always have a fully charged battery ready to go via the 240v charging option.

I've simply added the Anderson plug setup for my dual batt system to the power pack. So I can bypass the 240v smart charger and use my alternator to do the rest until I'm at camp.

That's when solar power takes over (except for one or two day trips).

Simple, but effective. And I can remove it from the vehicle for day to day use.

Cheers
Keithy

calaissix
28th May 2013, 08:57 PM
Has anyone considered the new narva voltage sensitive relay,will assure the start battery is up the voltage before charging the second,i agree with running the winch of the start battery as it can supply high amps and a deep cycle as a second for fridge,worse case you run start battery flat and jump of second battery

calaissix
28th May 2013, 08:59 PM
good to see a couple of Hunter Valley Landrover members on here,good work

TheTree
29th May 2013, 07:56 AM
Hi

The issue with simply connecting a second battery is that depending upon where the second battery is located, the voltage drop my be too great for the second battery to be charged. This is when you need a DC battery charger.

The setup needs to be different depending upon whether you want a second battery which can start the car, or simply as an auxiliary battery.

As far as electronic components failing, most of our vehicles are full of electronics, so that doesn't concern me in the slightest, provided they are properly specified and installed.

Steve

shane_vor
4th June 2013, 12:34 PM
Robustness in the bush?! :lol:

On an Aux battery system?

Don't even consider the diodes, relays, rectifier pack, wiring connectors, fuses, fusible links, suspended lead plates, oil pressure switch, or other myriads of items that are just as vulnerable to failure which can render the vehicle Dead..

Or simple relays which can fuse in the latched position, draining both batteries...

Good to see Luddites are alive and well in the modern world :D :)
Thanks very much.

Learner
5th June 2013, 04:07 AM
It's good that someone is addressing your nonsense.

numpty
5th June 2013, 12:32 PM
Hi

The issue with simply connecting a second battery is that depending upon where the second battery is located, the voltage drop my be too great for the second battery to be charged. This is when you need a DC battery charger.

The setup needs to be different depending upon whether you want a second battery which can start the car, or simply as an auxiliary battery.

As far as electronic components failing, most of our vehicles are full of electronics, so that doesn't concern me in the slightest, provided they are properly specified and installed.

Steve

It doesn't need to be different at all. The system that Bushie and I have used for so long works as both auxilliary and starter. Switch between battery 1 or 2 as and when required. ie either battery does the same thing.

My last 2 batteries lived for 5 + years.

TheTree
5th June 2013, 02:12 PM
Hi Numpty,

I should have said "Might need to be different"

E.G: If you want to start from the aux battery, the setup is simple. If you want an aux battery isolated from the main battery and it is not used to start, then you might need a slightly more complicated setup depending on the location of the aux battery etc

I am going to use an AGM deep cycle battery installed in my spare tyre area, so I need to add a couple of gizmos to make it all work the way I want it too.

The simplest setup for sure is a second battery of a matching type mounted under the bonnet with a manual isolation switch:cool:

Regards
Steve

POD
7th June 2013, 12:06 PM
And you thought you were confused before!!

It's clear that there heaps of different opinions on this. Have a look at Traxide's site, (Drivesafe on this forum), he sells a dual battery isolator which is very simple to install and use and works effectively.
Want one more opinion? here's mine: The whole idea of a dual-battery installation is to protect the starting battery form going flat when running a fridge and lighting etc whilst camping, to avoid being stranded. The size of the second battery will determine how long you can run your fridge, e.g. camping 2-3 days, and the quality of the dual-battery controller will determine how well protected your main battery is and how well both batteries get charged when the engine is running. Ideally a contoller should favour the starting battery, so that it gets charged first when you start the engine, then switch over to recharge the aux battery when the main reaches full charge. A problem with simple solenoid systems is, according to some sources, that the battery with the fullest charge will cause the alternator to 'think' that charging is complete, so the flatter battery will not get charged (this idea may or may not be true, just repeating what some sources say). Another problem is that 'deep-cycle' batteries can take several hours driving to get properly charged after running your fridge overnight, so on a typical touring trip it may never get properly charged.
I think the best way to go is a simple, well-sorted controller like the Traxide SC-80, plus a folding solar panel that can be clipped to the aux battery during camping stays to maintain charge.
Winches should be run from the main battery so that you are not drawing big currents through a dual-battery controller.

d5disco
6th October 2013, 08:21 PM
I support and re-inforce POD's comment . . . . . "so the flatter battery will not get charged " . . . I won't go into the technical details of why but it is technical fact that if 2 batteries are connected directly pos to pos and neg to neg (typically via a simple solenoid) the lesser charged battery will get less charging current than the charged battery. FYI - a 12v to 12v charger will fully charge the secondary battery using the primary battery as a source. I (and others) use a "Twin Charge" to perform this function - happily. I'm sure there must be other brands, but I know this one works.:)

drivesafe
6th October 2013, 09:21 PM
Hi folks and before I start, yes I design and sell dual battery controllers and full systems.

But this thinking that something as simple as an ignition operated relay is the cheapest way to go is anything but correct.

What is correct is that it is initially the cheapest to set up, but long term, you can save heaps more by using a system that improves your batteries life span.

If you fit a system that can, in many cases, do as much as double your cranking battery’s life span while helping to extend you auxiliary/house battery life span and add usable capacity without adding more batteries, you well and truly save far more money long term.

This is exactly what my isolators do.

Simply turning a relay on and off when the ignition is turn on and off is cheap but is not very beneficial to your batteries.

Furthermore, charging your cranking battery first then charging your auxiliary battery is a waste of auxiliary battery charging time and no standard isolator does that, even though a number of isolator sellers claim they do ( just deliberately misleading advertising ).

Many years back, when vehicles came with nothing more than a 45 amp alternator, then there MAY have be a reason for such operations but back then we used very little auxiliary power anyway so, even back then there was no real advantage.

Today, with the smallest alternators being around 80 amps, there is no reason why you can not charge your cranking battery and a number of auxiliary/house batteries at the same time.

Next, hi d5disco and you are getting mixed up with how batteries wired in series

Neg ( - ) of 6v battery 1 wired to earth.

Pos ( + ) of 6v battery 1 connected to neg ( - ) of 6v battery 2.

Pos ( + ) of 6v battery 2 is your 12v supply.

If one 6v battery is lower than the other 6v battery, then when the higher charged battery is full, charging of the lower charged battery stops.

With 12v batteries wired in parallel.

Neg ( - ) of 12v battery 1 wired to neg ( - ) of 12v battery 2

Pos ( + ) of 12v battery 1 connected to pos ( + ) of 12v battery 2.

All batteries will be fully charged if you drive long enough.

Furthermore, alternators do not stop charging a low battery if a higher charged battery reaches a fully charged state. An alternator has no idea when a battery is fully charged.

D3s, D4s and RRS have a BMS ( Battery Monitoring System ) that monitors the State of Charge ( SoC ) of the cranking battery just after you start the motor and then sets up a charging algorithm to suit the SoC of the cranking battery.

With the use of any other isolator, you will slow down the of the auxiliary battery, but it will still charge, just at a slower rate.

But with my isolators, because they draw accessories power from both the auxiliary battery and the cranking battery, when the motor is started, the BMS sees the cranking battery needs a charge and sets the charging algorithm accordingly.

This results in both the cranking battery and the auxiliary battery being charged at a higher voltage for a longer time.

There are a number of other features that add to your financial gain when you use one of my system, so while you may save up front with a cheap set up, you loose long term over what my systems can save you.

sillsymark
6th October 2013, 09:24 PM
Couldn't help myself - had to jump in on this one...:) I run a second battery in the rear of my td5 ( where the dickie seat would be) - its very simple to work out the best set up for you,based on what you want to use the power for.

Winch: always the starter battery
Fridge: Always the second battery
Isolator:(-I've got a solenoid one with a manual override switch) between the two or the fridge will drain both.

Look at power consumption on the fridge. If its 4 amps an hour - and you've got a 70 amp hour battery - it will only last a couple of days - and 4 hours driving plus to charge it...(at 2000 rpm or more).

So I run an 80watt solar to keep the rear battery charged.

If I'm running the winch I switch on the isolator manual over-ride to try drain the batteries together as much as possible.

If either battery falls to low low low (under 11) voltage levels while the other is sitting up high at full charge - you are going to have problems. ( especially if the batteries are different capacities/cold cranking amps). If possible - run similar .

I do a lot of winching as I have a large boat and front mounted trailer hitch. We use the winch 3-4 times a week, and the fridge hasn't been switched off since 2004.
I'm on my second rear battery and third cranking battery in ten years...they have all been cheap - but corregatted roads destroy all but the best... So if you do a lot of high speed on rough - pay up - they are worth it.
Cheers - mark

drivesafe
6th October 2013, 09:36 PM
If either battery falls to low low low (under 11) voltage levels while the other is sitting up high at full charge - you are going to have problems. ( especially if the batteries are different capacities/cold cranking amps). If possible - run similar .

Hi Mark and this is actually nothing more than an urban myth.

Any 12v lead acid battery can be wired in parallel with any other 12v lead acid battery and you will not have problems if they are dissimilar.

sillsymark
6th October 2013, 09:57 PM
Great to know - and thanks!!!! I'm really paranoid about huge amps belting though the wiring in between the two batteries. (5m apart in my rig).

Love to pick your brains!!!!

Cheers - mark

drivesafe
6th October 2013, 10:06 PM
Love to pick your brains!!!!

Ask away.

If I can by of any help, only too happy to try.

Slunnie
6th October 2013, 10:09 PM
1/ Install second battery.
2/ -ve terminal to a good chassis earthpoint.
3/ +ve terminal to Primary battery +ve with heavy cable.

Use a multimeter to monitor battery vs fridge run time.

voila

simple and probably best for winching too...

S

That's how I've been setup for the last 8 years or so after my Redarc failed. So far it's been drama free, but I don't setup a long camp or leave the fridge running for more than a day without moving either.

BDB
10th October 2013, 05:28 PM
I am just back from an 8 week trip, My ARK Pak did the job! with some on the trip adjustments! I.e. I had a lot of troubles with my disco 3HSE cig plugs and eventually wired the 240 v charger into an inverter and an Anderson plug that was there at the rear
It would keep the fridge a WAECO cool for 4+ days.

Most deep cycle batteries will not like lots of winching but a long jumper lead would let a rear mounted ARK Pak power the main battery?
Hopze this helps.

Homestar
10th October 2013, 05:57 PM
1/ Install second battery.
2/ -ve terminal to a good chassis earthpoint.
3/ +ve terminal to Primary battery +ve with heavy cable.

Use a multimeter to monitor battery vs fridge run time.

voila

simple and probably best for winching too...

S

That's how my 101 is set up and I've been out for 11 days straight now and have had no dramas. When set up for more than an evening, I put a 120 watt solar panel out that charges both batteries. Running a fridge, LED lighting and my ipad and laptop charger. Car has started easily when needed. I was going to put an isolator between the batteries but I don't think I'll bother now as this setup has worked so well.

Just for clarification, I have the cranking battery in its normal home and the second battery in the trailer I'm towing with a permanent 20amp supply running from the first battery. Solar panel connects to the battery in the fridge which keeps the cranking battery charged as well. Happy days.

roverrescue
11th October 2013, 04:40 AM
bacicat,
I too have upped my simple system with a 120W panel and reg.

A few weeks back, went bush and left ute for 3 days. I got back to ute at 930 batteries were at 13.5V engel and beer was at -1. Perfect!

And that is with panel just facing north at bout 45degrees, no chasing the sun.

So a little less simple but perfct for me

S

oztrax
13th October 2013, 04:58 PM
Well I reckon the best dual battery setup has a dual alternator as well.

Attached my circuit for dual batt/dual alt setup.

2nd alternator is from a Mitsubishi L300 55 amp, from a wrecker coz the
front shaft and bracket mounts means it fits the original D1 TDI 300 position as well.

can do all this with a lot of mucking around and $200 including battery which is a
Caterpillar deep cycle marine "wet" battery. Runs the 30 litre engel for over 24 hours.

regards
OZ

Dervish
2nd November 2013, 09:51 PM
Install second battery, same as starter and connect both through a 3 way marine switch. Cheap and effective.

Works for me. ;)

This is how I run mine and I think it's the best and simplest setup. The batteries are paralleled unless I feel the need to disconnect the cranking battery to remove the risk of it going flat.