Member Since: 01 Dec 2006
Location: nr Paris
Posts: 25
Rather take a look at http://www.traxide.com.au/D3.html It’s especially suited to LR Discovry 3 and RR Sport.Discovery 3 (2007) HSE TDV6 Java Black/Ebony Black, Privacy glass, Manual gear box
27th Nov 2007 7:18 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Thanks AM510657 for the plug.
Hi Nash, before you decide on which brand of isolator, you need to have an idea of just what you want to get from an isolator.
In many older vehicles, people fit dual battery set ups for use in a number of ways but they also look at a dual battery set up as a safety net should the cranking battery fail.
In these cases, having an isolator that has the ability to add a switch or operate a specific procedure that allows the isolator to be used to connect the auxiliary battery up to be used to start the vehicle is an advantage.
In newer vehicles, irrespective of what type of isolator you have, having the cranking battery put in a situation where it is going to be flattened on some many occasions that an emergency starting procedure is needed is not the answer to the problem, resolving the cause that is flattening the battery, is a far more realistic way to go.
In the vast majority of dual battery installs into D3s, the prime reason is to provide a power source for operating accessories, like fridges or inverters, for long periods with out either risking flattening the cranking battery or having to start the motor to keep the charge up in the cranking battery.
The D3 is one of very few vehicles that come from the factory with an auxiliary battery mounting already provided.
The only down side is that the size of this auxiliary battery mount limits the size of the auxiliary battery to a smaller battery than would normally be desirable.
It’s the way my isolators address this size limitation that is the basis for the advantages my isolators have over other brands but it still comes back to what you are considering installing a dual battery set up for in the first place.
Cheers.2008 TDV8 RR Lux + 2009 D4 2.7
27th Nov 2007 9:21 pm
AM510657
Member Since: 01 Dec 2006
Location: nr Paris
Posts: 25
Thanks « drivesafe » for details. Is it really truth you can get Discovery 3 with dual battery option in UK ?Discovery 3 (2007) HSE TDV6 Java Black/Ebony Black, Privacy glass, Manual gear box
There isn't a dual battery option available over here from LR
There are battery boxes on both sides as the positioning of the battery varies between left and right hand drive D3's and thankfully LR left room in the one not containing the standard battery to fit an auxiliary one, not sure if this was by design or it just worked out that way The End
28th Nov 2007 11:26 am
Nash
Member Since: 20 Oct 2006
Location: Barcelona
Posts: 108
Thank for the reply.
Reading in this forum I have read about all these isolators....
- Traxide
- Redarc
- National Luna
- Genesisparts
- Superpower
And now this
- Projecta".
Are all of them suitable for D3...any proble/advantajes... any recomendation.
I read in this forum taht isolator is the key part of a secondary battery installation due to the very specific D3 electronics...
Maybe it is not easy to find all of them in Spain.... Do you think all of them are a good choice?
NashNacho
DISCOVERY3 TDV6 HSE Zambezzi
28th Nov 2007 1:09 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
Depends how you want to use the second battery, if it's just to increase the capacity for vehicle equipment then all you need to do is conect the two in parallel using suitably sized cable (assuming the battery is one that will accept the raised charge voltage, such as the Optima D34) if you want to have it isolated when the engine is not running, then you just need to add a suitably rated solenoid (contactor). The one's I fit are rated at 400A with a coil voltage of 14V
28th Nov 2007 1:44 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi Nash, actually most isolators do NOT suit the D3.
If you are looking at fitting a dual battery controller to a D3 one of the isolator’s specs you need to know about is the cut-in voltage of the device being fitted.
To function properly in a D3, the device MUST have a cut-in voltage setting that is lower than 13.2 volts as this is the lowest voltage level the D3 can operate at and most isolators have a cut-in voltage of 13.5 or higher.
There are other situations unique to the D3 that can result in poor charging of auxiliary batteries that most isolator can not address and will cause the auxiliary battery to take much longer to recharge and may not charge at all, so take care when choosing.
I have the National Luna 'intelligent solenoid'. This seems to work ok, automatically isolating the battery when the starter battery voltage drops below a certain level. It also has a timer that makes sure the starter battery is charged for five minutes after the engine is started before the aux battery is connected to the alternator. So far I all seems to work ok.
I also have the NL 'battery monitor' unit, a fancy display with two LED bars showing the charge state of both batteries which connects directly to the isolator unit. The monitor unit also enables you to manually tie both batteries in case the starter battery needs some 'help' and offers 'overvoltage' monitoring. This does not work with the D3, because the lead-calcium battery has a higher voltage than traditional batteries. So, if the batteries are fully charged this always results in an overvoltage warning. Luckily, you can disble the audible alarm, but the LED bars will be flashing all the time. But the LEDs can also be switched off
I'm not sure if I understand what the 'cut-in' voltage thing exactly means, so I can't comment at that 2006 Zermatt Silver TDV6 'SE' Auto, Mantec sump guard, Frontrunner roofrack, Lightforce 140s, split charge system and... a Jetboil.
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28th Nov 2007 8:47 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
The 'cut-in' voltage is the point at which both batteries will be connected in parallel, the reason it is lower on a Disco3 is due to the charging strategy built into the ECM & ATCU (both of which control the alternator) at high ambient temperatures, the battery requires less charge voltage, at low temperatures it requires a higher charge voltage. In climates with a high average ambient, most charge controllers will have a fairly narrow window of charge time for the aux. battery (although most of Western Europe should be OK) This is one of the reasons I install a simpler system where the charge voltage is immaterial, the timer based systems are also immune from failing to charge the aux battery due to lower charge voltages
28th Nov 2007 9:35 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
There is a tad more to it than just the ambient temperatures.
Because the D3 actually monitors the state of charge of the cranking battery, if the cranking battery is fully charged, the system voltage is lowered, as the system sees no need for higher charging voltages.
This lowering of system voltage means if the auxiliary battery is low, the charging time needed to recharge the auxiliary battery will be much longer and in many cases, the system voltage may not be high enough to ever fully charge the battery.
This lower operating voltage should not be a great a problem in colder climates but again, it still depends on how low the state of charge of the auxiliary battery is as to whether there is going to be a major problem.
One more point, there is actually no need for a timed delay when starting a vehicle. We experimented with this idea many years ago and found there was no advantage to the cranking battery’s charging but there was actually a slight disadvantage to the auxiliary battery's charging.
This was done a long time ago and with more modern vehicle alternators, it is even less relevant now and we have found that the sooner you can get the auxiliary battery connected to the vehicle’s electrics, the quicker you charge the battery, particularly with alternators that are temperature compensated, where the the initial starting voltage is higher than the normal operating voltage.
Cheers2008 TDV8 RR Lux + 2009 D4 2.7
28th Nov 2007 10:26 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
Yep, fully agree with you there - the above was simplified but basically the same. As soon as two batteries are paralleled there is a 'balancing charge' across the two batteries, this negates any 'charge primary first' strategy, effectively making the 'flashy lights' solutions nothing more than a bit of eye candy at best and counter-productive at worst
28th Nov 2007 10:33 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi 10forcash, unfortunately and I’m not quite sure what you mean by “balancing charge†just connecting two batteries in parallel will not “trick†the D3 into increasing the charging the voltage to better charge auxiliary battery.
With any alternator, once the motor is running, the alternator’s voltage is the highest throughout the system so there will be no way of determining if one battery is at a higher or lower state of charge than any other battery in the system.
The problem is exacerbated in the D3 because it actually monitors the cranking battery and the voltage is adjusted according to the needs of only the cranking battery.
Again, this will not be as great a problem in low temperature countries but in warmer climates, the D3’s voltage management system causes some strange charging operations for auxiliary batteries when most types of isolators are used.
The problem that is occurring here on an all too regular basis is what happens once the D3 has been driven for a while.
Here’s a scenario that will give you an idea of the problem.
Family is ready for it’s long awaited holiday. Start the D3 in the morning. Because everything is cold, the operating voltage goes to 14.5 in just a few second.
Whether the Auxiliary battery is fully charged or not, the high operating voltage causes the isolator to cut in.
As the vehicle drives along, as the cranking battery is fully charged and everything under the bonnet warms up, accordingly, the vehicle’s voltage is lowered but this is not a problem as it is still well above the isolators cut-out voltage.
After a few hours, there is a stop, for fuel, food, what ever and the D3’s motor is turned off.
There is a fridge running in the back of the D3 or in the caravan or camper trailer being towed by the D3. This fridge quickly pulls the surplus voltage of the batteries and the voltage drops below the isolator’s cut-out level. Still not a problem.
After the break, the D3 is started, and here’s where the problem comes in.
Because the D3 sensor that the cranking battery is fully charged and the operating temperature is high, the operating voltage is set to just 13.2 and at this level, most isolator will not cut in.
So by the time the family gets to the overnight stop, they have ( unknowingly ) already been discharging the auxiliary battery.
There’s a good chance that on starting out on the first day, they would probably have a fully charged battery, but after three day of this type operation, they are now likely to pull up for the night to find they have a near flat auxiliary battery.
The correct cut-in voltage is paramount to the selection of an isolator for a D3 or RRS.
Cheers.2008 TDV8 RR Lux + 2009 D4 2.7
28th Nov 2007 11:22 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
A 'Balancing charge' can be illustrated by the following:-
If you had two barrels, one full of water one nearly empty with interconnecting pipework and a (closed) gate valve, once the gate valve is opened (the two barrels are in parallel) then there will be an initial inrush of water, restricted only by the size of the pipe. The full barrels level is controlled by a float valve, therefore, as water is transferred to the nearly empty barrel the flow of water to the rapidly emptying barrel increases, eventually, both barrels reach equilibrium and fill equally, the flow being reduced by the float valve as both barrels become full.
Completely agree about the voltage switching issue - which is why I only install 'simple' high current solenoids as a method of isolating the two batteries when the engine is not running
28th Nov 2007 11:34 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi again 10forcash, I suspected that’s what you meant.
Actually, what happens when two batteries with different States of Charge ( SoC ) are connected in parallel and there is no other voltage being applied, in other words, the motor is NOT running, the battery with the higher SoC will discharge into the lower battery.
The lower battery’s SoC will NOT rise, the higher battery will simply continue to discharge until it’s SoC is down to the other battery’s SoC. Note this will take hour to many days to occur.
On the other hand, when two batteries with different SoC are connected in parallel and there IS another voltage being applied, such as the alternator voltage, the highest voltage controls what current flows where and in this case as the alternator voltage is always the highest voltage, the ONLY current flow that occurs is from the alternator to both batteries.
There will be no current flow coming out of one battery and into the other.
This is one of the many myths that prevail about batteries and charging them.
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2006 Zermatt Silver TDV6 'SE' Auto, Mantec sump guard, Frontrunner roofrack, Lightforce 140s, split charge system and... a Jetboil.
