A final thought

[Wilbur]

This is my final post on the subject of dual batteries. It seems I am required to justify everything I write which is just too time consuming.

For those who wish to go the inexpensive route for dual battery systems on their Eighty thousand dollar motor cars, Jaycar are selling a dual battery system that seems to be similar to others on the market in that it partially charges the house battery and partially discharges the car battery to supplement the house battery.

Unlike others on the market, this one has ten user adjustable set points so that you can decide just how much you want to drain from the car battery. Thus if you are on your own in the middle of the desert, you might set it so that it takes nothing from the car battery, but if you are in a camp ground full of other vehicles bristling with jumper leads you might set it up to half-flatten the car battery.

The Jaycar one is rated at 100 amps. It uses solid-state switching to reduce the risk of spikes that could cause problems with the car ECU. It can be used to bridge the house batteries to the car battery to allow boost for emergency starting. It retails at $119 but for a bulk buy of ten units they discount this to $94.95.

Now I know nothing about the quality or performance of this item - I am just bringing the ad to the attention of anyone interested. It is on page 300 of the Jaycar 2011 catalog, cat number MB-3680.

I am in no way endorsing this product - I still believe that DC-DC convertors are the best way to go, but for those who want the less expensive route, this is an alternative.

Attached is my proof - a scan of the ad.

[drivesafe]

Wilbur, as pointed out before, there are people reading your posts who may think your “advice” is sound. Once again, it's not.

One of the problems that has been continually covered on D3/D4 forums is the low operating voltages of these vehicles and yet here you are with your wealth of experience, recommending the use of a device that clearly states in it’s own technical info, that it will introduce as much as a quarter of a volt drop between the supply and auxiliary battery, is of no help to anybody.

This sort of voltage drop would mean your batteries would take many more driving hours to charge and even then they would never be fully charged.

Wilbur, if you actually had any real experience in this field, you would know that FET and Diode type isolators are next to useless because of the voltage drop these device introduce into the auxiliary/house battery charging circuit and they have been disregarded as viable battery isolators for many years.

For anybody considering one of these devices for use in your D3/D4, be warned, you will create far more problems than you will hope to resolve if you use this device or anything like it.

[connock]

Hi guys

First I know nothing about electrickery. When I got my 2006 TDV6 it was already fitted with a battery separator smart soleniod. After all the discusions I wonder if this is going to work well once I have my fridge in the back and a camper in tow with its own battery?

Thanks connock

[trobbo]

oh dear.... I can't belive we are here again.

So if you were to go into a land rover dealership and ask them to fit a dual battery system to your D3/4 - what system or systems would they recommend? ;)

[Disco4SE]

oh dear.... I can't belive we are here again.

So if you were to go into a land rover dealership and ask them to fit a dual battery system to your D3/4 - what system or systems would they recommend? ;)
Went to my local Auto Elec in Rosebud. Been working fine for 15 months now with fridge running 24/7. First one they had done in a D4.
All the techo jargin aside, it works and works well.
Cheers, Craig

[PhilipA]

So if you were to go into a land rover dealership and ask them to fit a dual battery system to your D3/4 - what system or systems would they recommend? ;)
__________________
The one that makes them the most profit. ( without being known to cause warranty problems)
regards Philip A

[connock]

__________________
The one that makes them the most profit. ( without being known to cause warranty problems)
regards Philip A

That sounded so synical:) All I want to know is the one that came with the car OK or should I be thinking of changing it? Thats all.
Trobbo sorry but I didnt want to ask in the last debate.:(

[RoverLander]

One of the problems that has been continually covered on D3/D4 forums is the low operating voltages of these vehicles and yet here you are with your wealth of experience, recommending the use of a device that clearly states in it’s own technical info, that it will introduce as much as a quarter of a volt drop between the supply and auxiliary battery, is of no help to anybody.

This sort of voltage drop would mean your batteries would take many more driving hours to charge and even then they would never be fully charged.



Hi Drivesafe,

A quick test for of your knowledge... how does a voltage drop from 14.7v (normal voltage in a stable D4 as observed by me once I correctly connected my DC/DC charger) to 14.45 (.25V drop) translate into many more driving hours to charge. Is there a mathematical formula that works out time to charge that provides evidence of this?

I agree with them not being as fully charged but the difference is marginal. This is why I'm happy with the 15.2V my DC/DC charge puts out.

I'm pulling out of this (these) discussions.... I cant stand the endless free advertising you are getting from these discussions:D... send me a cheque if you want me to continue....

Peter

[rmp]

That was uncalled for RoverLander. Thread closed, we've had enough of these.