Thread: Dual battery/Isolator Help!

I can fully recommend the Traxide system, apart from a problem that I caused MYSELF(I inadvertently bypased the Traxide unit when i removed an inline switch)
After speaking to Tim for some advice(THANKS MATE) he put me onto the problem and it is now back to normal and going great again.

Can't recommend Traxide high enough

Baz.

Originally Posted by bruiser69

Hi Drivesafe,

I am also an electronics engineer, but in the medical field. I have read much regarding relay/solenoid isolators V electronic using mosfets.
The main argument against the relay/solenoid type appears to be the large surges induced on the 12V rail when these activate or deactivate second battery. The relay/solenoid camp say that the mosfets can't reliably handle the peak currents involved.
What are your thoughts on this debate?

Cheers..Bruiser

Sales pitch - What stops the surge induced when you turn 2 pairs of spot lights on/off 100 times/night... 4 * 100w lights is about 30amp (alot more on startup) cutting in and out by relay. How about the starter motor... nothing, your components can handle it.

Sorry I know you didn't ask me -but thats my thoughts...

Originally Posted by p38arover

Fair enough. Thanks Tim.

Some years back when I was doing my (radio) Broadcaster's Certificate of Proficiency (BCOP) course, one of our instructors was an electronics engineer. He mentioned that when he lived in the UK, he set his alternators at a slightly higher voltage. He claimed that in the UK winters this gave him a better charge than standard and he never suffered from failing batteries in winter.

Hi Ron and this is exactly how the electronic voltage monitoring system in the D3 and RRS works, it varies the voltage according to load requirements and temperature.

Hi in Australia it’s common to get readings down to 13.2 volts at the cranking battery, with the motor running and in the UK on a cold day, it’s not uncommon to get readings of 15+ volts

The D4 goes even further, but that another story.

Originally Posted by bruiser69

Hi Drivesafe,

I am also an electronics engineer, but in the medical field. I have read much regarding relay/solenoid isolators V electronic using mosfets.
The main argument against the relay/solenoid type appears to be the large surges induced on the 12V rail when these activate or deactivate second battery. The relay/solenoid camp say that the mosfets can't reliably handle the peak currents involved.
What are your thoughts on this debate?

Cheers..Bruiser

Hi Bruiser, I’ve been working with automotive electronics for about 35 years and every time I’ve designed something that needs to switch heavy current loads, after testing the latest electronic component at what ever period it happens to be, I inevitably always come back to relays.

Main reason is that they are just about bullet proof while electronic devices are getting very reliable, mosfet and the likes, I still find that the over all performance of a relay is still better.

And just to back my argument, Mosfet have their place in specialised areas but consider this, a mosfet is cheaper to make , smaller in size but is still not the automotive industries choice for switching high currents.

As to surge and spike protection, Bruiser, your on the right track.

Every electronic device, whether it’s in you vehicle or at home or where ever, it has built-in protection and it’s there for a number of reasons.

The obvious is to protect the device itself but it is also there to make sure the device meet the now VERY stringent Electronic Noise Emission controls set by the EU and followed up by most other countries, including Australia.

This is an area that get abused on a regular basis. You will often see advertising for certain brands of Dual Battery Controllers that read something like ” because our Brand X has suppression built in, if you don’t buy ours, your likely to damage your vehicle computer” and the likes.

This is total BOLLOX and the actual reason they have suppression built in, is to protect their own electronics and it is nothing more than a spinoff that it will aid the protection of other electronic devices in the vehicle if these other devices are not already protected, and that just not the case as all electronic devices are protected now days and have been for decades.

This is like those who say you must only use jumper leads with built-in suppression, WHY? It nothing more than a con job to get unsuspecting people to buy something they don’t need.

call me pedantic but I agree with drivesafe..

in all my time deaing with electronics on cars the only time Ive had problems that could be traced to the battery and charging gear has been direct operator stupidity. (this doesnt count things like a sensor dying from oil contamination or damaging the harness)

1. plugging a 24v gazillion amp jump pack onto a flat 12v battery and trying to start it.
2. welding on the exhaust manifold and clamping the earth lead onto the ecu casing
3. putting a battery in ass about.
4. welding on the chassis without disconnecting the alternator, fried the regulator and wound up with whatever the hell volts the alternator could push out till the battery boiled dry and couldnt restrict the alternator voltage any more.


if your really really worried about the voltage spiking thing fit a decent capacitor at each relay point light, motor and switch oh, dont forget blocking diodes across every coil, use a seperate PWM charger in for the second and subsequent batteries with a shaped charging profile.

or you could just not listen to the marketing hype of the kind of people who sell electronics that are as benificial as your average hiclone.

Originally Posted by Blknight.aus

call me pedantic but I agree with drivesafe..

in all my time deaing with electronics on cars the only time Ive had problems that could be traced to the battery and charging gear has been direct operator stupidity. (this doesnt count things like a sensor dying from oil contamination or damaging the harness)

1. plugging a 24v gazillion amp jump pack onto a flat 12v battery and trying to start it.
2. welding on the exhaust manifold and clamping the earth lead onto the ecu casing
3. putting a battery in ass about.
4. welding on the chassis without disconnecting the alternator, fried the regulator and wound up with whatever the hell volts the alternator could push out till the battery boiled dry and couldnt restrict the alternator voltage any more.


if your really really worried about the voltage spiking thing fit a decent capacitor at each relay point light, motor and switch oh, dont forget blocking diodes across every coil, use a seperate PWM charger in for the second and subsequent batteries with a shaped charging profile.

or you could just not listen to the marketing hype of the kind of people who sell electronics that are as benificial as your average hiclone.

Exactly - we could add some more auto parts to that list

Hi Blknight,

As an engineer I have always been sceptical of the supposed benefits of products advertised, and have always done extensive research before purchasing. Unfortunately when I bought my 2000 TD5, the issues such as injector harness oil leak & ABS issues were not known. However with the benefit of modern broadband Internet I have been able to solve these teething issues cheaply & still regard my Disco2 TD5 as the best & most capable 4WD that I have ever owned. Mind you if the "handbrake" agrees I will soon be upgrading to a D3 TDV6.
I also looked at Hiclone and totally agree. Maybe it might have helped pre Common Rail but doubtfull. Fitting a bigger intercooler & custom ICU chip - definitely.

As I'm approaching retirement I 'm already considerirng setting up my own company manufacturing equipment that 4WD and camper/caravan people really need at an affordable price without the marketing Bull..it!