- Nobody likes getting a flat battery and race cars are famous for always
having some small electrical device fitted that's constantly draining just enough
charge from your battery to ensure that next time you go to start the engine,
all you're gonna hear is that dreaded click from your starter motor solenoid.
It's one of the reasons, along with the huge safety benefits that they provide,
that we fit battery isolators to race cars.
Traditionally, battery isolators have been a mechanical device in the form of a large
switch with a big red key.
Now these do work but they require you to run the large main power
feed cables to a location within easy reach of the driver.
Often this isn't convenient or practical.
The isolator we're gonna look at here, is a solid state isolator.
And that means all if its switching is done with electronics.
There are no moving parts and you can remotely control the device
from a much smaller more conveniently mounted low current switch.
It also allows for an emergency switch to be mounted on the exterior
of the vehicle.
This allows a race warden to kill the electrical system
in the case of an accident.
Solid state battery isolators are not a particularly new development
but I'm really excited to have a look at the one offered by Motorsport Electronics,
as it includes CAN bus communications which allows the device to be more
configurable and to give you feedback as to the current being drawn from
or supplied to the battery.
This replaces the need for a traditional alternator warning system
and can even let you know if your alternator is only beginning to fail,
as you'll be able to log the current it's supplying,
compare this between various race outings and it'll give you an idea of whether
its efficiency is starting to fall off.
So without any more preamble, we'll open up this box
and have a look inside.
So we can see it comes in a fairly nondescript white box.
Which if we open up, straight away we've got some documentation
on top.
My love of printed documentation is well known because it is super handy
when your laptop battery has gone flat.
We've got a wiring diagram here which I'm gonna come back to and discuss
in a bit of detail as there's a really important point I want to make
about the alternator connection in a traditional battery isolator system.
On the back here we've got some information as to maximum and minimum
electrical supply currents and voltages, temperature ratings and there is a QR
code you can scan which will get you access to the full user manual.
It was also pretty easy to find the full user manual
on Motorsport Electronic's website.
Inside here we have information on the installation and switch connections.
There's an LED on the front of the device which is a nice multi colour LED.
They've made really good use of all its different colours to provide you
with feedback as to the current state of the device.
So if it's gone into any warning modes you'll be able to look at the flashing
colour code and determine what's happened.
It also outputs all those warning modes over CAN bus.
So you'll be able to set up your ECU or datalogging system to interface
to that and it could display what the current mode of the battery isolator is.
We've got power distribution ECU connections.
So that is a, one of the pins on the device is what's known as a logical output
and when I come to talk about that wiring diagram we'll have a talk about how
this affects the setup as well.
So we've also got our CAN bus output data format.
That's gonna be the key information you're gonna need to configure your ECU
or logging system to read the information the device is sending out.
So you'll be able to get all these status' the voltage seen at both the input
and the output of the isolator, and the current flowing through the isolator,
and which direction it's flowing, if it's going into or out of the battery.
So we've also got a DTM six way connector here.
Now we've been supplied with a DTM six way connector as we've optioned
the version of the device that has a flying lead and a DTM connector on it.
It is also available in a version that has a Mil-Spec connector.
We haven't gone for that because the DTM connection is more appropriate
for the electrical system we've got fitted to the vehicle we're going to put this in,
which is our 350z race car.
So getting into the device itself, it comes protected in a little bit
of bubble wrap.
That's always nice and we really hate for things to be damaged by couriers.
And bagged up, so we'll break our way in here.
And we can now have a look at the device itself.
So you can see we've got the flying lead version of the device here.
So this is gonna be nice tesda wire in here.
It's been sheathed in Raychem DR-25 and they've gone with SCL
for the booting method so that's gonna be really nice rigid
and well strain relieved.
Where it connects to the device, they've used a Hellermann boot,
and you can see how it would've worked if we had optioned the version
of the device that had the Mil-Spec connector.
That would've actually just protruded directly from the device here.
So they must be using a custom adaptor to accept this Hellermann boot,
which was gonna strain relieve everything and ensure the connections in there
are gonna be nice and reliable.
So we've got our input and output studs here.
So this is where our main battery connection is going to be made
from our battery positive and this is going to be the output connection
to the rest of the vehicle electronics.
Those are M6 copper coated studs.
So although they look like they're copper and they'd be really easy to strip,
they're not, they are just copper coated.
That's gonna give you the electrical conductivity you need,
but also the longevity if you're removing or installing these nuts often.
Now nice to see that they've given us Nyloc nuts.
So once they're installed they're not gonna be able to rattle loose.
And some insulation caps to go on top of those.
The construction of the housing itself, it's a flat plate on the bottom here.
And it'll be a CNC machined upper housing.
We've got four fasteners on the bottom here which looks like it's how they've
assembled it.
But there definitely wouldn't be anything serviceable in here,
so you'd never have any need to undo those.
And I suspect even if you did, the device is probably completely potted inside,
so you wouldn't be able to disassemble it.
Two mounting ears here.
The base plate is reasonably thin, and those don't look incredibly robust.
But if you're mounting it to a flat surface, they're definitely gonna
be more than adequate.
I wouldn't wanna go mounting this to anything that's got any sort
of irregularities on it though as I suspect you'd probably bend them
quite easily.
Got the status LED that we mentioned before on the front here.
So that's gonna be really handy, if the device is mounted in a visible
area, if it's not you've obviously got access to all the information that you
get from that status LED over the CAN bus network as well.
Now earlier on I mentioned there was a really important point that I wanted
to make in regards to alternator wiring when you're installing a isolator system
in a vehicle.
If we think of this as a traditional isolator system.
So that would be a mechanical switch with a big red key,
and we wired it up as shown here, that would be the battery connected
to just the input stud of that mechanical switch,
and the alternator, starter motor, and rest of the electrical system,
connected to the output stud, if the engine was running and the
alternator was supplying current to the battery and the rest
of the electrical system, and you came and turned that mechanical
switch off, separating the battery from the vehicle,
from the rest of the electrical system, it wouldn't actually kill the electrical
system in the vehicle because the alternator will continue to supply
the current required by the rest of the electronics.
So it won't disable the engine.
That's a reasonably dangerous situation to get into because you've expected
the engine to die when you've disconnected that switch and it hasn't.
But even worse than that is that you've just disconnected the battery
from the electrical system of a running vehicle.
And that will cause a situation known as a load dump spike.
What happens there is that the current that the alternator is supplying
can no longer use the battery as a reservoir 'cause the battery's been
disconnected.
So it will continue to supply a large current for a short but appreciable
amount of time and that large current will cause a very large voltage spike,
which the rest of your electronics in the vehicle will see.
And it's extremely common for them to be damaged by this.
Now the isolator supplied by Motorsport Electronics does show you to wire
it up in this potentially damaging way.
But they have been able to do that because they've included some clever smarts
in the device that prevent a load dump spike from being able to occur.
Now the way it does this is by providing you with a logical output wire
that you run to either your ECU or your power distribution module.
If the low current switches get triggered, which commands the battery isolator
to disconnect the battery from the circuit the first thing it does is use that
logical wire to tell your ECU or power distribution module to kill the engine.
Because the isolator is always monitoring the current flowing between these two pins
it knows when the engine's shut off, and the alternator is no longer supplying
current to the battery, and it's therefore safe to isolate
the battery from the circuit.
You can use commands sent over the CAN bus network to configure the battery isolator
for the maximum amount of delay it will introduce into the system.
So if that doesn't detect that the engine has been killed after say five seconds,
it will disconnect the battery regardless, this is a really crucial safety feature.
Some other interesting things on the wiring diagram here,
you can see it's got a facility for an external switch,
that's a switch mounted on the exterior of the vehicle,
which is a normally closed momentary switch.
They use a normally closed switch for this as it means if the vehicle's in a serious
accident and this wire gets severed, it'll no longer be connected to ground,
and that's the same as actually pressing the switch.
So a serious enough accident will cause the electrical system of the vehicle
to be disconnected.
The driver switch is a normally open latching switch.
And that'd be the main switch the driver would use to either enable the main
power of the vehicle or disable it when your race day is over for example.
They've also shown our CAN bus communication connections here.
So that's a twisted pair and they've used a reasonably common colour code
of green for CAN low and yellow for CAN high.
They've shown external termination resistors fitted,
as it does say in the main user manual documentation that the device doesn't
include any termination resistors.
Which given the option it's always nice that the device doesn't have termination
resistors as I really like to be able to choose where I put those
in the wiring harness.
Continuing on with the CAN bus side of things,
Motorsport Electronics have gone an interesting way with the configuration
of the device.
It's a pretty expensive process to go through to create a software suite
to configure devices like this.
And they've done it a different way.
Instead you configure its settings by sending it specially formatted
CAN bus messages.
Now they might initially seem a little bit cumbersome.
But the reality is, any vehicle you're going to be fitting this to,
and utilising its CAN bus communication facilities in,
is most likely gonna have other electronics installed in the vehicle
that are capable of generating custom CAN commands.
Now the full use manual does have a detailed guide on how you generate
these custom commands to configure the device.
Various things you can configure are the parameter ID that
the device will transmit on, the CAN bus communication speed
it will transmit at, and the logical setting of the output pin that you run
to either your PDU or ECU to kill the engine.
You can either have it switch high, switch low, or enable and disable pull ups.
Looking at the device on the bench here, there is an option I would've liked
to have seen, and that would be to have a right angled boot on the flying lead
connection here.
Probably orientated so it was coming out of the top of the device.
The amount of space required here is actually quite large to avoid
needlessly straining this flying lead.
So it's just something we will have to take into account when we're fitting
this into the vehicle.
Now on that front, we are actually going to be fitting this battery isolator
into our Nissan 350z race car.
As the battery isolation system in it at the moment is somewhat
sub optimal and it has given us a few issues.
That car also has a slight fault with the alternator which I've been slightly
dragging my heels on fixing as I really wanna get some data out of the car
before and after I fix the problem, to see the differences which this device
is really gonna let me dial in on with its CAN bus communication and being
able to see exactly how much current is flowing from the alternator
to the battery.
If you'd like to see more of that installation process in our 350z race car,
keep an eye on our social media channels, 'cause we will be doing an installation
video when that goes ahead.
That's the Motorsport Electronics battery isolator.
It's a nice tidy little package, quite lightweight,
looks very robust, and I can't wait to get it installed in the vehicle.