Thread: Traxide Dual Battery Voltages

If you're going to put a solar system on or use a maintenance charger it will be.

I'm happy with my old style SC80 and seem to be missing the advantages of the new updated one?

Originally Posted by drivesafe

The isolator specifically charges the AUXILIARY battery first, and then turns on to charge the cranking battery.

Surely priority should be given to the Start battery?

With my SC80, I simply connected the solar panels (and ctek charger) to the Start battery. So long both batteries are above 12V they both receive charge. If for whatever reason they drop below 12V and the isolator shuts down and separates the batteries, then in my case the solar (or ctek) would be charging the start battery and once it's up to 13.1V the isolator would rejoin them and charge both batteries again anyway.

Originally Posted by drivesafe

Quite a few occasions have occurred where the cranking battery was flattened to the point you could not unlock the vehicle.

If both batteries have low voltage, and only limited charging is available from solar etc, surely it would be better to have that charge going first to the start battery, to have the maximum chance of unlocking and opening doors and bonnet? With charge going to the Auxillary battery, but voltage still below the isolator cut in, no charge would be going to the flat start battery. Wouldn't you still be in a situation of not being able to unlock the doors?

Originally Posted by drivesafe

The isolator has been programmed to work this way so that if the cranking battery is not just flat, but has dropped a cell, the auxiliary battery will still be ?NEAR? fully charged and should still allow you to start the motor.

Surely there is an equal probability of the aux battery dropping a cell?

I've got the old SC80 and installed a Projecta dual battery monitor to try get a better idea on the SoC, but it really only gives me voltage numbers. Any tips for using it to gauge the level of charge via the SC80, especially of the aux battery?

Originally Posted by danialan

I'm happy with my old style SC80 and seem to be missing the advantages of the new updated one?


Surely priority should be given to the Start battery?

With my SC80, I simply connected the solar panels (and ctek charger) to the Start battery. So long both batteries are above 12V they both receive charge. If for whatever reason they drop below 12V and the isolator shuts down and separates the batteries, then in my case the solar (or ctek) would be charging the start battery and once it's up to 13.1V the isolator would rejoin them and charge both batteries again anyway.


If both batteries have low voltage, and only limited charging is available from solar etc, surely it would be better to have that charge going first to the start battery, to have the maximum chance of unlocking and opening doors and bonnet? With charge going to the Auxillary battery, but voltage still below the isolator cut in, no charge would be going to the flat start battery. Wouldn't you still be in a situation of not being able to unlock the doors?


Surely there is an equal probability of the aux battery dropping a cell?

the concept logic is to do with protecting the aux battery and allowing it to recieve the highest charge. As most people who install the traxide use it with the intent of a camping setup and a lot of people now do solar as well it gives priority of charge to the aux battery and when it is fully charged (near enough) then it connects up and cross charges to the main battery. this is to exploit "unused amps" that might be available from a camper trailer or caravan mounted solar/plug in charge system when the plug in aux batteries are nearly fully charged where the normal role for the traxide is to charge the aux batteries from the alternator.


with a good main battery, with the reversed setup even if the traxide remains disconnected and no charge goes into the start battery you should still be good for about 5 days without starting the engine and still be good for a start. What power is available for the aux systems from the panels all goes to those prolonging the life of your aux battery. this leaves your aux battery in a higher state of charge incase the main battery does die on you.

in a well used system the start battery is a little more likely to be the one that fails first especially if you do a lot of short run driving.

but lets not get confused here, the primary working of the traxide still works if you hook up to the main battery and it charges up to the point where the older traxide would connect the batteries, that still happens. With the new version it now cuts both ways. and heres the little extra kick for you..

if you wire it up right and use an external heavy duty anderson style connection for your aux battery connection without having the aux battery you can now use this to boost charge the main battery for an assisted start and power up the main battery powered systems even if its dropped a cell.

Originally Posted by Ben_Vapid

I've got the old SC80 and installed a Projecta dual battery monitor to try get a better idea on the SoC, but it really only gives me voltage numbers. Any tips for using it to gauge the level of charge via the SC80, especially of the aux battery?

Hi Ben, this should be of some help to you.

Hi danialan, just adding to what Dave has posted above, which is spot on the money.

With the original SC80, the batteries remain connected till the voltage dropped, through what ever reason, to 12.0v, then the isolator shut down.

With fully charged batteries, this could be 3 to 4 weeks after you last had the motor running. This was all good and well with vehicles used everyday but was a waste of battery power if you were leaving the vehicle used for long periods.

But this did meant that in most situations, if you connected an external power supply to the auxiliary battery, whether this is direct to the battery or via the Anderson plug at the rear, the two batteries were charged at the same time, AS LONG AS THE SC80 WAS STILL ON, when you connected the external power supply.

If, for what ever reason, the SC80 had shut down, the only way to charge the cranking battery was by applying a power source directly to the cranking battery.

With the new SC80, to avoid wasting battery power, if the vehicle is left for long periods, like the USI-160 and DT90 isolator, the new SC80 automatically shuts down after 72 hours, even though the batteries will most likely still be in a high state of charge.

In the vast majority of situations, this 72 hour TIME-OUT feature will do as intended and save battery power. But there will, and have been, situations where being able to REVERSE CHARGE the cranking battery would be advantageous. Like for people who may be storing their vehicle and only applying a maintenance charger every few weeks.

There is also the ever increasing situation where people are camping and charging their batteries using a generator/battery charger setup to charge their batteries once every few days.

In this type of situation, with the original SC80, if it had shut down, you had to connect direct to the cranking battery, to recharge it.

With the new SC80, this is no longer necessary, just plug the charger into the Anderson plug at the rear and you can now charge all the batteries.

NOTE, the OVER VOLTAGE protection has been added for these types of situations, to protect the cranking battery from erroneous charging supply voltages.

Originally Posted by drivesafe

Hi Ben, this should be of some help to you.

That does, thanks Tim!

Originally Posted by Ben_Vapid

That does, thanks Tim!

I keep a print out of Tim's SoC table in the car for reference.
You probably already know but these voltages are resting, so you need to wait awhile after charging and/or running the vehicle so that the surface voltage/charge has gone.
Another related point is that the 12.7V will drop to 12.4V with ignition on but engine off for a healthy cranking battery.

(NOTE: all knowledge interpreted from Tim in another thread).

Cheers,
Scott