Thread: PRojecta Battery Charger Negative Lead Placement

The Projecta should be fine. Mine has been great. The alligator clips will work fine. As the battery nears maximum charge the charger will lower the current. Once the battery is fully charged the Projecta will switch off. Periodically it will test the battery. If it has dropped it will charge it and then switch off again. You can leave it connected long-term without a problem. Our camper trailer is left connected for weeks at a time. This process is a good way to keep batteries healthy.

Originally Posted by bee utey

Redarc sell dual battery isolators that sense the main battery voltage and connect it to the auxiliary battery when it reaches a certain voltage. Unless your unit is different to normal it will link the batteries just fine in your situation. You should see a red light on the unit when the batteries are linked.

I had to disconnect my charger before it was charged as it was getting dark and I had the windows down and did not want those bluddy Asian geckos getting in the cabin as we have plenty of them. Sometime after, the red light on the Redarc was still glowing. Is that normal and when will it go out?

Originally Posted by Kidbeen

I had to disconnect my charger before it was charged as it was getting dark and I had the windows down and did not want those bluddy Asian geckos getting in the cabin as we have plenty of them. Sometime after the red light on the Redarc was still glowing. Is that normal and when will it go out?

The light will go out when the battery voltage goes down to around 12.7 volts. The isolator draws enough current that this will happen within a couple of hours at most. Flashing the high beams on usually drops the voltage below this point quite quickly if you want it to go out sooner.

If the red light shows the batteries are connected it means the starting battery is in good shape, probably at least 80% depending on where the cutoff point is set. So if the red light is on that's a good sign.
Bear in mind that about 12.8 is fully charged and 12.0 is about 50%.

Originally Posted by bee utey

The light will go down when the battery voltage goes down to around 12.7 volts. The isolator draws enough current that this will happen within a couple of hours at most. Flashing the high beams on usually drops the voltage below this point quite quickly if you want it to go out sooner.

Of course when you get back from a trip you don't think to look at the battery under the passenger's seat etc,. That's why I have never seen the red LED glowing on the Redarc.

Originally Posted by bee utey

The light will go out when the battery voltage goes down to around 12.7 volts. The isolator draws enough current that this will happen within a couple of hours at most. Flashing the high beams on usually drops the voltage below this point quite quickly if you want it to go out sooner.

Can stay on all night and into the morning when you start 'er up again.
I had to replace my new start battery a week or so ago due to a dead cell in the 'new' one(1 yr old).
On at least 3 occasions now, starter voltage has been at or above 12.7 after about 8 or so hrs of sitting overnight!

So just a heads up as to other possibilities, depending on the condition of the main battery.

Originally Posted by Kidbeen

Of course when you get back from a trip you don't think to look at the battery under the passenger's seat etc,. That's why I have never seen the red LED glowing on the Redarc.

You can easily setup an LED somewhere easily seen via the free blue wire with the insulated spade hanging off the isolator.
Just wire up this blue wire to the positive lead of the LED, and the negative lead wired to an earth. This lights up as the red indicator light on the SBI isolator.
You can get a cheap($2-ish) LED from Jaycar(or other such places) in a chrome bezel that is perfect for the job. Make sure that it's a 12v LED tho, otherwise you need a resistor.

Other tip is that you can add a switch on this same wire to enable the isolator as a jump start system if the main battery ever fails .. which is what happened to me a couple of months back.(that new battery with a dead cell!)
That same blue wire will hook up to a simple switch(two post switch is fine).
Nice easy jumperlead-less jump start if ever required.
Wiring up isn't too complicated either.

You could also buy a battery meter such as the ones made by Narva or others from Autobarn or the other similar shops, connect it to the battery and run the leads out the hole in the front of the battery box to somewhere where it can be seen, such as on the dash or console. Then you will always know the state of the battery.
I have one connected to my second battery, which is hidden down the back under the rear of the drawers and the seat, making it hard to reach, but I can see its state at a glance by looking at the meter, which is on the side below the window. If my second battery has plenty of charge I know it means my starting battery is also in good shape and the Traxide dual battery controller has the two batteries linked.
My rooftop 80 watt solar panel charges the starting battery, so in theory I should never have a flat starting battery, so the two batteries should always be linked. That's assuming I park in the sun and drive it regularly, of course.
BTW I have used my Projecta 240 volt charger on the second battery and on the camper battery plenty of times with the negative attached to the negative battery post and it has never caused a problem. It might only be an issue if your battery was sick and venting lots of fumes.
Defenders don't have many electronics, unlike Disco 3s and 4s, which have a special post in the engine bay to which the negative has to be attached to avoid disturbing their electronics.

What about one of these to check battery charge? Anyone got one?