Thread: Traxide SC80 Battery Controller

Originally Posted by garrycol

Thanks guys.

Thats what I have previously been told but certainly do not understand the logic, particularly as all the cars systems use the body as earth and generally do not run cables back to the negative terminal of the battery.

Hi Garry, as Tombie and bee utey posted, if you are running something with a small power requirement, then a body/chassis is going to work but if you have a look at the type of devices the vehicle manufacturers connect to the body.

They usually fix the earth returns for things like turn and stop light globes to the body but high current returns are usually fixed to a chassis point that, by design, THEY KNOW is a good earth return.

Whereas we as installers, professional and DIYers alike, do not have access to the manufacturers info so the safest way to guaranty a good earth return is to run your own. Can’t go wrong then.

Tim,

I have a question about the SC80 battery controller.

How does the controller react in the event of differing voltages between the main and auxilliary battery. Fo example, the main battery on full charge shows 12.8 Volts and the auxilliary 13.1 Volts. Is there any form of equalisation and if so, in which direction?

Oh, and on an aside, the CD that accompanied your product has gone beely up and is no longer readable - where can I get copies of the two files on the cd?

Thanks for your input.

Cheers,

Franz

Hi Franz, and if the batteries are all in your vehicle, meaning none are in a trailer or caravan that can be disconnected and the batteries can be discharged to lower levels than those in the tow vehicle.

While all the batteries are in the vehicle, because the SC80 ( and the USI-160 ) keep all the batteries connected till the common voltage of all the batteries drops below 12.0v, all batteries should be at the same State of Charge ( SoC ) at just about all times.

The one exception is when you have been camping and used a fair bit of battery capacity, and even if you didn’t discharge the batteries down to 12.0v, the isolator will still have all the batteries connected, BUT if you were then to drive for a short time, not long enough to fully charge all the batteries, then there can be differences be the SoC of the batteries.

For instance, most D3s and D4s, fitted with my isolators, will, in the most part, also have an Optima Yellow Top Battery as an auxiliary battery.

In this case, because D3s and D4s have high capacity alternators and the fact that Optima batteries can safely take full inrush current when charging. If you were to go for a short drive, the Optima will take a much high current charge than the Calcium/Calcium ( Ca/Ca ) cranking battery will.

So when the motor is turned off, the Optima will back discharge into the lower cranking battery.

While not a design intended feature it has proven to be a winner with these vehicles because many, prior to having one of my dual battery systems fitted, would continually get “Low Battery Voltage” messages.

Within a week of my kit being fitted, no more “Low Battery Voltage” messages.

BTW, send me a PM with your E-mail address and the installation instructions you need and I will e-mail you back a compressed PDF file of the full instructions

Thanks Tim that explains a few things.

I recently installed a new 75 AH AGM with one of your controllers. I was disappointed with the run time on the AGM and suspected that one or the other battery might have a problem and therefore did a few simple tests.

Upshot of my testing is that the main battery gets to 13.77 V and shows fully charged and once disconnected from the charger it drops to 12.65 V within an hour and a half with nothing connected.

The second battery is fully charged at 13.77 Volts also and drops to about 12.78 Volts with nothing connected.

Now I connect the two batteries through the controller and the main goes up to 12.71 Volts and the auxiliary drops to 12.71 Volts

Leaving the car parked for a day and a half without driving it both batteries drop down to 12.4 Volts. I’m not sure if this is normal but am beginning to suspect that something is trying to drain the main battery (without me running anything off it). I pretty sure the auxiliary battery is OK as I have a Baintech meter on it which gives me SOC and current draw (which reads 0).

So the way I’m reading it is that the reverse charging facility is not good for the SOC of the auxiliary battery which is used for running fridges etc.

I saw a post somewhere on AULRO describing how to measure current draw from the fuse block and will have to do some measuring. Unfortunately, I have little information on the Caterpillar Calcium starting and deep cycle battery (two years old) that I run as a main and am not sure if the voltage drop is normal or abnormal. What I do know is that the voltage drop of the main with nothing connected is faster than the auxiliary.

Cheers,

Franz

If you have a multimeter most have a current function (optimistically they camandle 10amps generally, however unlikely the leads will!)

For what you are doing it will be fine. Basically just put it in line on either side of the positive supply to the fuse block. Better still take the leads off of the positive battery terminal and place your multimeter in line. This will tell you what is being drawn. If there seems to be power draw but everything is off then tale the fuses out one by one to work out which circuit/item is drawing the power. Inveters are a common source of power draw, it is often best to be able to isolate them when not being used.

There are current clamps and even standalone ones that plug straight in to the fuse holder, but a simple multimeter is sufficient for what you are looking to do.

Leaving any battery partially discharged is not good for it, because of the back drain in an ideal world you woulD keep the batteries of identical design and age with this set up, but that isn't practical or economical.

If your driving it most days it will be giving the auxillary a chage anyway and wont really matter, if your not then it would be better to disconnect the aux battery to avoid shortening the life of your aux battery.

What sort of items are you running on your battery, this might give us a better gauge or some suggestions to improve your run time, certainly it back draining to the main battery is not helping things.

Hi Franz, unfortunately there is a lot more info needed to be able to determine whether you have a problem or not.

Forget the readings you get after using a battery charger, they charge batteries in a different way to what happens while your driving.

Now you say your batteries “SETTLED” back to 12.4v.

This does not mean they “DISCHARGED” back to 12.4v and while I was not surprised at the readings you got just an hour and half after your stopped charging the batteries as this was still just surface volts not battery SoC.

Your actually need to leave the batteries in a No Charger/No Load state for at least 24 hours to get any form of true indication of what the real SoC of your batteries.

The other factor for the voltage reading is just how long you drove for before leaving your vehicle for the day and a half?

If you have done a few short drive and then left your vehicle for a day or two, the AGM will normally take a charge quicker that your cranking battery, NOTE this “ONLY” occurs when charging from an alternator, not when using a DC/DC device or battery charger, so if your have done a few short drives, your cranking battery might be down a bit and your AGM is keeping it topped up.

There is an easy way to check if there is a problem. Next time you know you are going to be leaving the vehicle unused for a day or two. Before you turn your motor off, switch the USI-160 In-Cab controller to the IGNITION mode, ( switch the switch towards the LED ) and leave it that way.

In SHARED mode the common battery voltage has to drop to 12.0v before the batteries are separated.

In IGNITION mode once the common voltage drops to 12.6v, the batteries will be separated, so with your USI-160 set to IGNITION mode. the batteries will separate at a much high voltage and you can then see if either ( or both ) battery settles to a lower voltage or just keeps discharging.

Now a note, if your cranking battery is a Calcium/Calcium battery then is it not uncommon for them to settle back as low as 12.2 but they will still be in an excellent condition.

As posted earlier, because of the way my isolators work, they tend to keep cranking batteries in a higher state of charge than normal, and this is why you need to bypass the SHARED mod to test your batteries.

Use the chart below to determine the rough SoC of your batteries.

Originally Posted by drivesafe

Hi Franz, unfortunately there is a lot more info needed to be able to determine whether you have a problem or not.

Forget the readings you get after using a battery charger, they charge batteries in a different way to what happens while your driving.

Now you say your batteries “SETTLED” back to 12.4v.

This does not mean they “DISCHARGED” back to 12.4v and while I was not surprised at the readings you got just an hour and half after your stopped charging the batteries as this was still just surface volts not battery SoC.

Your actually need to leave the batteries in a No Charger/No Load state for at least 24 hours to get any form of true indication of what the real SoC of your batteries.

The other factor for the voltage reading is just how long you drove for before leaving your vehicle for the day and a half?

If you have done a few short drive and then left your vehicle for a day or two, the AGM will normally take a charge quicker that your cranking battery, NOTE this “ONLY” occurs when charging from an alternator, not when using a DC/DC device or battery charger, so if your have done a few short drives, your cranking battery might be down a bit and your AGM is keeping it topped up.

There is an easy way to check if there is a problem. Next time you know you are going to be leaving the vehicle unused for a day or two. Before you turn your motor off, switch the USI-160 In-Cab controller to the IGNITION mode, ( switch the switch towards the LED ) and leave it that way.

In SHARED mode the common battery voltage has to drop to 12.0v before the batteries are separated.

In IGNITION mode once the common voltage drops to 12.6v, the batteries will be separated, so with your USI-160 set to IGNITION mode. the batteries will separate at a much high voltage and you can then see if either ( or both ) battery settles to a lower voltage or just keeps discharging.

Now a note, if your cranking battery is a Calcium/Calcium battery then is it not uncommon for them to settle back as low as 12.2 but they will still be in an excellent condition.

As posted earlier, because of the way my isolators work, they tend to keep cranking batteries in a higher state of charge than normal, and this is why you need to bypass the SHARED mod to test your batteries.

Use the chart below to determine the rough SoC of your batteries.

Thanks for your elaborate answer Tim - I'll do some more testing.

What is the USI-160 in cab controller that you refer to?

BTW, did you get my email regarding the user instructions?

Cheers,

Franz

Hi Franz and first off, I did get your E-mail and will fix that tomorrow.

Next, I forgot you have an SC80 not the USI-160.

You can do the same test by disconnect the earth lead on the SC80 when you turn the motor off and see what happens to each battery.