Optima Yellow Top Issues

**seqfisho** · 28th February 2016, 08:14 AM

This is probably the wrong place but as it is in the battery compartment under Hanks passenger seat it definitely is Defender related

We were giving Hank the big clean out yesterday, 12 years of red dust and grime, while cleaning away I discovered the stereo wouldn't turn on, possibly caused by the fact that the center dash has been slowly self destructing most likely caused by 250K km's of corrugations and off-road travels.

So as I dived into the dash to fault find, expecting that the movement of the stereo unit had somehow dislodged a wire or plug. Unfortunately what I found was something akin to the Prince of Darkness's failed attempt at becoming a spaghetti maker, wow what a nightmare

Anyway after checking the power plug for the stereo it was discovered that it was only reading 6.3V, mmm me thinks a bad connection somewhere in this tangled mess, however after disassembling most of the dash and discovering the feed runs back to the auxillary battery I check it's voltage directly at the terminals and suprise suprise only 6.3v there too, which means I could have saved myself around 2 hours tracing wires and rebuilding the dash

As I have never had anything to do with AGM batteries before, do they drop cells like normal wet cell batteries.

Do they discharge that low if left for a couple of weeks before recharging.

Hank has a Traxide SC80 DBS, and the led is solid yellow which I believe means the main battery is ok and they are isolated from each other.

I didnt check to see if the voltage went up with the motor running as I was out of time and the mossies were congregating

We will be taking Hank for a run today and I'll check the battery when I get back, but I'm suspecting it will be stuffed

DiscoMick · 28th February 2016, 08:20 AM

How old is the battery? You could put it on a multi-stage charger for maybe a week to recodition it and see if it will hold the charge. Batteries, including AGMs, need regular charging to stay healthy.

Sent from my SM-G900I using AULRO mobile app

**drivesafe** · 28th February 2016, 09:47 AM

Hi Glen, the LED on the SC80 should only be solid after the motor has started and with such a low auxiliary battery, the LED could start flashing again not long after turning the motor off.

If the LED was solid before you started your motor, there is a problem and most likely at the SC80.

If you get a chance, measure te voltage of both batteries before you start your motor and again after after you start your motor.

**seqfisho** · 28th February 2016, 05:29 PM

Had a quick check when we got home, did a little over 250km all up with about 200 of that at 90-95kmh the rest was crawling and bush tracks although still with a few revs on.

Unfortunately I forgot to check with the motor running, but at rest the Aux still 6.3v and the main was 12.8v, the SC80 led was solid.

If I get home early enough one afternoon this week I'll kick Hank in the guts and measure again.

**slug_burner** · 28th February 2016, 05:30 PM

I have had my yellow top D31 I think, it has the offset round wound plates very flat and it comes back ok after a day or two on a multi stage charger.

Good luck, don't give up until you have tried to recover it.

DiscoMick · 28th February 2016, 06:44 PM

Needs more than a drive to recharge if that low. Give it several days on a multi-stage charger and then see. Doesn't sound good.
As Drivesafe said, also see if the light is solid yellow both before starting and with motor running.

Sent from my SM-G900I using AULRO mobile app

**drivesafe** · 28th February 2016, 07:14 PM

Originally Posted by seqfisho

Unfortunately I forgot to check with the motor running, but at rest the Aux still 6.3v and the main was 12.8v, the SC80 led was solid.

Hi Glen and there is a problem.

Can either sort it out on here, works as a good instructional session for others, or you can phone me and I will walk you through a few basic tests, but it does look like the problem may be the SC80.

**Fluids** · 28th February 2016, 07:50 PM

I'm with Tim on this one ... If the LED was solid, the SC80 has both batteries connected, and therefore, you should get as good as the same voltage reading at both batteries .... Except the SC80 isn't actually connecting the batteries, even though it says it is .... Meaning the aux optima hasn't been getting any charge for quite a while.

I could be wrong .... ???

**drivesafe** · 28th February 2016, 09:10 PM

Hi Kev and yes that is my ASSUMPTION at this stage.

Most likely the SC80, but it could be a number of other causes.

The most common problem I deal with is bad earth connections.

I had a situation just recently where the voltage across the auxiliary battery's terminals was 7.0v but the SC80 had 13.9v on both the input and output, with the motor running.

The auxiliary battery negative terminal to earth was measuring 6+v. It should have been 0v.

The earth connection to the body had not been tightened up properly and had worked itself loose.

DiscoMick · 2nd March 2016, 12:51 PM

So (sorry if this is a dumb Q but I'm just a mug punter about electrickery), should his first step be to make sure all his earths are good?
If the earths are OK, then what?
If the second battery is cactus, but the first battery is good, so the SC80 keeps them connected, then would the first battery be sucking down the dud second battery?

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