Thread: TD5 Defender Battery drain

Originally Posted by willie

Argh!

'02 TD5 Defender - with dual Exide Orbitals and a SC80 Dual Battery Controller. All new and installed six weeks ago. Previous battery was original - no change in driving habits. DBS set up working well - couple of 3-4 hour trips ...lots of shorties (daily driver).

The last couple of weeks, the truck has been hard to start first thing in the morning. It's getting cold, but face it, it's Perth. Turns over sluggishly a few times then nada - cranking battery flat - jump start with the aux. No problems for the rest of the day.

Check with multimeter. Cranking batt first thing in morning is down to 12v or less. SC80 has isolated aux at some point during the night (Thanks Tim). Alt recharges at 14v +

Possible candidate for shopping trolley syndrome (thanks Tim) so onto the charger overnight. Next day, no prob. Fol day, same, sluggish cranks, SC80 led flickering (ie. batts isolated) - jump start from aux. Kids getting used to passenger seat flying and jump lead surgery.

Poss that battery isn't holding charge. Swap over aux and crank (both exide orbitals) and next day, still same prob. I can hear the cranking batt working ...

Buy a fancy clamp ammeter. am loosing ~0.6 - 0.8 amps at the + terminal.

Pull all fuses and relays - no change

Disconnect alternator (disconnect batt first ... carefully tie up loose cable...) still no change - still loosing amps.

Where are those amps going?!

Anyone have an idea?!

w

You can eliminate the car's electrics from suspicion by disconnecting the SC80 circuitry, and leaving one battery connected to the car's electrics.(Return it to standard form, in other words) Check then whether there is any standing current drain.

From what you have described, it seems that the SC80 might be drawing too much current for some reason, and flattening the main battery.

Cheers,

Lionel

I had this problem on my car, but I think my problem was different. It occurred for me without the change in batteries or circuitry. I found that the ERPS on the car doubled the drain of the cars electrics. This, combined with us not driving the car much was causing the problem.

The thing is, with a 600 ma draw it should take a long time (at least 3 days at 15 amps a day) to knock the starting battery down until it won't start.

Hi Lionel, the SC80 will draw about 250-300ma while in the cut-in mode, but this current draw will not flatten a battery over night because it’s actually drawing off two batteries at the same time so would take at least a fortnight to get the two batteries down to a state where the SC80 would then cut out, at 12v, and would only be drawing about 25-30ma from there on.

Over the years I’ve come across two usual causes of this type of problem, the most common is a battery failure and the other, an alternator diode failure.

Just a couple of suggestions!

Hi Tim .. cheers. Thanks for helping me out intially via e-mail.

So while the SC80 led is lit, draw should be ~250-300 mA (or .25 Amps) ...plus the ~50mA that the alarm clock and radio draw (all factory) ... so say ~300-350mA (0.35 Amps). Then if the SC80 led is flashing (ie. batteries isolated) then it is 25-30 mA plus the 50 mA for accessories so say 75-80 mA or 0.075 Amps?!

I swapped over the batteries, so unless I've got two duds (ok, not beyond my run of luck ...) I'm pretty confident they'e not the culprit.

I'm not conviced the clamp meter is reliable. I disconnected the - and still got a reading at the + cable ... and depending on where you have the cable in the clamp changes the reading ... perhaps thats why it was only $75.00 ...

Went back to using multimeter in series with + and cable ... current draw is still there (and you can hear the battery churning away!) based on reliability of clamp meter (or lack thereof), might have to redo the fuses/relays with the mulitmeter method to double check my results.

Who are the usual suspect? How do I check the alternator diodes?

Cheers all.

Start by disconnecting the alternator completely and then checking for current drain. When I had a difficult constant current drain to diagnose recently I brought the mutimeter inside the cabin via a pair of jumper cables, touch the circuit together, and finally heard a relay operate which was wired wrong, i.e. permanently!

Originally Posted by willie

Argh!

'02 TD5 Defender - with dual Exide Orbitals and a SC80 Dual Battery Controller. All new and installed six weeks ago. Previous battery was original - no change in driving habits. DBS set up working well - couple of 3-4 hour trips ...lots of shorties (daily driver).

The last couple of weeks, the truck has been hard to start first thing in the morning. It's getting cold, but face it, it's Perth. Turns over sluggishly a few times then nada - cranking battery flat - jump start with the aux. No problems for the rest of the day.

Check with multimeter. Cranking batt first thing in morning is down to 12v or less. SC80 has isolated aux at some point during the night (Thanks Tim). Alt recharges at 14v +

Possible candidate for shopping trolley syndrome (thanks Tim) so onto the charger overnight. Next day, no prob. Fol day, same, sluggish cranks, SC80 led flickering (ie. batts isolated) - jump start from aux. Kids getting used to passenger seat flying and jump lead surgery.

Poss that battery isn't holding charge. Swap over aux and crank (both exide orbitals) and next day, still same prob. I can hear the cranking batt working ...

Buy a fancy clamp ammeter. am loosing ~0.6 - 0.8 amps at the + terminal.

Pull all fuses and relays - no change

Disconnect alternator (disconnect batt first ... carefully tie up loose cable...) still no change - still loosing amps.

Where are those amps going?!

Anyone have an idea?!

w

Did you sort out this problem?

Cheers,

Lionel

Right then, problem solved. Feel my pain.

I went back to the battery place and they checked the batteries ... well known Battery shop with a global name .. the tested the batteries with a multimeter and pronounced them fine ... performed the same magic with the motor running, pronouncing the alternator as working ... clamped a clamp meter on the pos cable (on, not around) and proclaimed parasitic drag as the culprit ... we had a discussion about Hall Effect and magnetic fields and shielded cables ... I left feeling disillusioned, bested by the 18 yr old clamp wielding under-assistant manager in training.

Rechecked my work. Rechecked drain (multimeter in series at battery, pos and neg, and at alternator ... jeez that's nervous work). Let duty cycle clear and hold the tongue the right way, and 20mA (0.02 Amps).

Right, charge both up overnight and start with a clean slate.

So, I disconnected the SC80; and for the next couple of days, all seemed fine. Morning starts not a problem. Main drops from 12.7 to 12.5 overnight, but cranks ok. Aux holding at 12.7.

Hmm, must be the SC80 or my wiring ... but, as Tim (Drivesafe) pointed out with the amount of current loss I experienced the SC80 should have been molten slag in the battery tray ... that, and when it was connected it did work as it was supposed too ...

Each morning, testing with the multimeter I noticed that the cranking battery would go from 12.7 to about ~12.3/4 overnight, and the totally isolated aux would do this more slowly, over the week ... that's not right.

Drive around for a week without the passenger seat and battery cover gives a new dimension to road noise. Luckily the kids don't usually ride up front!

I spent the best part of the weekend returning the system to stock and troubleshooting everything I could find on the crank side that might be draining the battery.

Sitting in the school pick up line, listening to the stereo, actually watched the volts drop on the multimeter ....

Enough, bypass the battery shop and went to Exide and had the batteries tested ... both have dropped cells, one totally and one well on the way.

The worst battery is the original cranking battery .. which makes sense (now!) as initially the SC80 had disconnected them and the cranking battery was well past 12v because it kept draining after it was isolated due to the normal parasitic drain, but the Aux was above and had enough omph to jump start ... and thinking back, when I swapped them over they still isolated but they were both around 12v ... so indicators were there if I had actually noticed the difference between the voltage readings (albeit subtle!).

So anyway, Tim (Drivesafe) was my first port of call when the problems started, and going back through the e-mails, his first question was 'are the batteries OK' ... 'go and have them load tested' ... my response 'mate, they're brand new ... can't be the problem' ...

The Exide chap (the Exide warehouse at Dianella) was brilliant. Tested, diagnosed and sorted in a few minutes, then straight onto the computer to find replacements - no stuffing around, no asking for receipts, proof of purchase, just no-nonsense 'we'll swap them out, no problem'. Stock arriving tomorrow; he was so concerned that I'd be stranded in the meantime he wanted me to take a cranking battery with me ....

He did say that they hadn't had many problems with the Orbitals, but if a battery was going to fail then they would in the first three months. He also said that although they were 'dual purpose' they did take longer to recharge ... so probably more prone to the 'shopping trolley' syndrome.

Thank goodness ... I was a day away from forking out for a new alternator ....

In my experience the SC80 is a dumb device (sorry Tim). It just sits in there all the time - sees what is going on and makes it's decisions based on the rules it has to work with (thanks Tim) It's the first thing people suspect but it's the last thing to go wrong.