Thread: Starting voltage threshold

I do not know but I do know that it is less than 11.5v as my RRS will start OK with the battery that low.

Garry

No worries thanks I have a 2010 d4 which won't start, battery is showing 11 volts while pressing the start button but no noise at all from the starter. With jumper leads on another battery battery voltage above 12 but with starter button pressed voltage drops to 11.5. This was all trying to start the car for the wife while I should have been at work. The trusty old d1 fired up so she has taken that, battery is currently on charge I'll try again this arvo also I'll try and reach the starter signal wire on the starter if I can get my hand in there test for a signal there. The d4 went swimming a month ago I wouldn't be surprised if the starter has suffered from it

You may have a failed starter. My 2010 D4 starter failed in similar circumstances at a shopping centre in Perth exactly 7 days after returning from a trip to Cape York, which obviously involved some swimming.


The starter is pretty well sealed and there was no sign of any water or dust damage in mine. However, the coincidence is too strong for me to ignore the link with the Cape York trip.


In my case there was a burning smell and smoke from the starter when pushing the button so it sounds a bit different to yours. However, there was no sound even though the starter was being activated and at first I thought it was a flat battery. However, it was the same when I used the Traxide USI 160 to link the second battery so I realized it was not the battery, which was confirmed when I saw smoke.


Bob

Hi Gav and as Garry posted, you should be able to start your motor using a battery with an SoC of 11.5v

There is a catch, the battery might be near flat but it must be in good condition.

So if your battery is on it’s way out, then it may be the problem.

But if your battery is in a good condition but in a low state of charge, the problem could be elsewhere.

Do you know why the battery was in such a low state?

Gee yeah smoke is bad, I have no smoke or burning smell the starter doesn't even feel warm after trying to start I tested the mega fuse too 0.3 ohms across fuse so it's all good

So the disco started but after a 10 second delay and turned over slower than usual on its own battery starting voltage of battery was 12.6 unknown during cranking once running with lights fan demister compressor battery voltage is 13.9 volts at idle so that tells me it's charging. Shut the engine off after 10 mind at idle and tried to start, no go..... Battery voltage is12.6 and depending on what part of the starting cyclist would fluctuate between 11.0 and 12.1 volts glow plug light would glow for a sec but a few normal clicks but no starter click. The battery is back on charge and I'll leave it there over night

Originally Posted by drivesafe

Hi Gav and as Garry posted, you should be able to start your motor using a battery with an SoC of 11.5v

There is a catch, the battery might be near flat but it must be in good condition.

So if your battery is on it’s way out, then it may be the problem.

But if your battery is in a good condition but in a low state of charge, the problem could be elsewhere.

Do you know why the battery was in such a low state?

Gday Drivesafe, The battery was in the car when we bought it in Feb, Its a century Din85L MF and being a century i'm guessing its not the original battery. The car is also fitted with one of your isolators/ battery chargers (SC80-12) with a D34m Blue top optima battery as a second battery.since buying The Disco, the led on the isolator was flashing most of the time when the engine was switched off so once i found out, that the isolator was trying to tell me that the main battery was below 12v also i noticed the optima was always very hot and swollen after a drive with that in mind, i guessed there must be a shorted cell in the optima and the meter told me 9 volts was the highest it would read when the battery was on its own. so the original battery would have always been drained to its 12 volts every time the car was switched off over night. I have no idea how long its been like this. I've disconnected the negitive cable off the optima and have been meaning to replace the second battery but are optima batteries really all that good?. in the mean time I have been operating a fridge off a power supply on the second battery side of the isolator which has been good If the fridge was on for to long the isolator would switch off keeping the starting battery healthy. it has been sent flat probably 3 times since Feb but only flat enough to not turn the engine it would still operate the lights. so there's some history on the battery. can you explain why a battery on its way out can cause This trouble instead of just turning the engine over slower? is it due to the battery not recovering from a high load quick enough? also there must be a voltage limit where the control module won't attempt to operate the starter motor. also is there a way to trick the charging system to charge all the time to ensure even on short trips the battery is being charged from the alternator? I have many questions... sorry but thanks in advance

measuring current draw from the battery

3.22 Amps with Ign off but dash centre and Radio screen lit
2.93 Amps immediately after the centre dash turns off
0.90 Amps 30 Sec or so after
0.55 Amps 30 Sec or so after again
0.50 with Electric brakes disconnected no other aftermarket features connected

over 20Amps (as it blew the meter's fuse) with the ign on.

I think my battery is stuffed but will charge over night see results in the morning.