Starting voltage threshold

[DiscoGav]

Does anyone know what the minimum battery voltage the module controlling the start circuit wants to see before sending a start signal to the starter motor when pressing the start button?

[101RRS]

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

[DiscoGav]

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

[BobD]

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

[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?

[DiscoGav]

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

[DiscoGav]

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

[DiscoGav]

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

[DiscoGav]

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.

[drivesafe]

Hi Gav, you don’t need to trick the alternator into running at a higher voltage, they know when a cranking battery is low and they adjust the charging algorithms accordingly.

I suspect the problem may be of your own doing.

When you drive, how long do you drive for.

Also, when you replace the auxiliary battery, go for an Optima Yellowtop. They are much better suited to what you need.

[DiscoGav]

It the wife's daily drive, 3 days a week it will travel 30km round trip with at least 2 or 3 stops the other 2 days would be less. I might take it to the shops some nights but I always go the long way ;-) than on weekends it gets some good runs. I have put the battery on charge once but have been meaning to charge it more often. So it mainly gets short runs. Thanks for the tip regarding the yellow top I guess having 2 healthy batteries would help too. Some battery brands recommend a n70zz size and some the din85l mf are these batteries similar in performance?

[SBD4]

I had to replace the original battery in my 2010 D4 2 weeks ago. I had couple instances over the paste few months were it would not start. If I left it for 15mins it would start. the message I got referred to steering lock being locked - thought it was an old gremlin that had raised its head.

Then, I had the situation were the car would not start at all. I left it over night and tried again next morning with no luck. I checked the voltage of the battery via the the secret menu which showed it to be 12.4V (accessories on) which I thought was plenty to start the car. I ended up doing a hard reset and tried again with the car starting immediately.

The service was due next day and LR reported that the battery was on its way out. I took their word for it and replaced the battery.

The car sees 200-230km round trips at least 2-3 times a week so it gets plenty of opportunity to charge the battery.

[DiscoGav]

What's this secret menu you speck of SBD4? I get "engine systems fault" but only after holding the start button for about a minute.

[SBD4]

What's this secret menu you speck of SBD4? I get "engine systems fault" but only after holding the start button for about a minute.

if you have the big screen you access the secret menu as follows

go to the home screen
touch the middle of the top banner for 5 seconds
touch the left of the top banner for 5 seconds
a number pad will display to enter a passcode
enter 753 then press 'OK'


the secret/service menu is displayed.

for 2010-2011 D4 see the vid below - I take no responsibility for the music, its not my vid!!
Using the Discovery 4 diagnostic screen multiple times during one session - YouTube

D3:
LAND ROVER DISCOVERY 3 DIAGNOSTIC MENU ENTRY - YouTube

[DiscoGav]

That first video is classic 90s "corona" I think that was, not the beer or the car.... Haha I have the poverty pack discovery which is still way ahead of the middle speck toyota..., so no sat navigation, that's a cool trick though

[DiscoGav]

Well found the problem and now it's all sorted, measured voltage at the starter motor on both sides of the solenoid and found battery voltage on battery post but 10 volts at the most. Some attempts to start measured as low as 2 volts and the starter made no noise at all. Pull the starter out and connected a battery to it and energised the signal post, nothing a small spark but nothing. Starter not working. Had some dinner and searched for new state prices $660 was the best I found. That was a motivator, pulled the brushes cover off and found the brushes corroded and jammed in there carrier. With a tidy up and lube I assembled the starter and tested all good. Fit the starter back to engine and started all good the engine is spinning faster than ever! I have taken some photos but in all the action tonight my camera has gone walking. Anyway thought I'd update

[drivesafe]

Good to hear you had a cheap fix.

Please post up the pictures when you locate your camera!