Another flat battery question

Another flat battery question

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Paulprior

Original Poster:

802 posts

82 months

Thursday 12th May
quotequote all
I am now getting a flat battery after 2 to 3 days, normally it would be ok for maybe 2 weeks, so I have read through a lot of old posts and started with a clamp meter on the battery negative, around 600mA with the door open, if I operate the door switch manually I get 2 scenarios, one the current drops to around 450 for 20s then drops to 300, second option I start around 500 which then increases to 600 as soon as I touch the switch and then drops to around 450 20 s later, so clearly something wrong here sometimes, at no point does my interior light come on though, so I guess one current change is from the delay timer coil, any thoughts on the second step ?

I have then pulled all the fuses one by one and 3 thst make a difference, so counting from the left I have no 4 that reduces current by approx 150 to 200mA but is a little strange in that inserting the fuse does not increase the current again, that only happens after I operate the door switch, this fuse is 30A, the other 2 fuses, no6 at 25A and no19 at 10A both decrease current again by 150 to 200mA but these ones see the current going back up as soon as they are re inserted, looking through the bible I do not see any of the layouts having fuses that seem logical, the one on p241 seems the closest but has differences on relays used, so is it a case now of pulling each of those fuses to see what doesn’t work or is there a more technical approach

Belle427

6,175 posts

210 months

Friday 13th May
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The interior light circuit is a popular one, try removing the relay, I think its the large yellow one top right in the fusebox.
Door switches are common problem areas, worth checking these are ok.
I'm sure there is a mod where you can replace the interior light delay relay with a normal one and it just means you lose the time delay on the light, worth searching for this.

Paulprior

Original Poster:

802 posts

82 months

Friday 13th May
quotequote all
Hi Bel427, yes the interior light delay relay shows up as the most common issue, I did try to remove it as I assumed that was the easiest test, but it refused to come out, not a good sign, I will try again today but need to find a way to support the fuse box first so I don’t whip the whole thing out, but even if removal stops that drain I still have 2 other circuits causing an issue

Steve_D

13,549 posts

235 months

Friday 13th May
quotequote all
Agree the interior light relay issues. Big yellow one. You will need to take out a mortgage for a new one.
Second issue is that in most cars fuse 4 is the cigar lighter.
Fuse 6 does, hazards, door opening & central locking.

If you PM me I can send you my circuit diagrams which may help you tracing things.

A common theme here looks to be the door switches. Due to where they are they get corroded.

Steve

ETA F19 is horn.

Edited by Steve_D on Friday 13th May 08:54

Paulprior

Original Poster:

802 posts

82 months

Friday 13th May
quotequote all
Hi Steve D, thanks for the cct, I will PM you.
If I remove the interior light relay and leave it out, I have no use for it, does that remove this cct as a battery drain possibility?
Have a little gadget as in the photo plugged into the cigar lighter, but surprised that it would so much current, normal lift it to break contact when I get out, but I also see that cigar lighter is also normally linked to wing mirror heater, any idea on how they switch on / off, the horn doesn’t sound a likely issue, I am sure I would notice that, but I will try tonight to remove those fuses one by one to see what stops working

Steve_D

13,549 posts

235 months

Friday 13th May
quotequote all
I'm not aware of any connection between cigar and mirror heaters amd the supply (F4) is permanent so the heaters would be on all the time.

Circuits sent.

Removing the interior light relay will remove the normal power drain issue however it should still be possible to switch the interior light on manually should you need it.

Steve

Loubaruch

1,033 posts

175 months

Friday 13th May
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Paul,

If you remove the coutesy light relay and simply short out two contacts on the relay base the courtesy lights will switch on via the door switches.
No time delay but m,akes things much simpler.

See here:

http://www.bertram-hill.com/courtesy-light.html

QBee

18,766 posts

121 months

Friday 13th May
quotequote all
I agree that the interior light circuitry is a pain in the bum.

Another "fault" that many people spend hours chasing and £££ on parts trying to fix generally turns out to be an old battery that simply needs replacing.
The 12 volt battery in a car has an average life of 6 years. Any idea how old yours is?

A knackered battery causes so much grief.

Tyre Smoke

21,353 posts

238 months

Friday 13th May
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Pulled my light relay. It came out in several pieces. I made up a jumper wire for the socket where it was, voila I now have light on/light off with the door opening or closing.

I also replaced the battery. They hate not being cycled and let's face it, a Chimaera isn't a daily driver.

Paulprior

Original Poster:

802 posts

82 months

Friday 13th May
quotequote all
Yes it could be the battery, it’s 5 years old, but then again how long would it stay charged with a new battery if was taking 0.6A all day long?
I have removed the interior light timer, it never worked anyway so not bothered about that, my current is now down to 250mA, so less than half of what it was, the strange thing now though is that if I pull fuses 4 and 19 which are cigar lighter and horn I get no further drop in current, I don’t see any logic in this
But anyway, I will see if the battery stays charged for longer now

Loubaruch

1,033 posts

175 months

Friday 13th May
quotequote all
250mA is still a substantial current drain.

Alarm/immobiliser and central locking are possible culprits for the additional drain.
I found that even with all circuits isolated from the battery there was still 20mA drain that I put down to leakage within the alternator.
As I store the car in a locked barn I completely isolate the battery, to remove all residual current drain.

My battery failed in 2009 while away from home and the RAC installed one that is still fine today, i.e. 13 years later !
The battery only has RAC markings but it must be something decent. Even more surprising in that the car is laid up over the winter months with the occasional boost charge.
Anyone know what make of battery the RAC supply?

Steve_D

13,549 posts

235 months

Friday 13th May
quotequote all
Don't forget that not all +12v goes through fuses so pulling fuses will not identify all possible losses.

Steve

Belle427

6,175 posts

210 months

Saturday 14th May
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If you can’t connect to a conditioner I’d look at an isolator, I think the car will run a bit lumpy for the first couple of minutes when you start it up due to the ecu being reset but that’s not such a big issue.
Some here have used the battery brain unit.

https://www.batterybrain.co.uk/

A quality battery from the likes of Varta or Bosch should last 5 years or more in my experience.
If you have a cd changer check this too, these can sometimes be a culprit for drains.

QBee

18,766 posts

121 months

Saturday 14th May
quotequote all
Paulprior said:
Yes it could be the battery, it’s 5 years old, but then again how long would it stay charged with a new battery if was taking 0.6A all day long?
I have removed the interior light timer, it never worked anyway so not bothered about that, my current is now down to 250mA, so less than half of what it was, the strange thing now though is that if I pull fuses 4 and 19 which are cigar lighter and horn I get no further drop in current, I don’t see any logic in this
But anyway, I will see if the battery stays charged for longer now
I removed the interior light completely from my car because it flattened the battery once too often. I also had the alarm/immobiliser replaced back in 2012 with the latest (then) Meta 99T because I was having weird immobiliser issues. My car will go over a month without being started or charged.

I also had a cut off switch fitted for the sake of guys working on the car. Now, when not using the car for any length of time, I simply isolate the battery.
But my car is not in sight of the road and is behind an electric gate. Battery Brain with remote activation is a far more elegant solution for general use than a simple switch.

I am told by my TVR guy that he fitted a battery switch on his Chimaera race car, turned it off in October and six months later the battery was still fine (at about 80% charge) and started the car first touch.

Paulprior

Original Poster:

802 posts

82 months

Saturday 14th May
quotequote all
I have been reading on this forum for several years and often hear stories of the Meta alarm and it’s issues, but I have the Foxguard one that rarely seems to get a mention, so these also have a history of issues?
Although removing fuses 4 and 19 no longer reduce the drain fuse 6 does, it seems to follow Steve D cct, thank you very much for that, with that fuse removed I am close to zero drain, but as it’s immobiliser and central locking I do need to refit it.
I have looked at the door switch, it looks reasonable but what I don’t understand is the central locking system, if I have the passenger door open and press the switch I hear a relay operate in the left of the dashboard, when I release it I get a clunk from just behind where the door opens, what is that relay and clunk doing, my reason for asking is that I get a variation in drain, sometimes pushing the switch in reduces the drain by 100mA and then back up when I release, but sometimes it does the exact opposite, I know it sounds like it should be the switch but if listen for the relay and clunk they always remain in the same sequence,, if I remove fuse 6 central locking doesn’t work but the doors still open and close and stay secure, so what is the clunk near the door latch doing if I am not locking the car?, it’s a 95 with the door opener on the rear wing.
I do have a CTEK conditioner but it would be nice to connect every time I get out of the car

Belle427

6,175 posts

210 months

Saturday 14th May
quotequote all
Door solenoids do get some abuse and moisture ingress so can do silly things.
I've not looked how the system wired so can't help much on the solenoid operation, probably how Tvr chose to wire it.

QBee

18,766 posts

121 months

Saturday 14th May
quotequote all
I have had to replace door solenoids a few years ago - not expensive. They are in the door frame behind the door.

Steve_D

13,549 posts

235 months

Saturday 14th May
quotequote all
The fact you say touching a door switch changes the drain makes me think they are still the issue.
Both door switches need to be carefully cleaned or replaced. When refitted you also need to ensure the body of the switch is making a good earth as it is fitted into fibreglass so there should be some sort of earth wire.
The clunk you hear from the left side of the dash is the central locking control module.

Steve

Paulprior

Original Poster:

802 posts

82 months

Sunday 15th May
quotequote all
Hi Steve D, any idea why closing the door should operate the central locking relay?, maybe the 100mA change I see is energising the coil?, the only thing I can think off that would change when closing the door is the interior light delay relay, but I have removed that, anyway I got bored looking at this today so I went for a drive, not good, misfire gremlins that I thought I had fixed last year came back with a vengeance, last year I tightened up all the spring connections in the pump and main power relays and the car has run perfect since for about 1300 miles, so all I have done this week is remove the fuses and disturbed the rats nest.
On returning home I kept the engine running and twisted and shook all the rats nest cables, nothing, taped all the relays and ecu to try and simulate vibration, nothing, stopped and removed the ecu, checked all the plug spring clips, they all look ok but if I insert a small spade terminal in each one there is a big variation in grip, how easy would it be to replace the ecu connector, the relay bases or the loom?, I have an NC 500 trip planned for July but if it keeps running like this I will need to take the wife’s mx5, that would be embarrassing

Belle427

6,175 posts

210 months

Sunday 15th May
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It’s annoying problems like this that finally led me to going to an aftermarket management system on my old car and replace all that Tvr wiring.
It’s expensive granted but if your cars a keeper it’s money well spent and will improve your enjoyment of the car.
Half the problem is the lack of quality spares now available for the ignition system.