Starter/Battery Cable (How Long?)
Discussion
The answer is well over 7ft!!!!
Or "Too Fooking Long"
A 2.25 meter run of suspiciously light gauge low amp starter cable that's been on the car for 16 years & suffered thousands of heat cycles from radiant engine heat.
Oh and then there's the earth path back through the chassis; for the poor old starter motor that must be a 15 foot loop!
Hmmmm
And people wonder why these cars suffer from difficulty when restarting hot.
The resistance during a hot start must be enormous
The plan is to make up a new one in some proper marine grade 6awg tinned copper cable & run an additional 6awg earth cable from the battery negative terminal direct to the engine block.
Add my new Odyssey PC1500 battery into the mix and hot start issues should be a distant memory
Or "Too Fooking Long"
A 2.25 meter run of suspiciously light gauge low amp starter cable that's been on the car for 16 years & suffered thousands of heat cycles from radiant engine heat.
Oh and then there's the earth path back through the chassis; for the poor old starter motor that must be a 15 foot loop!
Hmmmm
And people wonder why these cars suffer from difficulty when restarting hot.
The resistance during a hot start must be enormous
The plan is to make up a new one in some proper marine grade 6awg tinned copper cable & run an additional 6awg earth cable from the battery negative terminal direct to the engine block.
Add my new Odyssey PC1500 battery into the mix and hot start issues should be a distant memory
carsy said:
Never really thought of it like that but yes very good point. Think you`ve found a good solution to the hot start problem many have. So i take it, its going to be an additional earth to the engine as well as the battery to chassis earth.
Where are you getting your new cables made up.
Funny really when in my opinion the ModWise hot start kit has nothing much to do with fixing the hot start problem.Where are you getting your new cables made up.
The Modwise hot start kit is just a relay, it simply masks the fact that the relay in the immobiliser was never quite man enough to to take the amps required to energise the starter solenoid.
The Modwise hot start kit should really be called the immobiliser relay kit.
I believe the true hot start issue is down to having such a long starter cable that was not sufficiently heavy enough to deliver the amps to the starter motor when the cable gets hot.
As we know the longer the cable the more resistance, also the hotter a cable gets the greater the resistance.
When you look at the quality of the cable and how stupidly long it is, it should be no great surprise to any of us that sometimes our cars fail to restart after a quick stop at a petrol station on a hot day.
To answer your question I will be getting some proper 6 awg marine grade tinned cable from a chandler, the type of stuff used on a fishing trawler.
The current earth (battery earth terminal to chassis) lead will stay.
I will just add an additional earth lead in the same 6 awg gauge cable direct from the negative battery terminal to the engine block.
My recipe to a reliable starting TVR is like this:
1) Bypass the Meta immobiliser on the ignition circuit
2) Add a suitably amp rated relay to protect the ignition switch
3) Upgrade the feed to the starter solenoid with a higher amp rated wire
4) Ditch the weedy 16 year old 7ft starter cable with some decent 6 awg marine grade tinned cable
5) Fit an additional earth from the battery negative terminal to the engine block
6) Fit my new Odyssey PC1500 battery
It can only help what is currently a very marginal original set up from TVR.
Hmmmm, getting the new cable in, hadn't thought about that 
Only kidding folks
I went for the old Indian rope trick
1) Disconnect battery
2) Remove starter cable from starter motor
3) Cut various cable ties securing starter cable to main square section chassis rail & engine bay wiring loom
4) Attach thin nylon 8ft rope to starter motor end of cable using strong gaffer/duct tape
5) Return to passenger footwell and gently pull the starter cable through the grommet in the transmission tunnel
6) When the rope appears remove from the starter cable leaving the rope in place
When the time comes to fit my new starter cable I will simply tape the starter motor end to my rope and gently pull the rope from under the car.
Because my rope follows the original path of the old feeble starter cable my new cable will end up taking the exact same rout as I gently pull it through.
A few cable ties to secure my new cable and it's job jobbed.
Then off to the Indian takeaway for a chicken tika massala.
See, it's the Indian rope trick
Only kidding folks
I went for the old Indian rope trick
1) Disconnect battery
2) Remove starter cable from starter motor
3) Cut various cable ties securing starter cable to main square section chassis rail & engine bay wiring loom
4) Attach thin nylon 8ft rope to starter motor end of cable using strong gaffer/duct tape
5) Return to passenger footwell and gently pull the starter cable through the grommet in the transmission tunnel
6) When the rope appears remove from the starter cable leaving the rope in place
When the time comes to fit my new starter cable I will simply tape the starter motor end to my rope and gently pull the rope from under the car.
Because my rope follows the original path of the old feeble starter cable my new cable will end up taking the exact same rout as I gently pull it through.
A few cable ties to secure my new cable and it's job jobbed.
Then off to the Indian takeaway for a chicken tika massala.
See, it's the Indian rope trick
Edited by Chimpandtonic on Saturday 3rd March 21:06
Simon says said:
Or you could do none of this stuff and have a car that as spun over like a top for the past 6 years (even when stinking hot) with a 530A cranking batt and a Bosch starter that looks like its been fitted since day dot 
Of course i could say i am lucky but seeing as i don't believe in luck 
Just like the immobiliser relay you could argue it's just a matter of time. Of course i could say i am lucky but seeing as i don't believe in luck Honestly, just look at the length of that cable.
Show it to any experienced automotive electrician and they will tell you it's a bad design & ultimately a problem waiting to happen.
In my case I don't really suffer the hot start problem unless things are pushed to the extreme heat wise.
However, I take an "improve & re-engineer before I break down" approach to maintaining my TVR.
After all it's not like our cars have a fantastic reputation for reliability, which is a shame in my opinion.
The fundamental design of the car is excellent, the execution however left a little bit of scope for improvement.
But you leave it as it is mate, & the very best of luck to you
EGB said:
Chimpandtonic said:
Hmmmm, getting the new cable in, hadn't thought about that
Well done. Chimp and Griff minds, think alike.
Only kidding folks
I went for the old Indian rope trick
1) Disconnect battery
2) Remove starter cable from starter motor
3) Cut various cable ties securing starter cable to main square section chassis rail & engine bay wiring loom
4) Attach thin nylon 8ft rope to starter motor end of cable using strong gaffer/duct tape
5) Return to passenger footwell and gently pull the starter cable through the grommet in the transmission tunnel
6) When the rope appears remove from the starter cable leaving the rope in place
When the time comes to fit my new starter cable I will simply tape the starter motor end to my rope and gently pull the rope from under the car.
Because my rope follows the original path of the old feeble starter cable my new cable will end up taking the exact same rout as I gently pull it through.
A few cable ties to secure my new cable and it's job jobbed.
Then off to the Indian takeaway for a chicken tika massala.
See, it's the Indian rope trick
Well done. Chimp and Griff minds, think alike.
Only kidding folks
I went for the old Indian rope trick
1) Disconnect battery
2) Remove starter cable from starter motor
3) Cut various cable ties securing starter cable to main square section chassis rail & engine bay wiring loom
4) Attach thin nylon 8ft rope to starter motor end of cable using strong gaffer/duct tape
5) Return to passenger footwell and gently pull the starter cable through the grommet in the transmission tunnel
6) When the rope appears remove from the starter cable leaving the rope in place
When the time comes to fit my new starter cable I will simply tape the starter motor end to my rope and gently pull the rope from under the car.
Because my rope follows the original path of the old feeble starter cable my new cable will end up taking the exact same rout as I gently pull it through.
A few cable ties to secure my new cable and it's job jobbed.
Then off to the Indian takeaway for a chicken tika massala.
See, it's the Indian rope trick
Edited by Chimpandtonic on Saturday 3rd March 21:06
Hang on a minute?????
Simon says said:
ell I don't have the Meta so that's a start my car come with the Foxguard originally, that was replaced years ago with a Cat 1 system and the starter trigger relay mod I did a few years ago as preventive maintenance (Vauxhall ign switch was not exactly reliable on the sourced from models) 
Previous me fitting the MegaSquirt I had an earth cable rethink hence lots of extra earth/cables straps fitted.
MegaSquirt + lots of extra earth/cables straps. Previous me fitting the MegaSquirt I had an earth cable rethink hence lots of extra earth/cables straps fitted.Edited by Simon says on Sunday 4th March 09:12
Nice
If it wasn't for the cost, an ECU change & junking the distributor would be top of my list Simon.
Goaty Bill said:
Not to disparage your effort, because it makes perfect sense to me, but I had CB fit the 'hot start kit' on mine a few years back and it killed the problem. As I recall, the main issue was undersized relays (that has started to melt in my case IIRC).
You are absolutely correct I think, the hot start issue is a time bomb that will eventually get you if you leave it long enough. It certainly seems to be age/mileage related, and one thing is for sure, it doesn't improve once it starts happening.
One experience of having to wait 15-20 minutes at the petrol pump after filling up was more than enough for me.
Mate there are two issues with the starter wiring on these cars and they seem to get confused.You are absolutely correct I think, the hot start issue is a time bomb that will eventually get you if you leave it long enough. It certainly seems to be age/mileage related, and one thing is for sure, it doesn't improve once it starts happening.
One experience of having to wait 15-20 minutes at the petrol pump after filling up was more than enough for me.
ISSUE 1 IMMOBILISER RELAY:
This gives the following symptom - Disengage the immobiliser, turn the key to the start position and nothing, not even the faintest click from the solenoid
This is an immobiliser fault or more specifically the failure of a relay inside the Meta unit.
You can prove this (like I did) by putting a test meter on the starter solenoid feed wire with the immobiliser disengaged and the key in the start position.
In my case there was a solid feed from the ignition switch, but zero current exiting the immobiliser on the starter solenoid side.
The problem had to be inside the Meta immobiliser unit.
The hot start kit is just a relay that masks the fact that the immobiliser relay TVR originally used to energise the starter motor solenoid is inadequate.
This immobiliser relay often starts to show it's on the way out when the car gets hot, that's because the resistance in the entire system goes up dramatically when it gets hot.
To solve my problem permanently I bypassed Meta immobiliser on the ignition circuit only and added a relay back in to protect the ignition switch, this completely solved my immobiliser related starting issues.
ISSUE 2 STARTER CABLE & EARTH:
This gives the following symptom - Disengage the immobiliser and turn the key to the start position, the car fails to start but you hear a faint click from the starter solenoid
This typically happens on a hot restart, say after filling up with fuel on a hot day.
The solution in my opinion is to upgrade the feeble and very long starter cable with better quality higher amperage battery cable.
Further improvements can be obtained by upgrading the earth path, a short lead from the battery negative terminal direct to the engine block should be all it needs.
So the way I see it there are two issues that are getting confused & mixed up.
I have totally solved the immobiliser relay one but am still in the middle of sorting the inadequate starter/earth cable issue.
With both issues sorted and a decent battery in the mix it should be 100% sorted.
Well that's the theory anyway
SILICONEKID340HP said:
What size cable are you useing ?
Don't know yet Daz, I want to pay a visit to the nice folks at Danka batteries round the corner from me to see what they suggest.I will get them to advise me & make up the cables.
Tempted to go with 70mm2 tinned marine grade stuff, but I need to see how flexible it is.
At the end of the day, bigger is better.
How about some of this
Seriously though, this may help.
The cable on the left is 50mm2 rated at 345 amps & similar to what TVR used.
The cable on the right is the 70mm2 stuff I hope to use, rated at well over 400 amps it should be just the job if I can squeeze it in
Edited by ChimpanChampagne on Sunday 4th March 18:10
Looks like the 70mm2 cable is going to be overkill, it's tricky to get hold of & very inflexible so routing it would be difficult.
In the end I went for 50mm2, the difference in size from the original cable is significant (similar to the above photo).
I found some good quality tinned cable at a local electrical engineer who builds & re-winds industrial motors, it's flexible enough to route (just about) and is a massive step up from my weedy original starter lead.
In fact the electrical engineer took one look at my original starter lead and laughed, he identified it as 35mm2 and then condemned it as highly inadequate given the application & it's significant length.
He then gave me a lesson on voltage drop and amperage lost over a given length, apparently there is an equation you can use.
Double the length of the cable divided by the amps drawn by the motor & some other stuff that went over my head
Anyway, apparently it all supports my gut feeling that the starter lead is too long, or at least not really man enough for it's length.
The other thing I learnt is that decent tinned 50mm2 battery cable is not cheap
I can see now why our local travelling community has been borrowing all the train power cables of late.
In the end I went for 50mm2, the difference in size from the original cable is significant (similar to the above photo).
I found some good quality tinned cable at a local electrical engineer who builds & re-winds industrial motors, it's flexible enough to route (just about) and is a massive step up from my weedy original starter lead.
In fact the electrical engineer took one look at my original starter lead and laughed, he identified it as 35mm2 and then condemned it as highly inadequate given the application & it's significant length.
He then gave me a lesson on voltage drop and amperage lost over a given length, apparently there is an equation you can use.
Double the length of the cable divided by the amps drawn by the motor & some other stuff that went over my head
Anyway, apparently it all supports my gut feeling that the starter lead is too long, or at least not really man enough for it's length.
The other thing I learnt is that decent tinned 50mm2 battery cable is not cheap
I can see now why our local travelling community has been borrowing all the train power cables of late.
Edited by ChimpanChampagne on Wednesday 7th March 16:37
David Beer said:
The hot start mod is only on the solenoid circuit, not the starter wiring. No matter how heavy the starter cable is, it will not effect the solenoid engaging. The relay is placed so the TVR wiring only has to turn the relay on, it can do that! The range rover cable to the solenoid is fine.
I understand that perfectly David.I'm not talking about solenoid function, the point of the post is to highlight the potential failings of a rather light weight 16 year old seven & a half foot long starter cable cable.
It wont matter how good the feed is to the solenoid, if the starter itself doesn't receive enough amps you've got problems.
I cant think of many cars with a starter cable over 7ft long, or even half that long come to that.
And for very good reason.
It has to be a weakness that can be improved with some better cable and an additional earth from the negative battery terminal direct to the block.
carsy said:
Dave, are you using 50mm cable on the earth side as well?
The reason i ask is that i like your idea of a further earth strap to the engine block. But looking on eaby all the ready made earth cables seem to be only 16mm.
Yep, the earth will be the same 50mm² cable & as short as possible, I'm aiming for the existing earth on the left hand side of the block.The reason i ask is that i like your idea of a further earth strap to the engine block. But looking on eaby all the ready made earth cables seem to be only 16mm.
Carsy, like you say I wouldn't bother with a 16mm² earth cable, it would have an OD of 8.3mm and feel like a bit of string.
My new cables are 50mm² (OD 13.3mm), the originals are 35 mm²(OD 11.8mm), it doesn't sound much until you hold both cables in your hand.
My new 50mm² cable is rated at over 100 amps more than the original 35 mm² stuff, and that's if the original 35 mm² cable was new.
Which it most definitely isn't!
In fact my old skinny cable is proper crispy in places, it has sections with hard spots that are noticeably more rigid than others, in these sections it makes that nasty crunchy sound when you flex it.
I doubt it was delivering anywhere near the 240 Amps a new 35 mm² is rated at, even when cold.
As we all know resistance increases (up to a point) in direct proportion to the increase in temperature.
As the starter motor gets hotter & hotter it's internal resistance will increase & the resistance in my already crispy starter cable will also increase.
It all adds up, and with such a long run of cable that's only rated at 240 Amps there is significant scope for improvement, especially when you consider it's highly likely the starter motor draws 300+ amps.
The other thing that would significantly help would be to shorten the cable.
Sadly I cant see an obvious way of reducing the length of the cable other than converting the car to left hand drive thus relocating the battery to where the pedal box is now
So a bigger newer cable & a better earth it is; lets see what difference decent new cable rated at 345 amps makes during a hot start.
My thinking is it should help a lot.
Bassfiend said:
I'm suprised it's even 35sqmm ... Looking at my positive terminal on the battery on mine it looks more like 25sqmm!
I was considering going a slightly different route when relocating my battery to the boot and instead of running a very heavy cable which is harder to route I was going to run a couple of lengths of lighter cable (25sqmm) ...
...I was a little concerned when I read your early post about using #6 guage cable as that's only 13sqmm.
Phil
A double run is a great idea Phil, & yes I soon worked out #6 in American Wire Gauge would be feeble.I was considering going a slightly different route when relocating my battery to the boot and instead of running a very heavy cable which is harder to route I was going to run a couple of lengths of lighter cable (25sqmm) ...
...I was a little concerned when I read your early post about using #6 guage cable as that's only 13sqmm.
Phil
If you follow the thread you will see I went from 6 AWG up to 70mm², then back down to 50mm² - just thinking aloud as I posted each step, my cable knowledge improving as I went along.
Actually "0" AWG is more like the 50mm² I eventually settled on.
Moving on - I picked up the cables yesterday, the electrical engineer only held black stock which I didn't see as an issue.
To completely remove any potential confusion for a future owner/mechanic I simply wrapped the ends in red tape & fitted the red terminal cover.
Although the photos don't really demonstrate the difference between the cable diameter that well, I can assure you it's significant when you hold both cables in your hand.
I really don't think I could have gone any heavier than 50mm² without making routing them a headache, even at 50mm² it's going to be fun
I'm very happy with the work from the electrical engineer, the upgraded starter cable & additional earth should be a big improvement on the originals.
And finally a bit of extra heat protection where the starter lead runs closest to the o/s exhaust manlyfold.
Fitting tomorrow
Edited by ChimpanChampagne on Friday 9th March 11:06
UPDATE
Fittted my new heavy duty starter cable and additional earth last weekend.
I can't claim it was an easy job getting the cables through the grommet & routed nicely even with my helper rope in place.
After much struggling it all fitted in there very well, new Odyssey PC1500 battery in place and topped off with a BatteryBrain.
http://www.pistonheads.com/xforums/topic.asp?h=0&a...
All that remained was to arrange a nice hot start test, which came sooner that I expected after a run into London left me idling in horrific Finchley Rd traffic on Wednesday evening.
Turned the engine off after idling for quite a while only to see the line of cars up ahead had started pull away, typical
A perfect hot start test, this is just the scenario where the car would typically refuse to crank until it had cooled for 5-10 minutes.
Typically this would also generate much honking from the cars behind as they could see their only chance to move slipping away as the Muppet in front frantically tried to start his TVR.
Grrrrrrrr
So how did this all play out with the new cables?
Turn the key & pray.........
And she starts first time! in fact it cranks like never before
Success, hot start problem completely eliminated, just as I had predicted that thin guage 7.5ft starter cable was clearly the issue.
Fittted my new heavy duty starter cable and additional earth last weekend.
I can't claim it was an easy job getting the cables through the grommet & routed nicely even with my helper rope in place.
After much struggling it all fitted in there very well, new Odyssey PC1500 battery in place and topped off with a BatteryBrain.
http://www.pistonheads.com/xforums/topic.asp?h=0&a...
All that remained was to arrange a nice hot start test, which came sooner that I expected after a run into London left me idling in horrific Finchley Rd traffic on Wednesday evening.
Turned the engine off after idling for quite a while only to see the line of cars up ahead had started pull away, typical
A perfect hot start test, this is just the scenario where the car would typically refuse to crank until it had cooled for 5-10 minutes.
Typically this would also generate much honking from the cars behind as they could see their only chance to move slipping away as the Muppet in front frantically tried to start his TVR.
Grrrrrrrr
So how did this all play out with the new cables?
Turn the key & pray.........
And she starts first time! in fact it cranks like never before
Success, hot start problem completely eliminated, just as I had predicted that thin guage 7.5ft starter cable was clearly the issue.
roseytvr said:
Sorry to resurect this David (CoD/CoG) but can you remember what length of cable you eventually settled on for the Starter live and earth? A good read by the way!! Thanks
Ian I responded to your PM immediately last night.I see you have an NHS email address which will have some strong spam filters & junk mail settings.
Check your email again, and your junk, I have just re-sent what I sent you yesterday.
If it's still going to junk mail & auto deleting you will need to provide me with an alternative address that accepts emails from Hotmail.
Dave.
ChimpOnGas said:
roseytvr said:
Sorry to resurect this David (CoD/CoG) but can you remember what length of cable you eventually settled on for the Starter live and earth? A good read by the way!! Thanks
Ian I responded to your PM immediately last night.I see you have an NHS email address which will have some strong spam filters & junk mail settings.
Check your email again, and your junk, I have just re-sent what I sent you yesterday.
If it's still going to junk mail & auto deleting you will need to provide me with an alternative address that accepts emails from Hotmail.
Dave.
"What length of cable you eventually settled on for the Starter?"
Is: 2.2 meters
But I strongly recommend ripping out your old cable & measuring it, this way you can be 100% sure it will fit your car.
I take no responsibility if you get a cable made up at 2.2 meters only to find it's 10-15mm too short.
A TVR is a handmade vehicle and measurements like this can vary from car to car.
Take the old one out first & measure it, I expect you'll get the same 2.2 meter figure as I did, but it's certainly not guaranteed.
David Beer said:
It is absolutely impossible to cure the non cranking hot start issue with this rewire. It may improve the crank speed however.
Neither will a cheap relay that just disguises the true fault.Actually, the truth is many TVR's that have a hot start problem do indeed exhibit the slow starter, or no starter, precisely because the resistance is so high in the feeble & very long starter cable when it gets hot.
Replacing the starter lead is not a complete solution per-say, because there are in fact two different issues at play here.
Upgrading the starter cable should be used in addition to correctly resolving the most common reason these cars suffer from the hot start problem.
THE IMMOBILISER.
Or more accurately the way TVR wired the immobiliser.
My two modifications are proven, & unlike the relay kit are a permanent solution, they also don't add yet more poor quality wiring to an already bad situation.
Fixing the issues my way will not leave you with a false sense of security like the other supposed solution.
When the immobiliser finally gives up one dark night at a distant petrol station, you'll regret the day you bought that cheap additional relay.
I strongly recommend doing the job properly by completing an immobiliser bypass on the higher amp starter solenoid circuit, or better still a correctly wired replacement alarm system.
Upgrade the feeble tired 7ft starter cable and add an addition earth from the neg battery terminal directly to the engine block.
This way you'll be sorting the problem properly & for good, rather than disguising the true fault only for it to return at the most inconvenient moment.
Unlike others, I'm not selling anything here, just trying to help other TVR owners sort the problem permanently & properly.
David Beer said:
Replacing the big cable will only improve crank speed, putting a relay back into the circuit, TVR removed it, will supply the solenoid with 13amp rather than 6! The details have always been free from me or from the griff and chim pages. Glad to see you realised the non cranking was solenoid supply at fault.
As I keep saying there are two distinct issues, both of which need addressing.The failure of TVR to fit a dedicated relay in the starter circuit is certainty not best practice but it's also not the whole story behind the hot start fault.
If you do the immobiliser bypass & improve the amps to the starter the problem will disappear, with or without a relay.
Adding a relay at this point is indeed recommended as a belt & braces permanent & completely reliable solution.
However the relay in isolation should not be relied upon a definitive fix, marketing it as such is at best misleading in my opinion.
Edited by ChimpOnGas on Friday 1st March 10:53
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