Having moved battery to the boot.

[LongBaz383BHP]

I now appear to have what can be described as hot start symptoms. Starts great from cold, appers to have a flat battery when hot, leave to cool down for 20min and starts fine again. Never had the problem before even in France at 38deg.
Any thoughts?
Thanks
Barrie

[Discopotatoes]

What size cable did you use?

[LongBaz383BHP]

Thanks for the quick reply.
I put in 25mm, I think the original was only 16mm.

[QBee]

Have a read:

http://en.wikipedia.org/wiki/Electrical_resistance...

Three things I noted -
1. resistance is inversely proportional to the area of the cross section - the thicker the cable the less the resistance.
2. resistance is proportional to length.
3. resistance at room temps increases with temperature.

I suspect you are suffering from increased resistance due to 2 & 3 draining the power arriving at the starter, so the answer is to increase 1, the cross section of the cable.

PS, my Audi's battery is in the back corner of the boot, by the rear lights - bloody thick cables, very long car. Do you want me to try to measure them?

[db484bhpv8]

Also check your earths. Where do they pick up?

I tried all the above and it came down to a worn out old starter motor. If i had disregarded all the TVR advice it would have been the first item i would have replaced. Currently running a hi-torque landrover starter with no issues.

[LongBaz383BHP]

Morning Derek
Ran an earth cable as well as a live to connector blocks in the footwell

25mm in 16mm out if you see what I mean. Each connector block then has any live or eath wires attached.

Anthony
If you would be so kind that would be of great help.

Barrie

Edited by LongBaz383BHP on Monday 10th March 09:59

Edited by LongBaz383BHP on Monday 10th March 10:00

[SILICONEKID346HP]

db484bhpv8 said:

Also check your earths. Where do they pick up?

I tried all the above and it came down to a worn out old starter motor. If i had disregarded all the TVR advice it would have been the first item i would have replaced. Currently running a hi-torque landrover starter with no issues.

Do you have link for one of those ,do you have the hot start kit ?Does the high Torque starter motor require less power to spin it ?

[QBee]

LongBaz383BHP said:

Morning Derek
Ran an earth cable as well as a live to connector blocks in the footwell

25mm in 16mm out if you see what I mean. Each connector block then has any live or earth wires attached.

Anthony
If you would be so kind that would be of great help.

Barrie

Cannot get to the bare metal of the cable, but the cross section of both live and neutral, including insulation, is 13mm (measured with a ruler by eye, not a vernier).

How do you measure cables? When you say 25mm, I assume it isn't an inch across? So perhaps 25mm circumference?
If the 13mm of my Audi's includes a 1mm thick insulation, that would make the internal diameter 11mm, ie 35mm circumference.

This isn't the first time this comment has come from someone moving the battery to the boot - the longer cables make the resistance so much more critical, and so every component has to be up to spec.

When people talk about the hot start problem, it can actually be one of three things - a failing immobiliser, or issues caused by the poor quality and length of the cable TVR installed from battery to starter, or poor earths.

So, along with the quality of your starter and battery, there are a few other things to check. heat merely makes everything more marginal.

Edited by QBee on Monday 10th March 10:27

[K4TRV]

QBee said:

Cannot get to the bare metal of the cable, but the cross section of both live and neutral, including insulation, is 13mm (measured with a ruler by eye, not a vernier).

How do you measure cables? When you say 25mm, I assume it isn't an inch across? So perhaps 25mm circumference?
If the 13mm of my Audi's includes a 1mm thick insulation, that would make the internal diameter 11mm, ie 35mm circumference.

This isn't the first time this comment has come from someone moving the battery to the boot - the longer cables make the resistance so much more critical, and so every component has to be up to spec.

When people talk about the hot start problem, it can actually be one of three things - a failing immobiliser, or issues caused by the poor quality and length of the cable TVR installed from battery to starter, or poor earths.

So, along with the quality of your starter and battery, there are a few other things to check. heat merely makes everything more marginal.

Edited by QBee on Monday 10th March 10:27

If it helps (?) - when you have a hot-start situation, do you hear the solenoid click in or is it clicking-in and the starter motor not turning?? Two quite different problems there, IMVHO??

Do check the connection from the ignition switch to the solenoid and the earths, as already suggested (just as important as the supply feed!)
Hope that helps?

Trev

[LongBaz383BHP]

It was like I had a flat battery. Starter motot turned over very slowly then stopped.

[K4TRV]

LongBaz383BHP said:

It was like I had a flat battery. Starter motot turned over very slowly then stopped.

When was your starter motor changed-out?

Not to your knowledge?

Then I very respectfully suggest you compliment your battery move with a new starter motor, of the latest atributes (spins faster?) and don't spoil the Ship for a ha'peth of tar??

As QBee states, heat makes everything more marginal and starter motors don't have the best position in life and don't last forever?

T

[QBee]

LongBaz383BHP said:

It was like I had a flat battery. Starter motor turned over very slowly then stopped.

If you have half an hour to spare and a local battery place you trust nearby, i would suggest popping down there first (when the car does start!) and getting them to put their professional tester on the battery.

It would be a huge shame to fart about testing, or worse still, changing, loads of components when the real problem is simply a battery on the way out. It's surprising how often it is the problem, and with your battery in the boot you need it to be tip top

If you have changed it recently, or as part of the boot installation process, then that may not be the problem.

[db484bhpv8]

This is the landrover one i use now. I bought it second hand off ebay about 10 years ago as a spare for my SD1 and it sat in the garage since i bought a faulty new one for the TVR. Gave it a try and its been great.



Also made and fitted this. Maybe it helps.

[K4TRV]

db484bhpv8 said:

This is the landrover one i use now. I bought it second hand off ebay about 10 years ago as a spare for my SD1 and it sat in the garage since i bought a faulty new one for the TVR. Gave it a try and its been great.



Also made and fitted this. Maybe it helps.

Sorry Derek, at work and can't "see" any Pistonheads pictures when posted - will have a scrut tonight?

Sounds like QBee's battery suggestion is the first route, then I would still suggest something better than an EBay 2nd hand item? Did you check the brushes, end-float etc? I just think that you've done a lot of work and should consider the new-motor route?

Hope you get to the bottom of it?

T

[QBee]

PS, make sure whatever battery you do have, or do buy, has enough output. There was a thread on this recently, and numbers in excess of 600CCA (starting power) were being mentioned. The standard battery is about 550 IIRC. With the longer cables you might need a higher powered battery.....or a new starter motor!!

The output may well be printed on the battery.

[Colin RedGriff]

LongBaz383BHP said:

It was like I had a flat battery. Starter motot turned over very slowly then stopped.

That sounds like the problem is the current needed by the starter is not high enough rather than an issue with the solenoid wiring.

I would follow the advice given about checking the battery, starter motor and main cable.

[LongBaz383BHP]

This weekend I am going to replace the 25mm cable, I was going to go with 50mm. Is this to much? what have others used when moving the Battery to the boot?
It has been suggested that I use 35m eathing cable from a mig welder.
Thanks
Barrie

[gavgavgav]

If you can, I would try checking before swapping out the cables. Use jump leads/ another cable and try running from the -ve terminal on the battery to somewhere on the engine block, and then try the +ve terminal to the stater motor terminal post (have to go under the car for this one). This will rule out an earthing problem or undersized cable issue.

[LongBaz383BHP]

I have run both the pos/neg cables through the car and joined them at connecting blocks in the footwell. Both being 25mm.

[db484bhpv8]

LongBaz383BHP said:

I have run both the pos/neg cables through the car and joined them at connecting blocks in the footwell. Both being 25mm.

You need to run the bigger cable directly to the starter i think.
A chain is only as strong as its weakest link.