Right, onto the battery temperature modification. I spent a little time this weekend whilst changing the glow plugs and did a few tests.

Looking under the battery tray (Using the camera to take a pic and work out how to get at it!)

Taking the battery completely out and pushing the clips in it comes out upover, so I removed the sensor completely to take a look.

As I suspected it's a simple thermistor where the resistance is HIGH when cold and LOW when hot.
At cold ambient temperature (I'd reckon it was around 6oC)

So resistance was at 21/22k ohm.
I then heated the sensor up and the resistance dropped:

down to 17.4k ohm. So we now know a definite change to the resistance.

Going back to Leedsman's original idea of a 33k resistor, I reckon that is reasonable as that'll assume colder than 6oC and force it into full output from the alternator.
So I simply pushed the resistor into the connector:

That was a 33k ohm 1watt resistor (It probably could be less wattage, that is just being safe really as it's only signalling voltage needed).

So my testing results (engine running, minimal drain, no radio, no heaters, etc):

• No modification (stock), engine cold, outdoor around 6oC: 14.3volts
• No modification (stock), engine hot, and heated the sensor: 14.1volts
• 33k resistor in place: 14.4v

So although I wasn't getting much variance between hot and cold with the stock sensor, having the 33k resistor in place seems to give the top results.

I've removed the mod again and going to test the voltage periodically over the next few days driving, see what the change is actually, to work out if this mod is even worthwhile as at the moment I'm sceptical that it's needed unless you live in a REALLY hot country. Here in the UK I'm starting to think the temperature on the sensor is never going to get hot enough to reduce the charge sufficiently to be noticeable.

We'll see!

 

Crisp clean or what take it in...

 

- agreed other than the 12th of never, once a decade 'stonking' bonnet down airless cooking over 8 hours

- I'm only getting 13.9-14.0 with or without the resistor, and I'm looking for a permanent 14.4 regardless - for other reasons
- I'll put my proper meter on this week, rather than the 'Ring' and get the real figures off the Fluke.

 

The mod hasn't cured my starting issue, if it sits too long (from afternoon till next morning), it might not start when it's cold.
I've not checked the glow plugs yet, job for over the next couple of days.

The "new" battery as mentioned previously, has a sticker stating November 2014 on it. That may have been the day it went in, or the day the supplier got it into stock. If it was fitted in 2014, from experience, it might have been killed off already.

I've done a bit of searching today, and a guy called Grumpy Grandad on Honest John seems to have had success by fitting an uprated battery.

He'd came back 2 1/2 years later to state he had still never had any starting problems since installing the battery (1500cca peak)

Heres a link to the thread.
Chrysler Grand Voyager - flat battery | Technical matters | Back Room Forum | Honest John

And heres a link to the battery.
https://www.devon4x4.com/odyssey-pc1...r-battery.html

It's over £200, but as I plan to have the car for a long time, I'll check the glowplugs, do a desulphation then charge cycle on the current battery, and if that doesn't cure it, I'm going to take the plunge.

 

Thanks. Its to connect a reversing camera

 

I've long advocated a starting battery with 80/800 on every post I make, even one this big will not take care of a whole 365 day year of infrequent use. It does however give you more than a half year of starting security. I've changed my mind on batteries having been caught out by an expensive Bosch [I too suspect it was long in the tooth by delivery point]. Yes I looked at the Odessey range but the price was a bit too salty for my taste and now prefer the big BMW factory issue battery which is in fact a Varta [manufactured] F21.

 

The drum in hat parking brakes on our cars it seems to me are almost never inspected or service tested by garages, so when the stuff hits the fan the metal is thinner than lace and the pads are non existent. My point ..... it seems to me that its becoming obvious that a another service part like glow plugs are never inspected unless a car won't start at all and even then one of the four is never inspected or changed. I'm shocked by how many of the 2.4's now need 3 or more glow plugs all in one go.

 

Hi folks,

thanks for the kind comments, just like to put my experiences up, gives us all something to compare to.
Anyway, today arrived my cheapo cigarette lighter voltage tester.

(ebay £2.99)

And was on a long journey (1hr) so thought I'd watch what happened. At ignition on (and glow plugs on) dropped to 11.1v at start less than 10v which shows my battery isn't very healthy.
After starting, I was getting an indicated 13.7v on the unit and this remained pretty much constant for my entire journey. Same again on the way home, so that is with the stock temperature sensor installed, no fluctuation.

I then compared with my meter (Which I assume is more accurate. It's old, but it's trusty!) and I measured 14.3v so 0.6v difference, so that makes me think the cheapo cigarette plug-in is off by that amount.
QinteQ I reckon you're on the right track with yours being slightly off too, but still I'd expect it at least at 14v, I wonder if one of the diodes in your pack are nearing end of life, or the voltage regulator. I'm going to read up on where the voltage regulator is and what chipset it is on these cars, as that could be failing and causing a lower fixed voltage.
(The principle I think would be something like an LM317 where a resistor (thermistor) varies the LM317 sense and changes the output, so over time I'd expect the LM317 to suffer from 'fade', but this is theory. Let me read up)

I think a new battery later in the year for me, have spent enough for now so will cope with a sluggish starter motor RPM for a little longer!

 

Make a suggestion for me and I'll buy and test it, I'm looking for an arbitrary 14.4. Leedsman and I had a long debate in the past and my conclusion and assertion at the time was 14.8 to be just this side of 'boil point' so 14.4 should be same on [clean desulphed] SLA's. There's nowt wrong with a cheepo Chinese one quid plug in monitor such as the one you posted, it may be inaccurate but for most purposes its the diff between what is your norm and impeding failure that people notice.

On your battery [10v is goosed (needs a 4 week 5 or 7 stage charge)], you would normally have the voltage measuring device in the switch-able RHS, you should try it in the LHS 'direct wired' lighter socket for the most accurate reading. If it [won't reliably start] hits the fan, its catastrophic so I'll lend you my fully charged F21 for a month till you get a new one and fit it, I've got a NOCO as a back up.

On the wobble end if you want to borrow a good socket set for a month I'll lend you one.

Lose a part of the socket set or goose the battery and you replace with new !!!!!!! - let me know you know where I am ...... tomorrow.

 

QinteQ you sir are a real gent. But for now it's OK, I've got a spare that'd get me out of a fix if I have problems. I've got a wobble on it's way so covered there too, but once again thank you my friend for your kind offers.

I'm doing a bit of reading up and will let you know what I think would sort your charging problem.