After getting fed up of the constant state of near battery flatness on my 2007 Grand Voyager CRD I finally decided to get it sorted...

Its not that my battery was going completely flat, but it's always just on the edge, in the mornings it just has enough to start the car, but it's never fully charged. I have no excuses as I work in R&D with power electronics :-)

Step 1 - check the charging voltage... it was 13.5v both unloaded and with everything switched on, it was regulating correctly, but in my experience this is a bit low. My LR Discovery regulates at 14.4v and my neighbours Mondeo at 14.5-14.6v

Step 2- Unplug and measure the battery temperature sensor. It was reading about 12K ohms at 15C.

Step 3- I warmed the sensor up with a hot air gun until it was pretty hot, resistance dropped to around 3K ohms.

Step 4- Popped it in the freezer for half n hour, it went to 29K ohms

Step 5- made up a little wiring loom with a 22K ohm 1/2 watt resistor, plugged in in instead of the temperature sensor.

Step 6- checked the regulated voltage with the engine running, both unloaded and loaded, it's now 14.3v-14.4v

Step 7- shut the bonnet and bask in the smugness of a simple job well done :-)


To be honest I think the battery temperature sensor is an unnecessary gadget, I use a simple lead acid gel battery from Euro Car Parts, I got the biggest one that would fit, it cost £45 with a 4year guarantee, I'm happy to change it every 4 years for that price.

As I've used a fixed resistor it will always charge at 14.3v regardless, which isn't a problem.

I did this 4 weeks ago and it's been much better ever since, spins over great in a morning now.

 

Hi Matgriff,
This is the only solution to this problem, it drove me nuts. I got a 2.8 CRD voyager 2007. I bought it second hand in the summer and the battery went flat 3 weeks after, put a new battery and that went flat after 2 weeks, got the AA out and they said battery needs replacing. Took the battery back under warranty and got a new Bosch one. Now it was getter colder and after 2 weeks battery flat again. Checked altarnatorand done all the test with no fault. I found the solution right here and from a post from 2013 about the battery sensor. My charging output was around 13.5-7v, after restistor 14.3-7v average, load and no load. I will play around with some other resistors to get it to about 14.8-9v.
But a big thank you for posting.
I had no issues with my voyager 2.5 crd, because it didn't have a battery sensor I believe and def. no pre-heater.

 

Diesels : batteryMOD

 

Hi QinteQ,
Please explain what do you mean.

 

HiYa yableep, you have already [#2] done the Leedman batteryMOD and have benefited from the MOD.

The single best assist you can give a diesel winter CCA is the batteryMOD, put simply 14.4 used to be the old[er] charge rate. The current thinking of 13.8 is generally accepted battery charge rate.

To me that's too low for a 80aH battery in the winter. A cell on our lead acid starts to charge @ 2.25 x by our 6 cells is 13.8 in most/many cases that's gonna take one hell of a long time to replace just one winters morning. The ButtonMod is easy, 10 minutes, safe as houses costs less than a quid and delivers 14,4[ish] well inside the 14.5 gassing safety and a much reduced re-charge time particularly for those such as myself who have a 'lifestyle' that means two 15 minute trips per week. Our GV's draw a flaky IOD of .025 to .030aH at rest after the 16 minute sleep command and have a lot of electrical toys, add to that the big 3 litre lump of a UK ± °C cold compression engine and you have some big needs.

- 33K Ω @ 1/2 watt gave me the 13.9
- 22K Ω @ 1/2 watt gave me the 14.4 I wanted
- back to 'happy days' 'old school' charging rates

 

Hi QinteQ,
Currently I have a resistor of 33K Ω @ 1 watt installed and this gives me the 14.4 that is required for the bosh battery (S4009, 74aH, CCA 680), I installed this battery about 6 weeks ago and I think it had it, got flat a few times.
With 4 years of warrenty, I should get it replaced.
Do you know how much amps should the battery be charged, my clamp meter reads between 3.6 and 4.6 amps.
Thanks

 

Ordinary in vehicle clamp meters don't really give accurate results with our modern car batteries, what you want to know is how many CCA it produces. For example if your S4 claims a CCA of 680 you want to know does it give 680 cold cranking, or does in in fact only give you 450.

I've got an old which I've tested as accurate to 100-1200 CCA. So in short modern AGM batteries tested @ aH is in my opinion useless much better to answer the question you really want will it crank my car on a cold UK morning. See if you can get an accurate CCA reading from someone, then see if you can persuade them to change it out. Best of luck.

 

Thanks,
I read a few more posts with similar problems and they recommend an 80hA with 800cca, but to fit this battery I would need to cut the front of the tray.
What are your thoughs?

 

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You don't have to. To be frank it's just me that advocates 80/800. Yes you do have to chonk both the battery tray and the battery lip, I made an entire post with pictures on this forum somewhere. Your battery should be good enough if its used frequently for long enough - its infrequent or short stop / start trips that uses more aH than the alternator can supply in the time its driven for.

That's why I've long advocated the batteryMOD which fools the BCM into sending 14.4 rather than 13.8 volts to recharge the battery if it needs the extra charge rate. Can I assume you don't use your GV much ?

One+

 

Longest average run 15-20 mins each way.
I looked at the battery tray and 1 of the previous owners already chopped off the front part of the tray. Now the tray will accomodate 290mm. Maybe you could have a look if you can find the mod, if not I will have a look.
Thanks for all your help and advice.