so i did get my rig running right by replacing the front battery ... i had replaced both batteries in November of 2011 but due to the carnage i created on my fuel rails/alternator which had it sitting at a shop torn apart for a month or more, caused the front battery to go batshit a month ago. i recall that the most helpful people on this forum suggested to always replace both batteries and when i suggested that to the shop they said that they load tested both and only the front needed replacing. does this seem reasonable or should i replace the so called "ok" rear battery anyway?
joefeuerstein
Why would you want to replace a battery that load tested fine and is less than 2 years old ( what brand by the way)
I know others have said to replace both but I still am yet to see any logical reason to do both at the same time.
V10 batteries do 2 different jobs each and if one fails it doesn't destroy the other you just replace the failed one.
Single battery Touareg's use the same battery for starting and consumer electronics the only difference on the V10 is the 2nd battery for that big starter.
Save your money if it tested ok unless you like to throw it away.
Hey most good quality batteries have a 24 month warranty here in Aust your unit could still be covered.
Regards
Drag
my dad's v10 had some funny starting issues. Checked via vagcom which battery's voltage dropped with engine off.
The battery under the seat dropped to 8 volt within a few minutes.
I swapped the under seat battery only, cleared the codes and all is well.
Time will tell if the rear will follow suite. At least the rear one is easier to replace.
The battery under the seat dropped to 8 volt within a few minutes.
I swapped the under seat battery only, cleared the codes and all is well.
Time will tell if the rear will follow suite. At least the rear one is easier to replace.
Are both front and rear batteries the same ? I haven't pulled the front seat up yet but the rear battery is easy to get to so if I need size information I thought I'd take it from the rear if both batteries are the same.
Bails, The handbook does not state the difference but I am sure they are different capacities and therefore probably different sizes. I did have the info ..... can't find it just now but would have got it from this website. Dub
............
just found it.
Front is Lead/Acid 110AH 520A whilst the rear one is AGM 85AH 480A
They are both 178mm w and 190.5mm h. Front is 394mm lg and the rear is shorter at 350mm lg
Note: Info is from Precision Frame & Align.
Cheers, Dub
............
just found it.
Front is Lead/Acid 110AH 520A whilst the rear one is AGM 85AH 480A
They are both 178mm w and 190.5mm h. Front is 394mm lg and the rear is shorter at 350mm lg
Note: Info is from Precision Frame & Align.
Cheers, Dub
I thought I knew also. I had a battery die, car would not start, so replaced the rear battery, but guess what the front seems to be the battery that starts the car ?
Here's the specs on the V10 batteries.
http://www.clubtouareg.com/forums/f43/v10-battery-information-75728.html
The rear battery is for cranking and has a different spec that the front one, which is for the electronics.
http://www.clubtouareg.com/forums/f43/v10-battery-information-75728.html
The rear battery is for cranking and has a different spec that the front one, which is for the electronics.
But I repeat, my understanding is that both batteries should be AGM to avoid battery acid flying around the cabin in the event of a roll-over.
Thanks Guys this site rocks. I started off at the dealers, but they did not have one. Ended up at a Battery franchise , and paid the $300 plus for the rear battery, which was perfect except breather was on the wrong side ! Anyway sorted this with some extension tubing and all is good. I did research which was the starting battery and although the common sense was the rear , turns out it must be the front. If I have been driving the car starts all the time it is only if there is drain on the battery that I have issues. Whilst I was overseas the battery went , and this time it happened when I pluged the fridge in, in no time the car would not start.
I elected to replace the rear on the basis I would be sure that I had one good battery, and as I understand 5 years is a reasonable life from a battery, so thinking was if it was wrong then I haven't wasted money. Pitty both batteries are not the same.
I elected to replace the rear on the basis I would be sure that I had one good battery, and as I understand 5 years is a reasonable life from a battery, so thinking was if it was wrong then I haven't wasted money. Pitty both batteries are not the same.
It is definitely the rear trunk battery that starts the car.
The front battery under the seat runs the consumer electrics but will also start the car if the trunk battery is dead.
There is offical VW documentation on this site confirming this.
The front battery under the seat runs the consumer electrics but will also start the car if the trunk battery is dead.
There is offical VW documentation on this site confirming this.
Well I believe the front battery is the cranking battery:-
a) It has a much higher cranking rating .
b) It is a larger, makes sense since rating higher.
c) It was the battery that was flat and my car would not crank without switching to the rear battery.
d)No smart German would run power from rear to front and loose current through long cables. Definitely the front is the starting battery. All automotive designs try and have the battery close to the starter to reduce cable length and current drop or loss.
So based on my experience I would definitely say engine cranking on the R50 and I would think other V10's is the front.
a) It has a much higher cranking rating .
b) It is a larger, makes sense since rating higher.
c) It was the battery that was flat and my car would not crank without switching to the rear battery.
d)No smart German would run power from rear to front and loose current through long cables. Definitely the front is the starting battery. All automotive designs try and have the battery close to the starter to reduce cable length and current drop or loss.
So based on my experience I would definitely say engine cranking on the R50 and I would think other V10's is the front.
I agree your point D makes sense, but look at page 5:
http://www.billswebspace.com/Touaregelectricalsystem.pdf
My point of this discussion is to let others know from my experience. I don't know who produced the PDF, it may be correct but it makes no sense to draw high current over a long distance, ie: battery in the rear. The Germans are pretty good at engineering , why have the battery that is most needed to start at the rear. More to the point my personal experience says this is incorrect.
By the way Drag thanks for the heads up on the batteries, I am getting the silver battery as suggested by you. It's a pity that I thought the rear was the starting battery, as mine was still OK and I paid to much to a no name brand from a battery franchise . I have my old rear in the front for now until the new one arrives. Car starts fine . was a pain getting the passenger seat out took me about 30 minutes once I acquired the right tools, quicker next time.
LOL, are you still sticking with your interpretation? Page 22 shows AGAIN that the rear is the starting battery, schematics on page 24 do not indicate which battery is front and which is back so as to make any conclusion...this is really funny...
Well this is going nowhere , as stated I am basing my opinion on the facts, proven by experiment if you like. What others choose to do is up to them, but my experience is that the front battery on my 2009 R50 is the battery used to engage the starter motor.
No problems Bails all good sure it will work out for you.
I put a Century DIN95LC under my front seat. About 20mm shorter but all other sizes the same and 850cca it fitted perfect and have had no issues. We can go on about batteries and factory specs but in my thinking I put in a big battery to replace a big battery if you know what I mean.
I don't care which battery starts the car just as long as both are good
Regards
Drag
I put a Century DIN95LC under my front seat. About 20mm shorter but all other sizes the same and 850cca it fitted perfect and have had no issues. We can go on about batteries and factory specs but in my thinking I put in a big battery to replace a big battery if you know what I mean.
I don't care which battery starts the car just as long as both are good
Regards
Drag
The larger of the two batteries will be the starter battery, for providing the cold cranking amps needed to turn over a high compression V10 diesel motor. That electric starter is probably rated 2 or 3 HP just to turn a PD motor over with a 19:1 compression ration or there abouts, fast enough at 300 rpm's for things to pop off and fire up. VW is too cheap to spend extra money to run really fat, heavy copper cable from the back end to the front, with huge voltage and amperage losses, to the very front of the car to the starter, that would be an engineering faux pas for the Germans to do that.
Replace both batteries, other wise the weaker battery with the one weak or soon to be going bad cell will drain all the other stronger 2V cells down on both batteries. Anyone that has spent long term time in an RV living off the grid on generators, solar power and battery banks, with some engineering backround will tell you the same thing.
Replace both batteries, other wise the weaker battery with the one weak or soon to be going bad cell will drain all the other stronger 2V cells down on both batteries. Anyone that has spent long term time in an RV living off the grid on generators, solar power and battery banks, with some engineering backround will tell you the same thing.
I will have to disagree with you on this Niner, you arbitrarily assume that 900 CCA aren't enough to turn the V10 when you know nothing about the gears used on the starter side or flywheel side.
In my opinion it is completely logical to have the larger of the batteries power the infinite electronics on board the V10 than just using it to start the car up. I'll say it again, the fact that the battery under the seat (which powers the in-cabin electrics per SSP) has more CCAs than the one in the trunk is only a natural consequence of its size.
Bigger battery (amperage) more CCAs (usually)...and the V10 isn't exactly the average VW, its new retail price was close to 140k $, a top of the line model for rich people that are willing to spend this sum. Why would VW adopt a "cheap" strategy building this when it would only backfire on them by unsatisfied customers. I'm not saying that they have actually used a bigger copper cable to transfer the high current to the front, I'm just arguing that your argument does not hold ground based on the presumptions you made...
P.s. It makes even more sense to have the smaller of the two batteries cranking the starter when you take into consideration that there's always the back up power reserve of the front if needed...
It does not take an EE to know that it takes Current, in the form of amps, with a modicum of voltage, usually above 9.6 volts in a 12 volt system, to do the work to turn a starter motor. Which is why we have carbon pile load testers to 500 amps to load test worn batteries. Standard is 30 seconds, not to have voltage drop below 9.6 volts.
That the front battery can have a lower voltage and still be deemed charged at 10.6 volts versus the rear battery being charged at 11.6 volts, what does that tell you about where the amps that will turn the starter are coming from?
That the ignition is turned on and measures the voltage of the front battery and rear battery.
But your last paragraph says it all... the relay is in the same position whether both batteries are charged, or the REAR battery is discharged and the FRONT battery is charged. Well Standard Operating Procedure dictates with that sentence that the front battery is the starting battery, but if the front battery is dead, then, and only then, does the relay switch to the rear battery to start, based on relay positions.
Sort it out amongst yourselves... VW put batteries under the rear seat on their rear engine driven air cooled motors, and put batteries up front when they went to transverse motor front wheel drive water cooled engines. Vw pretty much always has mounted the battery very close to the engine to keep the thick heavy copper wire positive lead wire from the battery to the starter as short as possible, to minimize amperage and voltage losses. Basic car engineering. To this day, with the Touareg T3, the starting battery, and now there is only one, still sits under the drivers seat. VW got rid of all the fancy electronics and gizmo's on the T3 as a cost cutting measure, and in the process, got rid of the second battery in the trunk too.
It's absolutely terrible electrical design to ever hook two 12 volt batteries in parallel of unequal CCA or ampere hour ratings, that is a serious design flaw.
Ford doesn't do it on their diesels, they run 2 batteries, same size Chevy doesn't again 2 bats, same size , GMC doesn't, and the Dodge Cummin I6 is the only model diesel that will start on 1 battery, it's a huge battery, and it's the smallest in displacement, engine wise, of the bunch.
Consumer electrical, in the grand scheme of things, draws nothing in terms of amps compared to the starter motor. The problem lies in that the starter motor draws so much current that the voltage would drop to the point of trying to start that the consumer electrical voltage level gets too low to function properly, including the ECM the controls the electrical solenoid on the injectors on a PD. So the ECU doesn't see the crank sensor readings due to low voltage to know which injector to fire an electronic pulse to to trigger the injector.
I look at the schematic on page 24, and the starter battery A1 is located, in the schematic, closest to both the alternator, and the starter. Make of it what you will... I don't think schematics or batteries with the most amp hours lie about heavy consumers like 10 glow plugs and a starter motor all drawing at close to the same time on the bigger more amp hour of the two batteries in the vehicle. Sorry, that's how I see the logic.
That the front battery can have a lower voltage and still be deemed charged at 10.6 volts versus the rear battery being charged at 11.6 volts, what does that tell you about where the amps that will turn the starter are coming from?
That the ignition is turned on and measures the voltage of the front battery and rear battery.
But your last paragraph says it all... the relay is in the same position whether both batteries are charged, or the REAR battery is discharged and the FRONT battery is charged. Well Standard Operating Procedure dictates with that sentence that the front battery is the starting battery, but if the front battery is dead, then, and only then, does the relay switch to the rear battery to start, based on relay positions.
Sort it out amongst yourselves... VW put batteries under the rear seat on their rear engine driven air cooled motors, and put batteries up front when they went to transverse motor front wheel drive water cooled engines. Vw pretty much always has mounted the battery very close to the engine to keep the thick heavy copper wire positive lead wire from the battery to the starter as short as possible, to minimize amperage and voltage losses. Basic car engineering. To this day, with the Touareg T3, the starting battery, and now there is only one, still sits under the drivers seat. VW got rid of all the fancy electronics and gizmo's on the T3 as a cost cutting measure, and in the process, got rid of the second battery in the trunk too.
It's absolutely terrible electrical design to ever hook two 12 volt batteries in parallel of unequal CCA or ampere hour ratings, that is a serious design flaw.
Ford doesn't do it on their diesels, they run 2 batteries, same size Chevy doesn't again 2 bats, same size , GMC doesn't, and the Dodge Cummin I6 is the only model diesel that will start on 1 battery, it's a huge battery, and it's the smallest in displacement, engine wise, of the bunch.
Consumer electrical, in the grand scheme of things, draws nothing in terms of amps compared to the starter motor. The problem lies in that the starter motor draws so much current that the voltage would drop to the point of trying to start that the consumer electrical voltage level gets too low to function properly, including the ECM the controls the electrical solenoid on the injectors on a PD. So the ECU doesn't see the crank sensor readings due to low voltage to know which injector to fire an electronic pulse to to trigger the injector.
I look at the schematic on page 24, and the starter battery A1 is located, in the schematic, closest to both the alternator, and the starter. Make of it what you will... I don't think schematics or batteries with the most amp hours lie about heavy consumers like 10 glow plugs and a starter motor all drawing at close to the same time on the bigger more amp hour of the two batteries in the vehicle. Sorry, that's how I see the logic.
The above are just speculations of a "devil's advocate", I by no means claim expertise on the matter, I'm using common logic to build arguments here. This, and the fact that the SSP says what it says, of course...
Just a Question. It seems the rear battery starter crowd keep referring to a document that I believe is incorrect. so I ask this question. Why does the manual state that if your car does not start turn the key to the left to engage the Auxiliary battery , if the so called smart system does this automatically. My smart system has never changed to the rear automatically when the front is flat without turning the key ! The rear battery is called the starter battery because it is used to start the car when the main battery is flat.
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
