Thanks Jonny..I think you nailed it with information I've not seen before, namely that "emergency start procedure " (key ccw to select then cw to start) activates "both" batteries in parallel, ie NOT a switch from one single battery to another single battery Boom..you're the first person to outline this critical concept and it completely explains my confusion and it also explains my use of the royal "We" as I was, in my last post, working on the (incorrect) basIs that emergency switched one batt to another single batt..we now know it switches from 1 batt to both batt. You even showed me the component (next thread) responsible for the parallel switch.

This makes a lot of sense now, I do believe someone else posted "if main dead then even if starter batt is new then car won't start with normal key operation.

I think the other point worth making is that the term "starter battery" is a slight misconception, it may be providing power to the Starter Motor but it's not providing power to the rest of the electrics needed to actually start the car, starting the car requires power at Starter Motor AND power in main Batt for rest of electrics. Your "sharing" power in parallel across BOTH batteries perfectly explains this.

So to recap ...car sits 3 weeks, no life in lights or remote, manual key entry, = Main batt dead, Starter Batt is good, but, car doesn't start with normal CW key (as main batt, required for all the others electrics apart from S Motor, is dead) , then to resolve, flip key CCW, this "shares" power accross both batteries and car now starts with cw key .

Ok...but there is more confusion... .....being happy the car started as above I drove car 15 miles (but in Manhattan so rarely over 40 mph) thinking this would charge the main batt. I switched off car and and tried to start normally, but it didn't start unless I did emergency key ccw procedure (I recall lights and remote now worked normally so main batt had some charge in it.) I then charged the main batt overnight (but with negative cable in situ which I heard is wrong, should be disconnected) and the status quo remained, lights & remote were on but car didn't start unless emergency key ccw process was used. So now the situation is main batt working , right batt working, lights are on but car doesn't start with normal key. Why is this ? My guess is that while main batt is working for remote and interior lights etc, it is not working well enough to assist in starting car (despite a good Right batt), the emergency key ccw to "share" power is still needed to start car. Am I correct ?

Then a few days later, without any further intervenation, car miraculously started normally and does so to this day, the emergency key ccw procedure is NOT now needed . Why did it now start to work ? My guess is all the "sharing" of power, starting & revving till warm, charging..plus a few days time got the Main back into reasonable shape to work normally. Am I correct ?

I then bought a Midtronics pbt300 which I think is rated for agm. Main batt in situ tested "Yellow" (should replace) starter Batt tested "Red" must replace. (My brand new agm batt , not installed yet, tested green). I also read that capacitance testing in situ can be inaccurate due to croc clips not having access to clean terminal post.

In conclusion, I should probably replace both batteries, its time. As mentioned I already have the new Main Batt ready to install. I would prefer to do one battery at a time ...natural conservativeness.... that way I have one good batt (main) , then I'll buy and replace the starter.

I apologies for the lengthy post but it's all too easy to miscommunication by brief written messages so I tried to be accurate.

Thanks again , on your diagram look above the purple square box (which contains the yellow connector) there is a black box the size and shape of a pack of cigarettes, it's hard to see exactly from diagram. Does this also naturally lift off as I remove the other bolts and clip ?

I'm now ready to do the work, I'm good with the "keep wheels straight" and the window reset procedure. Should car doors be opened or closed during battery replace process where both negative cables removed?

FInally, would someone be so kind to detail the rest of the "reset" process, after battery removal, in detail , ie mirrors, seats and anything else, how do I reset these ?
Thanks indeed.

ctek charger
 

I've read somewhere that to charge a battery one must remove the negative cable 1st, then charge. Is this confirmed ? how does this match with the trunk cigarette lighter quick connector used to charge the battery as negative cable is naturally still connected.

Answered in red.

This is more of a safety procedure, as the battery tender is very low power, were as a battery charger can be high power and may damage the battery control module located behind the main house battery, or any other of the many components, I know on my Audi A8L W12 there is a special hex post for the negative side next to the battery for charging or jumping, this hex post bypasses the battery management module, people on AW have hooked up to the battery instead of the hex post and have blown out the battery management module with to much juice, now our Bentley's DO NOT have this hex post, that is why I remove both negative terminals, or I use a 2 amp charger while I am working on the vehicle and want power.


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Johnny...Thank you indeed for very detailed, accurate and simple instructions, it's most welcome. I stripped mini and spitfire engines as a teen but this is different ballgame And it's the small details that really help.

final question :) I recall a Bentley tech telling me: before I remove a battery to bridge it with a booster pack to maintain all the codes . This seems counter to the guidance to remove both negatives (start batt 1st, then main) before any battery removal . I have a booster pack for "just in case". Should I use it or not ?

NO !!! :eek: . hilarious

got it !
Could I use booster to start car in a situation when both battery failed ?

That would be up to you, I might or might not depending on the situation of where it was at, what I would probably do is disconnect the negatives and place the hand held high power jumper box on one of the batteries to charge it up for say 20-30 minutes, then reconnect and start, I have done this in the past on my A8L at 5 AM and 18 degrees leaving the Casino, and it worked, but I would never use a A/C powered charger in start mode to start the vehicle, but either way the proper jumping procedure is to hook the positive (+) to the right side starter battery (+) post, and the negative (-) to the left side house battery (-) post.

I removed and replaced the main battery, I'll write it up later.
4 questions:

1) when I replaced the main left yesterday( Disconnecting right negative first, then disconnect main negative, then replace , and reverse procedure to reconnect), car did "not" start with normal clockwise key but all the regular electrics lights etc were working fine. However Car did start when I turned key ccw then cw to start. In other words the new main battery powered the lights but prevented the car starting until I flipped to right side battery. I ran engine for 20 minutes. I switched car off then back on with normal CW key...bingo...it worked. Question : would you expect a new main battery to work 1st time or is it perhaps normal to require a ccw flip to right side battery ?
2) main battery had been sat in my house with no charger for 4 weeks. I bought it from interstate battery store. Do the battery stores keep batteries ,when in inventory, on trickle ?
3) could 4 weeks post purchase be the cause it lost power to start car
4) when I charge one of the batteries overnight by removing the negative do I have to remove both batteries negatives even though I'm only charging one battery ?

charging overnight
 

Apologies for duplication. The guidance on this thread is to remove the negative before overnight charge (not trickle charge where it's ok to leave connected ) . My question is do I have to remove both negatives from right and left batteries in order to charge 1 battery or can I just remove the negative of the battery I wish to charge and leave the other one connected ?

To be on the safe side why not just remove both the +/- from the battery you wish to charge, depending on which one we are talking about as we all know the right hand is way easier, I am not saying that it is totally necessary, but is what I would do, or if you are using a low amperage charger say a 2 amp, then you would really not need to disconnect anything, BUT do NOT leave a 10 AMP hooked up over night as that can lead to cooking the battery, as 10 amps normally charges in 3 to 5 hours, and although some say that they are automatic, I have seen where the charger keeps charging on and off once it has reached full charge, some six years or more ago when my dad put his "automatic" 10/2 amp charger set on 10 AMP on his boat batteries and forgot for a few days..... well they were toast when he went to the basement to check on them, some cells were dry and other were boiling away, and he said they were very hot, we re-filled them, but they were shot, and only one season old.


I myself would feel fine leaving the charger in 2 AMP mode over night with all hooked up, I know first hand while working on my build that when I have it set to 2 AMP and say lights on, dash lit up, or radio playing, all is fine, BUT put it on 10 AMP and you can hear it in the stereo and see it in the lights, maybe it's time for a new charger, it is Century 87102 and over 20 years old.....:o


But back to you charging, don't forget 10 AMPS is 3-5 hour to charge, 2 AMPS anywhere from 2-12 hours or more depending on the amount of discharge, also a slow clean charge is always better then a high power fast charge, JMO.


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Thanks Johnny. I live nyc and I have to be sneaky to connect a charger. I drive car infrequently so was planning on a 10 amp charge once a week and thanks..3 to 5 hours max . That said, I'm not inclined to remove the positive on the main every week so my question remains: when charging the left side main on 10amp (negative disconnected but positive connected ) should I also disconnect negative on the right side even though I'm not charging the right side ?

You should be fine with just the one negative of the battery you are charging disconnected, what I do NOT like is the 10 AMP charging of either once a week, that IS a sure way to kill the batteries by charge discharge every week, I remember reading that you did not drive the vehicle for three weeks at a time or so, at that point if you are not allowed to have a tender hooked up in your parking facility you would be better off disconnecting both negative terminals and saving your batteries life spans, or have a sincere conversation with whom ever you need to as to allow for the tender hookup, even at a monthly fee for the small amount of electricity used, if your batteries go dead you don't even have security alarm, and I thought you were in Texas.... :)

I can't leave a tender on permanently, they are strict with the rules at the garage where I Park. I can hook up a tender overnight once a week or so as their staff won't notice it. I'll try to drive a bit more but given it might sit for 2 weeks and I can't leave a tender on permanently what's my best plan during the 2 week period of no driving.

also I'm reluctant to disconnect both negatives and leave the car

I have never seen a store charge batteries on the shelf for sale. It is easily possible your new battery was less than fully charged. I always charge new batteries before I install them.


BTW, you may already be aware of this but if not...batteries have a sticker somewhere that shows what month and year they were made. When buying a battery off the shelf always get one that is less than 4 months old. Some of the battery's life is used up sitting on the shelf.

I have replaced both batteries and all is well. I wish to maintain them properly. I drive the car once every 2 weeks.

Question 1) Johnny Hotspur posted it was ok to overnight charge on 2 amp with battery terminals still connected. Given I cant leave the charger permanently connected what should I do during the two weeks of no driving ?...should I do a 2amp overnight charge once per week ? (you had mentioned that a 10amp charge once per week is bad practice)

Question 2) I just bought a CTEK 7002. It has a charging current of "7 Amp max". It does not allow me to select "2 amp" or any other specific amps. Its a smart charger so I guess it determines automatically what the battery needs. Question: can I use this charger "without" disconnecting the negative terminal ? In other words, if this charger is starting out at 7amps does this amp level require the Negative Terminal to be disconnected. [of note: CTEK sells the cigarette lighter connector so the implication is this is a convenient connector that does not involve the negative terminal being removed.]

Response in RED.


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CTEK - The Smartest Battery Chargers in the World - YouTube

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https://smartercharger.com/wp-conten...US-7002_us.pdf


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thank you. My garage will not allow chargers. Im guessing other garages are the same plus I now live in the same building as my garage which helps with drive frequency. When you read the danger warnings on the charger itself then its not surprising the dont allow it.

So whats the best plan for me, I realize my situation is not ideal. I do understand the point you made about the CTEK and that its designed for constant use but I'm thinking is there a next best plan. I can charge overnight once maybe twice a week but no more. So should I charge once or twice a week overnight ? or is this doing more damage than leaving it alone.

I've been in NYC 4 years and driving habit has been the same, I forced my self to drive every 2 weeks, in between drives there was no charger and the car worked just fine for 4 years with my 2 weekly drive method. ( typically less than 50 miles unfortunately) . Admittedly, you can tell when starting the car after 2 weeks that the battery is struggling - but it always started until recently when the main left just gave up. It could even have been the original 2005 battery. I bought car in 2010 and have not changed the battery till last week. So I'm ok with replacing the battery every 5 years, my question remains is there any form of charge overnight that will help and not hinder the situation ?

Put the CTEK on once a week and see what stage of charge the CTEK is in the next morning, but another note as you just hit on, you can hear it struggling when it doesn't have proper power, that in itself is no good because now that would be heating up the starter because of not enough juice to properly power the starter, then said starter gets hot, when it gets hot it is burning out prematurely, and that's a job you don't want to do, that's an engine out job, that's why it's always best to have your batteries fully charged.....

But now you have brand new batteries, you should be okay for a while, but if you feel it starting to struggle you may have to charge more often.

Thanks..your knowledge of primary and secondary issues is extremely helpful. I now see this is potentially a very serious issue, not simply a battery out issue.

Ill wait a week and charge and measure the stage. More thoughts arise:

1) while permanent tender is ideal, how many days between drives of adequate milage is deemed "ok" ...surely driving every other day is ok ? Maybe not..hence the question how many days is ok ?

2) given I'll ctek charge 1 per week per above, what's better...ctek overnight or drive the car ?

3) I bought a midtronics pbt300 battery tester. Given your comments on weak battery causing a strain on the starter motor...is it ok to assume if I'm getting a green light on the test that I'm therefore not straining the starter ? In other words... can I use the midtronics test to prevent strain on the starter even though I'm potentially doing some damage to the battery by weekly ctek charge (as opposed to the ideal permanent tender).

4) I'm ok replacing batteries more frequently. If this is the price to pay for my situation then I'm ok. Naturally I don't want to put any strain at all on the starter motor hence my comments. Again. Thank you. I'm sure others will be encouraged to use the tender based on your point re starter motor.

Hi All,
I need to change my battery (-ies maybe) as the main battery is not holding charge well enough. Was near flat recently and the car lost some programming on windows - now reset by doing the "button thing". But, the drivers' seat is stuck in far back position and won't come forward...apparently another reset issue..Any ideas or do I have to go to the dealer? The other battery related issue is that bootlid engine can act up on low battery..
Rabent / others, what is the experience with non-B batteries, such as Varta AGM 95Ah 850 EN?? Thanks !

Further to message..anyone know how to "re-program" the drivers' seat following a low/flat battery incident?

Its been a while now and everything is perfect with the VARTA AGM 95Ah 850 EN that I replaced in my 2004GT, it simply is better that the OEM Battery that Bentley offers, its got a larger capacity and VARTA is as good as the OEM or better.

Hi Johnny, another scenario. Lets say car has sat for 2 weeks and i havent been able to drive it or charge it during that 2 weeks, but i need to drive it immediately and there is no time to charge it. At this point i know the battery is weak and it will strain the starter motor if i attempt to start the car and i want to avoid any strain like the plague. Aside from "not starting it till i charge it" are there other options ie jump with remote battery pack or jump with charger on high voltage. I realize you advised against both of these in a prior post. My question is what is the down side to jumpimg as i described . In other words..what am i damaging by jumping

Thanks - can I just check as there are a few models of 95Ah 850... is this the correct one..Batería VARTA Start Stop G14 95Ah-850A ..at 236 EUR? Looks like the only AGM model.. And what is the best replacement for the RH smaller "starter" battery..Varta or Bosch but what size..

My car has the original 10 year old batteries (I know this since I've owned the car since 2 years old), so pretty good going. I didn't use to charge it at all, but after a 3 month stand-still I lost power and now use a CTEK MX 5.0 "smart" charger/maintainer...Which brings the main battery up to full charge overnight (all 8 lights lit on the CTEK). The secondary battery, whenever I put the charger directly on it, appears to be pretty full (full lights quite quickly - I do not have a tester so haven't confirmed properly) and despite being 10 yrs old seems pretty good ..

I am still hoping someone can tell me how to re-set the drivers seat ! Memory on mine has the "Set" button and 3 position buttons. Seat moves in all directions EXCEPT forward, and is stuck in aft most position. So. how do I get this live again?? Thanks for any advice.

WORD OF WARNING:Leaving the car for too long without moving it with a proper drive is NOT recommended.. there is risk that the Air Suspension rubber goes brittle and cracks, causing the car to sit too low overnight and the compressor to work overtime.. That is a $2,500- $3,000 a unit replacement..and once the problem arise Bentley will tell you..not before mind you.. so keep the beauty rolling from time to time..

I just replaced both my batteries in GT 05, not too difficult, the hardest part is keeping stuff out of the way as you remove / re-insert battery. I used Interstate on reccomendation of an ex bentley mechanic. so far works great.

With respect to re-program the seats take a look on the rest of this thread, i recall someone told us how. For me the only reset was the driver rear window, the advice is roll down window all the way, release, roll down again ( even though its already down) repeat 3 times, then do the same on roll up. I think the seats are the same, roll backwards, release, roll again, 3 times, roll forward and repeat. it seems it gets programmed at the extremities. as mentioned read the thread for more on this

Hi Johnny, with my new batteries, after 8 days of no driving I tested with Midtronics pbt300 and sure enough got green & yellow meaning needs to be charged. I charged and returned after 6 hours to find charge was complete so all this seems normal. I'll test at less than 8 days next time. Question: actually as repeat, forgive me, if battery is low but I really need to drive the car immediaely then I dont want to start the car on the low battery as this strains the starter motor. In this circumstance can I use a batter pack jump or a charger on high amp to start car. I realize you advised against both of these but I'm trying to avoid anything that might strain the starter, if I need to replace batteries every couple of years so be it, its less problem than engine out

ContinentalGt05,
I understand your dilemma, so yes if you want star at any given time when the starter battery is weak, yes hook up the jumper box to the right hand starter battery, and then start the car as normal.
Not the best situation but what else you going to do if you're low on power that's what you have to do.....

Okay back to my regularly scheduled program !!!

Thanks again. I try to write.with concise but complete details. I failed to mention one thing so i have 3 related questions arise from your response 1) so when i said the battery was low after 8 days i was referring to the Main left battery. The right tested just fine and i only charged the main, i did not charge the right. This makes sense as i recall its the left main that is used for electronics in the car that drain while the car is off, whereas the righr battery is not draining (im sure it drains a little in 8 days but not much). Given this scensrio of left low, right ok , do i still use the Booster Pack on the Right or can i assume the Right is doing the work with the starter motor so no need ? Q2) similar question...i would have thought if left low and right ok then to use booster pack on the Left ? Q3) if left is low after say 8 days days and Right is ok, , but i think it will start with normal key operation, albeit with strain on the starter motor lwhich i want to avoid), could i flip key counterclockwise then clockwise to start the car via shared batteries instead of the Starter Pack . In other words, same procedure had Left been completely dead, but its not dead in this scenario

If as in question number 3 the left is low but the right is strong then there would be no strain on the starter as the right is strong, if the left is low but still has enough juice to activate the electronics for proper normal starting then all is fine, again there will be no strain on the starter as it right for starter which is not low.

I think i almost have it sorted out, thank you . If left is low but strong enough for electronics and right is ok then good to start normally. Questions..ill try to make these the last ! a) When i hook up booster pack to right battery, given it needed it, do i literally just clip positive to positive and negative to negative and then start car immediately or do i wait a few minutes ? b) can i use the booster pack as a source of overnight charge. ? This might solve my dilemma. For example, car battery is low, can i clip on booster pack and leave a few hours to charge the car battery

The Owners manual shows instructions for jumping car with making connections of positive on left battery and negative on right battery.
-.02 cents

....I am new to this site...I am trying to remove the Main Battery...I am stuck...the car is 2010 Speed...I am half way into removal but cannot free up the large plastic electrical panel off the battery...I am trying to be very careful but I am stuck...any help greatly appreciated...

Hello Jim,
Did you loosen the positive terminal nut first, as the positive terminal comes off with that whole group of cables.

Hello Jim,
I saw your post in the other battery thread, although this is a picture of the starter battery on the right hand side, it is the same type of hold down for the main battery on the driver side.

Call me tonight if you would like to, sometimes speaking is better than typing.... :)

Johnny J J
908-507-6357
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....thank you very much for your reply. Its mid nite here in S.F., I will go down to the garage and see if I can get it done. I have gone very slow since I don't want to mess up. I see your picture...mine is little different...having problem seeing the positive post as it is under the plastic electric panel...I did lossen up the nut right by the post but it seems to be a captured bolt that dosen't come out?? Thanks again...also it is very tight space, just like the starter battery, I had to adapt my battery post puller tool, but that neg post came off easy....JimB

...its 1 am now just came up from garage....I did loose up the 13mm nut by the positive post, it seems to be a captured bolt, i.e. from what I see the bolt does not come out entirely, is that as you understand it? What has me flummoxed is the post and 13mm nut is in a 1-1/2 inch square space, there is no room to get a tool on the post clamp...how do you suggest I proceed??...I have been stuck here for a full day...very frustrating...JimB