Simon's new Xantia V6 and Leaf blog

[white exec]

Hi Simon,

There are stud extractors...

Spiral type (usually LH threaded, to unscrew) is very old. The square-shank ones much newer, and are very good.
Drill the old stud with a drill half or two-thirds the diameter of the bolt remains.
Drilling usually disturbs and weakens the stud thread grip, which helps.
Tap in the extractor without huge force, so it grips in the hole.
Unscrew with a spanner/grips.
Use as much WD/+Gas as you like.

The square ones are on Amazon.uk.

[lexi]

If you can get heat on to the remains plus copious amounts of diesel or plus gas you may get a grip with vise grip and wind an odd one out. Worth giving them some lube from other side, a bit at a time over the next few days. Mapp gas torch.

[Hell Razor5543]

It depends on how much of the thread is protruding. I have found that, with care, a Dremel can cut a decent enough slot for a blade screwdriver to get purchase, but you would also want to use a freeing spray for a few days to improve your chances.

I do agree with white exec's suggestion of copper grease on the bolts would make things easier in the future (as it is likely more cells will give up over time, and you are the sort of person not to let them stay like that for long).

[white exec]

Stainless replacement bolts might also be worth considering.
It's obviously a bit exposed under there, and likely not waxed .

[Stickyfinger]

Personally I would use galvanised as the surface/interface is passive, protect with marine grease or a "soft" lock-tight/thread seal rather than add in a conductor (copperslip)

[Mandrake]

Well that's the broken bolt/screw kit I linked to earlier arrived already, so I'll have a go with it tomorrow as I'll be at home and see if I can remove a couple of the bolts. Looks like it will work (especially considering all the bolts were turning before the head snapped off) so fingers crossed.

Didn't come with any instructions at all which is a bit odd! I wonder how many people don't realise they're supposed to use the drill bit in reverse as well. (Since it's deliberately a left hand drill bit to drill the hole)

[white exec]

Fascinated with the idea of drilling a Left Hand Hole

[Mandrake]

Fascinated with the idea of drilling a Left Hand Hole

I'm sure you know what I mean... They use a left handed drill bit presumably on the theory that the force from the drill digging in may start to unscrew the bolt before you even use the second spiral tapered bit that bites into the hole.

I have plenty of broken bolts to practice on, that's for sure...

[white exec]

Aha!

[Hell Razor5543]

And then Simon, trying to do some work around the house, is wondering why it is he cannot drill the holes in the wall to hang the new cabinets on (clearly having forgotten that, the last time he used the drill it was to remove some sheared bolts and utilised a left handed drill bit). The drill bits were not biting (and were new and sharp); but he had not flicked the drill back into the normal right handed rotation!

[Skull]

I thought I'd seen a warning online on your link Simon to use reverse drive and no hammer action on your electric drill - a low torque / slow start function should help get a good bite Good Luck .....

[RichardW]

I've never done that

[Mandrake]

At home most of today so I did some more on the battery pack disassembly.

Most of the M6 bolts around the top cover (over 40 of them!) came out however a couple snapped off, naturally, and one was rounded off. I thought I'd try the new bolt removal kit on the rounded off bolt. First I tried the drill bit they supply to drill the initial hole - complete waste of time. Regardless of whether I tried forwards or backwards it could hardly make an impression in the bolt head...

So I tried the new 4.2mm drill bit I'd previously bought and it drilled into it like butter. So a complete fail on the drill bit half of the kit. I then tried using the reverse spiral bit in the hole I'd drilled and it gripped tight enough however.......it then snapped off and left the broken bit embedded in the bolt head... So basically that kit is worthless. It might work for rounded off screw heads but for siezed bolts, forget it! I ended up just drilling the bolt out with a regular drill bit. Oh well.

The bolts have a spacer like a ferrule and screw into a threaded insert which screws into the plastic of the case. So of course some of the bolts were seized which resulted in the threaded ferrule unscrewing from the plastic instead... As the bolts are very rusty and there's a chance I might need to do this job again one day I've bought a bag of M6 bolts to replace all 40 something bolts..!

After getting the cover off I was greeted with the insides, all in clean, dry immaculate condition, thanks to an o-ring seal around the lid and the whole enclosure except for the air vents being sealed:

After identifying which three modules I needed to remove I removed the first two that were beside each other:

Each module has one small data connector and insulated bus bars to the adjacent modules in the string, after removing those theres two bolts and the entire module lifts out:

A couple of bolts and brackets come off the side then the metal plate comes off the top. Under the metal plate is a plastic cover that comes off revealing the CMU or cell management unit mounted on top of the cells:

The CMU has small screws into the battery termainals that are removed, a connector to the daughter board on the right and then it unclips. Once out the bus bars between cells can also be removed. Before the cells can come out some plastic rivets have to be cut to allow the plastic grid to be removed and finally a cell can be removed:

The replacement cell is blue in the picture above - I have no idea what significance the original cells being green and the replacement being blue has! I've seen them in pictures online in green, blue, yellow and purple, with blue seeming to be the most common...

After replacing four cells (conspicuous in blue) in three modules and refitting the modules, with just the air vent to go back in yet:

So that's the cell swap basically completed. I just need to refit the air vent and then sort out the cover bolts so I can put the cover back on - I have 2 or three snapped bolts that need drilling out etc...

Once the cover is on and the brackets bolted down it will be ready to go back in the car.

[DHallworth]

Following this with interest, Simon.

Have you checked the cells you removed and confirmed they are indeed knackered?

David.

[Mandrake]

Following this with interest, Simon.

Have you checked the cells you removed and confirmed they are indeed knackered?

David.

I wouldn't say they're "knackered" as such, as the car was still running of course, but they are certainly down on capacity compared to the others in the pack and continuing to degrade at about 4x the rate of the good cells.

Cells rarely fail completely and suddenly, usually they go bad over time where the capacity drops markedly and/or internal resistance goes abnormally high compared to their neighbours, so its usually a progressive failure over time.

I only got them out tonight so I haven't measured them out of the car yet but I will. The only precision charger/discharger I have is a SkyRC unit designed for radio controlled car and helicopter batteries, as it can only charge up to about 6 amps and discharge at about 1.5 amps on a 4 volt cell it takes a long time to test a 50Ah cell...

It took me about a week to test the four second hand replacements one by one to measure their capacity so it will take about the same amount of time to test the old ones, but I'm interested to see what result I get. It's not worth spending a lot of money getting a higher powered charger/discharger more suited to the job to test them quicker if I'm only ever needing to do this once or twice.

I can tell from the diagnostics from the BMU which cells were weak but could only get a relative sense for how bad they are, only external testing will tell me what their exact capacity is in Ah.