Derek Uzzell Posted February 24, 2020 Share Posted February 24, 2020 The battery-disconnect feature found on some Ducatos was referred to last month in this thread https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Battery-fitting/54196/ and on the thread’s 2nd page are photos of the starter-battery of a Ducato having the disconnect feature. I have copied one of those photos into the attachment below. Besides a big relay and extra cabling, it will be seen that there is still an earth cable (arrowed red) that connects to an earthing point on the chassis. Link to comment Share on other sites More sharing options...
John52 Posted September 21, 2020 Share Posted September 21, 2020 Gerry McG - 2020-02-23 2:53 PM or has it been added as a precaution given the well known ground strap issues? No because the ground strap issues were between the engine and bodyshell Link to comment Share on other sites More sharing options...
Derek Uzzell Posted September 21, 2020 Share Posted September 21, 2020 I’m not sure why you’ve chosen to revive this thread that ‘closed' last February, as it’s clear that Gerry McG’s question was fully answered by the subsequent postings from Robinhood. Link to comment Share on other sites More sharing options...
John52 Posted September 21, 2020 Share Posted September 21, 2020 Derek Uzzell - 2020-09-21 8:20 AM it’s clear that Gerry McG’s question was fully answered by the subsequent postings from Robinhood. Its not clear to me They are showing a strap from the battery to the bodyshell wheras the ground strap issues were the strap from the bodyshell to the engine. Link to comment Share on other sites More sharing options...
witzend Posted September 24, 2020 Share Posted September 24, 2020 John52 - 2019-09-03 7:38 PM These are what I use: https://www.ebay.co.uk/itm/Car-Engine-Gearbox-Battery-Earth-Lead-Strap-9-to-24-Inch-Choose-Terminal-sizes/322794821937?hash=item4b28121931:m:mxeX3kZ04RCh9mFozvU9dFA These maybe ok if just fitting a extra strap but if replacing the original I'd suggest a heavier duty strap like this https://tinyurl.com/y2svbw2u Link to comment Share on other sites More sharing options...
John52 Posted October 8, 2020 Share Posted October 8, 2020 witzend - 2020-09-24 6:42 PM John52 - 2019-09-03 7:38 PM These are what I use: https://www.ebay.co.uk/itm/Car-Engine-Gearbox-Battery-Earth-Lead-Strap-9-to-24-Inch-Choose-Terminal-sizes/322794821937?hash=item4b28121931:m:mxeX3kZ04RCh9mFozvU9dFA These maybe ok if just fitting a extra strap but if replacing the original I'd suggest a heavier duty strap like this https://tinyurl.com/y2svbw2u There is no right or wrong answer here. Thicker cable is always better. But you have to draw a line somewhere, and where to draw the line is a matter of opinion. Just like exactly when an old tyre is perished enough to need replacing is a matter of opinion. I remember a thread on the electrician's forum. The OP had installed a shower with 6mm2 cable, Inspector wouldn't sign it off, so he had to rake the cable out again and replace it with 10mm2. There followed pages of discussion with opinion split on whether 6mm2 was good enough or not. :-S Link to comment Share on other sites More sharing options...
witzend Posted October 8, 2020 Share Posted October 8, 2020 John52 - 2020-10-08 8:48 AM There is no right or wrong answer here. Thicker cable is always better. But you have to draw a line somewhere, and where to draw the line is a matter of opinion. Not my opinion knowledge from several years of training If replacing a earth strap if not using a OEM part its always right to use a compatible part not as You posted one with a smaller cross section which can cause untold problems with other electrical parts ECU BCM etc Link to comment Share on other sites More sharing options...
John52 Posted October 9, 2020 Share Posted October 9, 2020 The OEM part was faulty, so you don't want one the same. My 25mm2 works OK. I don't know what yours has got that could overload a 25mm2 cable 8-) Link to comment Share on other sites More sharing options...
Derek Uzzell Posted October 9, 2020 Share Posted October 9, 2020 The ebay vendor advertising for £4.99 228mm-long earth straps with an 8.0 mm diameter (25 mm square cross section) also advertises the same length strap with an 11.0 mm diameter (50 mm square cross section) for £6.95. As both of you appear to agree that fitting a strap with a cross section inferior to the Fiat original part would be unwise, provided that the 11mm diameter strap is sufficiently flexible, wouldn’t it be sensible for anyone considering replacing the Fiat strap to opt for the £6.95 version? Link to comment Share on other sites More sharing options...
Alanb Posted October 9, 2020 Share Posted October 9, 2020 John52 - 2020-10-09 7:39 AM The OEM part was faulty, so you don't want one the same. My 25mm2 works OK. I don't know what yours has got that could overload a 25mm2 cable 8-) Perhaps a starter motor? Alan Link to comment Share on other sites More sharing options...
John52 Posted October 9, 2020 Share Posted October 9, 2020 Alanb - 2020-10-09 9:59 AM John52 - 2020-10-09 7:39 AM The OEM part was faulty, so you don't want one the same. My 25mm2 works OK. I don't know what yours has got that could overload a 25mm2 cable 8-) Perhaps a starter motor? Alan But not ECU or BCM which appear to be the problems caused by unreliable conductivity of the original strap. I've just stripped back the insulation of the OE battery leads to check. Negative appears to be 35mm2 and positive 50mm2 - but both are thickly insulated and the positive also has a long run under thick insulation requiring thicker conductor. So whilst my 25mm2 works OK (as its a short cable with no insulation and ample ventilation) so I wouldn't bother replacing it, If you are replacing it 50mm2 would be better I agree. Link to comment Share on other sites More sharing options...
witzend Posted October 9, 2020 Share Posted October 9, 2020 The Fiat strap is approx 15cm long but the ends are designed to enable it to fit in the intended location it only fails after time so replacing with a original part is fine their not made faulty and it's possible that its design has been. To fit any other strap it needs to be longer so ideally larger cross section if a smaller lead is used you run the chance of the current finding a easier path back to the body and risk damaging any number of delicate parts, When the problems associated with earth problems is so documented why would anyone replaced with a inferior strap. I replaced mine with oem part just because it looked neater than fitting a 28cm loop which appeared to be a bit of a lash up I didn't really need to as cleaning the connections was all that was required but seeing as I had it delivered rather than return it it got fitted The starter motor drawing current when the earth lead is inferior or faulty is what causes the problem in the ecu and bcm Link to comment Share on other sites More sharing options...
John52 Posted October 9, 2020 Share Posted October 9, 2020 witzend - 2020-10-09 11:53 AM The Fiat strap is approx 15cm long but the ends are designed to enable it to fit in the intended location it only fails after time so replacing with a original part is fine their not made faulty and it's possible that its design has been. To fit any other strap it needs to be longer so ideally larger cross section if a smaller lead is used you run the chance of the current finding a easier path back to the body and risk damaging any number of delicate parts, When the problems associated with earth problems is so documented why would anyone replaced with a inferior strap. I replaced mine with oem part just because it looked neater than fitting a 28cm loop which appeared to be a bit of a lash up I didn't really need to as cleaning the connections was all that was required but seeing as I had it delivered rather than return it it got fitted The starter motor drawing current when the earth lead is inferior or faulty is what causes the problem in the ecu and bcm My understanding is that in the early leads the bad connection developed between the plain copper strap and the steel end. Thats why I always use tinned copper straps. They don't go to the expense of tinning the copper for no reason. ECU and BCM have to cope with a big voltage drop when the starter is operated, and the problems caused by the faulty lead were not when the starter is operated. The current is not going to find an easier path to the body because the tinned copper strap is 25mm not 50mm . If your motorhome is your pride and joy, and you have plenty of time, you aren't going to care if the part costs a bit more and takes a bit longer to fit. But when I worked in the trade I had to think twice about that. If you can save a bit here and there you do it, because it probably makes the difference between profit or loss at the end of the year, And you do your own vehicle to the same standard to make sure its OK. :-S Link to comment Share on other sites More sharing options...
witzend Posted October 9, 2020 Share Posted October 9, 2020 John52 - 2020-10-09 12:30 PM If you can save a bit here and there you do it, because it probably makes the difference between profit or loss at the end of the year, And there lies the problem fitting inferior parts to save money do it once and do it right fitting these parts only cause other problems in the long run. My last post on this now left to members to make up their own mines what to fit Link to comment Share on other sites More sharing options...
John52 Posted October 9, 2020 Share Posted October 9, 2020 A chain is only as good as its weakest link. There is no value in fitting a link thats stronger than the others. Or a replacement part thats a higher spec than the rest of the vehicle. Link to comment Share on other sites More sharing options...
John52 Posted October 10, 2020 Share Posted October 10, 2020 as I recall we used to keep a few 25mm2 in stock so we wouldn't have kept people waiting whilst we ordered in 50mm2 when the 25mm2 we had in stock would do the job. But if you are ordering one special you might as well have the 50mm2 Link to comment Share on other sites More sharing options...
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