Eating Batteries

[Tom2000]

I posted a few weeks ago about battery charging issues and fluctuating headlights. I took the car for a 70 mile round trip, next day I go to start the car and i get the "dead battery" sound. Tested multimeter and battery is showing 6.8V (no load!). None of the electrics had been left on. I double check engine earth and electrics and seem fine.

Battery was about 4 years old and had been through a number of long periods stood still whilst being rebuilt so I go out and buy another battery Varta Blue D21 60Ah 600A battery (showing 12.4V), the alternator is relatively new bought under 2 months old and is a 55Amp from a Fiesta. The new battery goes in, I try to start and I get the same sound of a dead battery !?!!?!? I jump the car off a Volvo C30, as soon as I turn the key the car fires perfectly. I drive near 300 miles from Norwich to Southampton. Next day I try start her up, dead.. again. So I test the battery and it's got around 7v. It's now been trickle charging off a halfords charger for nearly 28 hours and the battery is only showing 11.10V.

I purchased the alternator off an independant parts shop at the end of the road so took the alternator back to them for testing and will hear back tomorrow afternoon. Rather miffed because I suspect the alternator may have ruined a perfectly good battery.

Any thoughts?

[Nick Jones]

How long between fitting the battery and trying to start the car.  If there is a big static drain, you'll get a fat scary spark when you connect the battery - never a good sign! Did you measure the battery voltage on the car with the voltmeter probes on the terminals or battery posts?

Recently had a related issue with my Audi and it turned out that the inside sufaces of the battery clamps had a very thin, clear oxide layer coating which were doing a pretty decent insulation job.  This was causing very slow cranking due to volt drop and was also preventing the battery from charging properly for the same reason.  I was measuring a 2v diffence dependent on whether the multimeter probes were on the battery posts or the clamps.  I finally twigged because after a bout of prolonged, painfully slow cranking I burnt my fingers on the positive terminal when attaching jump leads......

So try cleaning your battery clamps.  You could also check all your earthing connections.

Cheer

Nick

[Richard B]

Holts No-Corrode on the joining surfaces of the electrical connections helps.

[Rich_s]

I had this happen on an old mini of mine, problem was finally traced to the regulator failing, it kept sending too many volts to the battery, was easily noticeable at night when the lights would go very bright for a few miles then go back to normal, easy way to check if it is happening is pull the plugs out of the top of the battery and wipe the bit that goes inside the battery with a white cloth, if it turns black the battery is being over charged and then they burn out, well mine did, then they hold no charge and finally give up altogether.

easy fix as is just a new battery and alternator, just expensive.

rich

[Tom2000]

932 wrote:

I had this happen on an old mini of mine, problem was finally traced to the regulator failing, it kept sending too many volts to the battery, was easily noticeable at night when the lights would go very bright for a few miles then go back to normal, easy way to check if it is happening is pull the plugs out of the top of the battery and wipe the bit that goes inside the battery with a white cloth, if it turns black the battery is being over charged and then they burn out, well mine did, then they hold no charge and finally give up altogether.

easy fix as is just a new battery and alternator, just expensive.

rich

Rich this is exactly what was the problem. However I am lucky in that my alternator was only 2 months old and purchased from a local shop that I know well so they sent it off to be checked, had the brushes and regulator replaced for free woop. Only issue is that the new battery I got only a week ago will only charge to 11.5V. So another battery :/

[sparky_spit]

Tom2000 wrote:

Only issue is that the new battery I got only a week ago will only charge to 11.5V. So another battery :/

How about telling this to the shop where you got the alternator and suggest that they might want to let you have a new battery at a seriously reduced price - 50% or proper trade/wholesale price? Might be worth a try?

[Tom2000]

sparky_spit wrote:

How about telling this to the shop where you got the alternator and suggest that they might want to let you have a new battery at a seriously reduced price - 50% or proper trade/wholesale price? Might be worth a try?

I went back and argued my point when the chap I know was in and he sorted me a new battery for £15. Car is running @ 13.94V with halogens on full, amplifier and stereo playing, wipers on and twin electric fans running @ 14Amp. So believe the problem has been solved. I believe I may be suffering from poor connectivity at the fuse box as my gauges are intermitently turning on and off, I checked fuses are fine and then used a multimeter to test each fuse connection and found that if I apply pressure to the top fuse everything springs back to life, the fuse didn't blow but quickly went a spotted rust colour so believe this may be my answer to shorting.

I've used contact cleaner but it makes little difference, presumably I need to remove it and clean the connections manually? Any tips as the wiring loom that it connects to looks complicated!

[Richard B]

Removal? bloody difficult. They built the loom through the fuse box.


Try cleaning all the contacts in situ with Holts No Corrode and retensioning the springs. Some of the clips are used to carry voltage through one end of the fuse. (Classic Triumph).


Alternatively (sorry I could'nt resist  ;D ;D ;D) cut out the fuse box and replace with another one. On my Spitfire I have a MkII Saloon 4 fuse unit separately mounted on the bulkhead for headlights, electric fan, O/D etc.

Putting that lot through modern plug-in relays with a separate direct feed from the battery, takes a load off of the OE loom.