Battery/Charging Issue

[justintime]

The calcium product is not the issue, all the manufacturers are making them now including century, exide, supercharge, etc.
The normal battery voltage at rest should be 12.5-12.6 volts
A charge rate under load of 12.5-12.7 is basically driving your car flat, that's why you're having the problems. The bosch alternators are good, however they can drain when standing due to the reg problems. With the engine off put a screwdriver new the pulley of the alternator, if it sticks to it or is attracted by magnetism it's drawing current. If it is charge your battery using your calcium charger and take it to an auto electrician who understands calcium batteries and alternators.

 

[mattman]

Howdy Yeah I mentioned the reg problem to the sparky when it was in for the current draw just before xmas. He knew what I was on about... had never once seen a new Bosch do it but tested anyway. Draw when car off is at about 50mA now, down from 1A from a stupid relay/BCM issue.

I cleaned the clamps last night, pos clamp I couldn't get it all off but it looked much better... car has been a bit better starting today but way too early to tell and is quite likely just placebo effect at this point

I was thinking tonight, and though I don't understand electricity fully.... I reasoned that it's possible for the voltages to look right, but if the clamps are dirty then possibly still not allowing enough current for a decent charge or to kick over the starter. IIRC it's current that dictates wiring guage - not voltage - so one would assume current is more likely to be affected by poor contact.

I repeat though - I really don't fully grasp electricity

 

[justintime]

A 1amp current draw at rest is definitely an issue, most cars I've tested are generally less than .05A , so 50ma should be good. I'd still give it a good charge using a Calcium charger, good ones are made by Redarc in Aust and CTEK. If it's fully charged and goes flat there are only three reasons, either the alternator is faulty, there's something draining the battery or the battery itself is faulty.

What concerns me is the low charge rate under load, this is definitely a concern. Just because the alternator is new doesn't mean it's not a problem. Get the sparky to check the current coming out of the alternator and also going into the battery using an amps clamp. A good one will be able to do this for you.

Electricity is no different to water flow. Think of volts are pressure and amps as flow, you can have ok volts (pressure), however have little amps (flow). Seems to me like there's little pressure and little flow....

 

[mattman]

Mmmmm ok, nobody else has highlighted the volts coming off the alt as an issue before... yeah there were some dodgy looking readings way up top of the thread but once I got an MM everyone seemed happy - including at least a couple of RACQ chaps who've tested it since.

Pretty much the only way to make it hit the battery at idle is to run aircon, highbeams etc all at once... but that never happens real world. Only need to hit about 900rpm to get alt to kick in fully so even cruising voltages are fine.

Thanks for confirming the possibility of amps being low even with ok volts though That does make sense with what I was thinking about dirty clamps. If the car runs better the next couple of weeks i'll probably replace them to hold off reocurrence.

 

[justintime]

It's much easier (and cheaper) to look at the really basic stuff first and resolve this befoe moving onto the more expensive stuff. Best of luck

 

[mattman]

Crikey, after all of this it seems that the contacts may just have been the issue.

Gave it a good run over the weekend (my weekday run is too short to give it a decent charge) and the last half dozen starts since then have been perfect... about a week and a half since it was last on the charger and it would normally be on it's last legs by now.

I'll keep on running it and see how it goes, but it seems we've found it. If it does turn out to be the issue I'll probably just end up replacing both clamps and trim the leads back again for a real nice fit - make sure it doesn't happen again.