Hi all, my Gf has a mk4 polo 1.6glx, and its having problems starting. It's turning over when she tries to start it, but is acting as though its got a half dead battery and doesnt fire up straight away. The car actually cut out on her once as she pulled away one morning. I wanted to eliminate the battery as being the problem by changing it for a new bosch, but wanted a bit of advice on changing batteries, as I havent done it before on a car. The fitting looks straight forward enough, but I'm not sure on the correct way of disconnecting and reconnecting the battery? Should the earth come off after the +ve when removing and the earth put on first when fitting?? Or the other way round? Any tips greatfully recieved.
You remove the earth first and re-connect the earth last to avoid shorting out on spanners etc. I don't really understand why its the earth but its what all the books say
ok, thx. Also, does anyone know how I can test whether or not the battery is on its way out? I've read that testing the voltage when the car is on could give an indication of a duff battery if its reading between 13-14v, and not the normal 14.4v, is that right?
You are right in saying earth first off and last on, this is because if you left earth on and undone the live and touched the spanner to earth while still on the lead it would cause a dead short, inturn melting the spanner, you hand to the spanner and usually battery goes pop, all this isnt a nice combination. As for your voltage there are two ways of testing it:- 1, load test, you connect battery to a tester and switch tester on for 10 secs and watch needle, if it drops and holds at say 10voltish its ok, if it stops lower it wants chargin, if it just drops and doesnt stop its shagged 2, specific gravity test, this involes removing some of the battery fluid via a tester and it will test the specfic gravity of the fluid, if it reads ok on gauge then move onto next cell if it reads 5 ok and 1 not its a dead battery, the easy option is to change battery if you cant be arsed with other two methods hope this helps,
my gf's 1.0 polo did the same, it took quite a bit of cranking to get it started occaisonally and it cut out once or twice too, i didn't think it was the battery cos it was cranking it over fine on the starter, i cleaned all the HT bits up with WD40 and replaced the blue temp sensor. this seems to have solved it. mike
what I don't get is if you took the earth off then accidentally touched the live terminal would that not be as equally bad as shorting live to earth ? I'm not gonna test this OK. Electrical engineers want to comment ! Edited by: warwickA2VR
he means if you touch the body (still earthed) with the spanner/wrench that you are undoing the live with (one end still on the live nut, the other touching the body), you get a short. once i accidentally shorted a battery with a piece of wire, it almost instantly burnt the insulation off in a cloud of black smoke then glowed red all the way along till it broke. this was in my bedroom too! mike
Thats is what i mean, if you short the live out on the body while the earth is still connected, once the engine is goin tho a flat battery wont make ya car cut out, cause the altenator is charging to replace loss of volts in bat when startin and the engine is running off this power, a good way to test old car altenators was to disconnect earth while the engine was running, if it stopped then the altenator wasnt charging, WOULDN'T do this on new cars as it might spike control units and such.
Negative first and clean terminals with emery cloth and then apply vaseline to ensure good connection that doesn`t corrode especially on earth. And also most cars I have had the pleasure of removing battery the clamp bolt tends to seize and have snapped a few so a bit of copper grease on bolt wouldn`t go amiss.
Do it what ever way you like If you cant hold a spanner good enoguh to not manage to undo the clamps without touching the body, dont try it Christ - why does something so simple and basic turn into the debate of the century! And as dave says, clean em up and vaseline them
At the end of the day andy some batteries on differnt vehicles are difficult to undo due to there location, we are describing the safest way possible to cause no harm to urself
