Help, New Battery Died

[ali125]

Toyota avensis diesel 2.0

Hi

I put in a new Bosh Battery from Halfords (bought two months ago http://www.halfords....yId_165762#tab1), yesterday whilst the engine was running i had a tomtom satnav plugged into the cigarette lighter, had the heater on, radio. I turned the car off and done my shopping, came back after 10 minutes, turned ignition and car won’t start. My brother done a jump start and the car started again.

Went to Halfords, and they said the Battery is fine.

Went to a garage and the bloke said the Alternator is ok. He said it might be the starter motor as when turning my engine he noticed a crank. He said the starter motor might be draining the Battery when it cranks as it uses the battery to turn on the engine.

Has anyone had this problem??

Would it be the starter motor that is draining the battery???

[averageuser]

Hi!

Relying on my experience, possible reasons may be:

Poor Battery terminal contacts and/or Battery grounding (simply clean from oxidation and tight up);

Battery energy leakage as via starter circuitry as any other way (when key is removed, connect multimeter leads across grounding cable, multimeter set to DC operation 200 mV. reading must not exceed few millivolts;

Poor battery (even brand new);

Starter winding is possibly shortened (enormous current consumption).

Thank you.

[t-spiritpete]

Why did you replace the original Battery in the first place, was it the same problem?

[Druid Boy]

I had a similar experience. Drove for about an hour, parked for about an hour, car wouldn't start. AA chap suggested starter motor was killing Battery as he had to use booster pack as well as jump leads to get it going - it was pulling a huge amount of power. Local dealer diagnosed simple Battery fault so new Battery fitted. Soon ahd the same problem. Dead battery. Turned out the starter motor was failing and drawing so much power that it was killing the battery. Got a new battery under warrnety but had to cough up for the starter motor. Worth getting your starter motor checked.

[ali125]

Thanks for the reply.

I replaced the old Battery because of the same problem. Thought this would sort it out. It might be the starter motor.

@ Druid Boy

Is your car problem sorted after changing the starter motor???

[Druid Boy]

^{Oh yeh. Totally sorted. The starter spins faster and the engine leaps into life. I was surprised by the amount of difference it made. Just be careful though - just because the symptoms sound the same doesn't mean the fault is the same - and starter motors are not cheap.}

[garethpaul]

many toyota starter motors suffer from worn contacts over time which present similar symptoms to that of a dead Battery (just a click when turning the key).

I had to change mine at around 100,000 miles.

These contacts are easily replaced and parts are available for no more than £10 on eBay

Search Google for "replace toyota starter contacts diy"

[frankie406]

funny that i just replaced my Battery last week on avensis d4d because she wouldnt start thought Battery was dead as it would even start with jump leads new Battery started right away. though thinking back now then starter did sound a bit lazy on it..must get it tested thanks for the heads up!

[+robster+]

most jap equipment i work on have small starter motors that dont last as long as others

they do put a lot of current through the starter solenoid contacts as mentioned but usually firstly due to a poor Battery on the premise of voltage vs current

low volts/charge to an accessory cause high current draw

high volts/charge to accessory cause lower current draw

so the moral of the story is

the Battery could have been poor and caused excess heat to the contacts

new Battery fitted problem solved for a while but ultimately contacts are now giving up

may not just be the contacts though as the brushes and armeture will have taken the same current loading

cheapest and best bet is a service exchange from an auto electrical garage who recon rotating electrics £100+vat ish for this if you can remove and fit yourself

[frankie406]

yeah rob thinking of taking mine out and getting it checked over it sounds lazy but thought that was just a toyota thing as ive heard a few like that.?

[cooper12000]

ok silly question how does a low voltage cause a high current. ie v/r=i 12/1k=0.012 amps or 12 mA 9/1k=0.009 amps or 9 mA

it might be me being thick or is it some weird thevnins (spelling) thing where u put a short across the Battery but it doesnt go bang.

not trying to argue just understand

coop

[+robster+]

Ohms law bud

The power source and wiring arent the whole system

The starter or other consumer is rated in watts

The calculation you show is a motor free wheeling which is correct lower voltage will just slow it down but the differences in voltage try ing to push the same thing is where the current differs

This needs to be takeninto the equation

Its tried and tested in my line of work

Poor tractiion Battery will eat contact tips. Motors. Transistors etc

t

Another observation on a lower scale is vehicle diagnostics

There is usually a block measuring Battery volts

This is to calculate the current neefed to correctly feed outputs such as stepper motors and scv etc

The higher a voltage the less current needed to work the consumer to do the same function

And vice versa

[+robster+]

This may make more sense http://m.ecmweb.com/design/highs-and-lows-motor-voltage

[+robster+]

Dont go trying the dead short over a Battery thing

Never heard of that theory

It will melt the wiring or if wiring is ample then Battery will explode especially if its been gassing due to a recent charge

But put a bulb in series and its ok

[t-spiritpete]

With regard to a DC motor, the voltage across the motor, minus IR losses, is proportional to the speed or RPMs of the motor. The current through the motor is proportional to the torque produced by the motor. Normally the back EMF created by the speed of the motor opposes the voltage being applied and limits the amount of current the motor draws and thus it's torque. As more and more load is applied to the motor, the motor slows reducing its back EMF allowing more current to flow, producing more torque.
With a lower applied voltage to the motor not only will the motor be turning slower, which reduces the back EMF and allows more current to flow, the losses such as the internal Battery resistance, the cable loss and the IR drop in the motor become more important. This may mean that the motor may not have the speed or torque to turn over the engine and stall. When the motor stalls there is no longer any back EMF and all the current goes towards heating up the motor windings and that can damage the motor.

Pete.

[cooper12000]

im just being thick i guess i cant see how somthing can draw more current if the voltage is dropped...

i wasnt suggesting trying short circuiting a Battery it was a therom we had to do for my onc it was one of thoes things that i just couldnt get my head around like trig identities i just had to hope it didnt come up in the exams....

however i can see that if the current was increased it would burn out the components quicker through arcing and sheer heat

thanks for trying to explain anyways

coop

[+robster+]

A higher current/ higher load on a component drops voltage
Think of your Battery dropping dropping from the 12s into the 9s on your meter when cranking( drawing current)
Its just the opposite mirror image of that
Thats the last input from me on the subject lol it can get quite deep subject to get into

heres an easy converter

http://www.supercircuits.com/resources/tools/volts-watts-amps-converter

put 12v base Battery figure in volts

put 3000 watts ( 3kw starter) in watts

leave amps blank and press calculate

now try 9 volts and 3000w

see if the amps go up or down

im gonna have to do some real world tests when i get time, i probably need refreshed on a lot of things as i mix ac/dc charging / powering and i mostly know what the problem is without thinking about it but need to brush up on my terminoligy for each so i reserve the right to look like a fud if ive gone off track with any above. lol

[t-spiritpete]

A higher current/ higher load on a component drops voltage

Think of your battery dropping dropping from the 12s into the 9s on your meter when cranking( drawing current)

Its just the opposite mirror image of that

Thats the last input from me on the subject lol it can get quite deep subject to get into

:lol2: ;)

[cooper12000]

robster please dont think i was picking at ya i was just trying to learn somthing new:)

[boboo]

theory right

formula wrong

not vir but piv

common mistake to quote the power formula as ohms law