Recommend me a battery

[FLI20Y]

Hey guys.

When my car gets to operating temp (160 degrees F), the fans switch on, and the car will not start without a jumper pack, which gets quite annoying. I have checked every possible scenario (alternator/earths/positive cable etc) and all of this is perfect, so I have put it down to the battery.

I also think when I have everything switched on at events (ie: line lock, radiator water spray pump) its killing the battery, and therefore the ECU drops below 12 volts and starts playing havoc with the way the car runs. Now I know shiat all about batteries, what do you think I should run as a solid battery?

Cheers in advance for the advice

[wld77]

could be the battery but how many amps is the alternator. if the battery is in the boot have you run a charge cable for the alternator or have you gone form the alternator to the starter!! just a few thoughts!

[Dynoryder]

well if your ecu needs 12volt than check the volts when it is all turned on maby need bigger alternator

my mate has a turboed harley it has biggest alt you can get but still cant supply the fule and oil pumps

but any way computer chips also need protection if you havent done it right then the fans might be puting the ecu into protect mode

what have you got like a sr20 in your datto there could be lots of probs with this

my bet is on the voltage drop so you will need a bigger alternator or a extra one

[YLD-305]

How big is the battery you have in it now?I'd get someone to check the battery you have now(checking the specific gravity of each cell and a load test)Id reccommend something with atleast 500cca.my LH has an N52(commodore/falcon size) my LJ has a N70ZZL(truck size) which is 580 cca and its mounted in the boot and never had a problem.Also make sure the power and earth leads are thick ones.

Check the alternator is working and has a heavy duty wire running to the starter(for charging batt)the more amps the alt puts out the better.Some thing around 80amps should do the trick.when it is running with everything on it shouldnt drop below 13v

Other than that just make sure you have good clean connections everywhere

[FLI20Y]

I have run a 13mm O.D welding cable from the battery to the starter motor, I have had 3 alternators checked out all fine and charging.

The car has never missed a beat up until recently, so in the past, and on the dyno and so forth, it has held 24psi of boost at 7500rpm and not one issue. So with that in mind, I think its a battery issue, as I have rectified anything it could be.

One thing that was suggested to me was plug gap, I just adjusted these accordingly and powerskidded a legal property , not one issue at all. I also dropped a few helis and no issues at all, so it may have fixed the misfire....but it still won't start hot. Keep in mind the car also ran 11.01 recently no misfire at all.

OH BTW - Alternator on a CA18det is 80 amps standard. The battery is CCA 430 I'm pretty sure...

[TUFFAZ]

optima redtop dude, not cheap, i use to have similar problems, in the end i brought a optima battery and never had another problem.

[ChevLX_77]

You wont fix volage drop by putting a bigger alternator on the car.

What is the vehicle actually doing when you hit the the key??

Try running a second positve lead from the battery to the starter. then fitting a bigger battery

[blwnlj]

The Alternator maintains all power to electrical accsessory items wether is a water pump, fuel pump,or what ever,once the engine is running, if the charging system is working correctly, NO power is drawn from the battery with the engine running.
The alternator must maintain output or the battery will slowly go flat.
A large battery may only be a band-aid for a charging fault,the flat battery will most likely reoccure just with more battery capacity it will take longer,I own an Auto Elect business so will help you if I can.Cheers.

[FLI20Y]

Originally Posted by blwnlj

The alternator must maintain output or the battery will slowly go flat..

Cheers for the help...so how do I test this?

[blwnlj]

MMmm well first ya need to check the charging voltage at idle and at about 2000rpm with a WELL charged battery,if all is ok the voltmeter should be around 14 volts with all accessories off,then you need to turn on all the gear,pumps fans what ever you have.Then same deal,the voltage hopefully will not drop below about 13ish volts at idle and should run back up closer to 14v at around 2000rpm held steady.If the voltage at the battery when running is heading towards 12.5 or lower the alt/wiring has most likely got issues as this needs to be better.Below 12 shes not charging at all.
Also check the belt is nice and tight and the alternator pulley is not red hot after a bit of a run.
Just another thought I see you have got a good size Batt lead on the positive side,whats on the neg side.Make sure if the earth is bolted in the boot somewhere, you have another earth loop somewhere for the body to engine block as the engine is rubber mounted and this needs to be bypassed.550+ cranking amp battery be fine in a standard case size or a N70ZZ or the larger capacity N70EX in a large case size if room.
If you do the charging tests let me know what you end up with and nut it out from there.