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What battery (ampere) do you run

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Bugaru03 Commited Dubber

70 posts · joined Mar 2008 ·

#815497
I have a 44amp battery for my Suby conversion EJ20 NA SOHC.
I've noticed during the night rides that when the radiator fun starting to run, the voltage in the lights is decreasing.

Do you experience this kind of trouble? Do i have to change my battery with a new one and more amp's?
...always there is someone faster than you...

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68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#815511
Bugaru03 wrote:I have a 44amp battery for my Suby conversion EJ20 NA SOHC.
I've noticed during the night rides that when the radiator fun starting to run, the voltage in the lights is decreasing.

Do you experience this kind of trouble?
Do i have to change my battery with a new one and more amp's?

YIKES...

do You have a lamp connected to the alternator??
[alternator lamp]

You may have a bad earth somewhere.. OR many bad earths

do You have an earth cable from the chassis to the gearbox?
earth Cable from chassis to engine...

the alternator will charge Your battery and keep any lights and fan running... [normally]

if all electrical connections are correct...

sounds like a very bad/poor connection somewhere..

Lee

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

Bugaru03 Commited Dubber

70 posts · joined Mar 2008 ·

#816455
All earths have checked from electrician, the alternator is ok, battery ok but we have found that this drop is occured from the light switch (that's why i mention that this happens only at night driving)!

In the next few days i will visit him again for ending this.

Nobody answers my original question....what amperes is your battery??

Thanks!
Jimmy
...always there is someone faster than you...

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Adsman Officially Full-On Dubber

393 posts · joined Jan 2007 ·

#816468
poor earth, corrosion inside light fitting or bulb, wiring too small or under rated switch looking to cause a fire??? Normally relay for lights and usually 3mm square wire for upto 80W bulb. Also check that some dill hasnt fitted 130W bulbs to the headlights, if so remove them and replace with sensible ones. Over loading of power supply circuit is also something to consider. Seen alot of cars that have 4mm square wire ran front to back ie. 4metres+ and one wire feeds all light circuits, interior circuits, brake and rear loom, stereo, amps, fans, etc. you get the idea. Just check that the main power feed cable is not too small. A really quick way to check is to use a large wire or jumper lead and connect directly from your battery to the lighting power cable. If all comes good than you have found your issue. Alternatively the earthing can be checked the same way. Often earthing issue appear as corrosion of alloy parts in the system or failure of smaller devices.

I believe without seeing the car that the radiator fan and headlights are either earthed off the same lug or feed from the same power circuit. Depending what rad fan you are running and battery location you could require 4mm square cables just to run the fans. Another thing is the condition of the fans ie. brushes, dirt, corrosion, bearing/bushes all of these change current draw from the fan.

To answer the original question generally 400CCA or better. If your battery is not charging fully or cranking slowly then it could be the problem. Check that battery has 12v or better (dropped cell check) and when running in the car 13-14.4V at approx 2000rpm (Alternator charging check).

More details about relay, fuse, battery, switch locations are needed. Also are your power circuits from the ignition switch run to relays or do they take the current load?
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ratbug aka toddy101

439 posts · joined Jan 2003 ·

#816792
I recon it could be quite normal. When the radiator fan motor starts up it pulls a lot higher current for half a second or so as the motor quickly accelerates to normal speed, this puts a bit of a surge through the 12v electrics including your alternator, wiring and earths, escpecially bad at idle as the alternator won't have enough speed to deliver the amps for that second, and will drop from 13.8 to say battery voltage (12.5). I have a voltmeter in my suby vw and it drops momentarily when then fans kick in, but then goes back to about the same level, you do notice the lights dim.
If you have a voltmeter, with the engine running, check the voltage between the engine block and the alternator +. Then check the voltage across the battery, should be similar, maybe up 0.1-0.2V different. Then check again with the fans running, lights on etc, may see it differ a little more, I would say anything more than 0.5V is bad. Also check the voltage between the engine block and the chassis of the car, this will check how good the engine earth is. Then check the earth between chassis and the lights ground and fan ground, if any of them are high you have a grounding problem. Then check the difference between battery + and the fan/light +ve with them running, if this is high you may have too small power wiring.

Also just checked my battery, I have a super compact one, its 400CCA and 30Ah. I have a high torque starter and the engine is turbo so less compression, it turns over ok but 400cca it used to struggle turning my EJ20 sohc with the vw starter. The 30Ah is also small, but just means I can't leave the radio or anything else on for too long without the engine running, and it goes flat within a week if I don't drive it.

But yeah as previously mentioned with the engine running your battery will have no affect on the electrics as the alternator will be supplying the power.
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Joel Now containing 100\% E-Wang

9,368 posts · joined Feb 2006 ·

#816803
Jim, the dimming lights is a common problem, it's the just from the stupid way VW wired up the headlights in 70s cars.

So that the headlights cant be left on they take power from the ignition switch and when you have fans, ecu, turn signals etc all taking power through piddly little contacts in the ignition switch disco headlights is the result

I used to have this problem when I had a huge stereo in,
Now with relays running my high and low beam even with 130/90w headlight globes, 55w foglights and 2 rad fans+1 a/c rad fan I dont get any dimming at idle

To answer your question I've got a 475cca battery

choppa Seriously Crusin Dubber

190 posts · joined Oct 2002 ·

#816899
Good info fellas.
I have an old 575cca battery that was great for everything, I also recon it made the car run better. Its so old now its struggling though.
I too run a seperate heavy power wire from the battery to the front and it feeds the relays for the fan, fuel pump and headlights, all switched by the standard wiring and switches.
Oh and I run 120w headlights no probs.

Bugaru03 Commited Dubber

70 posts · joined Mar 2008 ·

#821157
Joel, yes the dimming lights is pain in as... but i finally get the problem solved.
In my build thread here( http://forums.aussieveedubbers.com/viewtopic.php?tid=67945&page=4) I have mentioned that when the engine warm up and during the ride i have instantly three or four stalls, it's like that someone to cut the power or the petrol.
So i have realized that the dimming lights were the source of the problem. The driving distance is every day the same, home-work-home so back to home in the afternoon i need to open the lights and that cause the stall.
The fuse is overloaded with power and is gets really hot with result of losing power somewhere and instantly cut me off.
So the simplest test was to open the lights during the day and see if the problem comes up.
And guess..... Yes it stalls once more so it has something to do with the dim lights. So i will bypass the big scale and send it directly to battery or i will add a relay!

Appreciate everybody answer this post!

Regards,
Jim
...always there is someone faster than you...

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