Electrical Expertise

[S15_Spec_R]

I have a small battery on my car, think its 330 ca. If I leave the car for a week its unlikely to turn over. The battery is fine just my alarm and earthing kit possibly draining it.

My question is would it be better to relocate to boot area with a large battery or put one in the boot thats connected to the front. I like the sound of the later, I know its possible to bridge batteries. Any suggestions, once I have the power unit in the boot I will then be putting a couple of amps in for my choons.

 

[Paddy]

One thing to look out for is the size of wire you are running to a relocated battery. you may only get about 80Ah of current through a large wire. also, you need about 4meters of wire for live, and 4 more for negative.

can be messy. look into a full relocation kit but you may find you get a very (annoying) lazy start.

Tbh, check for a draw on the battery. even with 2x batteries, if you have a draw on it, they'll still discharge.

 

[S15_Spec_R]

Thanks paddy, what do you mean by draw? Is it something like an alarm or something using power in the background?

 

[Paddy]

Yup. If you have an multi meter, set to amps and and test the battery terminals to see how many amps are used while the car is off and everything in the car is off. then try setting the alarm. anything below 0.6/0.7 amps would be normal.

Draw on the battery can be caused by anything from a light etc being left on, or a wiring fault, ie partial short circuit.

Do you have a multi meter?

 

[Nicely]

Yep, I'd check the drain. You shouldn't be getting a flat 330A battery after a week of sitting. I had exactly the same problem and suspected the immobiliser or alarm (more likely) and got a fitter to check it out. He couldn't find anything specific, but re-did a few crap connectors. Problem disappeared....

 

[Paddy]

Also, just thinking. check the voltage and battery fluid levels. might have a dead cell.

 

[S15_Spec_R]

Its a new battery, or it was around christmas. I took it off the car and charged it for a long time until I could just about see the green indicator. Its constantly black (the indicator window) but still starts the car, however I have noticed one quirk and thats night driving. If the lights are on the rpm at idle raises and does not drop back to proper idle in between gear changes. So when I'm off the gas the car feelslike its driving itself. The rpm eventually drops if left to idle.

I have a multimeter and will check as per your instructions Paddy.

 

[Paddy]

one more thing. draw is not measured between the terminals like voltage is. Ie, dont put one probe on positive and the other on negative and expect to see the draw on the battery.

Remove one of the battery leads and attach the probe to the lead end, and the other probe to its terminal. when checking for draw, try to make this circuit...

--->positive wire--->probe1--->(multimeter)--->probe2--->positive terminal--->battery--->negative terminal etc...

That battery should be under Warrenty :nod:

 

[S15_Spec_R]

Shall let you know my findings - cheers Pad

 

[S15_Spec_R]

I think the battery is dead, almost. I charged it and the indicator never got to green. Its black which according to the diagram is discharged. Its actually a 300 ca battery.

So I am going to chaned the battery and my options are:

Relocate or bridge (want to run some amps at some point)

Firstly, if I relocate how would I fuse the positive connector to run to the rear (bolt two connectors together (new & old) and would I do thesame for the neg? How would I run the wires (under, through cabin)

Secondly, by bridging I can run a cable from neg to other batterys pos (right, no it would be pos to pos and local earht?) and earth other battery local? If this is the case could I bridge to a larger battery or does it have to be the same size (ca)

My battery size max is 20 cm (l) x 20 cm (d) x 14cm (w) so relocation is the best option as I am not going to be able to run amps of such a small battery.

Anyone relocated to the cabin, how about passenged footwell?

 

[Paddy]

Ok, for the indicator not to turn green, it would usually mean that you only have about 11 volts or less in the battery. so, dead cell. those batteries are usually sealed so you might not be able to check levels.

Relocation is a bit of a pain to do right. on the fire wall behind the inlet plenum and to the right of the brake servo there is a rubber grommet that you can run the wires through. they will come out behind the dash and can be tucked up underneath the trim covering the transmission tunnel. then fished out under the rear seat and into the boot. also it is very hard to secure the battery in the boot.

the grommet in the firewall is very tight so some wires may not fit. and this is the problem. smaller wires cannot flow high amps. i could get 4x lengths of wire through the grommet, 2 possitive, 2 negative. with alot of force. each one was about 1/4 inch in diameter and rated at 45 amps. so when i relocated, i could have put any sized battery into it, but still only got 90amps. side effects are a huge lazy start. the engine turns over sooo slow on the key. and it might take 4 or 5 seconds to start!

Honestly. because you battery should have a 2 year manufactures warranty, just get it replaced. If you have a FMIC and need a battery with reversed terminals etc, there is a tread flying around with the correct battery number to get. It is your best option.

As for bridging the batteries, both circuits you mention should work, one is parrallel, the other series. i cant remember which is the one to use in vehicle electrics, but would advise against it. I've never done it so i cannot comment. but one battery should be more than enough when its working right.

Paddy (in Florida)

 

[S15_Spec_R]

Hope you are enjoying your vacation, so I wont bother you too much .

So this would explain why my engine runs higher revs when the lights are on if its running lower voltage? Is 300 ca enough? It is sealed.

Could I not open the hole up to allow a standard power cable? (obviously fill in the areas to stop leaking) If a standard cable went through would the lazy start disappear?

I have a FMIC which is why I'm limited in size of battery and also I dont know if its a jap terminal (with the back against wing post is bulkhead/towards driver and neg is headlamp/FMIC).

How did you wire the clamps? I mean you have multiple wires going to your clamp for both pos and neg did you attach new cable into clamps and bolt clamps together or did you solder accordingly?

Cheers, Keith

PS If I was to bridge can you bridge to a larger battery?

 

[Paddy]

Hope you are enjoying your vacation, so I wont bother you too much .


:wave:HEHEHE, i'm living here now for next little while


So this would explain why my engine runs higher revs when the lights are on if its running lower voltage? Is 300 ca enough? It is sealed.



:wave:Yeah, basically, your battery is doing nothing but starting the car. so when you turn lights etc on, you altenator has to do all the work. so it revs up to increase power.



Could I not open the hole up to allow a standard power cable? (obviously fill in the areas to stop leaking) If a standard cable went through would the lazy start disappear?


:wave:yes and no, the bigger the diameter of the wire the better, but there is about 3.5m between the fuse box and the boot. there will still be a lazy start, just not as bad. 2 meters of wire has twice the resistace of 1 meter of wire.

:wave:My concern about opening the hole, would be a risk of wear on the battery wire insulation. If the grommet was modified, it could fail.



I have a FMIC which is why I'm limited in size of battery and also I dont know if its a jap terminal (with the back against wing post is bulkhead/towards driver and neg is headlamp/FMIC).


:wave:'Jap terminal' is more to do with the size of the terminals, they're tiny compared to EU batteries. I sounds like your battery was replaced at the time your FMIC was fitted so that the teminals could reach. if that battery was in good condition, it could probably start a truck. If there is a three digit number like '053' etc, get another one like that.



How did you wire the clamps? I mean you have multiple wires going to your clamp for both pos and neg did you attach new cable into clamps and bolt clamps together or did you solder accordingly?


:wave:I bought a few different battery terminals at the local motor factor, the 3 smallest ones i think. the clamps had a large area for fitting a wire, so i put both wires in the each terminal and tightened it up.

Cheers, Keith

PS If I was to bridge can you bridge to a larger battery?

^^^i've written answers in your text here:wave:^^^


I would sugggest an equal sized battery. although size technically shouldn't matter, as the voltage should be equal. be very careful and research the effect of joining two batteries together on voltage. one type of bridge can increase current, the other effectivly doubles the voltage. 24V will probably fry the ECU

Again, i dont recommend a bridged battery, the resistance of the wire on a scenic tour of your car would be huge, the electricity would follow the path of least resistance, which would be the battery in the engine bay. so most of the power will be from that battery, both for starting and everything else and the altenator will also supply most of the required power when running. the extra battery will therefore add very very little.

A the very least its a poor return on the cost and effort.

I returned the battery to its standard position in my car, because no-one would buy it with a lazy start, and wires all over the boot.

BTW battery under warrenty = FREEBIE

 

[S15_Spec_R]

Size doesnt matter eh, is that what you keep telling yourself!!

Na thanks for the input, I shall have a look for a replacement.

I found some jap batteries online and they allowed for the terminal to change (pos now neg and vice versa), did notice the thinner terminals but my batt has more girth!

So If I want an ice install I will struggle with a lickle battery, right?

How about relocation to footwell or even when I tak out back seats?

Seen any crocs, I was down the everglades a couple of years ago when I lived in Chicago - saw some big crocs. Florida is nice, your not retiring are you!! :thumbs:

Leave you alone for a bit

 

[Paddy]

Size doesnt matter eh, is that what you keep telling yourself!!

Na thanks for the input, I shall have a look for a replacement.

I found some jap batteries online and they allowed for the terminal to change (pos now neg and vice versa), did notice the thinner terminals but my batt has more girth!

So If I want an ice install I will struggle with a lickle battery, right?

How about relocation to footwell or even when I tak out back seats?

Seen any crocs, I was down the everglades a couple of years ago when I lived in Chicago - saw some big crocs. Florida is nice, your not retiring are you!! :thumbs:

Leave you alone for a bit

oh, so many sig quotes to choose from!

best place for a second battery imo would be opposite wing. if you have an upgrade air filter. that would be the best setup.

your battery could probably keep a 1000w sound system happy. but with the engine running, the altenator is carrying most of the load. main reason for second battery with ice, is when its left running while engine is off. then one battery would be drained in 1-2 hours.

The heat here is killer 29C today. here since wednesday and i've not seen any crocs yet, or any decent cars for that matter. one thing i am going to do is see a shuttle launch.
I'm not retiring yet, i just dont like working, thats all.

 

[S15_Spec_R]

I've been looking at batteries online and there are some (optima yellow top) which have good cycles or something - anyhow designed for ice.

If my battery is not fully dead which it isnt due to the fact I have been using it for months would this affect the spark and fuel efficiency or increase knock under heavy acceleration?

I dont have any space in the bay even with the aftermarket filter due to IC pipes. Since fitting an uprated rad though the cowling is off, would a rad running about 70-80 cent be a bad place to put it near (silly qyestion I know but I have to ask)

At least you have it nice then, its rain and the nights are drawing in here. Over and out Apollo 13.

 

[Paddy]

Over and out Apollo 13.

PMSL:rotfl::rotfl::rotfl:

yeah, there will be some performance drop. headlight flicker if you dont have relays on HIDs. Knocking at high revs/loads too. you will probably see better performance once fixed.

heat is bad... batteries like to explode...

Dont worry lunar module... theres a team of scientists working to find those 10amps to get you back to earth.....

 

[S15_Spec_R]

Well the battery has sorted out the increased knock points at higher speeds, its back to 12 from 50 at 140mph.

I still get it over revving with the lights on, not as bad as before - any ideas as to why it revs, its annoying!

Any nice trim out there so far