Tips for relocating battery to the trunk

[Fox]

i'm looking into relocating my battery into the trunk to free up more space in the engine compartment, just what to know how to hook it up for a quality install
would this wire be sufficient for the main power wire?
http://www.ebay.com/itm/2-Gauge-AWG-Welding-Cable-Rubber-Insulated-Red-per-ft-/380411374824?pt=LH_DefaultDomain_0&hash=item589248ece8
and how exactly should it be hooked up just extended from the factory battery positive or ?

[RoadWarrior222]

Looks good to me, I'd still keep it as short as possible, while avoiding hot bits and providing strain relief.

I might be inclined to stick it in conduit for extra armour under the vehicle.... just make sure it won't hold water.

[Dony409]

I am considering doing something like this but just adding an additional battery in the trunk for my stereo but I am wondering if I could just use the same cable as what has been run for the amp in the trunk. But if it was hard wired to the battery in the from I wouldn't want it cooking when I start the car

[johnl]

Some guys relocate to the front passenger side to make room for intercooler/pipes on driver's side and in doing so use a smaller battery. Their idea is to keep weight over the drive wheels and to transfer as much as possible to the lighter passenger side.

[Fox]

i would like to keep the battery weight over the front wheels, but i'm thinking i could almost hide it entirely in the spare tire well since the space isnt being used.
is running the wire through the inside the car completely out of the question? maybe better wire just to be safe

[shelbyvnt2]

I am also looking at a battery relocation. It doesn't appear to be as easy as I thought to keep it up front. I haven't given up on the idea but it won't be easy. If you could possibly keep your battery under the hood or atleast in the front it would be much safer. By running your battery cables to the rear without any fuse protection, a fire is much more of a concern. They don't call the wall between the passenger compartment and the engine bay a fire-wall for nothing.

[Dony409]

Yeah but it works both ways also so when the car burns your motors still good

[turbovanman²]

i would like to keep the battery weight over the front wheels, but i'm thinking i could almost hide it entirely in the spare tire well since the space isnt being used.
is running the wire through the inside the car completely out of the question? maybe better wire just to be safe

You can run the wire inside if you want. You must make sure the battery is vented unless your using a gel battery otherwise you'll fill the interior with hydrogen gas.

[Fox]

thanks i'll make sure to take care of that by getting the right type of battery, also i found this diagram posted in a thread here, i will be putting in fuses to prevent fires like it shows

http://i658.photobucket.com/albums/uu307/ShadowFox-7/CSX%20439%20build%20thread/remotebattery.gif

[rbryant]

thanks i'll make sure to take care of that by getting the right type of battery, also i found this diagram posted in a thread here, i will be putting in fuses to prevent fires like it shows

http://i658.photobucket.com/albums/uu307/ShadowFox-7/CSX%20439%20build%20thread/remotebattery.gif

Nobody ever does that... ;)

My diagram (which I am surprised that you found) above does things differently than most remote battery installs.

I came up with this scheme so that when they test the kill switch at the track (by shutting it off when the car is running) the alternator won't drive current back into the wiring harness and potentially cause voltage spikes.

Just make sure you drive all of the power connections that would have gone into the computer, interior of the car, etc are changed to go into the main power block and you will be good to go.

-Rich

[shelbyvnt2]

You are not going to be able to fuse the hot wire going from the starter/alternator to the battery. You will pull so much current it will blow almost any fuse you will find to attach to it. No car that I know of has a fuse on the battery cable, that is the very reason I told you it is best to keep it under the hood if possible. With the available current and the fact that your car is negative grounded if your positive battery cable wears through and touches the body of the car, under your carpet for instance, there is a very good possibility you will have a fire and no more car. It should only burn the inside of the car of course and the engine should be fine, thanks to the fire-wall.

I am looking at running two small lawn and garden batteries in the front of the car so I can eliminate this possibility. It isn't easy to do as my car has A/C.

[RoadWarrior222]

it will blow almost any fuse you will find to attach to it.


Well there's the ancient folk wisdom cure for that.... if the fuse keeps blowing, use a nail :D

[wallace]

If you intend to race this car at a track you should wire it so that when the kill switch is engaged it actually kills all electrical power to the car. It will pass if they switch it off and the car dies but using the diagram above you still have an active circuit to the front of the car.

[rbryant]

If you intend to race this car at a track you should wire it so that when the kill switch is engaged it actually kills all electrical power to the car. It will pass if they switch it off and the car dies but using the diagram above you still have an active circuit to the front of the car.


The diagram above does not have an active circuit on the front of the car as you state.

All accessories, ecm, etc only connect to the battery via the 4-8ga wire at the main block on the bottom left. The only connection on the other side of the kill switch is the dedicated line for the alternator and starter.

-Rich

[wallace]

? I see the power wire for starter and alternator feed has power to them with the disconnect switch on or off.

[rbryant]

? I see the power wire for starter and alternator feed has power to them with the disconnect switch on or off.

So?

The alternator and starter aren't connected to the rest of the car wiring.

That might have been more clear in the thread where I originally posted the diagram. :)

The only connection to the alternator and starter goes to the battery. All other power wires go through the main block which is on the other side of the kill switch. This is different from most wiring setups because I share the alternator and starter wire and everything else has a separate wire to the battery. It does cost slightly more because it requires an additional 8ga wire to feed all of the cars power.

-Rich

---------- Post added at 09:36 AM ---------- Previous post was at 09:30 AM ----------


You are not going to be able to fuse the hot wire going from the starter/alternator to the battery. You will pull so much current it will blow almost any fuse you will find to attach to it. No car that I know of has a fuse on the battery cable

Nonsense...

The 4ga wire is only rated at 135amps.

If you get a 150amp continuous duty fuse it will handle as much current as the wire is rated for and will also handle the spikes.

There are cars out there that have fusible links in the alternator harness. I believe that the LS1 corvettes have them for instance.

-Rich

[wallace]

Run the car into the wall and push the sheet metal up against the starter lug or alternator output into it, it's live now and there's no way to cut the power. This is a safety issue for the operator of the car and the track personnel. It will pass tech if all they do is operate the kill switch.

[rbryant]

Run the car into the wall and push the sheet metal up against the starter lug or alternator output into it, it's live now and there's no way to cut the power. This is a safety issue for the operator of the car and the track personnel. It will pass tech if all they do is operate the kill switch.

If that happens all bets are off in all setups. It is always possible that the car's sheet metal will cause a short. You could just as easily argue that the wire sheath gets cut and welds to the frame no matter where you run it.

The setup does have a fuse near the battery to protect against that anyway.

Many kill switches are actually not designed to shut off power to the starter and aren't rated with enough amperage to even work on the starter line. The common ones I see are only rated at 125amps, 250amp momentary and only have 1/4" stud connections. Sure you can get better ones but they aren't a "requirement."

Most kill switch diagrams (IIRC from moroso, etc) actually leave the alternator connected to the main car power when the kill switch is off. That leads to current spikes and might even allow the car to keep running if you have a big alternator. All of this is bad for electronics.

-Rich

[shelbyvnt2]

So?

Nonsense...

The 4ga wire is only rated at 135amps.

If you get a 150amp continuous duty fuse it will handle as much current as the wire is rated for and will also handle the spikes.

There are cars out there that have fusible links in the alternator harness. I believe that the LS1 corvettes have them for instance.

-Rich

Rich, I like you and your products but I would ask you to think about what you are saying as this is entirely inaccurate. I would love to see a picture of any fuse going to the starter on any car. Try a DC ammeter on your positive cable going to the starter and let me know what it reads while cranking.

[wallace]

They sell a switch that is designed for continuous duty it's made by Moroso. The NHRA has the specifications to wire your car so that it is as safe as possible for the the driver and track personnel....there's a reason that tracks use the NHRA regulations even if its not a NHRA sactioned event. Electing to use inferior components or not follow the guidelines is a recipe for disaster which can kill you or even worse someone who was just trying to help you out. To the OP I would use the NHRA guidelines if you intend to put the battery in the trunk. It costs more to do it right. Next to being dead the cost of an alternator or some electronic gizmo is not even worth considering.

[shelbymonster]

i recently bought a 100 amp breaker made for sounds systems , the car runs fine with that small breaker , there is more bigger ones available

[wallace]

I think you guys are talking about a fuse for the alternator charge wire? Plenty of factory setups using a fuse there. I used a 150A fuse on the charge wire on my setup.

[135sohc]

Both our 03 Concorde/02 Ram use a fusible link on the alternator feed. Guess they did it for simplicity by not having to incorporate more stuff into the fuse box/pdc.

[4 l-bodies]

Fuses and circuit breakers are common on vehicles positive cable where battery is located outside the engine bay. I'm currently working on a 2002 retro T-bird. Battery is in trunk. It most definitely is fused. Any stereo shop can set you up with a 150 amp or higher 12 volt breaker(s). Mark Christofferson's Fathers GLHT, my old GLHS #276, Steve Menzner's GLHT, and Quacks Masi GLHS, to name just a few, all have run perfectly with fuses or circuit breakers installed in positive cable. Some were installed 10 years ago or more! Also this makes for a nice quick way to shut off power to car for servicing or storage. All of these were installed with positive wire running inside car (not underneath it). BTW- GM made a nice compact box to connect positive cable to starter that fit perfectly in frame rail. They were found on all quad 4 motored vehicles and various other applications. It made for a neat factory installed look. Lots of other manufactuers have something similar. I would recommend 2 gauge wire or heavier for positive wire.
Todd

[rbryant]

Rich, I like you and your products but I would ask you to think about what you are saying as this is entirely inaccurate. I would love to see a picture of any fuse going to the starter on any car. Try a DC ammeter on your positive cable going to the starter and let me know what it reads while cranking.

Sorry but I am not backing down on this one. The idea that you can't get a fuse big enough would imply that you can't get a wire big enough which is just silly. A fuse is designed to protect a wire and at the amperage on a car it is certainly reasonable to get a big enough fuse and it has been proven to be fine by many many people.

While cars don't come this way from the factory it is common practice to put a master ANL fuse on the positive terminal of the battery when relocating the battery.
This fuse is before anything connects to it including the starter before it goes anywhere.

The starter will draw a max of 500-600amps for a very short period and then drop down far below that. Even then the ANL fuse is rated for constant duty and starting the car won't take over 30 seconds of cranking at a time even if you have big problems with starting which is not a constant duty. The 150A ANL fuse will handle 900A for .1 seconds which is how long the current spike lasts.

Even a 150A ANL fuse is going to be fine on our low compression turbo engines and I have 250A in the diagram. ANL fuses are available up to 600A!

Here is a good link.
http://www.stealth316.com/2-battery-move.htm

-Rich

[rbryant]

They sell a switch that is designed for continuous duty it's made by Moroso. The NHRA has the specifications to wire your car so that it is as safe as possible for the the driver and track personnel....there's a reason that tracks use the NHRA regulations even if its not a NHRA sactioned event. Electing to use inferior components or not follow the guidelines is a recipe for disaster which can kill you or even worse someone who was just trying to help you out. To the OP I would use the NHRA guidelines if you intend to put the battery in the trunk. It costs more to do it right. Next to being dead the cost of an alternator or some electronic gizmo is not even worth considering.

I am confident that my diagram is NHRA compliant. There is no requirement for a 4 terminal switch that I saw in the rule book. The rules say that the power must be removed from all electrical functions. That doesn't spec that the wire can't run forward.



NHRA rules:


Master cutoff switch is mandatory when battery is relocated. An electrical power cutoff switch (only one) must be installed in the REARMOST part of each vehicle and be easily accessible from the outside of the car body. The cutoff switch must be connected to the POSITIVE side of the electrical system and must stop all electrical functions. The off position must be clearly indicated with the word OFF. If the switch is push/pull type, push must be the action of shutting off the electrical system, pull to turn on. Any rods of cables used to activate the switch must be minimum 1/8 inch diameter. Plastic or keyed switches prohibited.



I agree that it would be possible to improve it slightly by putting the starter/alternator feed on the large terminals and the power feed line on the small terminals of a 4 post switch.

That however is not a requirement. In most 2 terminal switch configurations the alternator is still connected to the battery even when the kill switch is thrown.

The switch will stop all electrical functions because the starter solenoid and alternator control wires are both disconnected.

-Rich

[shelbyvnt2]

Rich, I could not see the diagram at work, the companies filter doesn't show linked photos. Now that I can see the diagram. I have some questions for you, what size wire do you recommend for a 250 amp fuse? I realize starting a car is a momentary load, what about a wire that has been chaffed and grounded to the car? Is that situation limited to a momentary load? Is it going to go away? What if this accidental load under the carpet only pulls 300 amps continuous? What do you think is going to happen? Will the fuse blow? Is the wire properly sized now? What does added load do to a series wound DC motor, such as a starter motor do? What is the maximum current a starter motor can pull? What limits the current? These are the very reasons that I was cautioning the OP about why he should think about keeping the battery under the hood.

I strongly uphold my position. The fact that I am a journeyman electrician and have a degree in Industrial Technology is why I am asking you to rethink your position. I tried to be nice about it the first time. Shooting from the hip is very dangerous.

[rbryant]

Rich, I could not see the diagram at work, the companies filter doesn't show linked photos. Now that I can see the diagram. I have some questions for you, what size wire do you recommend for a 250 amp fuse? I realize starting a car is a momentary load, what about a wire that has been chaffed and grounded to the car? Is that situation limited to a momentary load? Is it going to go away? What if this accidental load under the carpet only pulls 300 amps continuous? What do you think is going to happen? Will the fuse blow? Is the wire properly sized now? What does added load do to a series wound DC motor, such as a starter motor do? What is the maximum current a starter motor can pull? What limits the current? These are the very reasons that I was cautioning the OP about why he should think about keeping the battery under the hood.

I strongly uphold my position. The fact that I am a journeyman electrician and have a degree in Industrial Technology is why I am asking you to rethink your position. I tried to be nice about it the first time. Shooting from the hip is very dangerous.

I agree that there are several benefits to keeping the battery under the hood. Under the hood is the best electrical place for it but that isn't always possible and that is why we put in fuses. For instance there just isn't room on my 2.4l dodge charger. engine bay for the the battery.


I recommend 0Ga or 2Ga wire (as shown in the diagram) not because of the fuse size but because of the voltage drop. The 2Ga wire will easily blow the fuse without getting even a little bit hot.

As for pulling a continuous 300amps... No way, this is DC current not AC. The wire would weld its self to the body and start pulling more and more current until it blew the fuse.I really recommend not running too big of a fuse just for that reason. The smaller fuse will blow once something is out of the ordinary. That means a 150 or 200A fuse is probably good for us. I went slightly larger so someone wouldn't complain that the fuse blew with their high compression engine after using my recommendations from the diagram. The peak power from the starter might be 600amp but it will ultimately only pull up to what your battery can provide and the starter will pull less than 250 after the initial peak current.

Lets leave degrees and/or claims of expertise out of this and just talk about it technically. From experience, lets not start degree measuring contests as you would lose some, I would lose some, etc.

-Rich

[shelbyvnt2]

I agree that there are several benefits to keeping the battery under the hood. Under the hood is the best electrical place for it but that isn't always possible and that is why we put in fuses. For instance there just isn't room on my 2.4l dodge charger. engine bay for the the battery.


I recommend 0Ga or 2Ga wire (as shown in the diagram) not because of the fuse size but because of the voltage drop. The 2Ga wire will easily blow the fuse without getting even a little bit hot.

As for pulling a continuous 300amps... No way, this is DC current not AC. The wire would weld its self to the body and start pulling more and more current until it blew the fuse.I really recommend not running too big of a fuse just for that reason. The smaller fuse will blow once something is out of the ordinary. That means a 150 or 200A fuse is probably good for us. I went slightly larger so someone wouldn't complain that the fuse blew with their high compression engine after using my recommendations from the diagram. The peak power from the starter might be 600amp but it will ultimately only pull up to what your battery can provide and the starter will pull less than 250 after the initial peak current.

Lets leave degrees or claims of expertise out of this and just talk about it technically.

-Rich
Rich, this is exactly what I was after. I just wanted you to look at it a little more technically is all. I can tell the OP doesn't have a lot of electrical experience. I wasn't trying to get into a pissing match with you, I just wanted the OP to have a better idea of why things are done a certain way. It isn't "my way" it is the way that has been proven safe. I understand wanting to move the battery to the trunk area for room because it is easy. I just wanted him to know there are some dangers involved and that is the very reason , no car company that I am aware of, puts a battery in the trunk of a car. With the amount of current available from a full sized car battery you take a chance by running the wire inside the car. There is more than enough energy to start a fire. That is the point I was trying to make.

I still don't agree with all of your above statement but like I said I am not here to get into a pissing match with you so I will leave it alone. I think the OP will get the idea. The best thing to do if mounting the battery in the trunk area would be to get a sealed battery such as a gel cell and when running power wires to the battery or amplifier or whatever, run them in an area that will avoid damage and use grommets to protect the 12 volt + wire from damage when entering and leaving the body or sheet metal of the car. Due to the electrical resistance I would run the 0 gauge wire.

[minigts]

Rich, this is exactly what I was after. I just wanted you to look at it a little more technically is all. I can tell the OP doesn't have a lot of electrical experience. I wasn't trying to get into a pissing match with you, I just wanted the OP to have a better idea of why things are done a certain way. It isn't "my way" it is the way that has been proven safe. I understand wanting to move the battery to the trunk area for room because it is easy. I just wanted him to know there are some dangers involved and that is the very reason , no car company that I am aware of, puts a battery in the trunk of a car. ....

There may not be a lot of car companies doing it, but there are factory cars that have batteries in the back. GM for one I know puts them in some of their cars, don't know all the ones. Corvettes do, my friends Pontiac G8 GXP does and I'm sure there are others that do as well. It's not THAT common, but it's not as uncommon as it used to be. I think some Cadillacs have them in the rear, too.

[shayne]

2008- and up srt-8 dodge challenger has its battery in the trunk.

come to think of it do any of the lx platform cars have them underhood?

[Fox]

thanks for the info guys, i will put alot of thought into this and decide after my engine is complete on where the battery is going to be i could probably fit a Odyssey pc680 somewhere in the engine compartment without it being in the way and save some weight in the process and not worry about fires ;)

[RoadWarrior222]

There may not be a lot of car companies doing it, but there are factory cars that have batteries in the back. GM for one I know puts them in some of their cars, don't know all the ones. Corvettes do, my friends Pontiac G8 GXP does and I'm sure there are others that do as well. It's not THAT common, but it's not as uncommon as it used to be. I think some Cadillacs have them in the rear, too.Yah, there was at least one Jaguar model too.

[shadow88]

This may help - http://www.powerstream.com/Wire_Size.htm

As you can see the, 2 gauge wire in the original post would work fine. I don;t think anyone's starter is drawing an excess of 100 amps in these T-M's I have the exact same wires used on my battery relocation on my shadow (passenger side) the wires are run carefully and there have been no problems in about 7 years.

Regarding fuses, guys, you gotta look outside of automotive. There's plenty of 150+ amp fuses in the trucking industry.

My turbo neon had a trunk mounted battery, wires run inside, unfused for the last 3 years or so. I know I should add a fuse, just haven't got to it. The neon's a "00" wire and that's overkill.

[Juggy]

I have been running Rich's diagram setup for about 4 years now.

I ran the main power (starter/alternator) with 0 guage stereo wiring, with a 250 ANL fuse off the battery, and another 150 ANL at the alternator. the wire splits to a 3 way block that rests right onto of the trans mount. since these 2 sources have the ability to create power, it is best to have them fused. a starter only draws power so the initial fuse at the battery is all it needs.

power to the kill switch/accessories was done via 4 guage stereo wiring, with an 80 amp fuse off the battery. it runs to a distribution block that then feeds the wiring harness as well as other items I have that need 12v power when key is on.....

I have never had a problem with this setup, and I have also tried to get friends to set up their systems like this as well. separating the charging/starting system from the rest of the electronics does really make sense.

---------- Post added at 10:10 AM ---------- Previous post was at 10:05 AM ----------


i would like to keep the battery weight over the front wheels, but i'm thinking i could almost hide it entirely in the spare tire well since the space isnt being used.
is running the wire through the inside the car completely out of the question? maybe better wire just to be safe

i ran my wiring inside the vehicle, and it goes through grommets in the fire wall..

[rbryant]

Rich, this is exactly what I was after. I just wanted you to look at it a little more technically is all. I can tell the OP doesn't have a lot of electrical experience. I wasn't trying to get into a pissing match with you, I just wanted the OP to have a better idea of why things are done a certain way. It isn't "my way" it is the way that has been proven safe. I understand wanting to move the battery to the trunk area for room because it is easy. I just wanted him to know there are some dangers involved and that is the very reason , no car company that I am aware of, puts a battery in the trunk of a car. With the amount of current available from a full sized car battery you take a chance by running the wire inside the car. There is more than enough energy to start a fire. That is the point I was trying to make.

I still don't agree with all of your above statement but like I said I am not here to get into a pissing match with you so I will leave it alone. I think the OP will get the idea. The best thing to do if mounting the battery in the trunk area would be to get a sealed battery such as a gel cell and when running power wires to the battery or amplifier or whatever, run them in an area that will avoid damage and use grommets to protect the 12 volt + wire from damage when entering and leaving the body or sheet metal of the car. Due to the electrical resistance I would run the 0 gauge wire.

I just wish that you had started off by asking questions rather than saying that something is wrong when you really didn't know or even look into it. It isn't productive to simply say that you don't agree with a setup when you haven't actually even looked at the diagram.

I certainly make mistakes on some things but we should talk about why they might be a mistake in an informed way. With this topic I actually have a better background with electricity, electronics, microprocessors, etc than with cars so I did think it through quite a bit.

My 2001 BMW has the battery in the truck from the factory so it certainly isn't a new thing or even a rare thing....
More and more car manufacturers are actually moving the battery to the trunk so it really isn't a bad thing if done properly. The amusing thing is that the standards are actually lower for cars that come with a battery in the trunk than for the ones that are modified to put it there. There is no rear switch requirement for the BMW, etc.

I agree that there is always room for improvement and that is why Warren had a point about using a 4 post switch as an addition to the setup. That would be even better than the diagram but even with that switch the fuses should still be there. I do however stand behind the diagram years after posting it.

-Rich

[tryingbe]

no car company that I am aware of, puts a battery in the trunk of a car.

My friend's 2000 BMW 528i has the battery is the truck, so is a Saturn ION, so is a CTS, etc



I am looking at running two small lawn and garden batteries in the front of the car so I can eliminate this possibility. It isn't easy to do as my car has A/C.

I'm not sure why you think you need two batteries.

[shelbyvnt2]

My friend's 2000 BMW 528i has the battery is the truck, so is a Saturn ION, so is a CTS, etc


I'm not sure why you think you need two batteries.
Do these cars have a firewall or some kind of barrier between the battery compartment and the passenger compartment? Where do they run their power cable? The old rule of thumb is the battery will pull about 1 amp per cubic inch under normal conditions. That is whay I didn't think 150 amps would be sufficient. Fox's recommendation of the Odyssey pc680 battery, which I was unaware of, would eliminate the need for a second battery. The reason I was looking into two LG batteries is because the quality of most of these batteries is questionable. If I had two in parrallel and one died the other should get me home. I don't mind not being able to mow my grass but it is another thing entirely to be stranded because of a battery in your car.

Rich, I could not see the diagram. The problem with that is that you can't see what you can't see. The spam/virus filter at work blocks all linked photos, it doesn't even leave a space to let you know something is missing. Hand extended as an apology. Pat

[rbryant]

Do these cars have a firewall or some kind of barrier between the battery compartment and the passenger compartment? Where do they run their power cable? The old rule of thumb is the battery will pull about 1 amp per cubic inch under normal conditions. That is whay I didn't think 150 amps would be sufficient. Fox's recommendation of the Odyssey pc680 battery, which I was unaware of, would eliminate the need for a second battery. The reason I was looking into two LG batteries is because the quality of most of these batteries is questionable. If I had two in parrallel and one died the other should get me home. I don't mind not being able to mow my grass but it is another thing entirely to be stranded because of a battery in your car.



The BMW does have it in a true trunk. It also doesn't have fold down rear seats which does separate things but you can punch out the center behind the armrest if desired as it is perforated. The BMW battery is also not a sealed battery and isn't even in a true box (just a plastic cover over the trunk/body metal) so it does have a vent line on it. Interestingly when I got mine the battery had been replaced and didn't even have the vent line connected because the connection wasn't quite the same so I had to fix it.




Rich, I could not see the diagram. The problem with that is that you can't see what you can't see. The spam/virus filter at work blocks all linked photos, it doesn't even leave a space to let you know something is missing. Hand extended as an apology. Pat

I just think it is better to wait until you can see the whole post before making assumptions.

No problem though, technical discussions should never be personal and I didn't intend for any of my comments to be interpreted that way.

I work in a very confrontational technical environment so I am conditioned to quickly defend my positions. Sometimes I go too far with things. Hopefully I wasn't too blunt or crass, I can be a bit obnoxious at times and I should work on it. :)

At any rate... other opinions are always welcome and make for good technical debate and improvements to our cars.

-Rich

[shelbyvnt2]

Just to see what the total amperage is when starting my 2.2 turbo engine I brought home my Fluke 337 Clamp on meter and set the max hold function to see what the maximum current draw would be from the battery. It registered 421.9 amps max current. I cranked it with the injector harness unplugged and the ammeter read anywhere from 115 to 140 amps continuous. I tried it a second time and the max starting current had dropped to 249.7 amps max current, I assume because everything was up on oil. The continuous readings were the same as far as I could tell both times I cranked the car. I could see every compression stoke putting resistance on the starter, hence the difference between high and low readings. Someone might find the information useful.

[rbryant]

Just to see what the total amperage is when starting my 2.2 turbo engine I brought home my Fluke 337 Clamp on meter and set the max hold function to see what the maximum current draw would be from the battery. It registered 421.9 amps max current. I cranked it with the injector harness unplugged and the ammeter read anywhere from 115 to 140 amps continuous. I tried it a second time and the max starting current had dropped to 249.7 amps max current, I assume because everything was up on oil. The continuous readings were the same as far as I could tell both times I cranked the car. I could see every compression stoke putting resistance on the starter, hence the difference between high and low readings. Someone might find the information useful.

That is great real world info. Thanks!

That shows precisely why a 150A ANL fuse is about the min required for the starter and that 200-250A ANL fuses are good ones to use.

How short was the max current spike? Was it about 1ms like the guy on stealth316 suggested?

-Rich

[shelbyvnt2]

Rich, I am not sure, the ammeter isn't smart enough to tell me the duration, just the max amperage. I might check it again in the morning on my way to work to see if it reads about the same. It will be a little cooler in the morning.

[tryingbe]

Do these cars have a firewall or some kind of barrier between the battery compartment and the passenger compartment? Where do they run their power cable? The old rule of thumb is the battery will pull about 1 amp per cubic inch under normal conditions. That is whay I didn't think 150 amps would be sufficient. Fox's recommendation of the Odyssey pc680 battery, which I was unaware of, would eliminate the need for a second battery.

No idea on the rear mount info, I just look at them and thought "cool" and walk away. I don't stare at them and write down the info.

PC680 works great.

http://www.thelostartof.net/tryingbe/dodge/omniproject/hood1.jpg

[thedon809]

All lx cars have their battery in the trunk along with a fuse box. I have never seen a problem with lx batteries being in the trunk in my 2 years at a dealership. I worked on a couple of vipers which have a battery in the trunk. Early 90's miata I played with had it's battery in the trunk.

[shelbyvnt2]

I put my clamp on ammeter on the battery cable again this morning and checked the max and cranking amps. I did it twice just as I did last night. The results were not what I expected. The first time cranking the max amps was 246 the second time the max was 296. The sustained cranking amps both times were comparable to last night and they ranged from 108 to 143 amps. I really tried to watch it and get the high and lows today.

Last night the max amps the first time was 421 and the second 249. The only thing I can figure for the unusually high initial cranking amps is due to the car not being started for a week. This morning the second cranking amps was higher than the first. The only thing I can figure is last night the engine was coming up on the compression stroke when the engine stopped. When I started to crank it the first time the cylinder pressure had bled off and reduced the load. Interesting experiment anyways.