battery relocation question
- Thread starter lppro
- Start date
It's cheaper than silver 
Since the thread is beyond salvageable I have no further comment except that what Chip and Grimjack said makes way too much sense...
Since the thread is beyond salvageable I have no further comment except that what Chip and Grimjack said makes way too much sense...
taka21;1729105 said:
i have this same problem when my car was running and i didnt even move the battery to the back yet, there is times that i get 11v with the lights on and radio and fan, during the day when things are off i get 13.5. could be a faulty alt
It could be, and checking it is quite simple - when you are getting only 11v, open the hood and put a voltmeter from the alternator output to the alternator ground. If the alternator is the problem, there will only be 11v showing - if there is still 13+ at the alternator, the problem is further along the wiring.Heavy D;1729458 said:
^^^ i would agree on that, i bought a brand new alternator, and my turbo timer kept blinking and saying 11V so i grabbed my DMM and i put it on the alt and still said 11V still, kinda sucks that i cant bring it back where i got it from, i got a discount from a garage and my moms BF dont work there no more, so im gonna have to get it some where else, but i have a stock alt, i think this time im getting more AMPS since i have HIDs and i like my a/c
^ my alt is brand new and its putting out 14.6 v and i ran brand new wire to where the battery was and im getting the wierdest load issues like when my windows are all the way down and i hold the button the voltage jumps up and the voltage drops when im just driving around its crazy
Old thread... but I had to add this because I saw some confusion about it.
The starter does draw much more than 150 amps, but a 150 amp circuit breaker does not blow immediately when you reach 150 amps. You can exceed that by a certain amount, for a certain amount of time. The more you exceed the amperage rating, the faster it will kick the breaker off. This is also why most kill switches are rated for only 250 amps and they don't melt even though you might be putting 400+ amps through it when you crank the engine. Crank the engine for a really long time though, and that switch will get HOT and you will blow the breaker. OEM starter solenoids actually get very hot if you crank for too long, they aren't rated to crank the starter continuously either.
Your cables though... they need to be rated for the full amperage you plan to run through them. If you undersize the cables you'll end up with a voltage drop under load, which is really bad.
For the people doing this for street use (and not trying to comply with any racing rulebook), next time you're at the junkyard take a look at a few german cars for ideas on how to run a reliable and safe trunk/rear mounted battery. Keep in mind though, they have vent tubes on their batteries (or they use a sealed AGM battery, like the Miata), so you still need a sealed box to keep the acid and hydrogen gasses contained. If you can't find the battery in an Audi, pull the bottom rear seat cushion up. Interesting to note is that they all ground to the chassis and none (that I have ever seen) use a sealed battery box.
The starter does draw much more than 150 amps, but a 150 amp circuit breaker does not blow immediately when you reach 150 amps. You can exceed that by a certain amount, for a certain amount of time. The more you exceed the amperage rating, the faster it will kick the breaker off. This is also why most kill switches are rated for only 250 amps and they don't melt even though you might be putting 400+ amps through it when you crank the engine. Crank the engine for a really long time though, and that switch will get HOT and you will blow the breaker. OEM starter solenoids actually get very hot if you crank for too long, they aren't rated to crank the starter continuously either.
Your cables though... they need to be rated for the full amperage you plan to run through them. If you undersize the cables you'll end up with a voltage drop under load, which is really bad.
For the people doing this for street use (and not trying to comply with any racing rulebook), next time you're at the junkyard take a look at a few german cars for ideas on how to run a reliable and safe trunk/rear mounted battery. Keep in mind though, they have vent tubes on their batteries (or they use a sealed AGM battery, like the Miata), so you still need a sealed box to keep the acid and hydrogen gasses contained. If you can't find the battery in an Audi, pull the bottom rear seat cushion up. Interesting to note is that they all ground to the chassis and none (that I have ever seen) use a sealed battery box.
Im having a brain fart right now... Okay IM going to relocate my battery to the rear to make room for my ffim piping. I got the power wires with a distribution block, but for the grounding.... the wires that ran to the battery where are they to ground now? Do I need another distribution block to run to the ground wires from the front to the rear? I have seen people just grounding to the rear of the car but what about the factory grounds that ran to the battery up front?
Depending on the shape of your chassis, you could theoretically just ground in the back, and run the wires that used to be in the front to the chassis as well. This uses the chassis itself as the ground.
However, in a car that's seen a lot of use, corrosion, dirt, etc, can reduce the effectiveness, so running ground wires all the way back to the grounding points at the front will solve any problems you might see.
However, in a car that's seen a lot of use, corrosion, dirt, etc, can reduce the effectiveness, so running ground wires all the way back to the grounding points at the front will solve any problems you might see.
See that is what i thought so I may just have to run double wires from the front all the way to the back for both power and ground. Thanks Grim.
What size breakers are everyone using on the battery side? I definitely want a breaker on my starter + run but i am worried about purchasing a 250a breaker and it not being large enough to support cold start cranking.
got it. and I would think a 100A alternator would dictate a 100A breaker for the + alternator line?