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Adding Second Battery


cuedude's Avatar
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01-02-05, 06:45 AM   #1  
Adding Second Battery

I've got a 2005 Astro van, and need to install a second battery. (Truck is a rolling Locksmith shop). My question is how do I determin which is the Field lead on the alternator? Instructions I have say to hook to the common for both batteries. (Or am I over thinking this and it actually means the ground side of the batteries?) Any help here will be appreciated. Thanks.

cuedude

 
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the_tow_guy's Avatar
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01-02-05, 06:51 AM   #2  
I have a second battery on my wrecker for a little extra reserve capacity and it is merely hooked up in parallel with the chasis battery with regular battery cables to the terminals (actually the chasis battery has both top and side terminals. It's regular connection is to the top posts and the second battery is connected to the positive side terminal + to + with the second battery grounded directly to ground). You could also install a battery isolator that will prevent the second battery from running down if you leave the lights on. Check with an RV place and you'll probably get some good info/advice.


Measure it with a micrometer; cut it with an ax.

 
cuedude's Avatar
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01-03-05, 04:14 AM   #3  
Thanks Tow Guy

I am putting in a Battery Isolator switch as I'm putting in a HUGE inverter to run key machines, lights, a vacuum system, and an extra motor for deburring keys with. I took your advice on contacting an RV place, but have not received a reply. (Yesterday being Sunday, I didn't expect one). Again thanks, and I gotta say, I like your quote on the bottom of your post. Sounds like you are ex-Navy.

cuedude

 
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01-03-05, 05:24 AM   #4  
Retired Marine.


Measure it with a micrometer; cut it with an ax.

 
cuedude's Avatar
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01-08-05, 06:37 PM   #5  
Sorry

Sorry Tow Guy, I should have seen the haircut.

cuedude

 
GWIZ's Avatar
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01-08-05, 07:52 PM   #6  
Inverter
You should read this link before doing any thing.
And read my post on that link.

http://forum.doityourself.com/showthread.php?t=194311

 
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01-09-05, 05:41 AM   #7  
Ok, Ok

You make a good point, and thank you. Here's what I've done so far. I have purchased, and run 4 awg cable (like on a welder) throughout the van to supply power to the 2500/5000 watt inverter. I ran romex throughout to supply the machines. I haven't worked it out yet, but the power supplies to the machines and lights will be on breakers to protect the circuits. I am going to add the second battery, and plan on leaving the engine running when cutting any keys. (Bear in mind, asside from the lights, only one motor will be running at one time).

As for the isolator switch, I will have my choice as to which battery, or both batteries to put online. This system has proven itself in a competitors vehicle, and he's using more equipment than I am, larger lights, and his truck radio is allways on as well. Hope this gives you more info as to what my plan is. Still waiting on something from the RV place I wrote to.

 
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01-09-05, 08:54 PM   #8  
In your case an isolator switch is a good idea but for the common person who just wants to run simpler things while the motor is off and still be able to start the vehicle later there is another way.
Hooking from the pos. on one battery to a ford starter solenoid then to another battery and whatever is using it from the other side and to isolate one from the other make the connection normally used to crank the engine (the small wire) hot only when the motor is running.
This charges the battery while the motor is running and removes it from the system when its not.

 
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01-10-05, 12:16 AM   #9  
cuedude,
Your on the right track for what your doing.
I though you wanted to run 3 motors at the same time.
If you can, you may want to check what size you competitors alternator is, just to know.
Some times its marked on the alternator.

I would add a relay or a disconnect switch on the battery for your 4ga wire. or will the isolator do that.
if that cable shorts out you may not stop it when it turns red hot melting thru the carpet.
----------------------------------------------------------------------------------------------------------
The only thing I can add, is notes for others thinking about inverters.

A 2000 watt inverter can not supply 2000 watts continuous if an alternator only supply's 660 watts to the inverter.

The inverters step-up 12 volts to 120 volts, which is a factor of 10 times.
With that said. an inverter will draw 10 amps at 12 volts to supply 1 amp at 120 volts.
The inverter needs 10 times the amperage to give you 10 times the voltage, that's the trade off .
30 amps at 12 volts gets 3 amps at 120 volts.
3 amps X 120 volts = 360 watts.
30 amps X 12 volts = 360 watts.

I'm not including that the inverter may use some power.

 
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01-11-05, 04:00 AM   #10  
Second Thought

This is all good stuff to know. (The need to know power stuff). For those that may be thinking of doing something like this, (and I don't work at one), don't forget to check out the Marine Hardware store. They have the heaviest duty parts. Reliability is what I am after, so why not you too? One thing about these stores, don't forget to prepare for an outlay of heavy cash. This is really an expensive mod. So far, about $700 and it's not too complicated.
Just the basic items. And yes, I did buy some items I didn't use. These I'm hanging onto for when the house starts overloading. Anyway, just wanted to add this suggestion for those who may be following this thread.

cuedude

 
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