Do I need to run an battery isolator if I decide to use dual batteries in the trunk. I am going to use a 7AL-2 box along with an electric water pump and fans and want to make sure I have enough reserve battery power for some in town cruises. Also, if I don't need an isolator, how should I wire up the batteries, in "series", or "paralell".
Isolator with dual battery set up?
- Thread starter malibulvr
- Start date
I run an isolator in my 'bu wagon, and all my other cars. When the car is off, the batteries aren't "dueling", IOW, if one battery is going bad, or doesn't hold the SAME EXACT reserve, it won't drain the good battery. Trust me, every car/truck I own has 2 batteries. When the car is running, the alt is charging both batteries, when the car is off, if the main battery dies, the spare will still start the car. good set-up. Especially with ALOT of electronics like I have.
Also, run the batteries in parellel, voltage stays the same, current adds up.
in series, voltage adds up, current stays the same.
Also, run the batteries in parellel, voltage stays the same, current adds up.
in series, voltage adds up, current stays the same.
In series the current draw is reduced over parallel because of the increased voltage, but you still don't want to run in series to get 24 VDC. You'll smoke a lot of stuff.
Tommy
Tommy
Why not run an alternator? If you're concerned about drag at the track, use a switch to shut it off when you race it.
Personally, I wouldn't run without an alternator. You lose more power from a weak ignition than you do from the parasitic loss of the alternator. Everyone always says "I always keep my batteries charged between rounds". I've never met anyone who didn't have a dead battery at the track at least once.
Tommy
Tommy
I am planning on running an alternator, just want to make sure with all the electrical stuff that I am wanting to run that my alternator isn't charging itself to death to keep them all going. I just figured between the 7AL-2 ingnition, electric W/P, electric fans, electric fuel pumps X2, and electric vacuum pump that it may be too much for one battery. I don't want to have a problem if I decide to go on a day long cruise or something.
You shouldn't rely on the battery to power your components when the car is running. Essentially you use the battery only to start the car, and the alternator handles the issue of charging and keeping your components going. If they're drawing more than what the alternator can produce, it's time for a bigger alternator. If you can find the current rating of all your stuff (include lights, radio, etc. as well), that should give you a good idea of the alternator you need.
Doober said:
X2! You can have 18 batteries & you'll still go dead on a long cruise/race if the alternator isn't capable of keeping up with the load. A good rule of thumb is to total your amperage loads, then add about 15-20% to find a rough alternator peak output rating.
Tommy
Never thought about it that way. I have a single 1000 CCA battery right now so I guess that would be ok. I know the more powerfull alternators take alot more power to run, but guess I can always switch it off when racing. Thanks!
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