Reply With QuoteCell matching is extremely important when you wire in series. For a parallel connection, it's not particularly critical that they be perfectly identical.
I ordered my new boat with a high performance sound system.
In the past this included an extra battery.
When the boat was delivered, no second battery. The sound system is hell on the single battery.
I was blindsided assuming the two batteries. Dumb$#!+ me
The dealer wanted a fortune to install a second battery, and others I've talked to say my dealer does a real sloppy, crummy job., so I'm doing it myself for less than $75.
No bfd really, takes less than an hour. Just positive to positive, neg to neg.
Battery folklore question:
Is it just a rumor that both batteries have to be new, or the same age?
They both load test pretty much the same.
Any other tips or tales?
I've never asked a question where something good was'nt learned.http://www.hotboatpics.com/pics/data...dy_001-med.jpg
Cell matching is extremely important when you wire in series. For a parallel connection, it's not particularly critical that they be perfectly identical.
If you are going to run two batteries the way you are describing it is important that they both be of close to the same age. It just results in both batteries having a longer lifespan and equal charging. If you are running two batteries due to the sound system you are describing you would be better off running the sound off of one battery at a time and using a switch. By running them in parrallel you are strictly at the mercy of your alternator and your good sense. If your alternator doesn't provide enough power to keep one battery charged while playing tunes then it is not going to provide any additional power for charging two batteries. If you let it go too long you will eventually find yourself looking for a tow back to the launch ramp. If you wire to a battery seperately and you kill that battery then at least your starting battery can get you home. (you'll even be able to listen to tunes on the way). The only reason I can think of to run the batteries the way you are describing is if your alternator is large enough to
1. run the engine ignition system and
2. run other accessories needed and
3. run the stereo with maybe the need for a little extra reserve when hitting some of the deep bass notes.
If your alternator is large enough for this then maybe you are heading the right direction, otherwise you are headed for a tow back. Although I will say no matter how you wire the system you are better off with two batteries than one.
Just my .02
correct ! if you have a weak battery it will pull the other down to its level if wired parallel . also if you want to be sure you have starting power put a battery isolator between the two and run the stereo off of one and leave the other for starting . using the isolator also voids having to use two fresh batteries because the two never "see" eachother
just my .02
C.T. :wink:
Originally posted by Cheap Thrills
correct ! if you have a weak battery it will pull the other down to its level if wired parallel .
Only if it's down on voltage because of a bad cell, or whatever. I think you're thinking of a series connection which is only as strong as the weakest battery. Also, when connecting in series... if you push it too far, you can reverse the current flow on the weakest battery and then really bad things happen.
In a parallel connection, however, the battery most able to shoulder the load... will.
We spend long hours at the sandbar, engine off listing to music.
The single battery meant having to start and idle the engine to recharge it every hour or less.
The 2 battery theory is for longer playtime with the engine off.
Thanks for the replies,,
Originally posted by Tom Brown
Only if it's down on voltage because of a bad cell, or whatever. I think you're thinking of a series connection which is only as strong as the weakest battery. Also, when connecting in series... if you push it too far, you can reverse the current flow on the weakest battery and then really bad things happen.
In a parallel connection, however, the battery most able to shoulder the load... will.
I agree Tom thats what I was referring to .
Ive had batteries in my solar array for my amateur radio repeater give me trouble due to a a bad cell on a bank of 10 parallel 12v.
I don't know too many people out this way running 6 volt batteries in series to obtain 12V though I suppose it would be useful in a high current audio applications . just alot of weight
and yes reverse current flow on a battery or polarized capacitor, led acid battery esp. is not a good thing . could cause for increased heart rate and a hellofa mess.
Cheers
C.T. :wink:
Mickey is absolutely correct! Batteries in parallel will equal easch other out after a while. If one has a bad cell it will eventually drain the other. Batteries in parallel need to be same type (even make) and need to be close in age. Otherwise, the batteries will never charge correctly unless disconnected from one another. If you try and charge different batteries that are paralleled, then one of the batteries may overcharge and/or the other undercharge do to differing resistances in the batteries (meaning that one will charge quicker than the other, if the one that charges quicker opens the field on the regulator the other battery will have an insufficient charge. If the quicker charging battery does open the field on the regulator, do to an odd restistance seen by the field, the result would be an over charge on that battery).
Flying tiger,
Are you running any sort of switch that you can selct 1 2 or all?
do it like this and you wont have to worry about a switch setting .
An Isolator doesn't cost much more than a switch
and if you still want a switch also that would be good too.
C.T. :wink:
http://www.***boat.com/image_center/...y_isolator.jpg
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