Charles Battery Charger 5000 Series Question

[bluedolphin]

Hi, folks. I need help with this unit. It's a 24VDC unit that I bought used, and I did not realize it's a 24 VDC until I got it home. I have 2 12v batteries on my 22' Aquasport, so I asked Technical Support of Charles Marine if I can use this unit with my 2 12v batteries. The answer was - yes, I have to put the 2 batteries in series to make them 24v. That's easy enough, but all my accessories run on 12v, so I will be running those accessories on 24v, which I'm sure will not work. Any suggestions? Thanks.

[RickK]

Unless something has changed, your motor uses 12V too, not 24V.  Hooking your batteries in series will work for charging them but there is a "potential" problem after that, unless you come up with a fancy switch setup to throw them in series for charging and then either separate or parallel, for use, with another switch.



Connecting 2 batteries in series creates a "potential" problem if you don't connect "to them" correctly.  The left image shows the batteries in series like you're needing to connect them to charge them.  Notice the voltages - from the bottom the voltages start at 0 and then on the other side of the lower battery is +12V. Now is when it gets troublesome - the top battery's neg terminal is NOT at 0 potential, it's at +12v (or -12v because that is the way you want your meter set up to read correctly) and the other side is +24V.  Yes, that is 12V potential across it but the negative reference is not 0, which could cause electronics a problem.  Normally, everything in your boat uses a common "potential" reference and it's done by connecting all the battery's negatives together - so your low reference is 0 in that case.
By connecting them in series to charge them, you've lost your House and Starting battery capability to use them. The right picture shows where you would connect everything so they have the same negative potential.  Hence, only one battery for everything.
I would (and not in any preferred order) 1) either come up with some fancy switching, which will run you about the same as the cost to 2) buy a regular 12V multi-bank charger. (#2 is my choice)
My $.02
I'm sure we'll get some more help here in a few minutes.

[LilRichard]

Take the charger back and get a 12V setup...

[RickK]

You could also buy 2 more batteries and a 24v trolling motor setup to use with the battery charger that you bought AND buy a 12v dual bank charger for your regular batteries.

[scott_gunn]

RickK has the right idea.  You really have no choice now except to buy a brand new 24V trolling motor.

[bluedolphin]

Thanks, all. I've decided to re-sell the item on Craigslist or e-Bay. Thanks again.

[GoneFission]

If you have a 24V trolling motor, it need (guess whatP) 24 volts!  So you need to set up the classic combo 12/24 setup.  

Typically this uses separate grounds to the batteries to make either 12 or 24 volts.  It's not hard to do if you think about it.  The mains will be on 12V and the trolling motor will be on 24V.  

The outboard will only recharge the 12V main battery, so you need to recharge the other using a 24 volt charger

http://www.basspro.com/webapp/wcs/store ... rchResults

Using a 24 volt charger works for both batteries.  Keep your grounds and power leads in mind - all of it works together when it's right...