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Old 03-02-2004, 12:19 PM
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Default Two batteries providing both 12v and 24v

Twin engines with four batteries. Each motor will have a starting battery. The other two batteries will be house batteries for electronics.

Can I have these two house batteries tied togther to give me both 12v's and 24v's at my console? I understand how to wire two 12v batteries to get 24v's. But I'm not sure that these two battereis can still be used to supply 12v power at the same time? What are the 'rules' concerning this?
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Old 03-02-2004, 03:52 PM
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Default RE: Two batteries providing both 12v and 24v

Doesn't sound possible unless you have a transformer or switch of some sort to isolate the voltage of one battery. If you wire 2 batteries together for 24 volts, then you have 24 volts.
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Old 03-02-2004, 04:14 PM
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Default RE: Two batteries providing both 12v and 24v

I asked for help re my 24 volt requirements for radar and got some good answers . . . here is the info

http://thehulltruth.net/forums/threa...=2707&posts=15

HOPE this helps
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Old 03-02-2004, 06:50 PM
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Default RE: Two batteries providing both 12v and 24v

This would work similar to the way that your house gets 120 and 240 from the same panel. The batteries are connected in series to get 24v across the outer terminals. The potential from either outer terminal to the middle terminal will be 12 volts.
[ 12 ]-[ 12 ] or [-battery1+][-battery2+]
Tie pos1 to neg2, use neg1 as your ground,
You'll get +12v at the pos1/neg2 terminal and +24v at the pos2 terminal. You just have to make sure that you have a common ground all around. Could get tricky, but this is very dooable.

Charlie
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Old 03-02-2004, 08:42 PM
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Default RE: Two batteries providing both 12v and 24v

A good idea but how do you charge the batteries once they are wired like that ? I don't know ? Electricity is not my strength
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Old 03-02-2004, 09:54 PM
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Default RE: Two batteries providing both 12v and 24v

Good question...I don't know. You could still charge the batteries individually at 12v apiece as long as the alternator wasn't grounded. You'd need a circuit to allow the alternator to switch between batteries. Somebody must make one....back to the drawing board.

CT
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Old 03-02-2004, 10:46 PM
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Default RE: Two batteries providing both 12v and 24v

Auguste: How would they be charged?

Individually.. I have a three bank charger with 4 batteries. 1 for the motor which is charged as I run and not tied to the charger. Then there is the other two for my trolling motor and one for the electronics. With the exception of the starter battery the other three are on the 3- bank on board battery charger. One bank for each battery even though two are tied together for 24V they are charged by all three banks individually. Plug it in and walk away.

JC
22' Cape Horn Bay 250HPDI
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Old 03-03-2004, 02:26 AM
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Default RE: Two batteries providing both 12v and 24v

PierPressure ,


I'm assuming you're using an AC feed at the dock for your 3 bank charger. What do you do when on the move?

cat
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Old 03-03-2004, 10:12 AM
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Default RE: Two batteries providing both 12v and 24v

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Old 03-03-2004, 11:27 AM
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Default RE: Two batteries providing both 12v and 24v

Buck,
I have two batteries in the front of my boat wired like Hotspots diagram. I get 24 volts for my trolling motor and 12 volts for my depth finder. I bought an on board battery charger from Cabela's that will charge two batteries. One set of leads to one battery, the second set to the other. No problem. I suggest you use a volt meter to double check you connections before you actually hook up things up. Good Luck.
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Old 03-03-2004, 01:37 PM
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Default RE: Two batteries providing both 12v and 24v

Looks like that will work, and saves buying an electronic box to boast power from 12 volt to 24 volt

That is a $500 savings . . . now I have to check my batery charger system to see how that works

? ? ? Any problems with the alternators on your engines ? ? ? Anything special to consider ? ? ? Doing anything special eg flip switches etc ? ? ?
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Old 03-03-2004, 04:35 PM
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Default RE: Two batteries providing both 12v and 24v

Auguste,

If you do that, may I suggest you install two isolation (on-off) switches...one to parallel the batteries (normally off) and one to series connect them (normally on). You can then use the combined batteries to start the motor if needed with 12 volt (parallel on, series off).

Harry
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Old 03-03-2004, 04:56 PM
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Default charger will work only if.

It would have to provide complete isolation between the 24v output and the 12v input. WHat is the 24v device ? radar, reels?
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Old 03-03-2004, 05:09 PM
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Default RE: Two batteries providing both 12v and 24v

Thanks Hotspot!

That is what I am looking to do. BUT I will have a lead from each engine going to each of those batteries to charge them. Which I understand that will be charging them as 12v. A lot of times when I am trolling I shut off one engine there so one of these batteries won't be getting charged.

Should I just not ever turn both engines off or could I put those two 12v in parallel?
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Old 03-03-2004, 10:24 PM
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Default RE: Two batteries providing both 12v and 24v

Buck,

Are you wiring this yourself? I'd make sure to keep the 12v circuits separate. Hotspot shows the grounds as solid lines, but the "ground" on batery2 is 12 volts higher than the ground on battery1. This is OK as long as the two circuits don't get crossed up.

-Charlie
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Old 03-03-2004, 10:53 PM
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Default RE: Two batteries providing both 12v and 24v

Buck and anyone else interested, Yes you can get 24 v out of configuring the battery banks to provide 24 v. It does get tricky when you start charging them by the engines. The Battery chargers are another issue and can handle the 12-24 division without any problem. The engines are another issue and if you are not careful you could put 24 back into the boat/engine and really screw things up. If you are trying to run a Raymarine 10KW radar, you can get a setup transformer for about $250. I think that is what I sold the last one for. This is the best way and the safest way. The other way you have a good chance of screwing something up, by flipping a switch or hooking up a wire incorrectly. If you are interested in the power converter, either call me @407-925-3462 or email me @TSMSS@aol.com. Good luck Hope I was some help.
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Old 03-04-2004, 09:30 AM
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Default RE: Two batteries providing both 12v and 24v

After more research...I think I may want to scratch using the Yamaha built in Isolator and buy one. Do they make an isolator that has two inputs (twins) with four outputs (4 batteries)? This would solve my problem with sometimes only running one engine.

Then if I run 24 volts from the house batteries to the console can I buy a converter that will give me both 12v and 24v? Who would make something like this? I looked at Guest's website and had no luck.
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Old 03-04-2004, 09:55 AM
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Default RE: Two batteries providing both 12v and 24v

I just payed 235.00 dollars for my 12-24 step up converter from Majorpower.com.. It does have a switch on the back of it but I dont know if its for poweroff or 12 or 24 volt. Call them and ask they where easy to talk to. I think it was John that I talked to .
Good luck , Dave
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Old 03-04-2004, 11:25 AM
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Default RE: Two batteries providing both 12v and 24v

Buck,

Check out thhp://www.bepmarine.com and look at their VSRs. A nice little unit that charges the starters first, then the house banks. I've got the 717 management system and added another paralleling switch, plus swapped the wiring on the battery switches so I can use any battery or combination of batteries to start either motor. Uses relays, so voltage drop either.

Harry
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Old 03-04-2004, 03:05 PM
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Default RE: Two batteries providing both 12v and 24v

hey hotspot,( i am using your diagram) if i have the batt's in series and if im wireing a 24 volt t motor to pos-batt 2, and neg of batt 1=24 volt set up, AND hook up a radio, pos and neg to batt 1, and an amp, pos and neg to batt 2, can i run all that at same time? can i be running my t motor while i'm jamming the tunes-scaring away all the fish?
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