Best way to tap 24v trolling batteries?

[BobG]

I'd like to get your recommendation on a quality voltage reducer. This seems to me like the best way to go. Especially if there are ones which hardly waste power.

LM7812 (12 volt IC voltage regulator).

http://www.ti.com/lit/ds/symlink/lm7805c.pdf

Never mind, it has a VinMax of 19 volts.

[JBO]

For me that is actually a lot more complicated. I'd be buying a new battery, running a bunch of wire to an area I don't really have to, moving all my plans away from the console where I want everything to be, etc. If I just buy this one little box it solves all my problems. Plus without buying an expensive new battery, it sounds like a really bad idea to run all these accessories off of your engine starting battery. Then there's the stock battery that I'd have to figure out something to do with. With my luck, I'd get out on the water and forget or something would happen, and I'd be stranded. Definitely not going to run anything off of the current engine battery.

Most boats, from what I've seen, run a single house-battery and run all accessories off of it. Unless you fish ALL day without your main motor and have an undersized battery, it shouldn't matter. We run a Humminbird 999 (big screen) and have no issues. Having sufficient RC is the key.

[photonfanatic]

Does it have to be a specific voltage, on the reducer? Take this one, for example. It says it takes 72v, and reduces it down to 12v. Would that work for my needs? Since I'm only going to be reducing 24v, down to 12v. Cause there are some less expensive ones, say for $50 instead of $80, but they're higher voltages, down to 12v. Not 24v, down to 12v.

http://www.ebay.com/itm/Golf-Cart-DC-Co ... d1&vxp=mtr

[teecro]

Does it have to be a specific voltage, on the reducer? Take this one, for example. It says it takes 72v, and reduces it down to 12v. Would that work for my needs? Since I'm only going to be reducing 24v, down to 12v. Cause there are some less expensive ones, say for $50 instead of $80, but they're higher voltages, down to 12v. Not 24v, down to 12v.

http://www.ebay.com/itm/Golf-Cart-DC-Co ... d1&vxp=mtr

No you need to look for something that matches you input voltage better. That one is built to accept an input voltage of 55 to 90 volts DC hence why it is being marketed toward a 72 volt cart...

[grouser]

With a smart two bank charger won't it charge the batteries at different rates as needed by each battery? Therefore eliminating the problem of over-charging one while charging the other?

[teecro]

With a smart two bank charger won't it charge the batteries at different rates as needed by each battery? Therefore eliminating the problem of over-charging one while charging the other?

That should work out very well I would think..... What is cost of a dual bank charger verse the voltage reducer and 24 volt charger would be the question.

[photonfanatic]

With a smart two bank charger won't it charge the batteries at different rates as needed by each battery? Therefore eliminating the problem of over-charging one while charging the other?

That should work out very well I would think..... What is cost of a dual bank charger verse the voltage reducer and 24 volt charger would be the question.

VS? Wouldn't I need the charger anyway? I was going to buy a 4 bank charger just in case I ever wanted to add that 4rth battery to my boat. I mean I still have to charge the batteries, and that seems like a separate issue. Maybe I'm misunderstanding the post. Anyway what do you think about this converter:

http://www.amazon.com/Pyle-PSWNV720-Pow ... +converter

Also, notice that first link says the converter is 720 watts. I'm assuming that means its only capable of outputting 720 watts? This next link, is one that you gave me for one of the better converter. But it doesn't say the wattage anywhere, unless I'm missing it.

http://www.golfcartking.com/20-amp-Volt ... t-2000.htm

[teecro]

Actually just like a generator there is a surge rating and a constant rating; the 720 watt output is the surge while it is rated for 360 watt constant output which will give you roughly 30 amps while costing you roughly 15.6 or so amps of 24V power...

Also unless I'm mistaken the 20 amp unit I linked to will give you 20 amps or 240 watts constant with a 480 watt surge...

[JBO]

With a smart two bank charger won't it charge the batteries at different rates as needed by each battery? Therefore eliminating the problem of over-charging one while charging the other?

Any differences in voltage will equalize between the two batteries. That's why one bad battery will drag down the other (if wired in parallel) and continually have parasitic draw on the good battery. 3-4bank charger will charge each battery individually.

[photonfanatic]

Actually just like a generator there is a surge rating and a constant rating; the 720 watt output is the surge while it is rated for 360 watt constant output which will give you roughly 30 amps while costing you roughly 15.6 or so amps of 24V power...

Also unless I'm mistaken the 20 amp unit I linked to will give you 20 amps or 240 watts constant with a 480 watt surge...

So that's like 240 watts RMS with a speaker, right? Something like that. If I wanted to run a pair of docking lights that were 200 watts total, would i need to go higher when I purchase one? That would only leave me with 40 watts to spare. Yeah I'm a total noob lol

Also thanks for the post JBO. Doesn't seem to be a "multi quote" button around here.

[teecro]

Sit down and figure out how many lights, gadgets and gizmo's you just got to have onboard your boat running off of your 24 volt battery system add up their amp draw or wattage then find a power converter that's twice as big so that when you decide to add some more lights, gadgets and gizmo's (and you will) you've got the reserve power to do so.

OR

Get a big 30 amp switch like I referenced to before and switch between both batteries so as to roughly equalize the drain on the batteries. Keep your troll batteries plugged into either a 24 volt charger or a dual bank charger as much as practical.

[photonfanatic]

Sit down and figure out how many lights, gadgets and gizmo's you just got to have onboard your boat running off of your 24 volt battery system add up their amp draw or wattage then find a power converter that's twice as big so that when you decide to add some more lights, gadgets and gizmo's (and you will) you've got the reserve power to do so.

OR

Get a big 30 amp switch like I referenced to before and switch between both batteries so as to roughly equalize the drain on the batteries. Keep your troll batteries plugged into either a 24 volt charger or a dual bank charger as much as practical.

Ok I think this is the concept I'm missing here. Your big "or" lol. I feel like a dumbass now, but why wouldn't you still need the power converter, if you had the big 30 amp switch? I mean the batteries are still wired in series, so how would a switch help? And if its the case, that the switch is somehow switching them out of series and putting them into 12v mode, wouldn't I lose trolling motor function when I was using my lights? Since the trolling motor needs 24v, but the lights run on 12. I'd like the ability to use them at the same time. Just in case, and I think that I actually might want them to work at the same time, since I'm wanting to do a fair bit of night fishing. Thanks again for all the help, sorry this is taking so long.

[teecro]

+24VDC------(+)--B1--(-)------(+)--B2--(-)------24VDC-

Above is your base series hook up to power your trolling motor which never gets disconnected....

Via a separate tapping you can hook up to B1 for 12 volts just as well as you can hook up to B2 for 12 volts the only difference is in the polarity which is easily "switched" during use by way of a selector switch.

Using a DPDT High Amperage Toggle Switch with 6 terminal connections you can toggle your 12 volt load to run from B1 or B2 as selected one or the other but not both...

This switch can even handle 50 amps http://www.mcmaster.com/#8001k32/=yszcgw it just does not have a center OFF as the 30 amp switch http://www.mcmaster.com/#8001k13/=yszc47 does which would be nice to power down your newly created 12 volt load center. Think of these switches like a "Y" whereas you can feed 2 power sources in through the arms and have the output switched through the bottom foot.

Is this an unbalanced load? Absolutely it sure is. Thus it is up to you the human to attempt to balance the load by periodically switching from B1 to B2 as often as practical such as between useage.

[photonfanatic]

With a smart two bank charger won't it charge the batteries at different rates as needed by each battery? Therefore eliminating the problem of over-charging one while charging the other?

That should work out very well I would think..... What is cost of a dual bank charger verse the voltage reducer and 24 volt charger would be the question.

Been awhile but I'm just now getting back to this project. Been really busy at work and haven't had time to mess with the boat much.

Anyway I wanted to ask you if I have to have a 24v charger for my 24v trolling motor battery system. Or can I just the 2 12v batteries individually? Would this be a good deep cycle charger? Its only a 4.4 amp charger though... so does that mean its a bit too weak?

http://www.amazon.com/NOCO-G4-UltraSafe ... le+charger

And then there's this one, which is 15 amps. What's the difference? Does one just take longer to charge?

http://www.amazon.com/Guest-2613A-Batte ... ry+charger

[photonfanatic]

Also my friend came over and better explained what he was talking about. We made a little pic to show what he wants to do. Basically we would just be running series, AND parallel at the same time. Is this possible? Trolling motor would of course be running off the 24v, and all these lights that I want would be running off of the 12v. And I would of course want them to be able to run simultaneously, because I'll be doing some night fishing.