12v draw from 24v batteries + Finder/gps

[fucawi]

Re: 12v draw from 24v batteries + Finder/gps

Robert I think thats a great idea a 7 AH Gell Cell with a a simple VSR to charge it from the outboard.....an even simpler way would be an extra rectifier under the OB hood ..cheap from radio shack and no moving parts under $10 ..I have found that you can often get your 7 AH battery as part of a silly starter charger thing at K mart for less than buying direct and often in the bargain bin...Great idea .

 

[Biff.McGerk]

Re: 12v draw from 24v batteries + Finder/gps

Thanks guys for all your responses and help.

After reading a ton of stuff last night i decided to go the 4th battery route and put all the 12v applications in my boat directly into that. I have an extra Optima Yellow Top Deep Cycle that i can use to 12v apps. I read some posts that state there has been lots of reports of interference with fish finders on trolling motor batteries. I actually had a bit on mine as well when it was 12v. I am also going to put a marine battery switch between the cranking battery and the 4th 12v in the back. This will allow for both charging either battery or both from the alternator and also isolating it when using fish finders. It can also be used as a backup battery in the event my cranking battery goes dead as robert had specified above.

The only downside is i was trying to save costs, but with this method i will need to remove my brand new 2 bank Dual Pro onboard charger and replace it with a 3 bank DualPro Sportsman... bit pricey.

I re-did my diagram so hopefully someone else can benefit from it as well(if it works !)

any thoughts on my setup?

 

[Silvertip]

Re: 12v draw from 24v batteries + Finder/gps

You mentioned earlier that you didn't really have room for the fourth battery so that raises another issue. You do realize that all of the connections between the dual battery switch and the fourth (accessory) battery must use the same size cables or larger as those that currently run between the start battery and the engine? If you don't do that and then attempt to start the engine from the accessory battery you will have smoke and fire. If that circuit has a breaker or fuse it would obviously open, but then you also are prevented from starting the engine from that battery. If the fourth battery is located any distance from the switch then the cost of cables can get expensive as well. Just making sure you understand the remifications of this plan.

 

[Biff.McGerk]

Re: 12v draw from 24v batteries + Finder/gps

You mentioned earlier that you didn't really have room for the fourth battery so that raises another issue. You do realize that all of the connections between the dual battery switch and the fourth (accessory) battery must use the same size cables or larger as those that currently run between the start battery and the engine? If you don't do that and then attempt to start the engine from the accessory battery you will have smoke and fire. If that circuit has a breaker or fuse it would obviously open, but then you also are prevented from starting the engine from that battery. If the fourth battery is located any distance from the switch then the cost of cables can get expensive as well. Just making sure you understand the remifications of this plan.

Thanks Silvertip

I have 1 extra spot in the back and didn't want to use it, but i am going to.

No i didn't actually understand that, thanks for pointing it out. The crank battery and the accessory battery are only 2 1/2 ' apart, so not a problem on the wiring. When you say size of wire, you mean just use the same or larger gauge between the battery switch and accessory battery correct ? not a problem on cost as well.

I just want to get this right before i start. I have new stuff and don't want to fry anything. I appreciate your suggestions and comments.

This post here has a picture of the switch wiring with 2 batteries: http://forums.iboats.com/showthread.php?t=526390 I was going to use that as my reference on the battery switch wire up on crank batt and access batt.

You also made a comment in that forum that stated this:

"ALL accessories (meaning everything currently connected to the +12 volt buss system) get connected to the COM terminal on the switch. This allows the most versatility for the entire system". I planned on hooking my stereo and 2 fish finders directly to the 4th access batt. I hope this is correct !?

thnx again !

 

[Silvertip]

Re: 12v draw from 24v batteries + Finder/gps

OK -- now I'm going to make just one more comment and then leave this thread because it is really getting "over the top". 1) you have a dual battery swtich with two batteries connected to it. 2) Instead of using the switch as it should be, you elect to power a fish finder and whatever else from the BAT #2 in that system. 3) Why not connect them to the COM terminal on the switch which is the way it should be to provide the versatility the swtich provides. Either that or use an ACR instead if you are switch challenged but unless it has a COMBINE function you would not be able to start the engine from that battery. If you run BAT 2 down you would have to switch to BAT 2 or BOTH to charge it. Contrary to popular belief, you do not have to continually fiddle with the switch. Set the darned thing on BOTH, go to wherever you are going and fish. If you are going to sit in one spot for a couple hours or so, perhaps THEN is might be worth setting the switch to BAT 2 to protect BAT 1. For those short start stop sessions there is no need to worry about BAT 1 going flat. Don't get me wrong here. This is your boat and only you know how you use it. However, there are very few situations where the switch MUST be wired other than what I describe. Even the output from the on-board charger should be connected to the COM terminal as you can then select either or both batteries for charging.

 

[Biff.McGerk]

Re: 12v draw from 24v batteries + Finder/gps

OK -- now I'm going to make just one more comment and then leave this thread because it is really getting "over the top". 1) you have a dual battery swtich with two batteries connected to it. 2) Instead of using the switch as it should be, you elect to power a fish finder and whatever else from the BAT #2 in that system. 3) Why not connect them to the COM terminal on the switch which is the way it should be to provide the versatility the swtich provides. Either that or use an ACR instead if you are switch challenged but unless it has a COMBINE function you would not be able to start the engine from that battery. If you run BAT 2 down you would have to switch to BAT 2 or BOTH to charge it. Contrary to popular belief, you do not have to continually fiddle with the switch. Set the darned thing on BOTH, go to wherever you are going and fish. If you are going to sit in one spot for a couple hours or so, perhaps THEN is might be worth setting the switch to BAT 2 to protect BAT 1. For those short start stop sessions there is no need to worry about BAT 1 going flat. Don't get me wrong here. This is your boat and only you know how you use it. However, there are very few situations where the switch MUST be wired other than what I describe. Even the output from the on-board charger should be connected to the COM terminal as you can then select either or both batteries for charging.

Not sure what you mean by over the top. I am only trying to understand the "switch" and how it works. I wasn't sure whether to wire stuff direct to the battery or to the COM like i just learned 1 post back. This thread has taken some twists, i didn't realize it was going to take me down this many paths. I figured it would be pretty cut and dry, i wired the 12v system w/2 ff's and didn't have any problem. It was the 24v stuff that threw me for a loop. I never took into account how to get it to 12v correctly (based on factory recommended methods)

So wire up the lead from the charger as well. I didn't know i could do that either. I would also wire the COM to the circuit panel under my dash too i believe... hope i am accurate on that. But keep the wire gauges at the same size or > . You have a diagram on how to hook up a switch in that other post i saved for my reference.

thanks again.

 

[Robert of Arabia]

Re: 12v draw from 24v batteries + Finder/gps

I like your style Biff

For future reference.....i'm a "mean" man..
i was talking about just using jump leads in an emergency....ha ha
system sounds good but make sure, as Silvertip suggests, the cable are the correct gauge for cranking purposes... and maybe consider a small (cheap) 6 way fuse box and earthing point for future expansion making next upgrade quick and easy....
One point.. on your diagram you have disconnection from start battery but none from accessories to slave battery? dont want that going flat....do ya?

R of A

 

[Robert of Arabia]

Re: 12v draw from 24v batteries + Finder/gps

Not sure what you mean by over the top. I am only trying to understand the "switch" and how it works. I wasn't sure whether to wire stuff direct to the battery or to the COM like i just learned 1 post back. This thread has taken some twists, i didn't realize it was going to take me down this many paths. I figured it would be pretty cut and dry, i wired the 12v system w/2 ff's and didn't have any problem. It was the 24v stuff that threw me for a loop. I never took into account how to get it to 12v correctly (based on factory recommended methods)

So wire up the lead from the charger as well. I didn't know i could do that either. I would also wire the COM to the circuit panel under my dash too i believe... hope i am accurate on that. But keep the wire gauges at the same size or > . You have a diagram on how to hook up a switch in that other post i saved for my reference.

thanks again.

My best advice Biff if you're not sure is keep it simple... i wasnt joking about the jump leads..!!! (or being mean)
Connect battery as in your diagram and just get into the routine of turning it on and off to take a charge whilst engine is running... worst case senario will be it goes flat...this is the exact reason you're fitting it??? you can turn switch on and continue fishing off start battery or that can be your flag to fish elsewhere sticking a charge back in the slave battery... i honestly cant imagine that you will have a problem with battery going flat it should take days....
a tell tail sign the battery going flat will be the radio volume getting lower... or clipping if its turned up loud... Or sell boat on ebay and fish from bank???

 

[Biff.McGerk]

Re: 12v draw from 24v batteries + Finder/gps

Thanks Robert for all your help. Silvertip has definitely given me some good advice and direction as well !

I think i pretty much have it or at least some direction thanks to you guys. I will update my diagram to reflect this Switch as well a little closer. I was looking at the Blue Sea Add-a-battery switch last night and already have a DualPro 3 bank sportsman on order for this project. I will also take your advice and get the fuse box as well, thanks for that !

I know this might be a bit much for my level of electrical ability, but i have taken an interest in it ! I ordered a book last night off amazon called: "Boatowner's Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems". I figured i might need to educate my self a little bit better before moving on. This book seemed to be highly rated, so i figure i have all winter to read and learn before doing. I still have basic questions that i don't want to bother people with like where in this mess do need to put fuses / breakers, how to ground everything properly, just too much to ask... and based on some responses, i might have used up all my "gimmees"

I was only considering the switch between the cranking and the starting for a backup just in case. I haven't worn a battery down yet out on the water, but i did have one dead when i got the boat in the water once. I am thinking this is a great way to still manage in the event.... heck i will even get the jumper cables as well. I would imagine i could use them to help someone else out as well on the water.

I have included my updated diagram but i am sure it will change once i am done reading that book.

Thanks for chiming in Robert !

 

[Biff.McGerk]

Re: 12v draw from 24v batteries + Finder/gps

My best advice Biff if you're not sure is keep it simple... i wasnt joking about the jump leads..!!! (or being mean)
Connect battery as in your diagram and just get into the routine of turning it on and off to take a charge whilst engine is running... worst case senario will be it goes flat...this is the exact reason you're fitting it??? you can turn switch on and continue fishing off start battery or that can be your flag to fish elsewhere sticking a charge back in the slave battery... i honestly cant imagine that you will have a problem with battery going flat it should take days....
a tell tail sign the battery going flat will be the radio volume getting lower... or clipping if its turned up loud... Or sell boat on ebay and fish from bank???

To keep it simpler as you mentioned, i am looking at a this device but wanted to get yours or some guru's opinion on whether this is a good bet to run my 12v applications off of. Its a 24v to 12v DC converter that hooks to my 24v series batteries. Any thoughts on whether this is a better idea than running off a 4th battery or hooking applications to the first battery in the series?

Samlex 20 amp
24V to 12V Converter
http://www.chargingchargers.com/converters/sdc23.html

Not sure if anyone has tried these or something similar ?

thnx !

 

[Robert of Arabia]

Re: 12v draw from 24v batteries + Finder/gps

To keep it simpler as you mentioned, i am looking at a this device but wanted to get yours or some guru's opinion on whether this is a good bet to run my 12v applications off of. Its a 24v to 12v DC converter that hooks to my 24v series batteries. Any thoughts on whether this is a better idea than running off a 4th battery or hooking applications to the first battery in the series?

Samlex 20 amp
24V to 12V Converter
http://www.chargingchargers.com/converters/sdc23.html

Not sure if anyone has tried these or something similar ?

thnx !

Hi Biff let me have a look for you in next few days (got family with me for festive period) and i'll get back to you...

Rob

 

[Silvertip]

Re: 12v draw from 24v batteries + Finder/gps

In the last diagram you presented you would not need the converter. Keep the trolling motor batteries for their intended purpose. The diagram is now nearly correct. You have two options for buss bars. Some fuse/breaker panels have a ground/earth buss built into them, some do not. If the panel has a ground buss then that point must be connected to the negative terminal on one of the of the batteries and all device grounds connect to the buss. If the panel does not include a ground buss then you need to add one. It gets wired the same way as an integrated buss.

 

[Biff.McGerk]

Re: 12v draw from 24v batteries + Finder/gps

Thanks Silvertip for your recommendations, you guys are very helpful ! I was looking at the busbars from blue sea as well with the water proof caps. Just need to get the correct wire gauge sizes for the bars.

Can you recommend a circuit panel that you mention in your last post? I found a bunch from bluesea but there are so many to choose from.

Also, Minn Kota has a 60amp circuit breaker for the TM wiring. Blue sea also has many circuit breakers but only 50 and 70 amp. Do you feel the 70 amp would be adequate opposed to the minn kota 60 ?

thank you

 

[Silvertip]

Re: 12v draw from 24v batteries + Finder/gps

Breakers are rated for the amperage at which they "open" the circuit thus protecting the wire it feeds. So a 70 amp breaker requires more current than a 60 before it opens. Therefore, if the wire can only handle s 60 amps and you have a 70 amp breaker, the wire gets hot and burns before the breaker opens and you can then have a fire. Minnkota recommends a 60A breaker. So use a 60 amp breaker. What fuse panel you need depends on how many circuits you have, and whether you want the blade type fuses (like those in your car) or the glass type. Can't answer that question until you give us more detail. If you have four circuits you need a four circuit panel minimum. A six circuit would be better even though in that example two would be unused. That leaves room to add other accessories in the future.

 

[Biff.McGerk]

Re: 12v draw from 24v batteries + Finder/gps

Thanks Silvertip again. I think you have answered all my questions.

I will be ordering over 600$ in electrical equipment to rewire my whole boat. Thanks to you and other comments i think i have everything i need. This is a great forum for help. Here is what i will be ordering:

- DualPro Sportsman 3 bank charger
- Blue Sea Add-a-battery ACR / Switch
- 60 amp breaker from minn kota
- bluesea bus bars / fuse panels
- heat shrink and connectors
- 25' 6 gauge +/- and 20' of 8 gauge(may change)

thanks again!

 

[Silvertip]

Re: 12v draw from 24v batteries + Finder/gps

If you are rewiring the entire boat you will need some 16 gauge wire as well. Accessories like bilge pumps, lights instruments, fish finders etc., do not need to be wired with heavy gauge wire. #10 wire between the switch and the fuse panel is adequate as well - although #8 can be used but would be a bit overkill.

 

[Robert of Arabia]

Re: 12v draw from 24v batteries + Finder/gps

Merry Christmas all....

Rewiring the whole boat Biff..? Next you'll be fitting a new kitchen and bathroom in the house...!!!!
Project looks good and Silvertip has answered your questions....you probably dont need me.....
Shame about you changing to a 3 bank charger.. what you going to do with the old one???
A thought...maybe keep it for the moment and hold off buying the bigger one and go with the rest of the system and see if you really need to change it...if you're going to use the slave battery as an engine back up it will get a charge from engine when battery switch is operated..This may be all you need to keep it topped up?? you can always buy charger at a later date and it keeps the installation simpler..?
I like the fuse box and other items just plan everything before you start install. Make sure you can get to items to make connections and avoid any school boy errors.. if you have room it might be an idea to mount fusebox on a peace of marine ply you can also put an earthing point on this (an M10 bolt through the ply will work) then you're all set for any future upgrades with easy hook up...
Good luck and let us know how you get on.... and most important....connect battery LAST....

Rob

 

[Biff.McGerk]

Re: 12v draw from 24v batteries + Finder/gps

Merry Christmas all....

Rewiring the whole boat Biff..? Next you'll be fitting a new kitchen and bathroom in the house...!!!!
Project looks good and Silvertip has answered your questions....you probably dont need me.....
Shame about you changing to a 3 bank charger.. what you going to do with the old one???
A thought...maybe keep it for the moment and hold off buying the bigger one and go with the rest of the system and see if you really need to change it...if you're going to use the slave battery as an engine back up it will get a charge from engine when battery switch is operated..This may be all you need to keep it topped up?? you can always buy charger at a later date and it keeps the installation simpler..?
I like the fuse box and other items just plan everything before you start install. Make sure you can get to items to make connections and avoid any school boy errors.. if you have room it might be an idea to mount fusebox on a peace of marine ply you can also put an earthing point on this (an M10 bolt through the ply will work) then you're all set for any future upgrades with easy hook up...
Good luck and let us know how you get on.... and most important....connect battery LAST....

Rob

Thanks Rob, I decided to go with the 3 bank 10amp Dual Pro Sportsman, not only for the 3 banks, but for the higher amps and quicker charging times. I only had a 2 bank dual pro recreation series / 5 amp's per bank. While it worked well, it wasn't good if you need a charge in under 4-5 hours. So i went with the larger one. I will probably sell the 2 bank charger as its only 4 months old !

The reason i decided to rewire most stuff on the boat... after reading and learning from these forums and the book i bought on boat wiring, i realized that the boat was not wired properly. I had a short in the motor at one point last year, the TM breaker trip a few times... and when i put the TM on 10 speed, it would start/stop/start/stop... might have been the wiring. But generally i suspect that it is not done correctly. I am not going to touch the bilge/stereo/pumps, just move those wires but isolate them on the house battery. The house battery will run everything including all FF's separated by the BlueSea Add-a-battery with the switch and ACR. So when i run the main motor both batteries will be charged, but isolated when off... basically just circuit protection.

I received the BlueSea Add-a-battery unit... looks nice ! a little bigger than i thought.

thanks again everyone for the help! silvertip and robert ! I will snap some shots of it once i am done... so you guys can pick it apart