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Author Topic: 6 ----> 24 volts  (Read 3041 times)

Desert_Rat

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6 ----> 24 volts
« on: December 30, 2016, 05:10:51 PM »
Anyone see any issues with this first (test) bank?

1) Double crimped
2) Dialectric grease applied
3) 2 AWG cable. I wanted 2/0 but ordered incorrectly. Based on what I've read, it's fine. Bank will be < 5' from MPPT and Inverter

edit: Couple of questions I have are:
1) I'm surprised + is on the negative lead, and visa versa. I guess I should attach the black cable to the + terminal?
2) How much of a gap between batteries should I have when I move them to the box? I'll have 1 24v fan and a vent, both about 3-4" squared.
« Last Edit: December 30, 2016, 05:30:55 PM by Desert_Rat »

SeilerBird

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Re: 6 ----> 24 volts
« Reply #1 on: December 30, 2016, 05:20:09 PM »
never mind
« Last Edit: December 30, 2016, 05:37:53 PM by SeilerBird »
I would like to apologize to anyone I have not yet offended. Please be patient and I will get to you shortly.
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Desert_Rat

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Re: 6 ----> 24 volts
« Reply #2 on: December 30, 2016, 05:22:34 PM »
Funny, I saw a reference to that an hour ago and was all.... what tha...?

Is that really legit?

SeilerBird

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Re: 6 ----> 24 volts
« Reply #3 on: December 30, 2016, 05:29:07 PM »
Funny, I saw a reference to that an hour ago and was all.... what tha...?

Is that really legit?
I am sorry, that is wrong. It only gives you 12 volts and you wanted 24. What do you want 24 volts for?
I would like to apologize to anyone I have not yet offended. Please be patient and I will get to you shortly.
Life list of birds:
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https://goo.gl/photos/aXQPbnVpgzNvs4Jq8
My portfolio:
https://goo.gl/photos/Cx4SaYhGfYFShSty7

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #4 on: December 30, 2016, 05:32:05 PM »
One MPPT for over 2kw of PV. Pretty much mandatory, and on the low side - I'll still need a 100A MPPT.

SeilerBird

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Re: 6 ----> 24 volts
« Reply #5 on: December 30, 2016, 05:39:01 PM »
I don't know much about solar since it is such a losing proposition. I'll let the solar experts chime in.
I would like to apologize to anyone I have not yet offended. Please be patient and I will get to you shortly.
Life list of birds:
https://goo.gl/photos/xuP9zPD2KP2swN1g8
2016 photos:
https://goo.gl/photos/aXQPbnVpgzNvs4Jq8
My portfolio:
https://goo.gl/photos/Cx4SaYhGfYFShSty7

HueyPilotVN

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Re: 6 ----> 24 volts
« Reply #6 on: December 30, 2016, 06:38:12 PM »
The series wiring of the four 6 volt batteries will give you 24 volts.

I am still however not sure that I understand why you want to make your system in a non standard (for RVs) voltage.

There is an advantage in that 24 volt systems might use smaller cables than a 12 volt system just as 110 volt systems also do not need large conductors.

The biggest disadvantage is that you are going to need to convert much of your electrical system back to 12 volts either at the battery bank or multiple times at the loads.

You are also going to have to take this into consideration with every component that you buy or convert to 12 volts.

I am just throwing this out there since you are mostly still in the planning stage.

Good Luck with whatever you do and keep us in the loop so that we can learn from your experience with this different approach.

As a side comment my company does use 24 volt power in our Mobile Hospital Units for certain dedicated uses.  The electric servo motors for the hydraulics in the huge slideouts are 24 volt systems but these are stand alone closed systems and the standard for other DC uses in these unit is 12 volts.
« Last Edit: December 30, 2016, 06:49:20 PM by HueyPilotVN »
Bill Waugh
40' Country Coach DP
34' Stacker Trailer, Trailer Toad
Jeep Commander
Mustang Bracket Race Car
35 years on the road

AStravelers

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Re: 6 ----> 24 volts
« Reply #7 on: December 30, 2016, 06:52:11 PM »
Anyone see any issues with this first (test) bank?

1) Double crimped
2) Dialectric grease applied
3) 2 AWG cable. I wanted 2/0 but ordered incorrectly. Based on what I've read, it's fine. Bank will be < 5' from MPPT and Inverter

edit: Couple of questions I have are:
1) I'm surprised + is on the negative lead, and visa versa. I guess I should attach the black cable to the + terminal?
2) How much of a gap between batteries should I have when I move them to the box? I'll have 1 24v fan and a vent, both about 3-4" squared.
I don't see anything wrong with the way the batteries are wired for a 24V system.  So don't understand you question #1.

I don't know that you need a gap between the batteries, but they should be tied or clamped down.

These are flooded cell batteries so you need good ventilation.  Using a fan I would push air into the compartment.  I am not sure if an exhaust fan could ignite the hydrogen gas given off by the batteries.   

The wire size depends on how much current you push though the wire.  Assuming you used a wire size calculator and accounted for 10' of wire and not the one way distance of 5' then you should be OK. 
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

HueyPilotVN

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Re: 6 ----> 24 volts
« Reply #8 on: December 30, 2016, 07:15:38 PM »
One MPPT for over 2kw of PV. Pretty much mandatory, and on the low side - I'll still need a 100A MPPT.

As I reread your post it may be that your choice of 24 volts may be mostly driven by your plans for the way you intend to handle the "Solar Charging" side of the system.

Most Solar Power systems in RVs take advantage of the fact that there may well be several sources of recharging your batteries.  These input sources include a convertor/charger, possibly an Invertor/Charger, the Alternator from the vehicles engine, as well as the fact that you can have multiple charge lines from different Solar Charge Controllers.

If in fact you are committed to using a single very large charge controller, then you will need large heavy cables to carry the amperage to the batteries.  However this is not the only way to get lots of electrical charge back into your batteries.  You can use multiple charge controllers, (all with smaller cables feeding into a common point).

This will allow you to leave all of your 12 volt system intact.

I have also mentioned in other posts that another alternative is using more than one dedicated battery bank and splitting the loads and the charging sources.
This option would also reduce the weight as opposed to mounting one large battery bank on your trailer tongue.

Just trying to help with alternate suggestions.
Bill Waugh
40' Country Coach DP
34' Stacker Trailer, Trailer Toad
Jeep Commander
Mustang Bracket Race Car
35 years on the road

HappyWanderer

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Re: 6 ----> 24 volts
« Reply #9 on: December 30, 2016, 07:56:52 PM »
Positive is on the negative post because your test leads are reversed on the meter.

Ernie n Tara

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Re: 6 ----> 24 volts
« Reply #10 on: December 31, 2016, 08:24:51 AM »
I'd reconsider the 24 V issue. There are two reasons for that; first conversion back from 24 to 12 V is going to be perhaps 90% efficient so you're giving away 200 W of that hard earned power when you use your standard appliances. Second, 24 V equipment is usually much more expensive, if you elect not to down convert, since it is less used and usually designed for commercial applications.

I can't believe it won't be more eficient and less costly to just use larger cables (or more of them).

Ernie
Ernie 'n Tara

2011 Winn Journey 34y
2012 Jeep Rubicon - Dozer (orange - kinda)
2006 Jeep Wrangler

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #11 on: December 31, 2016, 09:07:37 AM »
I don't see anything wrong with the way the batteries are wired for a 24V system.  So don't understand you question #1.

If you notice, the red lead (standard + lead)  is tied to the + terminal, but my voltmeter is connected in reverse to get its positive reading. I'm just curious why the positive charge is at the negative terminal on the bank instead of at its positive terminal. It's obviously inherent to a series connect but I found it odd is all.

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #12 on: December 31, 2016, 09:12:53 AM »
Y'all may not believe it, but if I chose to share this project on a board centrally dedicated to solar, this 12v curiosity would be about 48v instead. 'You can't use 24v, that's just wrong!' 'I would highly recommend you move to 36 or 48v instead'

Yup

Understand that I've been researching this project for a good while, and while my conclusions may not be perfect, they are conclusions I'm determined to run with. I understand the advantages and disadvantages of 12, 24, 48v. Each has been thoroughly weighed, and my reasoning to go 24v has been addressed here for all to see. This is not a 400 watt project that would be more suitable at 12v, it's gonna be over 2kW and you simply cannot competently manage that at 12v, or you shouldn't have to anyway.

The reason I'm sharing is because I'm a novice with all skills necessary to build the system properly, so I'm seeking more informed guidance along the way. Like I said on my battery box post, 'I'm not a carpenter or metal worker, but I think it came out ok'. But did it? Will 1.5" pine be able to withstand 720lb of batteries... on the road no less? How about tongue weight (that was covered). Was my 2 AWG fitting crimped properly? Are the different cable lengths used considered ok?

Thank you for any and all input.

markbarendt

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Re: 6 ----> 24 volts
« Reply #13 on: December 31, 2016, 09:25:40 AM »
If you notice, the red lead (standard + lead)  is tied to the + terminal, but my voltmeter is connected in reverse to get its positive reading. I'm just curious why the positive charge is at the negative terminal on the bank instead of at its positive terminal. It's obviously inherent to a series connect but I found it odd is all.

The black lead should be plugged into the "common" on the meter. Once you correct the plug positions it will read correctly.

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #14 on: December 31, 2016, 09:30:47 AM »
Look at the voltmeter, it's reading correctly as is - backwards

Must be inherent to a series connect. positive charge on - terminal, negative charge on + terminal.

markbarendt

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Re: 6 ----> 24 volts
« Reply #15 on: December 31, 2016, 09:36:29 AM »
If you notice, the red lead (standard + lead)  is tied to the + terminal, but my voltmeter is connected in reverse to get its positive reading. I'm just curious why the positive charge is at the negative terminal on the bank instead of at its positive terminal. It's obviously inherent to a series connect but I found it odd is all.
Second point. No.

When working with electricity and meters it is important that you understand what to expect.

Finding it odd was the correct response to the reading you got.

When you get an unexpected reading like that asking why is the next step, you did well asking here.

Never assume odd results are inherent, they almost never are.


Desert_Rat

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Re: 6 ----> 24 volts
« Reply #16 on: December 31, 2016, 09:38:15 AM »
Excellent point. Electricity is not to be trifled with.

markbarendt

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Re: 6 ----> 24 volts
« Reply #17 on: December 31, 2016, 09:39:49 AM »
Look at the voltmeter, it's reading correctly as is - backwards

Must be inherent to a series connect. positive charge on - terminal, negative charge on + terminal.
No

Swap the wires on your meter.

Black to "Com" Red to V

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #18 on: December 31, 2016, 09:44:11 AM »
What tha... didn't notice that. I'm blaming it on the dog. yeah, that's it!

markbarendt

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Re: 6 ----> 24 volts
« Reply #19 on: December 31, 2016, 09:57:13 AM »
Can't tell what the dog breed is exactly from your avatar but both Ausies and Border Collies are too smart to get that wrong.

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #20 on: December 31, 2016, 10:12:34 AM »
Definitely, although the new Aussie pup is presently destroying the joint. Teething stages are terrible.

I'm sitting here wondering what kind of crap I would have caused if I took this voltmeter's readings for fact and used my other one to finish the wiring. Jesus. I recall this old supervisor I had way back when who used to insist we start electronic troubleshooting at its source. "Is it plugged in" and on from there. I thought it was patronizing at the time but have learned that he was right.

SeilerBird

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Re: 6 ----> 24 volts
« Reply #21 on: December 31, 2016, 10:42:46 AM »
I don't wish to insult you but I am worried that if you can't hook up a volt meter properly you might not have the chops to wire up a solar project like this.
I would like to apologize to anyone I have not yet offended. Please be patient and I will get to you shortly.
Life list of birds:
https://goo.gl/photos/xuP9zPD2KP2swN1g8
2016 photos:
https://goo.gl/photos/aXQPbnVpgzNvs4Jq8
My portfolio:
https://goo.gl/photos/Cx4SaYhGfYFShSty7

Lou Schneider

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Re: 6 ----> 24 volts
« Reply #22 on: December 31, 2016, 12:02:23 PM »
The only thing wrong is the color of the test leads.  They're reversed at the meter and also reversed at the batteries, with black going to the + terminal and red going to -.

So in this case two wrongs do make it right.  And in San Francisco, three rights make a left turn.

Gary RV_Wizard

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Re: 6 ----> 24 volts
« Reply #23 on: December 31, 2016, 02:40:15 PM »
Back to the 24v vs 12v question, I think the sources used in your research are for static systems rather vehicles. The arguments for using a higher voltage are sound, but [in my opinion] the more overwhelming consideration in a mobile solar set-up is that the vehicle & RV systems all run off 12v. It would be much better if they upgraded their operating voltage, but until that happens it's a fact of life.  The conversion of the system run voltage down to 12v will surely cost whatever is gained by using 24 (or 48) volt for the storage system. It may even cost more than what can be gained at 24v.

Automotive designers have known they need to switch to 24v or 48v for over 25 years now.  There were plans in place to make the change-over back in the 1980's, but the cost & difficulty of making the transition has kept it on the back-burner all this time.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

HueyPilotVN

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Re: 6 ----> 24 volts
« Reply #24 on: December 31, 2016, 03:31:49 PM »
I value Gary's opinion as one of the most if not the most respected on this Forum.

I agree with what he said for several reasons.

I also have come to the opinion that your planning is more inline with a residential system than a RV or vehicle solution.

There is nothing wrong with thinking out of the box, However mobile electrical systems are built around a long established 12 volt standard for everything from light bulbs to electric motors to relays, entertainment systems and appliance controls.  I could list even more but I think the point is established.

Having said that if you are willing to address all of these challenges, you may well design a system that works for you.

There is also at least one more major hurdle that you will need to consider if you go with 2,000 watts of solar panels.

I have just over 1,500 watts of panels, (10 panels), and it take up much of the roof space of both a 40 foot diesel pusher and about half of a 30+ foot Stacker Trailer.

Here are two pictures of the 5 panels on the stacker and the 5 on the dp.

Edit for Lou:  Towing a Stacker I have been known to make three left turns to make a right turn.   LOL


 
« Last Edit: December 31, 2016, 05:26:23 PM by HueyPilotVN »
Bill Waugh
40' Country Coach DP
34' Stacker Trailer, Trailer Toad
Jeep Commander
Mustang Bracket Race Car
35 years on the road

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #25 on: December 31, 2016, 07:17:24 PM »
Back to the 24v vs 12v question, I think the sources used in your research are for static systems rather vehicles. The arguments for using a higher voltage are sound, but [in my opinion] the more overwhelming consideration in a mobile solar set-up is that the vehicle & RV systems all run off 12v. It would be much better if they upgraded their operating voltage, but until that happens it's a fact of life.  The conversion of the system run voltage down to 12v will surely cost whatever is gained by using 24 (or 48) volt for the storage system. It may even cost more than what can be gained at 24v.

Automotive designers have known they need to switch to 24v or 48v for over 25 years now.  There were plans in place to make the change-over back in the 1980's, but the cost & difficulty of making the transition has kept it on the back-burner all this time.

Maybe it won't work reliably but where I'm at is just adding a 24 > 12v step down. Very small, very easy, very efficient. I don't see the problem.

edit: I should be done with the wiring tomorrow and I'll be sure to update on my results (minus actual PV). The step down (image) is rated at 40 amps, and AIMS didn't see an issue with how I was to use it. I was initially concerned with its small terminals for connectivity, but I'll just use a bus to resolve. The only real 12v issue I've faced is with the slider motor which the manufacturer says needs up to 100A @ 12vDC to pull the slider in. I'm going to resolve that by adding a 13th battery, this one much smaller so I can fit it into a nook in my battery box. I figure a 200+ CCA unit will work fine but I may be test driving a few.
« Last Edit: December 31, 2016, 08:09:28 PM by Desert_Rat »

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #26 on: December 31, 2016, 07:38:14 PM »
I value Gary's opinion as one of the most if not the most respected on this Forum.

I agree with what he said for several reasons.

I also have come to the opinion that your planning is more inline with a residential system than a RV or vehicle solution.

There is nothing wrong with thinking out of the box, However mobile electrical systems are built around a long established 12 volt standard for everything from light bulbs to electric motors to relays, entertainment systems and appliance controls.  I could list even more but I think the point is established.

Having said that if you are willing to address all of these challenges, you may well design a system that works for you.

There is also at least one more major hurdle that you will need to consider if you go with 2,000 watts of solar panels.

I have just over 1,500 watts of panels, (10 panels), and it take up much of the roof space of both a 40 foot diesel pusher and about half of a 30+ foot Stacker Trailer.

Here are two pictures of the 5 panels on the stacker and the 5 on the dp.

Edit for Lou:  Towing a Stacker I have been known to make three left turns to make a right turn.   LOL

I've mapped the roof out thoroughly. I'll have to relocate the TV and radio antennas, or maybe I'll just toss them. I don't use either anyway. Don't miss the video at the bottom https://www.altestore.com/store/solar-panels/solarworld-340-watt-solar-panel-sunmodule-sw340-xl-mono-p40538/

HueyPilotVN

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Re: 6 ----> 24 volts
« Reply #27 on: December 31, 2016, 08:42:17 PM »
I checked out your website for the solar panels.

This site seems to mostly be geared to residential or commercial uses which may be fine and is in line with your wanting to use large panels in higher voltages than commonly used in RV applications.

That does not mean that they will not work, However I would look carefully at the mounting system, framework and frame systems needed to support and mount the panels.

They are rated for high winds but I would ask questions about going down the road and road vibrations.  Not being negative, just saying be sure that you know what you are getting.

There may be a difference in mounting a large array on a stationary platform and a mobile solution.

Each panel measures about 6.5 feet by a little less than 4 feet or 26 square feet.  Six panels would require about 156 square feet of roof space for 2,040 watts.

Be sure to mount them where no shadows will fall across the panels.  You might also try to plan the layout to allow you to move around them or otherwise access them.

The cost per watt is very low but you may make it up with the frame structure and mounting UFO's.

Good Luck and keep us advised of your progress as this will be a learning experience for us traditional guys.

Edit:  These 24 volt panels wired in parallel could certainly also be used with MPPT controllers to work with a 12 volt battery bank
« Last Edit: December 31, 2016, 08:46:50 PM by HueyPilotVN »
Bill Waugh
40' Country Coach DP
34' Stacker Trailer, Trailer Toad
Jeep Commander
Mustang Bracket Race Car
35 years on the road

Desert_Rat

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Re: 6 ----> 24 volts
« Reply #28 on: December 31, 2016, 08:45:31 PM »
All good info, and which brings a question to mind...

AStravelers

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Re: 6 ----> 24 volts
« Reply #29 on: January 02, 2017, 08:29:18 PM »
If you notice, the red lead (standard + lead)  is tied to the + terminal, but my voltmeter is connected in reverse to get its positive reading. I'm just curious why the positive charge is at the negative terminal on the bank instead of at its positive terminal. It's obviously inherent to a series connect but I found it odd is all.
Sorry, but in the photo in the OP does NOT show where the meter leads are attached.  The leads go off the bottom of the photo.  I just went back and looked at the photo in the OP.  I suppose my Firefox browser doesn't show the full photo. 

Since I can't see where the meter is attached all I can go by is the way the battery is wired and it looks like the black cable comes to the top left neg terminal and the 4 batteries are wired in series to the red cable on the plus terminal.  Looks OK to me. 
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

 

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