House Battery Setup and Batter Switch Question

[JT4SC]

Hey guys,

I have spent alot of time re-configuring my house battery set-up to be balanced and safe.  I have drawn up a schematic showing how I have the batteries tied together and where they go (Picture attached). 

A couple questions for the battery experts:

- How does the interconnected wiring look from a battery balance POV?  I used the smartgauge website schematic found on another house battery post.

- Do I have the inverter wire going to the correct battery (battery 2) or should that wire also be connected to battery 3? 

- My schematic shows a battery switch (Picture also attached).  One of the positive cables shown on Battery 3 goes to a pole on the switch, which ties in to another wire which goes to the main house breakers inside the bus.  The second positive wire goes to a different pole on the switch.  This wire connects with the smaller red wire coming off the bus battery solonoid to help charge the house batteries when the bus is on.  I added an in-line fuse to the that wire because Gumpy yelled at me a couple years ago for not having one and almost starting a fire.     

My main question here is: 1.) does this set-up make sense or should it be done different and 2.) I have the dial at "Both", should I always keep it at Both or should it be on 1 or 2 depending on if the bus is on or not?

- There is currently no fuse on the wire from the battery to the inverter, which I am 99% sure there should be (thanks Mike).  I believe it should be a catastrophe T-fuse, which should be installed on the wire running from the battery to the inverter.  Is this correct?

- Anything else I should be doing?  TIA!!!

[buswarrior]

What batteries are these? 6, 12?

Perhaps I didn't interpet the picture correctly?

That looks like a bunch of batteries, connected in parallel, with a whole bunch of unnecessary cables, with battery 1 going to fail first, battery 3 doing all the work, and 2 and 4 somewhere in between?

The battery switch shown seems to have no purpose in switching anything other than perhaps on and off?

This is a hard topic to work on via the Board, keep feeding us info, we'll get you right!

Happy coaching!
Buswarrior

[gumpy]

Pretty much what BW said.

Need to know a) what voltage you're going for on your battery bank. b) what batteries you are using (6v?, 12v?) c) how you're planning to charge the bank (inverter? converter? alternator?)
d) whatever else you can supply.

There should be one ground and one hot wire on the bank and they should be a opposite ends of the parallel string. There should be a fuse on the hot wire and the switch should be the first thing after that. The inverter should be after the switch, not directly to the battery. Same with the charging

[bevans6]

I am not a huge fan of obsessing over how you connect up batteries for optimized balance.  You do have them configured for equal and optimal balance in terms of charge and load if you move the connections to the switch (bus charge and bus load) to the same terminal as the inverter positive load is connected to.  I wired my switch so that it was between the batteries and the inverter - I can connect my inverter to just the house bank, or I can connect it to both the house bank and the bus start batteries/alternator.  House bank is on "1", bus batteries are on "2", my switch can do OFF, 1 or 1+2.  

Iota PDF on exactly what you are doing:  www.iotaengineering.com/pplib/balancedcharging.pdf

[gumpy]

Iota PDF on exactly what you are doing:  www.iotaengineering.com/pplib/balancedcharging.pdf

Ok, now I see what he's trying to do. 

I personally don't think there's much difference between the balanced charging and the "perfectly" balanced charging schematic. I use the balanced charging method and got 12 or 13 years on my last set of Trojans. It's more important to have a good quality three stage charger and have it's output adjusted for your particular battery bank.

[JT4SC]

Thanks everyone.  I was rushing to get to work and forgot to mention the size.  They are 12 volt batteries.  I also forgot to ask where exactly the battery charger should be placed, and the iota engineering link helped me solve that, thanks bevans6!

I'm going to think through more about your advise on the switch, I don't completely understand what you said - specifically on when it's most advantageous to be in 1, 2 or both position, but after I'm done at work and a have a cocktail it might just come to me.  
Jim

[richard5933]

It's confusing the way you have the diagram shown. It looks like you have a single battery bank and your switch is choosing between charging from the bus alternator and/or running the house 12vdc load center. This is not how I would have used the switch.

I looked into using a switch like this, but my purpose was to use it to bridge the house and chassis batteries so that I could charge the house batteries from the bus alternator while driving. In the end I went with a solenoid to bridge the two battery banks together when necessary. I would have started the engine with the switch set to connect only the chassis batteries. After starting I could have connected both the house and chassis batteries in order to charge them all while driving. Once parked and with the engine off, I could have switched to house batteries only to run the 12vdc circuits with no danger of running down the chassis batteries. In the end I installed separate on-off switches for the house and chassis batteries, and then used a high amp capacity constant-duty solenoid to bridge them together when needed.

Please post a bit more information about your setup so that we can give better advice. Do you have separate house and chassis batteries? What is your goal for using the switch? Etc, etc.

Richard

[bevans6]

OK, I have two switches - the three position "combiner" switch and the bus master disconnect switch.  The "combiner" switch is the marine type off-1-1+2 switch, and it is connected to feed just the inverter, since the inverter is the only significant battery load that I have (4000 watt Magnum inverter).  It is set up so I can completely disconnect the inverter, have it fed from just the house bank, or from both the house and the bus battery/alternator.  When it's switched to "1+2", it combines the house and bus batteries so I can charge the house bank from the bus or I can boost the bus start batteries from the house bank for starting.  If I stop for the night, I switch to "1" position and run the inverter from the house bank for overnight.  If I am on the road, I switch to "1+2" and run the inverter mostly off the bus alternator so I can run my rooftop air-conditioner while I drive.

There are a few other scenarios.  Lets say I loose a battery in the bus start bank (my bus has two 12v batteries in series for 24 volts), as I did on a recent trip.  Bus would not start on the bus batteries, and the alternator was unable to charge the pair, one of the batteries was toast.  I simply disconnected the bus start batteries by opening the bus master disconnect switch, put the "combiner" switch in "1+2" and ran off the house bank only for the rest of that trip.  I can "jump" the start batteries if it's cold out, I can charge just the house bank from the inverter, or both the house and start banks from the inverter, I can charge just the bus start batteries from the alternator, or I can charge both bus and house banks.  Much flexibility.

I do have some small 12 volt loads that I feed from a center tap on the house bank, with a Vanner equalizer in a standard manner.  You will have larger 12 volt loads, since I assume you have a 12 volt bus.  In your case I would supply all bus 12v loads as stock, and supply all 12 volt house loads from the same terminal as your inverter is fed from, and use the switch as I do, purely to switch between combined with the bus for loads and charging, or to isolate the house bank, or to disconnect the inverter from all batteries.

Brian

[richard5933]

Is your house battery bank also 24v?

Richard

[buswarrior]

What voltage is the original poster aiming for with this battery bank?

12 volt individual batteries, hooked up to make 12 volt or 24 volt bank?

Happy coaching!
Buswarrior

[JT4SC]

Hi Richard/ BW-

This will be a 12 volt house battery bank.   This was how it was when I bought the bus and my goal is just to make it better (balanced) and safe; neither was the case when I bought it.  I'm also trying to understand why the battery switch is there and if it should be modified to work within an overall more logical/correct system.  Of course I didn't know any of this because I'm coming from a place of knowing nothing about busses or conversions, so it's been a lot of learning.  I'm thankful for all your help!!!!

The way the battery switch is configured has also not been changed in any way since I bought it.  I remember Mike trying to explain it along with the rest of the bus but it was like drinking from a fire hose kind of information overload.  I'm laughing to myself as I write this because of how naive I was.  I was 28 going on 15.  Ugh!!

Bevans6 -

My bus system is 24 volt.  The bus batteries are 2 8D batteries in series. The house batteries are 12 volt.  

I've attached 2 pictures:
-  first picture is a close up of the solenoid located in the bus battery comparment, with the red wire on left of solenoid running from the bus battery compartment back to the house battery switch.  

- second picture is one I took a couple years ago when I tried to burn my bus down.  It shows the the solenoid with the red wire fried where it connects with the solenoid.  I've since added an in-line fuse.  The main reason I wanted to share this pic was to show how it is also connected to the Vanner (which I am still trying to understand).  

My understanding is the bus batteries help charge the house batteries but not the other way around.  
So far with your help I know I need to move the inverter positive cable to the switch and not have it directly connected to the battery bank.  However I don't know which port on the switch it should go, and if I need to move/remove any of the other cables which are currently connected to the switch.  If possible can you post a pic of how you have the back of your marine switch hooked up?

** note it wouldn't let me post the close-up pic of the solenoid because of the file size, I will try to reduce the size and post it.  

[richard5933]

Couple of things...

1) If you're trying to charge the 12v house batteries from the 24v chassis batteries, then keep using the Vanner. There are some great instructions and wiring diagrams on their website which will show you the correct way to connect things together. They also show some ways not to connect things, so pay attention to which is which. I believe the Vanner will draw from your chassis batteries even when you are not actively using it, so the switch for the chassis batteries should go between the batteries and whatever is connected. The purpose of the Vanner is to draw 12v from your 24v battery bank while maintaining an equalized charge to the 24v batteries. If you simply tapped into the point between the two batteries you'd get 12v, but doing it that way would cause one of the 24v bank batteries to overcharge, the other to undercharge, etc. The Vanner is designed to tap into the 24v bank and pull out the 12v properly.

2) My guess is that the solenoid was their at one time to enable you to connect/disconnect something (don't know what) from a distant location, probably the dash. The solenoid is nothing more than an electrically activated switch. The two large lugs are for the line that you want to make/break. Doesn't matter which of the large lugs is used for the two ends of the line that you are seeking to make/break, as those two lugs function as a simple on/off switch. The two small lugs are the power to the magnetic coil which activates the internal switch. Put + to one of the small lugs and - to the other and you'll open/close the contacts. Most I've seen are normally open and applying power closes the switch. You'll have to investigate to see if the solenoid is 12v or 24v. Maybe the solenoid was originally wired to automatically turn off the Vanner when the bus was not running?

3) The battery switch looks like a Blue Sea. If it is, they have diagrams for all their switches posted on the individual pages for each switch. Get the diagram - it will be helpful. The 1 & 2 switch can be used to connect two loads to one source OR to connect two sources to one load. In other words, you can use it to switch one load between two different battery banks, or you can use it to switch one battery bank between two different charging sources. I'm not sure how you're using it, but from the diagram you posted it looks someone was using it slightly differently than either of those. First though, are you sure that the lead labelled as coming from the bus battery alternator isn't actually coming from the Vanner? Would make more sense. What it looks like is someone connected the battery switch to give you four options: a) disconnect house batteries, b) charge house batteries, c) use house batteries to run inverter AND to isolate from chassis batteries, d) or both b & c.

There are still a lot of options on how to get this set up. Still lots of unknowns as well. Do you know what the solenoid was being used for?

Hope this helps.

Richard

[JT4SC]

Hi Richard,
I have no idea what the solenoid was originally used for, it's been connected the same way for as long as I've had the bus.  There are 4 wires to it, I'll make another schematic for that thing and post it here.  I'll also try to make a new schematic of the battery bank and switch based on what you all have helped me learn and post it and see what you guys think.  

Another general question I have is the battery charger.  They now make inexpensive 3 stage smart battery chargers you can buy at O'Reilly's, etc. You then have the $250-400 chargers that have more bells and whistles but don't seem to do much more than charge in stages just like the newest ones you find at O'Reilly's.  Here is a link to one - https://www.amazon.com/Schumacher-SC-1200A-CA-SpeedCharge-Automatic-Battery/dp/B000BQSIWK

Interested to hear what other people think about this?

[richard5933]

Biggest difference between chargers like the one you linked to and the more expensive ones is capacity. The one in your link will only do 6 amps normal charge. That will run a few lights in the house system and that's about it. I had a Progressive Dynamics 9270 with 70 amps output. You may not need 70, but odds are you'll need far more than 6.

Richard

[Oonrahnjay]

... odds are you'll need far more than 6. Richard

      Yeah, if you have a 400 Amp Hour battery bank, you'd wait weeks to get it fully charged.