What is the correct way to hook up a Battery Inverter/Charger

[Fred Mc]

The lowest price I have found for the Balmar Smartgauge is $240 from West Marine.

I bought one because it is simpler to hook up but more importantly, doesn't appear to need constant attention to provide accurate information.
But I haven't hooked it up yet so can't comment on its use.

[Oonrahnjay]

Bruce, your link does not work.  Here is what comes up:

404. That's an error. 
The requested URL was not found on this server. That's all we know.

Thanks.  Try again.

https://photos.app.goo.gl/BjhAyZrBQgl55Omj2

[sledhead]

I was told to always have your cables the same length = + and _  so looking at your drawing it looks like you will have way more length on the + side then the _ side


dave

[Stormcloud]

The first sketch ( battery bank) is generally considered to be the best way to connect multiple batteries for a bank.

The second sketch ( battery bank 2 ) with the fuses between + and - posts of adjacent batteries provides protection for the rest of the battery bank, should one of the batteries short internally.  If that happens, an excessive amount of current will be diverted to the defective battery to recharge it, causing the fuse to fail, which in turn protects the rest of the battery bank.

Each fuse should likely be rated at 100amps or greater. A fuse of lesser rating may fail when you draw maximum power out of your inverter.

Also, a catastrophe fuse should be wired on the circuit somewhere, designed to fail in case of (you guessed it) catastrophic failure of the bank.

YMMV.

Mark

[Oonrahnjay]

The first sketch ( battery bank) is generally considered to be the best way to connect multiple batteries for a bank.  ...
Mark 

    Thanks, Mark.  Your sketch shows a 24V battery bank, right?   Thanks,  BH

[Oonrahnjay]

I was told to always have your cables the same length = + and _  so looking at your drawing it looks like you will have way more length on the + side then the _ side

dave

      Thanks, Dave.  I think that you're right but I don't have a way to measure resistance of the cables and ground straps yet.  What I was trying to do was to make each battery see a similar resistance.  So if a battery has a short positive path and a long negative path, it should be balanced to a similar resistance as a battery that has a long positive path and a short negative path.  This is the detail factor that has me stumped.   If it makes any difference, here's another scheme that separates out the ground path for each section of batteries.  Does that matter?

https://photos.app.goo.gl/b7WOsLeENDANdE9A2 

[Stormcloud]

    Thanks, Mark.  Your sketch shows a 24V battery bank, right?   Thanks,  BH

Hi.

The battery banks in my sketches could be either 12 volt or 24 volt, depending on the batteries installed in the bank.
If the batteries are 6 volt, then it's a 12 volt bank. Similarly, if 12 volt batteries are used, then the bank is 24 volt.

If Gary had a shorted battery in his bank configuration, the blown fuse would tell him which is the bad battery.

YMMV

[Oonrahnjay]

...  If Gary had a shorted battery in his bank configuration, the blown fuse would tell him which is the bad battery.

YMMV 

         Thanks for the voltage info.

         Oh, yes, I hadn't thought of the way that might work but - sure - Ohm's law, if it starts sucking watts, the amps go way up (to make the heat) and it either starts a fire or overheat condition or it blows the fuse.  Nice.  Thanks for that info.

[Gary Hatt - Publisher BCM]

Thanks for all of the help.  I will do some more testing before I replace my old batteries. 

I talked to my battery guy this morning and he convinced me to replace my six 4D Interstate deep-cycle 12V batteries with eight Trojan T105 6V batteries.  He said they have more duty cycles and should last longer.  The eight 6V batteries will also give me more Amp Hours as well.  Not only that but they are much lighter than the 4D batteries that are about the same size as 8D batteries and more readily available.

[Iceni John]

The first sketch ( battery bank) is generally considered to be the best way to connect multiple batteries for a bank.

The second sketch ( battery bank 2 ) with the fuses between + and - posts of adjacent batteries provides protection for the rest of the battery bank, should one of the batteries short internally.  If that happens, an excessive amount of current will be diverted to the defective battery to recharge it, causing the fuse to fail, which in turn protects the rest of the battery bank.

Each fuse should likely be rated at 100amps or greater. A fuse of lesser rating may fail when you draw maximum power out of your inverter.

Also, a catastrophe fuse should be wired on the circuit somewhere, designed to fail in case of (you guessed it) catastrophic failure of the bank.

YMMV.

Mark

A few years ago Sean Welsh recommended putting the catastrophe fuse on the negative, so I've done exactly that with my system:  http://www.busconversions.com/bbs/index.php?topic=22290.msg244760#msg244760   He knows way more about such matters than I ever will, so I'm happy to defer to his wisdom!   Actually I have two separate battery banks in parallel, so I have a 300 amp Class T fuse for each bank's negative.   The positives will still get their own load fuses.

John

[Oonrahnjay]

    Looking a bit more.  I realized that I had put two rows of batteries "long side along" because there was not room for two columns of batteries turned the other way.  But (I'm pretty sure, not at the bus now and I'll have to go measure for sure) there appears to be enough to have two unmatching sets of batteries, as shown in the photo link. 
    This new setup has a lot of advantages -- the upper set is the traditional ladder-arrangement and the lower set is electrically the same but with a slightly different physical layout.  It makes installation and battery tiedowns easier and gives the simplest *positive at one corner and negative at the other* to balance the charging.  It also allows me to add two more batteries to the parallel setup at a later date.
    About the only disadvantage is that my battery box has a metal lip at the top and bottom edge; that's to seal the compartment covers and this layout puts more of the batteries under the lips and that would mean a slightly more fiddly installation and make checking and maintenance a little harder (but that's a less important factor since my batteries are AGMs).  Oh, I also found a large-capacity battery cut-off switch from a racing supply store -- not shown on the sketch is that I'll have the switch on the positive cable with a main fuse near the first positive connection.
    Finally, don't worry about what looks like large arcs in the positive cables.  That comes from showing the separation between positive and negative connections.  It appears that I can get a dependable separation of the cables and ground bar with very slight bends in the positive cables so extra length of the positive cables is not a factor in real life. 

    Comments appreciated. 

https://photos.app.goo.gl/G6CWTl9XTWIyITnv2

[Gary Hatt - Publisher BCM]

Oonrahnjay,

I have two battery slides one upper and one lower so my plan is to go with double 6V batteries, one behind the other and there will still be plenty of room to slide them out to water them monthly.  But your idea is an interesting set up.

Gary