Wiring a battery bank.

[ontheroadagain]

I am buying 3 deep cycle 12 volt 105ah batteries for my RV.<br />When I connect them together would 4 gauge wire be ok since they are so close together?<br /><br />If someone has the time, could you insert a picture of what a fuse for the positive side of the battery would look like? I see so many different styles and sizes that I am not sure what to order. Can you buy fuse holders that attach right to the 5/16 screw post on a deep cycle battery and crimp on your wire to the other side of the fuse holder? Would I use the same fuse setup for the + wire coming off the solar panel?<br /><br />thanks folks<br />Rick

 

[highdesertranger]

it depends on the load, &nbsp;remember the bigger the better for wire size.&nbsp; what type of load do you expect? &nbsp; i personally would use a circuit breaker and not a fuse for the reason if a fuse blows it's junk you have to&nbsp;put a new one in.&nbsp; if you ever get a short keep replacing fuses while troubleshooting gets expensive.&nbsp; with a breaker you can just reset.&nbsp; highdesertranger

 

[wrcsixeight]

The thicker the cables between the batteries, the more they act like one big battery.<br /><br />But unless you are running a 2000 watt microwave via a 3000 watt inverter, using 4/0 wire is likely overkill.<br /><br />Beware of auto parts stores battery cables. &nbsp;They use steel crimps. &nbsp;Here are some I cut off sticking to a magnet.<br /><br />&nbsp;

<br /><br />I had 2 4 awg ground cables going to my house bank. &nbsp;My clamp on ammeter showed that while both wires together were passing a 4 amp load, the one with copper lugs was passing 3.2 amps, the steel crimped one, 0.8 amps.<br /><br />After cutting off the steel lugs and crimping on copper, both cables shared the current 50/50.<br /><br />So the cable terminations are just as important, or even more so, than the thickness of the cable, in reducing resistance.<br /><br /><br />I do not use a fuse on my house bank. &nbsp;I can start the engine with the house bank and starter current can easily blow a 250 amp fuse.<br /><br />http://bluesea.com/category/5/21/productline/overview/378

 

[gadgetMe]

<a href="http://www.marxrv.com/12volt/12volt.htm" rel="nofollow"><span style="text-decoration: underline;"><span style="color: #0000ff; text-decoration: underline;">12 volt side of life</span></span></a><br /><br /><br /><br />although&nbsp; a little outdated ......This is the most complete information you will find on the net for .... 12 volt systems<br /><br />Although not cheap<a href="http://www.powerwerx.com/fuses-circuit-protection/resettable-circuit-breaker-cooper-bussmann.html" rel="nofollow"><span style="text-decoration: underline;"><span style="color: #0000ff; text-decoration: underline;"> here</span> </span></a>is a very good industrial grade circuit breaker,<br /><br />Fuses have jumped to very high prices lately, I agree the circuit breaker would be best.<br /><br />Putz

 

[peacetara]

You might be cheaper to buy 2 6V batteries and wire them to make 12V and get the same or more AH.&nbsp; 12V batteries tend to have super low AH ratings, where 6V batteries tend to have high AH ratings.<br /><br />As for wire sizing, it totally depends on what your max load will be in amps, and the distance you need that load to go.<br /><br />i.e.&nbsp; for 20 amps max with a distance of 3 feet you only need 8 AWG wire.<br /><br />for 20 amps and 1 foot of distance, 14 AWG wire is sufficient.<br /><br />(this is allowing for 1% loss)<br /><br />You can size your own cable needs <a href="http://www.solar-wind.co.uk/cable-sizing-DC-cables.html" rel="nofollow">here</a>.

 

[Willy]

I did the 2x6v deep cycle battery thing and ended up getting shafted when one of them went bad. It left me with one 6v battery.. totally useless. That's why I use 12v deep cycles. Also, my battery needs are modest enough that 2 batteries, one for my Waeco/lights and the other for everything else is sufficient, especially during the summer. ..Willy.

 

[josephusminimus]

Willie:&nbsp; Any idea what went bad in the 6v battery?&nbsp; Cell, strap between cells melted?&nbsp; Bad separator between the plates in one of the cells?<br /><br />If you have any notion what went wrong with it I'd be interested in knowing.

 

[blars]

Search "anl fuse holder" on google for a variety of pictures.&nbsp; The ANL fuses bolt in, and you use ring terminals on your wires same as your battery connection.&nbsp; Many have a cover that helps prevent shorts.&nbsp; I got one on ebay with 200 amp fuse for less than $10.

 

[ontheroadagain]

Thanks everyone for the help.<br /><br />I feel the same way Willy does on the 6v batteries.<br />The breakers instead of fuses is a greater idea.<br />I did not know you needed to get copper ends. <br />I haven't seen any connecter ends online that actually state what they are made of.<br /><br />thanks for all the great input

 

[Willy]

&nbsp;One of the 6v batteries had a dead cell and it was 'game over'. Still have the good one sitting here and waiting for some unsuspecting SOB to come get it.. for free! ..Willy.

 

[peacetara]

I would think you would be better off with something more along the lines of 20AMP fuse, not 200AMP.<br /><br />Sure you can pull 200AMPS out of some battery banks, but something tells me that's super rare for most "house" uses.&nbsp; I rarely pull more than 6 or 7 amps, personally.<br /><br />You want your fuses to blow when something 'abnormal' happens, so you want them to be a little more than whatever your max pull is.<br /><br />If you are blowing fuses enough that you want to upgrade to a breaker instead, perhaps you should look closely at what you are doing.&nbsp; You shouldn't be blowing fuses really EVER.&nbsp; Blowing a fuse means something is WRONG.&nbsp; if you don't know what is wrong you should spend the time/effort figuring it out.<br /><br />Any electrical supply house should carry inline fuse holders, and most auto shops will sell them as well.<br /><br />Normally you just have a fuse running from your battery to your load, whatever that is, on the positive wire.&nbsp; (switches go on the positive or red wire as well).

 

[sl1966]

Sweet jebus!!! I've read this stuff 100x and still get lost in the details. I'm really gonna need someone's help (in person) when I wire up my rig. I know I'll electrocute myself if I don't.<br /><br />

 

[VanTrekker]

<p>There is one thing you don't have to worry about though... It's unlikely 12 volts will push enough current through your body resistance to electrocute you...&nbsp;Unless you fall&nbsp;in a hot tub while holding the wires.&nbsp;Even then it's doubtful...&nbsp;Sorry, I had to add a little levity here for ya.<br /><br />Doing the wiring can be intimidating but in general, if you go a little bigger, you'll be better off in terms of the gauge.&nbsp; I took the easy route (short distances) and just used a few butchered up battery cables.&nbsp; <br /><br />I am using&nbsp; the ANL fuses and got them from Ebay.&nbsp; I have a separate one for each of the two batteries.<br /><br />Have a great one!</p><p>Brad</p>

 

[ontheroadagain]

sl1966 that's the way I feel about getting this all organized. I don't think I will die but I have zapped myself shorting a car battery. Scares to bejebious out of ya.<br /><br />Good quality wire isn't cheap and neither is good battery cables with real heavy wire.<br />I know it is best to pay it now instead of having to change it out later. I had read that 0/1 is best for connecting batteries together but it seems like over kill for a 10" piece.<br /><br />Here's another thing I just thought of. My batteries has both have the top posts like for a car and top 5/16 threaded poles. Would it be good to connect the two batteries together using standard <br />car battery cables cut down. I could buy two cables and some extra terminal ends and make up what I need. Then I could use the threaded posts to connect the incoming wires from the controller and out going wires to the inverter and house 12v.<br /><br />thanks<br />rick

 

[peacetara]

For 200AH and a load of 20AMPS at any given moment, it doesn't matter.&nbsp; The load is small enough, you can get away with anything, and chances are it will work just fine <img src="/images/boards/smilies/smile.gif" border="0" align="absmiddle"><br /><br /><br />I agree, in the sizing of 12V we are talking about here it won't kill you, but it will confirm you are awake if you zap yourself <img src="/images/boards/smilies/smile.gif" border="0" align="absmiddle"><br /><br />rule #1: Never ever touch positive(red) and negative(black) together.<br /><br />figure out how far you need the cable to go.&nbsp; Wander to Home Depot/Lowe's etc and ask them, they will probably just do all the math for you and connect you with the connectors you need.&nbsp; OR If you stop off at a Solar store, or a battery store, and ask them for cables, they will probably sell them to you pre-made, ready to go for your battery for a few dollars.<br /><br />Most 12V electrical cabling in vehicles is 14AWG, because they know their amp draw is small enough that 14AWG will work.<br /><br />You can't really go wrong in running bigger cables than you need, but they get expensive.&nbsp; If you are tooo lazy to use the calculator to figure out cable sizes, you can run 10AWG and be totally fine, for pretty much everything you could want to do I bet.<br /><br />If you happen to run into me wherever I happen to be at the moment, I'd be very happy to help you.&nbsp; I'm sure Bob (forum owner) and Steve would as well, they hooked me up really well with mounting my Solar Panel.<br /><br />With Love,<br />Tara

 

[bee]

sl1966 that's the way I feel about getting this all organized. I don't think I will die but I have zapped myself shorting a car battery. Scares to bejebious out of ya.<br /><br />Good quality wire isn't cheap and neither is good battery cables with real heavy wire.<br />I know it is best to pay it now instead of having to change it out later. I had read that 0/1 is best for connecting batteries together but it seems like over kill for a 10" piece.<br /><br /><br />Here's another thing I just thought of. My batteries has both have the top posts like for a car and top 5/16 threaded poles. Would it be good to connect the two batteries together using standard <br />car battery cables cut down. I could buy two cables and some extra terminal ends and make up what I need. Then I could use the threaded posts to connect the incoming wires from the controller and out going wires to the inverter and house 12v.<br /><br />thanks<br />rick

<br /><br />You can always use all the terminals on the battery to keep it less cluttered.<br /><br />Do you only have to run wires connecting the batteries to each other? &nbsp;The other cables going to the rest of the vehicle are up to spec? &nbsp;The reason I ask is that you can find large quantities of cable on ebay for a decent price. &nbsp;If you only need a few feet though then it probably isn't worth it. &nbsp;Just a tip though ebay/car stereo stores are overloaded with aluminum wire which is inferior to copper wire when comparing the same gauge to each other, its cheaper, but you have to up-size accordingly.<br /><br />I believe most places usually run 2 gauge between batteries as standard, though it really depends on how many amps you plan on drawing out of the batteries or putting back in at any given time. &nbsp;Lower the amps smaller the gauge you can get away with and vice versa.<br /><br />The point of a battery fuse (catastrophe&nbsp;fuse) is to protect the wires leaving the battery. &nbsp;The concept is if the wire gets shorted to ground, rubs up against a sharp piece of grounded metal for example. the fuse will blow before the wire melts/ catches on fire etc. &nbsp;The fuse is not supposed to protect your appliances, they should have their own fuses rated accordingly to their needs.<br />I recommend ANL as well since they are cheap and if you do screw up and blow one you can find them at any store that sells car stereo equipment.<br /><br />I glanced quickly at that link that was posted above and I am pretty sure they are telling you to wire it wrong, you want to wire it "balanced" which is explained here&nbsp;http://www.smartgauge.co.uk/batt_con.html<br /><br />Edit* &nbsp;Be careful when buying 12v deep cycle batteries. &nbsp;Often they are not true deep cycle batteries, they are actually somewhere in between deep cycle and regular start batteries, which may reduce life when discharged regularly.