legacy battery upgrade

[gmerrill]

does anybody know the best way to install a battery and possibly invertor capable of operating
small entertainment devices, dvd players, etc

[Salty19]

The idea of installing a new electrical system takes some planning.   I tend to plan for the future.  That means if it were me, I would install the battery in a battery box, hold it down with some sort of fastening system (tie down bar or straps) and really lay out the rest on paper. If you don't plan it well, it will be a wiring rats nest that will be dificult to troubleshoot.

Next think about what else you want to do with it.  You need a way to distribute the + power to not just one accessory, but probably several in the future.  Check out Blue Sea fuse blocks and switch blocks.  The idea is run your power ONCE to the fuse block from battery with a heavy guage wire.  Then wire in your accessories to the fuse box.  Then you need a way to switch off/on the accessory.  Some of the fuse boxes come with switches..that is the way I would go, but you can also wire in new switches.

1.) Use heat shrink wrap with reckless abandon.  The goal is to not have any wiring showing.  Yes, the copper wire is cased in vinyl but you want another layer of protection over it.  Plus it will really keep things organized.  You can buy red heat wrap for hot wires, black for ground in various sizes.  Use a lighter to shrink the wrap.  And for those wires going to battery, use the lighter to shrink the tubing AWAY from the battery.

2.) Use marine grade wire.  Not automative grade. Marine wire is tinned throughout the wire.  It will resist corrosion longer.

3.) Solder connections or use spade connectors.  DO NOT just twist the wire connections into one of those cone shaped electrical joiners as used in your house.  And those little wire splicers where you just snap the connector into place are TERRIBLY UNRELIABLE.  Throw them away!   Wrap heat shrink tape over the connections.  You may also want to tie those little zip ties tightly around the end of the heat wrap in the splice areas. That will relieve tension on your soldering job or connector (making them more reliable).

4.)  Wire everything up with the fuses removed.  Only plug in fuses when you're satisfied the job is 100% complete.  

5.) Be careful around the battery.  Don't drop tools on it.  If you touch both the positive and negative post with a wrench, big sparks WILL fly and you'll probably get zapped with several hundred amps of power.  That could be fatal.  I leave on the plastic post protectors until I'm ready to connect to the battery.  That's my last step before putting fuses in.  

All your accessories are going to need to be grounded.  Probably the best way to do this is to use a terminal block.  They sell them at Radio Shack for cheap, but they are the small type. All ground wires connect to the same terminal block and another heavy guage ground wire goes from this block to the battery negative post.  Try to avoid having too many items directly plugged into the battery.   Shoot for one wire on the postive, one of the negative. If you have a solar or other charger, that may force you to use two connections on each of the battery posts (one to the fuse block, one to the charge controller) because you want it to charge regardless if your master switch is turned on.

If you do run fuse blocks for + and terminal blocks for -,  go real big on the wire.  As big as can be installed.  this will lower resistance caused by the wire itself, raising efficiency.   The more amps you pull the fatter the wire needs to be.  Since this ONE wire will handle the load for all accessories, it needs to be sized correctly (ie of a lower guage than the acessories).

Route your wiring neatly.  You can buy little wire organizers and epoxy them where needed. Last thing you want is to yank out a live wire.
Electrical tape is not a substitute.  Tape comes loose over time.

The inverter is simply another 12V appliance.   So it would have the positive running to a switch that is protected by a fuse and runs to the battery (either through the fuse block or directly). And the negative to either the negative terminal block or direct to the battery.   You may find depending the inverter that it may come with "alligator clips" to attach directly to the battery.  The reason why they do this is convenience and they already determined the wire guage and lenght that will work well.  That is fine to do that, but consider it a temporary install.  I would rather spice in terminal rings and attach directly to the battery along with a switch that will turn off the inverter when not in use (even if it has an off/on switch, it still may cause parasitic (unwanted) draw).  But then again if you're going to use the inverter elsewhere, use alligator clips so it's easy to remove.

I really encourage you to draw out what you're planning to install (or even MIGHT install later on) so that you can size everything for the future.   Also also encourage the use of relays for high draw (greater than 5 amps) appliances.  And run diodes on the power wire to the relay (one way going to the relay only). The relay will prolong the life of switches and allows you to run a reliable master kill switch. It also reduced the lenght of the wiring that is running current to your appliances through it (the shorter the wire, the less resistance, the more efficiency).   The master switch turns the power off to the relay, the relay powers the fuse block.

As for the battery itself, I'm not in the market at the moment so I can't help there.  But I like the AGM batteries.  They are tough, they have slow self-discharge rates, are maintenance free and last a good long time. Note that a special AGM charger needs to be used.  Actually you need to be very critical of ALL chargers with any battery.  The right one makes a big difference.   But I'm not an expert on batteries so don't take my word this is best decision.

With this said, if you have no idea what I'm talking about...get professional help. But if you just want to connect the one inverter and that's it, it should be as easy as connecting postive of the inverter to postive on the battery, negative to negative same way.    But I suspect it won't be that easy.  How are you going to charge the battery?

[kchunk]

Hi gmerrill!

Your question is a little vague and the answers will mostly be subjective. For instance, I have a little 1000w Honda generator/inverter and love it. It installs simply, I just carry it on when I'm going to need it. Now if you wanted a more "permanent" installation. The WHAT to install depends on how much you want to spend and the "best way" or HOW to install will both be subject to many differing opinions.

I suppose if I were planning out an upgrade such as this I'd have to consider things like my present electrical demands and my future demands ... try to keep wiring circuits relatively simple and as short as possible ... consider heat dissipation and that your inverter will be heating the cabin ... consider maintenance and the fact that you will probably need access to parts of your new system in the future. These are all just a couple of considerations.

As to HOW to install it, stick with marine grade wiring, solder or crimp your connectors, and an important thing to remember is label your systems wiring. Right now you may know which wire you're installing goes from where to where, but 6 months or a year or two down the road, ringing out wires that you installed and didn't ID is frustrating...trust me on that one.

This answer wasn't much help, but if you have any specific questions, feel free to ask.

--Greg

[gmerrill]

I THINK YOU TOLD ME WHAT I NEED TO KNOW WHEN YOU MENTION THE INVERTOR STRAIGHT TO THE BATTERY.
THEY MAKE INVERTORS WITH PLUG INS TO RUN SMALL DVD PLAYERS AND WHAT NOT.  NOTHING MAJOR JUST SOMETHING
SMALL AS MY LEGACY HAS A SMALL CABIN AS IT IS.  THANKS FOR ALL YOUR HELP AND THE GREAT TIP

GREG

[botelerr]

Greg, if I connect to the battery with a 350 watt inverter , is there a danger to leave it connected to the battery or would you recommend disconnecting after use? I leave my 19 in a wet slip and may not use it for a week or two. The inverter is most likely more automotive than marine. Rob

[kahpho]

botelerr,

You'll want to disconnect the inverter when not being used. It will draw some power from the battery even if nothing is plugged into it, wasting some of your batteries capacity. All inverters I've seen do this so nothing wrong with yours.

mel

[kchunk]

Not sure which Greg you're talking to (I see there are a couple of us here), but some inverters have an ON/OFF switch and if you leave it on, some will have a cooling fan that runs. If its hardwired, switch it to OFF or open the breaker. If it clips to your battery, I'd unclip it when not in use. If it plugs into a cigarette lighter, unplug it.

--Greg

[curtisv]

does anybody know the best way to install a battery and possibly invertor capable of operating
small entertainment devices, dvd players, etc

Very carefully.

There were some really good detailed answers so far.  I don't have much to add.

I have a ProWatt 600W inverter.  I hardly every use it but got it at end of season for cheap.  I think it draws a rated max of 65A.  Put the inverter very close to the battery and use the largest wire practical.  4 gauge wire is not unreasonable.  Try to keep the wires under 4 feet (each way) if you can.  Make sure your battery can handle the peak load without shortenning the battery life.  If you are actually going to use the inverter, consider two group 27 to group 31 in parallel or a large battery such as a group 4D or 8D (but keep in mind that an 8D weighs in at 160 lbs and two group 31 are maybe 80 lbs each or lighter).

You don't want to leave a lead acid battery discharged, even partially discharged, for very long.  So figure out how you are going to charge it.  Taking the boat out for a week and then charging when you get home is a sure way to kill a battery.  If you have a slip with electrical hookup, then charge there.  Otherwise you need some form of charging.  Solar or wind is good for a float charge but not good for taking a discharged battery up to charge quickly.

Put a battery switch in the circuit so you don't have to pull the battery cables.  If you have a solar panel disconnect the loads and leave the panel on the battery.  Fuse the charging and loads separately and not the battery.  You don't want a battery fuse to blow and 17V directly from your charging to your loads.

Curtis