Wiring & Installing A Battery Monitor

[rikhall]

Originally Posted by Maine Sail

Yes a 200 A ANL or MRBF would be fine.

Perfect. Many thanks.

I will be in Salem MA in two weeks to help a buddy bring his "new-to-him" boat back east to Canada. I will pick up a fuse while I am there.

Rik

[n0w0rries]

I'm getting ready to buy a Xantrex Linkpro and came across this thread while doing my research. I'm going to buy a 25' cat6 cable to use for $4.44 instead of their connection kit that costs $120+. What a joke!

Thanks for the great info--hope I was able to give something back!

Oh yeah here's a link to buy the cable: http://www.monoprice.com/products/pr...seq=1&format=2

Originally Posted by Maine Sail

Jos,

I personally like the Xantrex Monitors slightly better than the Victron if price is not the objective. I use a Link-Pro on my own boat and have a pile of monitors to use anytime I want including a Victron BMV-602. The Links are harder to install but the total added time is about 20 minutes and once your done that's it.

If you got it cheap then buy the communication kit. The proper wire for these is very difficult to source in small quantities. I have looked high and low. If someone has a source PLEASE let me know I'll buy a 1000 foot reel and re-sell it and still save people TONS of money.. It needs to be multiple twisted pair. The "twisted" part is important as it cuts any induced noise which can throw the monitor off.

Like most things Xantrex doe not build these monitors they "source" them. The price of the TBS built Link-Lite and Link-Pro is OFFENSIVE when you include the communication kits. If you knew my cost on a Victron you'd have a better idea of just how offensive....

Both are good products but I do think the LINKS are more robustly built. I have never once had a single failure or issue with a TBS Electronics built LINK monitor and I can't say that for the older Cruising Equipment Link-10, 20, 2000 & 2000R. TBS began making monitors for Xantrex with the XBM and make the current LITE & PRO...

[efiste]

Really great information here. I am installing a Blue Sea Systems monitor (VSM 422 Vessel Systems Monitor) over the next 2 weekends along with an upgraded battery bank, high output alternator, etc.

I have a 1987 Catalina 34 that was built with #4 wire for all high load positive and negative wire. Due to very helpful information at the Catalina 34 Organization website (thanks Stu, Jim, and others), I am familiar with the limitations of this stock wiring size and distances, and I am addressing some of this with an upgrade to various components. My Blue Sea monitor looks to be a similar setup, and I now understand how to configure the shunt with negative loads downstream.

My question is what to do if also installing an inverter that calls for 2/0 wire to support high DC loads. Assuming the negative needs to be a similar size, will I also need to use this size negative wire from the battery to the shunt and from the shunt to the negative load bus bar? According to the wire sizing chart I referenced, #4 wire can only support up to 100 amps over a short distance and the negative should not be more than 1 size smaller than the positive.

Thanks. I think this is one of the last pieces of the puzzle to complete my wiring plan.

Eric

[mitiempo]

Eric

Best solution is to use 2/0 wire for all the runs from batteries to inverter, shunt, switch, and starter. 4 awg is undersized for all but panel loads in my opinion. I never use wire smaller that 1/0 for any battery wiring.

[Maine Sail]

Originally Posted by efiste

According to the wire sizing chart I referenced, #4 wire can only support up to 100 amps over a short distance and the negative should not be more than 1 size smaller than the positive.

Neg return and pos should always be the same size or no sense in having one larger than the other. DC circuits are loops so all wire should be the same size. It is the CASE GROUND of the inverter than can't be any smaller than one size below the DC wiring. This is a green wire connected between the inverter case and your ships ground/Earth, usually the engine.

The older Catalina wiring was undersized. All the newer Catalina's such as the C309, C310 & C320 uses 1/0 or larger from the factory.

4GA is marginal at best especially when folks start adding batteries and the lengths get longer....

[asdf38]

This is a nice thread that I just read for the first time. To its original point I think one helpful comment is that once you install a shunt such as this you should change your thinking to consider the shunt as the new GND and stop thinking of the battery (-) as GND - it no longer is. If it helps, when doing a diagram you could draw the battery and shunt together with a box around them and the GND symbol on the far side of the shunt.

Also you can remember that a shunt is just a carefully calibrated piece of very very low resistance metal - not something functional and not something that can break . To put it in perspective the shunt in the original example (500A=50mV) is a 0.0004 ohm piece of metal which is equivalent to ~1' of 2AWG wire. The monitor and that positive wire to the shunt could both fail and it would still be exactly equivalent to a 1' 2AWG wire.

[chrisferro]

That was a great a write-up for installing the Victron, and it's a great monitor; but I recommend the Nasa Clipper BM1 battery monitor for a single house battery system. I did a very exhaustive study of all of the monitors out there and ended up settling on the BM1. It's very easy to install, gives you voltage, tells you in amps what you are putting into or taking out of your battery (charge/discharge), has a vertical bar graph to illustrate % of battery capacity, tells you in minutes how long at the current rate you will deplete your battery, has a bigger display so it tells you more at a glance than the Victron and has a backlight. I love it. And I think the price is about the same.

I have the BM1 on my house battery, and a simple Voltminder voltmeter on my start battery.

Just my 2 cents...
chris