Battery Monitoring

[cutwater4me]

Has anyone installed a Xantrex battery monitor meter or similar device to keep a close eye on your house battery level. If you have a solar panel, is the digital battery readout accurate enough to track battery condition. I'm a nut about never getting my batteries below 50% discharged.

Any thoughts from the group would be appreciated.

Thanks,

Kurt
CW 28 LE
2819

 

[SnugTug]

There is a string or two on the Xantrex monitors. Believe Red Raven has one installed with pics in his album. Search forums with "Xantrex" and you will see references.

 

[cutwater4me]

Thanks John. Helpful. I'd love to see if any others have installed and their experiences.

 

[Red Raven]

Yes, I have installed a Xantrex battery monitor. It works really well. I especially like being able to turn S ystems on and off one at a time and see exactly how much current is being drawn by each system. It helps me control my power usage to maximize the time on the hook or dock without power.

The Xantrex minimum % capacity setting defaults to 50% so it took me a while to figure out the % capacity numbers relative to the actual volts and amps. With this default setting you can take your batteries to 0% on the meter (actually 50% capacity!) and not degrade your batteries before recharging. Once I understood this, it all made sense (but a little confusing for an engineer who was watching the volts and amps numbers). You can change this minimum % capacity default if you want to know the "real" numbers but you then need to avoid discharging below 50% on the meter. There are several other settings you can adjust in the settings as well but I'll leave that to those who are really interested.

The installation was fairly straight forward but it does require installing a 500amp shunt (comes with the monitor) and you need to run twisted pair wiring from the shunt to the monitor. The wire does not come with the monitor but a separate wiring bundle kit is available. I bought the kit but I see no reason that you could not use standard cat 5 Ethernet cable as the kit is around $100 as I recall. You will need to have at least one additional battery negative cable made for the shunt Connection (custom crimped or bought pre assembled) depending on where you install the shunt and the shunt needs to be the first and only connection to the negative side of the house battery (I use the Xantrex to monitor the house battery only as it can measure capacity and current for one bank though it can measure voltage for another which added no value to me). I put the shunt I the battery compartment and I chose to put the monitor in the cave/chart desk area to simplify the wiring run and not have to fish wiring to the helm. House battery capacity is not something you need to monitor while under way so I figured a dash installation was not necessary.

The only other minor issue I have had is the Morningstar solar panel controller appears to charge the batteries in bursts. This means that when the Morningstar reads 3 amps of solar charging current you do not necessarily see that on the Xantrex monitor but then suddenly there will be a huge burst of current on the Xantrex that then rapidly falls off again making it hard to verify how much charging you are really getting from the solar panel. Just trust the Morningstar panel I guess.

All in all I am extremely happy with the system. One of the best mods we have done to the boat. I always know exactly how much capacity is left in the house batteries and how much I am currently using.

I hope this all makes sense and is useful.

Curt

 

[knotflying]

There was a recent post referring to the Balmar battery monitor. That one seems even easier since no shunt is required. I do it the old fashioned way and correlate voltage to state of charge. The biggest hog is the refrigerator. I use all LED lighting etc. Usually after a night on the hook I am down to 12.40 volts. This is about 80% state of charge.

 

[cutwater4me]

Thanks Red Raven and Knotflying for your replies. I put a Xantrex on my Nordhavn 43 and it was really useful especially because there were so many power hogs on that boat! I was not sure it would be that useful on my new CW28.
As I plan to be on the hook a fair amount, Curt's reply has helped me make the decision to install one on my new boat. I also agree, I don't need to measure voltage on a second battery-- I just need the state of charge on my two house batteries.

Thanks again for your feedback.


Kurt Antonius
Telesto
CW 28

 

[SGIDAVE]

Here is a review of the Balmar Smartguage. I've got one and like it. You would do yourself a favor to read through this before leaping into a LinkLite, etc.

It is arguably more accurate and much less fussy than the shunt-based Ah/coulomb-counter kind of monitors. Easier to set up too.

My endorsement is from the perspective of a satisfied customer and I have no material or other interest in Balmar.

/dave

 

[Red Raven]

For what it is worth here are the current draw numbers for systems on our boat.

Red Raven house batteries current draw:
All off = .5A - .8A
Cabin lights = .3A
Dining/Galley lights = .2A ea
Reading lights = .05A ea
Head Light = .05A
Anchor light = .1A
Cockpit lights = .8A
Stereo = .3A
TV = .5A
Refrigerator = 4A
Cockpit Freezer (we added this to the generator compartment as we have no generator) = 3A
Inverter (idle no load) = 1A
Microwave = 85A!
Water pump = 7A
Webasto heater fan = 1.3A
Chartplotter/GPS Radar Off = 1.5A
Chartplotter/GPS Radar On = 1.8A


I don't think you can get this information with the Balmar. I find I use the current measurement as much as SOC (State of Charge). The Balmar looks like it has some simplicity advantages though. I wasn't aware of the Balmar when I bought the Xantrex LinkLite. It was a recommendation from Capt Mac with Ranger Tugs.

 

[Hydraulicjump]

Thanks! This is a really useful list of amp draws. Are the lights LED? And of course, since the fridge and the freezer cycle a bunch, that draw has to be corrected for usage over time.

I have the Balmar and love it because it is simple to use and install and I am too lazy or stupid or both to track amp usage. I just want to know how much capacity I have left on the battery bank, and then use that as a guide to what I will do overnight on the hook.

One criticism of the Balmar, and their tech confirmed this. It does a good job of tracking the drawdown of battery capacity, but it does not do as precise a job at tracking charge. That is, I have noticed that it will commonly underestimate the state of charge after a short to moderate period of charging, whether by alternator or solar panel. So in this sense it tends to be real conservative.

If you like lots of precise information, get an amp monitor. If you are lazy but want to track battery usage to guide your activity, get the Balmar. If you are a gadget lover, get both!

 

[Red Raven]

Yes, I have the LED package as supplied from the factory.

Yes, you have to consider the use cycle to get an average for some of these items like the fridge and freezer. I haven't measured but they seem to cycle at about a 50% rate. I actually often turn the freezer off a night if we are planning to stay more than one night and everything is still well frozen in the morning so that saves power as well (of course it is fairly cool up here in the PNW so that may not work elsewhere!). The microwave draws a lot when it is running but the cycle time is so small it doesn't actually amount to much. Just don't leave your inverter on when you are not using it.

I thought the numbers may be useful to anyone that may not want to bother with adding a shunt based monitor. Put this list on your boat somewhere and keep the numbers in mind when you use the systems. Most of the Ranger Tugs and Cutwaters have similar systems.

Curt

 

[knotflying]

So explain something to me and I am not trying to be critical here. I am just trying to understand the value of a battery monitor. After 5 years of cruising I have a pretty good idea of how many amps I use while anchored out. And I also know what my voltage should be when I get up in the morning, hence my state of charge. Knowing in advance your typical amp consumption and amperage availability, in my opinion, is more valuable than knowing what it is after the fact by looking at a battery monitor display. I can see how having this information on a large vessel where many appliances and equipment could be turned on and off will be valuable. However, on such small boats with limited equipment I am trying to figure out if the cost and installation time can really make a difference in the grand scheme of things. As an example, I know what the microwave draws and I never use it on the hook unless I have the engine running at the same time.

 

[Red Raven]

Knotflying. I have several responses. Take your pick.

1) Agreed. Nothing here we wouldn't learn with experience. However, we didn't want to wait for 5 years (or even several trips!) to figure it all out. This is our first boat bigger than a 19 ft ski boat. When we got our tug we had no clue what our typical power consumption would be. I'm sure you could use your boat without half the electronics on the dash as well (maybe even none of it) :mrgreen: That is what experience brings. Doesn't mean the fancy stuff on the dash is not useful.

2) Our factory training captain who had made multiple trips to Alaska highly recommended it so we added it. Haven't had any issues and has been instrumental in learning our systems draw quickly.

3) I'm an engineer. :ugeek:

To each his own I guess.

Curt

 

[knotflying]

Red Raven,

Thanks for the insight.

 

[Red Raven]

I see it a lot like the fuel flow meter. Totally unnecessary but extremely useful. Without one you still know how much fuel is in the tank and based on usage experience you know how far you can go. With one it's all just easier and makes the learning faster.

 

[Cutwater28GG]

a side question. I have a cut28. how are you guys turning off the fridge/freezer specifically? As far as I can tell I dont have a dedicated switch - its just wired into the house batteries?

 

[SnugTug]

Cutwater28GG -

Our tugs have the fridge on a breaker on the main panel. I can't imagine that yours would not be as well (unless it's on a sub panel). Maybe the breaker on your panel isn't marked or is wired to a "Spare" breaker?