Xanthrex Remote Control - Battery Monitor?

[shemandr]

I am about ready to order a battery monitor but have a question about my Xantrex remote control. Is it a battery monitor? Between it and the needle gauges which selectively measure volts and amps flowing in or out, in each battery, I have information about voltage and amperes going in or out of the battery. What is the difference?
I'm not complaining about the expense of buying the monitor. I would just like to understand the difference.

 

[Stu Jackson]

Andrew,

Simple. The monitor counts the amps laving and coming back in. Do you really sit at your ammeter and keep track?

That's what they do. And most of us are pretty good at figuring out what comes OUT of our batteries (energy budgets are pretty simple) but it's what goes back IN that's harder to measure because of battery ACCEPTANCE, where the last 20% of charging goes slower, and slower and slower as time goes by.

The Xantrex charger remote panel only tells you what the charger is doing. Voltage alone is not a good battery condition and SOC indicator, as Maine Sail has discussed many, many times.

Here's a discussion on battery acceptance:

We've had some discussions about battery acceptance (search on "acceptance") in the past. I thought it might be helpful to describe just what happens, step-by-step when charging after, say, a simple day sail.

The battery acceptance drops off the ability to recharge, to an incredibly low rate of charge as the bank gets fuller and nearest to full. Many times, now based on my Link 2000 experiences, it takes almost overnight to fully recharge a bank.

What goes OUT of your house bank becomes easy to learn from the Energy Budget previously discussed and posted. It's what goes back IN that most people are missing, and relates to the state of charge of your house bank in a very direct manner.

What I've seen, for example is this, from our Link 2000:

--- Return from a day sail, bank is down 15 amp hours, plug into shore power with our 75 amp charger, batteries will only ACCEPT 15 amps (360 AH house bank, they're pretty fully charged if only 15 ah down)

--- Most people will then assume that it will take an hour to replace the 15 amp hours at 15 amps of charge

--- NOT!

--- As the batteries absorb that 15 amp charge, they get fuller

--- The charge RATE goes down to 10 amps after 15 or 20 minutes and the bank is now down to 10 amp hours down

--- Now, it should only take another hour to charge those minus 10 amp hours at 10 amps -- wrong assumption again; we're now up to an hour and twenty minutes to fully charge, right?

--- NOT again, because this keeps recurring

That's why a full charge takes a LOT longer that most people expect.

What goes OUT is easy, what goes BACK takes MUCH, MUCH longer. That last 15% to 20% takes a long time because of the REALITY of battery acceptance.

Please believe me, folks, because I see this all the time now that I have the Link 200 installed and working.

Please note that this true with alternators as well as shorepower chargers. Battery acceptance usually "rules" the charging regimen, so even with 100A alternators or shorepower chargers in excess of 40 A, the battery acceptance will determine the amount of charge that can go back into a house bank, usually around a max of 50A for a 400 ah bank. And it "tapers off" as the bank gets fuller as noted above.

This is why people say the BEST investment for un-knowledgeable and knowledgeable skippers alike is to buy a battery monitor FIRST. Wish I did, because I'd been chronically UNDERCHARGING my house bank, even after all the spouting I do here and on other forums!

Please, believe it!

 

[Stu Jackson]

And when you get your monitor, Andrew, read this, the Gotcha Factor for the monitor algorithms:

http://c34.org/bbs/index.php/topic,4922.0.html

Any questions, please let me know.

Stu

 

[Ed Schenck]

That was quite a dissertation Stu. And appreciated. Along with that I was excited to be able to really watch the amps get doled out. Before my Link 2000 I just had that little bar graph on the Freedom 20 remote. First thing I did was make a chart of all my electrical and electronics. This really helped me understand my requirements. And yes, I could have done that with a cheap digital ammeter. Then there is the ability to set your house bank's amp-hours so that you can see what Stu is talking about, the State-Of-Charge. But could I have sailed to Florida over a period of several months with just the original controller? Absolutely and nothing would have changed. I would have watched the voltage and charged accordingly.

 

[shemandr]

Got it. And I'll place that order.
Stu - I've read the gotcha threads. I need to review those - I remember that it was something about setting charging regimens. Oh yeah, that the sensing capability of the charger resets itself before the battery is charged fully - or something like that.
I am really endebted to this forum and especially the very knowledgeable participants who have increased my understanding of these issues beyond measure. Sometimes you even save me money.

 

[DAVA390]

As a rookie with a small boat, I am loving all of these discussions this winter.Unfortunately, all my money savings may be because you all are scaring me off getting a bigger and more complicated boat.

 

[seadaddler]

Freedom Remote

I think my freedom 20 remote gives what needed info I need like when my house bank is low and when inverter is being used it shows me how much of my house bank is being used and gives me info when I need to start the charge mode and how much the house bank is being charged also.
I don't think I really need to spend $$$$ for another battery monitor.
Nick

 

[Stu Jackson]

I think my freedom 20 remote gives what needed info I need like when my house bank is low and when inverter is being used it shows me how much of my house bank is being used and gives me info when I need to start the charge mode and how much the house bank is being charged also.
I don't think I really need to spend $$$$ for another battery monitor.
Nick

Nick,

I disagree, and so does Maine Sail and lotsa other people.

Regardless of what Andrew says, I love to spend other people's money!!!

But seriously, the instrumentation you have is adequate if you know exactly what you're doing.

But MOST people will say that in the 21st Century, it would be helpful to have one.

Why?

'Cuz as I said in the long post above, most folks have no idea of how much they are UNDERCHARGING their house banks.

ONLY a battery monitor will tell you that.

Can you still drive around with a 1990 electrical system? Sure. Ed said so and I believe him.

But since it's available, the real trick is this: The $$ you spend on a battery monitor will be saved almost immediately by lengthening the life of you batteries. A one year payback is a pretty good deal to me.

Been there, done that. In fact, i waited eight years to install my Link 2000 and it was the dumbest wait for anything I ever did - I even had the equipment, just didn't install it.

Just my 2 cents.

 

[Bob 04 H260]

Stu with all respect I'm afraid I don't see the logic here.

Does the battery monitor tell you how long it will take the battery to be fully charged ?

A battery monitor is nice to have and interesting to check out but really as you said if you have a 40 amp smart charger and it is pumping 35 amps into your battery you know it is very low and needs to remain on for some time, if it is only running 10 amps into the battery it is almost charged. When you get down to an amp or so the battery bank is charged. You have no way to change that with a monitor.

The flow of current going into the battery is telling you the state of charge of the battery, just like a monitor does.

With a bit of experience on your boat you know when it is drawing 10 amps out of the charger it will take another 6 hrs (or what ever) to charge this bank.

So while I might add one to my boat at some point I do not see that it will give any information I can't get reading my Blue Sea digtal volt/amp meter and the panel on my Xantrex charger and appling my experience with the boat. The same way I will do it if I add a battery monitor.

I think the most important thing is to fully recharge your batteries and keep a trickle charge on them after that. Having a smart charger at the dock and a solar panel when away from the dock are the tools to do that.

Just my experience with these tools, Bob