Battery monitor malfunctioning?

[John]

A month or so ago, I posted a question here regarding a Xantrex battery monitor that I'd installed and that I was unable to program. As it turned out, the product was defective and Xantrex sent me another one. I've installed it and it seemed to be functioning properly, but now there seems to be a new issue:

The monitor registered negative amp hours about a week ago. My understanding is that this means that amp hours have been drawn out of the batteries being monitored. I thought it was some drain on the batteries that I was unaware of, so I hooked up the shore power and left it connected for almost a week. (The batteries and even the bilge pump were turned off.) When I returned (this morning) it was still showing -20.3 ah. It registered that the shore power was charging. It also registered an amp draw when I turned on some accessories and turned off the shore power and then registered charging when I turned the shore power back on.

I'm going to recheck it tomorrow. When I arrived at the boat this morning, it was showing -20.3 ah. (I don't remember exactly what it was showing when I first hooked up the shore power.) If it's showing the same tomorrow, I'll suspect that this unit is defective also. Do people agree? It just seems too unlikely that two of these units would be defective, although this problem is different from the previous one.

 

[blue noser]

John,

sounds to me like maybe a polarity problem, hence the negative number, check that, or reverse and see if it says +20 or so, there amp hours are there as there is no such thing as -20 its an absolute number, not sure but hope this helps

bn, ps if it works send me an email, would love to know

 

[Bryce22345]

John
there's a function on the monitor to reset the AH's. once the bank is fully charged, initiate the AH reset function and you should be good to go. until its calibrated the monitor doesn't really know where its at in the discharge cycle.

 

[sailingdog]

I believe Bryce is correct.. you probably have the "zero" point for the bank capacity set wrong..

 

[Stu Jackson]

Link 1000

John,

I suggest that you recalibrate the unit. Remember, the instructions require you to start it with FULL batteries. Re-read the instruction manual, charge your bank up completely (may take overnight) and when you're sure the bank is full, regardless of what the Link says, recalibrate it by dumping the power by removing the power fuse, or just reintialize it like the manual says, and start all over again. It is NOT a polarity issue, if it was, you'd have popped fuses.

Also, now that your "new" unit allows you access to the function things that the old one didn't, get into the functions and make sure you set them properly, including house bank size and Peukert's equation settings, usually 1.25, for the bank.

Also, remember that the recalculation of the amp hours being put in only occurs after the first six or so discharges, so consider this: (also described on page 43 of the manual...also see page 44 Synchronizing the Link)

1. charge bank fully (forget about Link for time being, leave it where it is)
2. reset Link
3. deliberately discharge the bank, by, say leaving lights on and UNPLUGGED from shorepower for a day or (you can get to the boat every other day, can't you?)
4. Recharge the bank, might take an overnight on shorepower because the last 10% of amps take a looong time to put back.

I learned this from long discussions with Donlex and Rich way back when I put our Link 2000 in. You could do a search on Link 2000 with my name on them and find those threads (like this one: http://forums.catalina.sailboatowners.com/showthread.php?p=537006). I may have given you that written material by email, too.

5. Do 3 over again five or six time until the Link "learns" the system -- you can do this by going out sailing, too!!!

See page 21 (29 of 74 in the pdf file) of the manual: Resetting Values, plus check the initial setup instructions.

 

[John]

Just returned from the boat and...

and what I found was that the monitor now showed -23.5 (vs. previous -20.3). It also showed -.1 amps, in other words a net discharge, despite the fact that my Xantrex 20 charger/inverter showed it was functioning and the AC switch light was on. What I realized was that yesterday I'd switched the Link 20 from the setting bulk/absorption/flood to bulk/absorption (because I'm charging to agm batteries). When I switched it back to the former setting, the monitor immediately showed that the batteries were being charged.

Anyway, I mention all of this because some other novice out there might learn from my mistake.

I will see in a day or so what the monitor shows as far as amp hours.

I also have another question: Which temperature should the charger be set at in my area (SF Bay)? There are three options - cold, warm and hot. I have it set for warm, which also shows 14.3/13.4 for agm. I assume this means the voltage. Is this correct?

I will follow Stu's suggestions and let you know what's happened.

Thanks for the responses. (I also don't think it's a problem of polarity because if it were, then it seems to me that the monitor would not show amp charging and discharging correctly.)

John

 

[Stu Jackson]

John, why are you not using float? Even for AGMs, I would think bulk/absorption being plugged in all week would not be good for the batteries. Check the manual again, and look for the AGM settings.

The manual also discusses the range of temperatures. Our water's 57 degrees year round, and 70 inside the boat if we're lucky. I'd use the middle setting, which I do with our Link.

That said:

HOWEVER, your Link does NOTHING in that regard for either charging or temperature, BECAUSE it DOESN'T control your Truecharge charger. A link will ONLY control a Freedom charger.

All you have is a battery monitor. Think about it...

Warm on the Truecharge is correct.

 

[Stu Jackson]

Parasitic Loads from Link 1000

You mentioned the (minus) 20.6 AH reading.

Parasitic load is what the Links impose on the system.

The manual says 90 ma, so figure 0.1 A when everything is off. You didn't say how long you hadn't been to the boat, but let's say seven days.

0.1 amps times 24 hours = 2.4 AH per day times seven days = MINUS 16.8 AH.

So, you have to DO THE MATH.

Simply sounds like your batteries weren't completely fully charged when you left and a week's worth of parasitic load was not to be unexpected.

You also mentioned Link 20, I thought you had a Link 1000.

 

[John]

correct, and...

Stu is correct, I have the Truecharge 20 inverter/charger and the Link 1000 monitor. I apologize for that confusion.

As to his other question: I had the dock cord plugged in and the battery being charged for the last week. Despite this, it still showed -20.3 ah. Just to repeat: It had been charging for about a week and still the battery was down. It also didn't read that it was charging, according to the monitor although the charger/inverter's lights were on and the ac main light was on.

One of the switches on the Truecharge inverter/charger has three settings:
(1)bulk/absorption/flood; (2)bulk/absorption; and (3) (I forget exactly what it says, but it shows also 13.5, which I assume is the voltage.) I originally had it set on #2. When I switched it to #1 it the monitor showed that it was charging and within five minutes the ah went from -20.3 to -20.2.

As for the temperature settings, I have it on the middle one. I assume that this would be the correct one in our area.

 

[Stu Jackson]

John, it really sounds like it's not recalculating. Suggest recalibration as discussed earlier in reply #5.

I don't know how your boat is wired, but are you SURE that the charger works when your A.C. panel is shut off? You can easily check that with the Link by checking the battery voltage. If you switch your A.C. panel off and the charger runs through there, then it ain't gonna be charging all week, even if you're plugged in.:cry:

One of the switches on the Truecharge inverter/charger has three settings:
(1)bulk/absorption/flood; (2)bulk/absorption; and (3) (I forget exactly what it says, but it shows also 13.5, which I assume is the voltage.) I originally had it set on #2. When I switched it to #1 it the monitor showed that it was charging and within five minutes the ah went from -20.3 to -20.2.

The reason for that is that in position #2 (corrected later) the charger STOPS charging at the end of the absorption cycle and will NOT trip to float. By stop, it turns OFF. This is stated as ONE HOUR at this rate in Appendix B of the manual. Only you can determine how you want to charge your batteries, but the best information I've received is to charge the batteries FULLY and then take them off float, and that they will decay more quickly if left undercharged.

I'd set it at the three stage charge. The third position is constant 13.5V and you do NOT want that, chronic undercharging will result.

So, come back to the dock at minus 20 or 30 ah, charge overnight INCLUDING float til the Link says 0, then unplug.

You will never fully charge them in position #2.

That's what I think is happening.

 

[John]

AC

Stu:

I think you misunderstood me. I'd written that it was not showing a charge despite the fact that the AC main was on and the light was on. You are right about the fact that it won't charge if the AC main is off. In fact, this was something you showed me the time you came to my boat; I hadn't known that before. (In fact, it may also be the reason that my previous batteries died, after I'd thought I'd been charging them!)

The monitor wasn't showing a charge until I reset the switch on the charger/inverter to "bulk/absorption/flood" (from "bulk/absorption"). I'll go back there tomorrow and see what the state of the batteries is.

 

[Stu Jackson]

Then that's what happened John. By turning the TrueCharge to position #2, bulk/absorption ONLY, you effectively had it turn itself off after an hour or two!

Dare I say itredface, because I rarely do it myself, but re-READ the manual, including the Appendices.

I've found it helpful, because, for instance, our link, like yours, has so many features, that I can't remember them all, so I keep the important manuals on board and reread them. Just last week, on the hook at Clipper Cove, I re-read the regulator manual, and came up with a good idea for alternator charging. See: http://c34.org/bbs/index.php?topic=4454.0 both pages of the thread.

Good news? Looks like you found the answer without having any gremlins - operator error is a surefire answer to most of MY problems.:Liar:

 

[John]

The latest

I went down to the boat this morning. Everything was left plugged in with the AC main on. It showed -22.8 amp hours, which was more than it had been a few days ago (-20.3 I think it was). It also showed -0.1 amps, meaning that it wasn't charging. I want to emphasize: All of the last few days the AC main had been on and the AC main light was on. I turned off the AC main and ran a few accessories. The monitor then showed -22.9 ah. I then turned back on the ac main and the monitor showed that it was charging. However, the strange thing was this: Despite the fact that the monitor showed a positive charge (when set to amps), when the select switch was changed to time remaining, it showed 255. When the batteries are being charged, this display is supposed to show "ccc".

 

[Stu Jackson]

What did you do with the charger

switch?

 

[John]

It could be the switch. I did notice the last time that the AC main light (showing the AC main is on) was flickering a little bit. I'm not sure if it was doing that before. Maybe that switch is bad?

 

[Stu Jackson]

More forensics required

We'll need to check some voltages at different positions when you get back. Have you re-calibrated the Link? It seems as if you've corrected the switch position on the Truecharge to the three stage setting -- is that correct? Are you absolutely sure you wired everything properly to the shunt?

 

[Bill Roosa]

A couple of things

since there are some odd things going on and i really don't get the whole story you and Stu are discussing.
FWIW
Battery chargers are not always charging. they can be on and waiting for the battery voltage to drop to a "begin charging" level. my true charge is like this once the batteries are charged. it cycles on and off even though it is "on" on the panel. This could be your mysterious discharge even though the charger is on problem
The monitor clearly is reporting incorrectly. if there where even 50% of the AH in the battery showing as a positive you would know it from the less than 11 volts they where putting out. if it shows negative AH and a good battery 13.6 voltage then the unit just needs it's "batteries fully charged" memory reset to "Batteries full"

I'd use the rational man method to diagnose this BTW.
unplug from shore power
turn on various things and see if the monitor accurately shows the current being withdrawn from the battery and the changing voltages.
find one load that has a nice round number of amps greater than 2 amps and leave it on for an hour. Read the monitor AH before and after. does it show the correct reduction in AH (load amps * 1 hour = AH taken from the battery)?
turn off the DC main and pull the fuse on the bilge pump and other "always hot" items like stereos. Connect to shore power and turn on the battery charger. Since the batteries have been discharged a bit the charger should come on as noted by a sudden (in 5 sec) rise in battery voltage. my true charge takes about 15 seconds after being turned on to sense the battery voltage and decide to turn on or not so be patient.
Does the monitor show the correct battery voltage?
Does it show the correct amps going into the battery?
Does it show AH increasing. Remember when you add to a negative number the value of the number gets smaller till you reach 0 then things act normal again.

 

[Stu Jackson]

John, Bill's post is a very good systemic

checklist of what we've been discussing. It's a great step-by-step approach to checking the compnents of the system.

 

[John]

Summary & latest

Okay, here's a summary of what has happened, so far:

I left the shore power connected and the AC main on. After a week, the ah showed a negative number ( slightly over 20). I double checked this a few days later and the number was a greater negative. I reset the inverter to the float mode. I turned on some appliances and looked at what happened. The monitor showed an increase in the negative amps (more battery discharges). Also, the hours left did not register that the battery was being charged. (It's supposed to show "ccc" when the battery is being charged, but it didn't show that.)

Today, I went down to the boat and it showed -22.8 ah and the hours left ("h") didn't display "ccc" as it should. So what I did: I cranked up the motor. At that point, the amps showed around 1 (not -1 - in other words it was showing positive). With the motor running, I fiddled with the AC switch as well as the breaker (a push button) for the charger. The "h" showed "ccc" - in other words, it displayed that the battery was being charged. I left the motor running about 20 minutes. After that time, the monitor displayed -20.6; in other words, it had charged the batter .2 amps worth. Then I killed the motor. It showed it was charging the battery at a rate of about .2 amps and the "h" displayed "ccc".

From all of these symptoms, it seems to me that something is wrong with the AC main switch or maybe the breaker. I'm leaving town for 10 days, and when I get back I'll look into this mystery a little more. If, in the meantime, it rains buckets, the bilge pump runs the batteries dead and the boat sinks, then you will hear me crying all the way back in Maine and Florida!