I received email correspondence from one of our C34 IA members about this topic.
He wrote: “I am curious about setting up my Link Lite based on this algorithm message board topic. Normal weekend is: hook up electric when I arrive Friday night, charge overnight. Disconnect, sail for the day. 80% of the time anchor overnight. Return by mid afternoon on Sunday, hook up to shore power. 50% of the time it is on over night, the other half it is charged 3-4 hours while I pack up. The fridge is first on, last off DC appliance. It will be interesting to now be able to monitor what is really going on. Anyway, based on this how should I set up the Link Lite? Data and questions are
on the attached Link Lite Set up Instructions.”
This reply includes the Link Lite instructions from the manual, with specific questions and responses on a few of the Function settings that control these important measurements for the Link to measure battery bank “refills.” Please note that some of this covers differences between the Link 2000 model and the Link Lite. They both use the same algorithm but the Link 2000 has a third feature, the ability to manually change the recharge efficiency factor, which it appears the Link Lite does not. This is NOT a concern for changing the other two parameters (float voltage and % of current) to avoid the “gotcha” issue.
F01 Battery capacity. Your Main battery's capacity in Amphours (Ah). Default: 200Ah Range: 20 – 999Ah Step size: 1Ah
4 Sam’s golf cart total of 420 amp hours @12V. Should I set F01 to 420 or 400 to give some cushion on 50% discharge?
The is NO need for any cushion. Why confuse things? The Link is doing all the work in the calculations and should be set up with your actual bank size. The step size is in 1 ah increments, so you should use what you actually have installed: 420 in your case, mine is 360. Our Link 2000 goes in 20 ah increments, so 400 and 420 are available, but use the right figure for each of your banks. Since the ah capacity is used in the "full" measurement in the algorithm (the default 2% of battery capacity) using the right number is the right thing to do, even if you do change the % default value as recommended.
F02 Charger's float voltage (Auto-sync parameter). This value must be equal to your battery charger's float voltage. which is the last stage of the charging process. In this stage the battery is considered full. Default: 13.2V Range: 8.0V – 33.0V Step size: 0.1V
According to the TrueCharge 20 face plate this should be 13.5v for flooded, warm setting. Are you saying this should be 15v?
Yes, that is correct. The Link Lite float voltage setting is ONE of the TWO parameters that are used to calculate “FULL” and Rich recommends that BOTH should be changed and that this float voltage default should be RAISED significantly to avoid the “gotcha” issue. The TrueCharge 20 panel says the wet cell float voltage for “warm” is 13.5V, and the float voltage is higher and lower for “cold” and “hot” conditions. Regardless of this small difference in float voltage settings for the charger, if you do NOT change the Link float voltage setting that is used for calculating the “FULL” bank, the “gotcha” starts interfering with the “real full” bank. The algorithm uses this float voltage and the “default” 2% current of house bank capacity to calculate “full” which is the “gotcha” issue that shows a “full” bank when it really is NOT. The Link will say “full” only when BOTH of the TWO parameters (float voltage AND percentage of charge) are met for the specified time period, at the SAME TIME and not simply when it goes to float on the charger.
Also, this particular statement in the manual is plainly INCORRECT: "In this stage the battery is considered full." [Ed.-] Float is NOT necessarily completely full, it's just the last stage of charging. The statement may be somewhat misleading to skippers who are new to electrical system issues, but most of you know that already... Once the charger kicks into float, there may be many hours left to fully recharge the bank, covered in the acceptance topic on this Message Board (a hyperlink to that thread is provided below).
[Added July 14, 2009] Another reason why I say "float is NOT full" is because of this Gotcha itself. In the first post on this topic above, I noted that since our Link 2000 controls our Freedom I/C the charger would go into float almost immediately after only a daysail. So, while it looked like the bank was full, it certainly wasn't. So, unless you UNDERSTAND the way the Link algorithms work, you'll be being fooled that the batteries are charged when either the Link says FULL and you manually turn off your charger, or your Link 2000 is controlling your charger on your Freedom and it switches to float. For those of us who don't leave our boats plugged in all the time, this can be very misleading, since if the Link says full or the charger goes to float, the bank must be full, right? Wrong! The reason? Simple, if you follow the logic of the algorithm's switch to FLOAT: there's STILL that pesky 2% left to top up the replaced amps. Right?
F03 Charger's float current (Auto-sync parameter). When the charge current is below this percentage of the battery capacity (see Function F01), the battery will be considered as fully charged. Make sure this Function value is always greater than the minimum current at which the charger maintains the battery or stops charging. Default: 2.0% Range: 0.5 – 10.0% Step size: 0.1%
Default is 2.0%, should this be set to 1.0%?
Yes, this is what Rich & Donalex both recommended and is the SECOND of the TWO parameters that are used to calculate “FULL”. It appears that your Link Lite does not have a feature that my Link 2000 has (and Rich’s Link 20), which is the ability to ALSO reset yet a THIRD feature which is changing the “recharge efficiency factor TO manual of 0.94 instead of the automatic setting of 0.95. This will stop the automatic recalculation and fix the recharge efficiency to be 0.94.” If you don’t have that the ability to manually change the recharge efficiency factor on your Link Lite, you obviously can’t make the change. Check the rest of the manual to see if it does or not. If it doesn’t, it should be no problem since, first , you simply can’t change it, and second, at least you now know how the Link Lite works to calculate “full” with the first TWO of the parameters.
What I found is that once you start using the Link you’ll get more comfortable with it. It’s a matter of “trust & understanding,” so what you’re changing are the two parameters you do have on your unit for the “full” calc, and it’s either always using what’s built in (recharge efficiency factor), or it’s changing/recalculating it like described in the first Message Board thread on this topic. That doesn’t matter if you change the two parameters that you can change because the Link won’t be incorrectly reporting full anymore.
Your experience with the way you charge, as you’ve described, is a GREAT application for the Link, since you’ll be able to see what the effects of how your operation and timing of being plugged in will get you. The first post on the acceptance topic [http://c34.org/bbs/index.php/topic,4787.0.html
] will be exactly what you’ll see when you get home and plug back in.
Please let us know what you learn from your new Link. I think you’ll find out much more now that you have your Link as to what you’re really able to put back into your house bank in your charging scenario of “50% of the time it is on over night, the other half it is charged 3-4 hours while I pack up.“ What you might want to consider is turning off your fridge first, because it’s gonna stay cold for hours anyway and then its cycling on and off will eliminate its impact on the recalculation of the Link after you plug in when you return. It shouldn’t matter if you reset the parameters as discussed here.
Your sailing experiences are much like ours and others, and will exhibit house bank discharge in the range of 20 AH for a daysail and 80-100 AH when a night on the hook is involved. By the time you get back to your dock, your house bank is either in the 80% discharge area or below that in the 50% - 80% range (the simple daysails compared to anchoring makes the difference; these percentages are based on a nominal 400 AH bank; with a smaller bank the %s will be different and higher), however, in all cases that last 20% takes a lot to put back. There was a thread where I discussed this, see reply #4 in the excessive alternator heat post [http://c34.org/bbs/index.php/topic,4454.0.html
] as well as the acceptance topic noted above.
It’s when you’re trying to minimize charging time, like with generators or the engine alternator ONLY, like Rich uses on his mooring, that this really becomes a really critical issue. It is also similar to your “limited” recharging time because you unplug when you leave the boat. It’s also pretty much what each of us faces when we return from a daysail or a night out at anchor and we do not want to leave the boat plugged in all the time. For those of you who do leave the boat plugged in, the “gotcha” issue is also important, because you want to be able to depend on the validity of the Link to really tell you the bank is full. That’s why I posted this topic in the first place. Without these changes, eventually the Link will be fooling you sooner or later that the bank is full when it’s not. This will require recalibration or reset of the unit unless you make these recommended changes to the default settings.
The approach is to recognize that the issue is not necessarily only how you use your boat in terms of how and to what level you end up discharging your house bank. It is, rather, more important to recognize what condition the batteries are in after a discharge when you do have an opportunity to recharge, and that knowing and trusting that “full” on the Link meter is actually representing a “full” bank. “How the Link Algorithm Works” is the purpose of this discussion topic. SUMMARY
The “GOTCHA” Fix: "The fix for this is to reset these two of the Link 20 parameters to 15v and 1%." What does the 15v represent?”
Answer: The reset to the 15V represents ONE of the two factors that the unit uses for measuring full, the other being the % of current. If the Link default of 13.2 V and your charger are BOTH almost exactly the same float voltage, when your charger goes into float AND the 2% calc are also met at the same time for the specified period, the Link will say “I’M FULL!!!” even when the banks are not. The way this happens was explained in the first post on this topic.
We are simply suggesting changing BOTH parameters so “it won’t get fooled again.” Resetting the Link float from the default 13.2 V will work because it’s higher than your actual charger float voltage. The charger float current percentage of the battery capacity is changeable in 0.1% increments so changing from 2.0% to 1.0% is easy. Mathematically and “algorithmically” you could theoretically change only one of the two parameters and it would/should/could suffice, since the combination of the two parameters would never be met anyway. I recommend that you change both.
Remember, if these modifications are not performed, the Link units will incorrectly report full batteries and you will be in an undercharged condition which is bad for the life of your expensive batteries.
Please also note that for those of you who have Freedom-series combination inverter chargers AND Link 1000 or 2000 units, this "full" charge Link measurement also kicks the charger function to float, because the Link is controlling the charger. The Link and the charger are connected by a telephone cable. It then becomes a very critical issue for "timely" charging, 'cuz if the Link kicks the charger into float too soon it'll take a long time to recharge your bank.
Those of you with "separate" Links and chargers where the Link does not control the charger function, simply do this visually by looking at the Link and controlling your chargers manually.
There are three very important issues with boat electrical systems:
1. A good design and installation
2. A healthy charging system with alternator(s), shorepower and other means
3. A battery monitor that you understand, and that you know how it works.
For years, this and other message boards have been suggesting that one of the FIRST and BEST things you can and should do is buy and install a battery monitor.
My personal experience was the opposite, and I now regret not installing my Link when I first bought it way back in 1998!
Buy a battery monitor, and understand how it works and you will avoid undercharging your batteries, extend their life, and enjoy your cruising more by having a working, capable and trustworthy electrical system to support all of your electrical "appliances."