How to set up your charging system

[Guest]

The voltage regulator and battery monitor are shipped from the factory with their default settings. These are not optimal for battery life, engine running time, or peace-of-mind. Here is how to set them up.

DISCLAIMER
The following is provided for your information. Author believes it to be correct, but assumes no liability for errors or omissions.

CAUTIONS
1) This information is correct for standard equipment as of US Hull #149. TPI/Pearson Composites and J/Composites change vendors and specs from time to time during a production run. Make sure to check this against the faceplates on actually installed equipment and owners manuals shipped with your boat.

2) If you are not reasonably familiar with marine electrical systems or do not feel comfortable with any of the steps described below, consult your commissioning yard.

Background
The standard batteries for the J/109 (at least US production as of Fall 2003) are Sonnenschein Power-Tech 8A31DT Absorbed Glass Mat (AGM), with a 20 hour rating of 105 AH. There are two banks (starting and house) on a standard boat, and three banks (two house banks wired in parallel) on a boat with optional factory installed electric refrigeration.

In short, AGMs are different in construction from conventional flooded cell and gelled electrolyte batteries. They use a valve regulated lead-acid technology, which means that rather than venting to the atmosphere, hydrogen and oxygen recombine during charging. The case is therefore sealed except during extreme overcharging. The plates are interleaved with a fiberglass mat, which is saturated with electrolyte. The plates and mats are tightly packed; as a result, the batteries are vibration resistant, and have relatively low internal resistance. This leads to reduced charging time, higher terminal voltage under load, and cooler operation under load. However, they are sensitive to undercharging, and must be recharged to 100% capacity after every discharge cycle or their longevity will be affected. For further information on care and feeding of AGMs, see the article by Steve D'Antonio in the November/December 2004 issue of Ocean Navigator.

The J/109 comes with a sophisticated external regulator and battery monitor. These need to be programmed with settings appropriate to the batteries. Once this is done, batteries will charge rapidly and fully, extending their lives. Also, it will be fairly easy to know how long to run your engine for charging, know when you need to re-charge, keep an eye on on-board power consumption.

Programming the Regulator
The Xantrex (ex-Heart Interface) Digital Alternator Regulator (XAR), which is standard on the J/109 (at least as of Fall 2003 US production), comes factory programmed for universal operation. This is a "safe" setting if the battery type is unknown. However, bulk voltage and absorbtion voltage are .3V lower than recommended for AGMs.

The regulator is located under the quarterberth, on the bulkhead facing the saildrive. You will need to remove the cushions and plywood cover. A flashlight (electric torch) and inspection mirror will be helpful. You'll also need the magnetic screwdriver provided by Xantrex. Following instructions in the XAR owners manual, have a helper turn ignition key on, but do not start engine; ignore the engine alarm. Hold the magnet against the magnetic reed switch in the lower aft quarter of the XAR. The #5 amber LED (the one in the middle of the status array) will illuminate and the #6 red above it will flash. Hold until the red stops flashing and the #7 amber illuminates. Continue to hold as the program selection cycles until all four green LEDs are illuminated, indicating that Program 4 (AGM) has been activated. Then move the magnet away. The instructions also describe what to do if you cycle to the wrong program. When the #7 (second from the top) amber LED flashes, the program has been saved.

The XAR will now bulk charge at 14.4V, absorbtion charge at 14.2V, and float at 13.4V. You will notice the alternator driving at 80A or more immediately after the regulator has ramped up (105 seconds after the engine starts). If the battery banks have been lightly discharged, a short motor out of the harbor will now be enough to recharge to near full capacity.

As an aside, the XAR's optional battery temperature sensor is not standard equipment on the J/109. Aftermarket installation may be a good idea, especially if you sail in the tropics.

Programming the DC Monitor
As of fall 2003 production, a BEP Marine 600 DCM2 DC Monitor was standard on US boats. Programming should be done with all battery banks fully charged, preferably by a smart shore powered charger, left on overnight. To start programming, hold down the V and C buttons simultaniously until the EXIT/RESET/SETUP display appears (3 seconds). Then release and press C to enter setup mode. Then (using the V = up, A = down, C = enter buttons as described in the manual, set the monitor up as follows:

Set Alarm: your preference. It can be irritating at 0330, but not as much as flat batteries.

Battery 1 label:
Battery 2 label: Bank 1 is the nominal engine bank. Bank 2 is the nominal house bank. Bank 2 is also paralleled with Bank 3 on boats with factory refrigeration. It would be a good idea to check the battery connections with a meter.

High Voltage Alarms: Terminal voltage should never exceed 15.0V.

Low Voltage Alarms: Terminal voltage should never get below 11.8V, at which time it is fully discharged.

Low Amp Hours Alarm: Batteries shouldn't be permitted to get much below 50% of charge. If you leave your battery selector at "Both" while not charging, this would be 150 or 160 AH for a 3-bank (factory refrigeration) boat, 110 or 100 AH for a 2-bank boat. If you keep the starting bank isolated while discharging, use 100 or 100 AH for a 3-bank boat, 50 AH for a 2-bank boat.

Actual Capacity: Make sure to set up when batteries are fully charged. Use 210 AH for a 2-bank boat, 310 AH for a 3-bank boat.

Maximum Capacity: Same as Actual Capacity when all banks are fully charged.

Amp Hour Capacity Reset Voltage: 13.4 V
Amp Hour Capacity Reset Amps: 9 for 2-bank boat, 12 for 3-bank boat (monitor considers battery to be full when regulator has been at float for 5 minutes, and drawing less than 4% of bank capacity; these settings may be a bit too high).

Charge Efficiency: This is a fudge factor used by the monitor, and really isn't related to specs provided by the battery manufacturer. .90 is recommended for gel cells. This also seems reasonable for AGMs, although it might be a little low.

Peukert's Exponent: This constant mathematically relates discharge rate to remaining capacity. See the BEP manual for a brief explanation. The manual suggests a science experiment involving completely discharging the batteries twice; I do not recommend doing this. Using manufacturer's data for 20 hour and reserve capacity, the calculated value of Peukert's Exponent is: 1.18.

Voltage Calibration: Should not need to be changed. If you're paranoid, you may want to get a good digital voltmeter and check the battery voltage against that shown on the BEP.

Amp calibration: Best not to mess with this.

Reset Capacity: Do this when the batteries are all fully charged (ideally from shore power, overnight).

If your boat has a different DC Monitor, some of this information may still be helpful.





[Posted by: Dan Grossman
]

[nc_109_driver]

Dan, have noticed that when I am plugged into shore I see the "usage" swing to the positive side on my monitor. And my capacity goes up slowly to 100%.

But when I am motoring I do not see this. Just what I am using. Get the feeling I am charging since if I get back to the dock and re-plug into the dock the meter immediately goes to 100% charge.

Any insight into a possible issue?

[Guest]

Craig,
Dunno. Is this a recent problem, or has it always been that way? If it's recent, has there been electrical work done on your boat?

If you set the meter to read voltage, does the voltage increase from maybe 12.2 V to 14.3 V about a minute after you start the engine? If so, the alternator is definitely charging the battery. In that case, my first guess would be a wiring error of some sort. Perhaps the alternator is connected to the shunt backward?

If you're unfamiliar enough to be asking advice, I'd recommend having a pro look at it.

Dan

[Posted by: Dan Grossman
]

[nc_109_driver]

So we get 14+ volts on the meter when the engine is running. But, the meters amps window does not show a positive number going in as I would expect. Saturday we had 93% showing when we motored in. Still had 93% when we shut-off the engine. When we turned the battery charger on it took 2 minutes to register 100%. Not likely the battery charger offered anything other than getting the meter to display the right info.

Ah, modern technology.

[Guest]

Sounds like the meter isn't seeing current flow from the alternator across the shunt, or it's seeing it backward. Possibly a wiring problem, like maybe the alternator to ground connection across the shunt is backward or missing?

[Posted by: Dan Grossman
]

[falletti]

We managed to cook the house batteries on a delivery from ME to VA. The optional temperature sensor cable (Alternator Temperature Sensor, 54"L [too short, must be extended], West Marine #128244, MFG Part# MC-TS-A, $37.99) goes from a battery teminal to the XAR Digital Alternator Regulator, and controlls charging current from the engine's alternator. AGMs (Sealed Lead Acid) batteries vent when overcharged (bulging case and battery too hot to touch), resulting in permanent loss of electrolyte (i.e., dead batteries, many $$). Unfortunately, the shore power battery charger does not have a temperature sensor option, and it also will overcharge and kill batteries if left on for a week at the pier.

[falletti]

Update: (1) There is temperature sensor sold by West Marine which is the correct length. West Marine #128251, Balmar #MC-TS-B, which is still listed as 20" in the online catalog, but is actually much longer, maybe 20'. (2) The battery chargers will over heat and finish off a weak AGM battery, as the battery never reaches the charger shutoff voltage. The chargers cycle off eventually, and restart after a pause. Repeating this cycle continuously (long transit under power, or leaving the shore power charger on) will over heat and kill a weak AGM battery.

[Vento Solare]

I just installed two new house batteries to replace two that had been cooked, and adjusted the regulator for AGM batteries per the post above. I just ordered the MC-TS-B temperature sensor and will install it on the battery to feed temperature info to the Xantrex regulator... Hopefully this will stop the batteries from being cooked.

[Vento Solare]

I can report success after a full season with the charger and regulator setup properly for AGM batteries. I have a temperature sensor installed on the center battery for each of the charger and the engine. There has been no sign of overheating the batteries and capacity is very good.