Sailboat battery upgrade plan

System
System Posts: 2,511 admin
in General Solar Power Topics #1
Guys,

Sent the following to NAW&S e-mail before I realized there was a forum. I wonder if any of you could look this over and help me out with some answers/advice:



I am interested in purchasing three Sun Xtender PVX-1040T AGM Sealed Batteries.

I will be configuring the three batteries into two banks installed aboard my 30 foot sailboat.

One bank will consist of a single battery for starting.

The second bank will consist of the remaining two batteries configured in parallel for "house" power.

I have a typical marine battery switch aboard the boat which allows me to isolate or combine the banks and to charge in either configuration.

The boat is powered by a Yanmar 2GM20F auxiliary diesel fitted with a 55 amp alternator. At my normal steaming RPMs (between 2500 and 3000) the alternator outputs 42 to 50 amps per spec.

I also have a year 2000 vintage guest battery charger aboard which will change 2 banks at 10 amps.

I currently have two wet cell batteries installed, a start and a deep cycle (75 AH - at best). The deep cycle just doesn't have the power I need and I want to have identical batteries/identical age for start and house in my future configuration.

Based upon the above I have a few questions before I buy

1. How much to ship the batteries to Albuquerque NM?

2. Are these batteries suitable for marine use?

3. Do you see any issues with configuring two of these batteries in parallel per above description?

4. I have read conflicting reports of charge voltages and charge cycles being the same or different for wet cell and AGM, what is the truth? Will I be able to retain my current charger and my current alternator?

5. Very important, what kind of cranking amps can I get out of your Sun Xtender PVX-1040T? I assume you have that data although I don't see it at your web site. I understand that your typical application would be a fixed installation and constant load so cranking amps would be a non issue for a solar power system. Obviously I need that data for the start battery. My Yanmar manuals states 375 MCA required for starting but I would like at least 500, the more the merrier.

Any other thoughts on my plan?

Thanks,

Mike
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Comments

  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #2
    Re: Sailboat battery upgrade plan

    Mike,
    2. Are these batteries (three Sun Xtender PVX-1040T AGM) suitable for marine use?

    Concorde’s Sun Xtender batteries are very high quality batteries. Their intended application is for renewable energy (RE) applications (long, slow discharges), so they may not be suitable for high-current applications such as starting a boat engine.

    Instead, Concorde’s Lifeline brand of AGM batteries is intended for “hybrid” marine and RV applications, both starting and deep-cycle. Another choice might be AGM batteries from MK Battery.

    See: http://www.lifelinebatteries.com/
    and: http://www.mkbattery.com/images/lagm.pdf
    3. Do you see any issues with configuring two of these batteries in parallel per above description?

    No. Just makes sure the main battery cables are connected in a “diagonal” fashion to the battery bank terminals [i.e., (+) cable to battery #1, and (–) cable to battery #2].

    See: http://www.solarseller.com/battery_bank_wiring_diagram.htm
    4. I have read conflicting reports of charge voltages and charge cycles being the same or different for wet cell and AGM, what is the truth? Will I be able to retain my current charger and my current alternator?

    AGM batteries typically require a somewhat lower absorption voltage [~14.2 V– 14.35 V at 77 F (25 C) for a 12 V battery] than do flooded-cell batteries [~14.4 V- 14.8 V at 77 F (25 C)]. Unlike flooded-cell batteries, AGM batteries do not require equalization. You’ll need to check the specs for your charger and alternator/regulator to determine compatibility. The Guest charger might be OK with the AGM batteries, but I suspect the alternator/regulator voltage is likely too low for either battery type. If so, you may want to consider an alternator and/or charging regulator from Balmar.

    See: http://www.balmar.net

    If your batteries are to be subjected to hot or cold ambient conditions, you’ll need a charger and/or regulator that includes a feature known as temperature compensation.
    5. Very important, what kind of cranking amps can I get out of your Sun Xtender PVX-1040T?... My Yanmar manuals states 375 MCA required for starting but I would like at least 500, the more the merrier.

    MCA definition: The number of amperes a lead acid battery at 32 degrees Fahrenheit (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).

    True deep cycle batteries are typically not used for engine starting applications, so specs like CA, CCA and MCA typically don’t apply. I’m not aware of MCA specs for the Sun Xtender batteries. However, the MCA spec for the Lifeline GPL-27T (similar in size to the PVX-1040T) is 715 A.

    See: http://www.lifelinebatteries.com/marinebatteries.php

    HTH,
    Jim / crewzer
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