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Thread: [E32-3] Adding new battery bank, installing monitor

  1. #1
    Makes Up For It With Enthusiasm Geoff W.'s Avatar
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    [E32-3] Adding new battery bank, installing monitor

    So I started this thread when I got my boat: http://www.ericsonyachts.org/infoexc...ictron-BMV-700

    But now that it's getting summer-y, and I have lubber cruise-mates coming aboard with CPAP machines and various electrical demands on a week long cruise, and given that their comfort is pretty important to me, I figure it's time I go through with upgrading my battery bank and getting the Victron installed.

    The scope of this project looks like this:


    • Remove two current Group 24 deep cycle Napa Auto Parts batteries
    • Install two new 6V AGMs in parallel as house bank
      • Trojan T105-AGMs
      • Install these under aft-most port settee
      • Install battery box?

    • Install new 12V Group 24 starter battery as backup
      • Installed in current battery box

    • Install new Battery Charger? Currently have a Guest 20A dual bank charger.
    • Install Victron battery monitor
    • Install Negative Bus Bar along engine stringer a la Christian's and Maine Sail's setups I've seen elsewhere.


    I think there's plenty here to keep me busy, and I'll have to learn where a lot of negatives are grounded, run new wires, and so on. I'm thinking something like this picture:

    Name:  battery.png
Views: 90
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    Note that locations of the bus bars / shunts are more for the logical flow rather than where I think they'll physically end up. My biggest questions right now are around the wires themselves - do I somehow need to try and pre-measure lengths of wire so I can figure out what lengths to get? Do I need special tools to make custom lengths of heavy gauge wiring, or is this best shipped out to a pro?

    Also, is a battery box going to be highly recommended if I have 2 6V batteries under the settee? I can just squeeze the two T105's in per virtual measurements, but not sure I can fit a prefab box.
    Last edited by Geoff W.; 05-16-2019 at 06:52 PM.
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    Curator of Broken Parts toddster's Avatar
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    I'd think, especially if you are putting lead acid batteries in the salon, a closed battery box, vented to the outside is recommended. But you can probably fabricate one in place to fit your space. IIRC, there is an example in one of the yacht maintenance bibles.

    It may be time to spin the dial again on researching lithium-iron phosphate batteries. The up-front cost is still a shocker, but cost per usable amp-hour may come out way ahead. And it sure would be nice to get all that weight off the boat. And no battery box.

    Like you, I have long planned to install a new house bank at the end of the current re-fit. Still haven't decided if I can afford LiFePO4. Or if the ones that I might be able to afford would work correctly. Not this weeks problem though.
    s/v arcturus E29 #134

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    Moderator Christian Williams's Avatar
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    Do I need special tools to make custom lengths of heavy gauge wiring?

    I prefer to buy pre-made cables on line from some place like

    https://www.amazon.com/ABN-Marine-Ba...K7SPP7EVJBM56N
    Last edited by Christian Williams; 05-16-2019 at 05:47 PM.
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    Hello Geoff,

    Making cables is extremely gratifying and easy to do after you do your first one. Both West Marine and Beacon Marine where I am have crimping tools where they are handy and will allow you to do your own cables on site. Beacon even has a heat gun to do the heat shrink insulation on the ends, check with your local chandlery. If they have the stuff I highly recommend giving at least one cable a go, the rest will follow. (You'll keep your first cable on the saloon table for a week to show to everyone who happens to be within 500 yards of the boat, I know I did.)

    https://marinehowto.com/making-your-own-battery-cables/

    I also did the (shunted) Victron 712 when upgrading to LiFePO4 batteries. It wasn't that difficult to add a bus bar and made all the negative connections required much simpler. The 712 has a built in bluetooth connection to a phone app which makes monitoring the system much easier too. Most of your negative connections probably terminate at the battery anyway, so it shouldn't be too difficult to manage.

    Toddster - LiFePO4 is the way to go if you can get over the immediate pricing issues. I'd do it again in a heartbeat without a second thought. When comparing batteries take a close look at the BMS (Battery Management System - https://battlebornbatteries.com/what-is-a-bms/).

    The quickest way to kill LiFePo4 is to over charge them or to deplete them 100%. A good BMS will prevent over charging and put depleted batteries into a sleep mode for self protection. The Victron shunt can also be set to close at a programmable voltages. LiFePO4 are super happy taking on huge amounts of current to get to 100% charge and do not need a maintenance charge to keep them happy. They will not self discharge overtime if left in storage by more than a few percentages, no trickle or Float charge needed.

    I highly recommend Battle Born Batteries (aka Dragonfly) for quality, competitive pricing, easily accessible information, customer service, and built in BMS. I did a ton of shopping around when it came to replacing my old West Marine (Deka) AGM batteries - researching and comparing Lead Acid/AGM/Gel/Carbon Foam/and LiFePo4.

    Basically there are a handful of lead acid battery factories that everyone puts their own labels on, Deka - East Penn, Trojan, NRG, YUASA, NorthStar and a few others, each with their own reputation mostly around recovery from sulfation. The quickest way to kill lead acid (AGM, Gel) is to undercharge them creating a Partial State of Charge (PSOC) which in turn creates sulfation. Your battery charger (or solar regulator) equilization mode is designed to compensate for sulfation.

    Lead acid (AGM, Gel) should also not be depleted below 50% of their AH ratings. LiFePO4 can be depleted to 10% without any reduction of total capacity or battery life. I constantly checked in on my SOC (State of Charge) with the old AGMs using a Balmar Smartguage to monitor and to prevent PSOC. (The Balmar great piece of equipment, no shunt required, free to a good home for postage as it won't work on LiFePO4,) With the new batteries I rarely give this a second thought and find myself trying to discharge them enough to give the solar panels something to do in their spare time.

    Never thought I'd make the leap to Lithium Iron, really happy I did, wouldn't go back despite the initial cost.
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    Makes Up For It With Enthusiasm Geoff W.'s Avatar
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    I read something saying you can run AGMs down to about 80% without killing them too badly? Is that not true?
    s/v "Delightful"
    1987 E32-3
    Hull #712

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    Makes Up For It With Enthusiasm Geoff W.'s Avatar
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    Another question:

    I currently have a Guest 20A battery charger, like this:
    http://www.marinco.com/en/2720a

    I will likely want to upgrade to a 30A if I'm going to a bigger bank, right?

    I'm looking at this one, which is quite a bit more expensive:
    https://www.westmarine.com/buy/proma...67?recordNum=5

    Not sure how critical an upgrade this is, though.
    s/v "Delightful"
    1987 E32-3
    Hull #712

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    The difference between 20A and 30A will depend on how deeply you discharge the batteries and how long the boat will have at the dock to recharge them. You'll need to do the math for your own conditions.

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    Curator of Broken Parts toddster's Avatar
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    Or save up your boat-bucks for a combination inverter-charger... Victron make a nice one that plays well with their other toys.
    s/v arcturus E29 #134

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    Quote Originally Posted by Geoff W. View Post
    I read something saying you can run AGMs down to about 80% without killing them too badly? Is that not true?
    Yes, that's a primary advantage of AGM vs FLA. But it gets tricky with the battery's actual ratings. AGMs are just better in general at deeper discharges, But keep in mind that battery life is complex combination of cycle count, depth-of-discharge, rate-of-discharge (and rate-of-charge) and temperature, float voltage (the voltage charger is kept at to trickle when fully charged), etc. For me, AGM's primary advantage is not leaking acid, then comes depth of discharge. If you're routinely going to 80% into your batteries capacity I'd suggest getting a larger or more battery. If cost isn't a big obstacle, getting a LiFePo drop-in (about $1200) is way better all around.

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    Quote Originally Posted by Geoff W. View Post
    I read something saying you can run AGMs down to about 80% without killing them too badly? Is that not true?
    You can discharge to 80% however...

    The deeper the discharge the fewer cycles you'll get out of your battery life. Let's say you discharge your battery bank to 80% and get somewhere around 1000 cycles. The same bank discharged to 50% would last roughly a third longer or about 1500 cycles. I'm fudging the math, but you get the idea. The batteries will also degrade slightly over time. A battery "life" has ended when the battery has degraded to about 50% of the original AH rating.

    My West Marine Group 31 bank (Deka - East Penn) lasted about three years of daily use, meeting 95% of my energy needs, until their performance prompted replacement. There was still some life left, but not the same life as when we started. By my best guess I'd say I was getting about 60% to 65% of the original amp hours.

    To discharge less get more AH's to meet your needs. There are plenty of energy use calculators on the interweb to assist.

    Cheers,

    Max
    Last edited by fool; 05-17-2019 at 10:48 PM.
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    Quote Originally Posted by Geoff W. View Post
    Another question:

    I will likely want to upgrade to a 30A if I'm going to a bigger bank, right?

    Not sure how critical an upgrade this is, though.
    Not critical. How quickly do you need to get your batteries back up to full charge?

    Let's go to a stadium event (rock concert or ball game) with general seating. It'll take longer for the stadium to fill up if they only open 20 gates than if they had 30 gates open. At first the stadium will start to fill pretty quickly, and then slow down as the seats get taken. Just before the start of the event finding a seat gets more difficult and takes longer. This is a pretty good analogy for charging batteries that'll go pretty quickly to from 50% to 85-95% capacity, and then take just as long to get in that last 10%.

    My "30 amp" charger is wired into each of three batteries (as banks) separately, giving each a load of 10 amps and not 30 per battery or bank. The Promariner "automatically distributes 100% of available charging power to any combination of batteries in as many as three banks". So if you wire for a 100 AH bank and a 200 AH bank, it should open 10 gates for one stadium event and 20 gates for the other. The data sheet for the Guest on Board states it'll put 10 amps each into two banks, so 10 gates per event no matter how big the stadium.

    I didn't review the "stages" for each charger (bulk, absorption, float, or equalization). The explanation for the first three is here https://www.batterystuff.com/blog/3-...-chargers.html. Equalization, which if I understand correctly is programmed to run every 20 days or so on some chargers and overcharges the batteries to reduce the amount of sulfation. (Don't use or need this feature on LiFePO4).

    Clear as mud? I thought so...

    Max
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    Quote Originally Posted by debonAir View Post
    For me, AGM's primary advantage is not leaking acid, then comes depth of discharge. If you're routinely going to 80% into your batteries capacity I'd suggest getting a larger or more battery. If cost isn't a big obstacle, getting a LiFePo drop-in (about $1200) is way better all around.
    Well said.

    LiFePO4 Batteries from Battle Born are currently running $950 for a 100 AH group 27. A similar battery from Renogy is currently $899, both appear to have similar BMS's installed in the battery.

    The weight of Lead Acid (AGM, Gel) is the lead inside, the heavier the better. Not an issue with Lithium Iron.
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