batteries/solar/alternator/ Adler Barbour. ..arrangement..

[RonE]

I have a 1988 Cat. The PO installed a 130w solar collector. This summer I purchased 3 new AGM batteries, one from WM and the other 2 are Trojan 31's. I was hoping the Trojans would support my Adler barber refrigerator while I was cruising. Again the PO wired the charging system as such,  the starter battery is dedicated to the engine with the alternator being it's sole charger. The aux batteries are only charged by the solar collector (and of course the 30 amp dock power,when plugged in) not the alternator.  You get about 7.5 solar amps at max sun time. I noticed the trojan batteries drop off very quickly after sundown, about 11.8 v. The morning sun pushes it back up to 13 or more in a few hours..   The question is, can this system support the A/B refrigerator, or am I just killing good batteries.

[KWKloeber]

I have a 1988 Cat. The PO installed a 130w solar collector. This summer I purchased 3 new AGM batteries, one from WM and the other 2 are Trojan 31's. I was hoping the Trojans would support my Adler barber refrigerator while I was cruising. Again the PO wired the charging system as such,  the starter battery is dedicated to the engine with the alternator being it's sole charger. The aux batteries are only charged by the solar collector (and of course the 30 amp dock power,when plugged in) not the alternator.  You get about 7.5 solar amps at max sun time. I noticed the trojan batteries drop off very quickly after sundown, about 11.8 v. The morning sun pushes it back up to 13 or more in a few hours..   The question is, can this system support the A/B refrigerator, or am I just killing good batteries.

though not exact/100% accurate, what's the amp=hr rating of the house batteries?

Ken

[RonE]

CAPACITY AMP-HOURS

5-Hr Rate       82

10-Hr Rate     92

20-Hr Rate     100

100-Hr Rate    111

[KWKloeber]

CAPACITY AMP-HOURS

5-Hr Rate       82

10-Hr Rate     92

20-Hr Rate     100

100-Hr Rate    111

This is totally non technical and very "approximate"

So your solar panel can replace, say in round numbers, 7 amps x 10 hours, or 70% of a brand new Trojan 20-hr AH (5 amp) rating.  That's provided the voltage control actually lets that current get to the battery (if the battery is "up", the recharge current will be way down.)

The A-B uses (depends of course on your climate, usage, etc etc etc) let's say 5 amp, 50% of the time, or 5 amps x 12 hrs, or 60 amp-hr.  So if you use nothing else AT ALL, the solar recharge barely covers the A-B use.   In reality, (real world) it probably doesn't cover all the A-B use for many reasons (Trojan rating in accurate, solar not charging a 7 amps, etc etc etc).  So the alternator will need to make up the difference, and that gets into a whole 'nother discussion of alt capacity, external regulators, temp compensation etc etc.  ie, just because you have, say, a 100-amp alt, it doesn't charge at 100 amps -- some fraction of that for a short period (depending on Trojan state of charge,) then continually tapering off as battery resistance increases.

You would need a complete work up/energy budget to determine the req'd house size and solar panel, etc.


kk

[Stu Jackson]

or am I just killing good batteries.

Ron, yes you are.

1.  Ken got partway there.  It's not only how much goes out & in, there's also battery acceptance (where the amount can you return is governed by the SC of the ban: the higher the SOC the less can be returned in amps).

2.  Your wiring & charging system is inherently faulty and should be repaired immediately.  The switching should always allow one or the other bank to do either dedicated start or (sometimes required to be limited) house loads.   There is never a reason to combine banks UNLESS WHEN CHARGING.  Your alternator should feed your house bank.  Your shorepower charger should feed your house bank.  Your solar should feed your house bank.  The reserve bank gets charged by either B on the switch or an ACR.

3.  There are many threads in the Electrical Systems 101 topic.  You should become familiar with them and then you can come back with some more specific questions.

[KWKloeber]

or am I just killing good batteries.

Ron, yes you are.

1.  Ken got partway there.  It's not only how much goes out & in, there's also battery acceptance (where the amount can you return is governed by the SC of the ban: the higher the SOC the less can be returned in amps).

Ahem...

<<That's provided the voltage control actually lets that current get to the battery (if the battery is "up", the recharge current will be way down.)>>  ie. S.O.C.   

[mainesail]

I have a 1988 Cat. The PO installed a 130w solar collector. This summer I purchased 3 new AGM batteries, one from WM and the other 2 are Trojan 31's. I was hoping the Trojans would support my Adler barber refrigerator while I was cruising. Again the PO wired the charging system as such,  the starter battery is dedicated to the engine with the alternator being it's sole charger. The aux batteries are only charged by the solar collector (and of course the 30 amp dock power,when plugged in) not the alternator.  You get about 7.5 solar amps at max sun time. I noticed the trojan batteries drop off very quickly after sundown, about 11.8 v. The morning sun pushes it back up to 13 or more in a few hours..   The question is, can this system support the A/B refrigerator, or am I just killing good batteries.

Unfortunately your PO did you no favors. On a boat a 130W panel is capable of delivering approx 17- 48 +/- Ah's per day, depending upon conditions, and panel temp, and this is only if it is wired correctly and set up well and using an MPPT controller. So no, your solar array will not support your refrigeration...

The bottom line is your AGM batteries should not ever dip below 12.0V at the dead bottom or more like 12.1V as your indication to charge.

The system needs to be wired properly and your PO did a University of Rube Goldberg job....

Rx

*Wire the alt (and ALL other charging sources) directly to the house bank with a fuse at 150% of the alts rating within 7" of the house battery bank + terminal.

*Charge the starter battery via an ACR (automatic combining relay) or Echo / Duo type charger

*Add more house bank capacity, 200Ah's is on the very, very low end if you want to run refrigeration and other normal house loads.

*Make sure your battery switching allows for isolation & redundancy so the start battery could be used for house & starting if it needed to be and the house could do the same.

*Immediately stop allowing your new AGM's to go below 12.1V!!! You are murdering them...


This was two identical Kyocera 140W panels one fed to a PWM controller and one to an MPPT controller and measured over a real world 7 day period. The panels were flat mounted just as they would be on a boat. Cooler panel temps actually helped the results for MPPT here. In hotter climates the MPPT would not have produced as much.. On a perfectly good day (absolute ideal conditions) on a boat a 140W panel is capable of somewhere around 50Ah's but don't ever count on this as money in the bank.....

[mainesail]

or am I just killing good batteries.

Ron, yes you are.

1.  Ken got partway there.  It's not only how much goes out & in, there's also battery acceptance (where the amount can you return is governed by the SC of the ban: the higher the SOC the less can be returned in amps).

Ahem...

<<That's provided the voltage control actually lets that current get to the battery (if the battery is "up", the recharge current will be way down.)>>  ie. S.O.C.   

With a single 130W panel and 200Ah's of AGM's, and refrigeration, acceptance is really a non issue because he will never get there unless the boat sits for a few days with zero loads...

The lower/smaller the available charge current the later in the SOC curve the bank will hit absorption and begin "limiting current". With a 130W panel and a 5A +/- charge current he probably won't limit current (hit absorption voltage) until he's well over 95% SOC.... With an alt that is different because you have a lot more current and will hit the limiting voltage sooner in the SOC curve.  With a low enough current you can literally charge a battery to 99.5% + SOC before hitting absorption voltage and current limiting occurs..

The discussion around battery acceptance is much more applicable when we get to massive arrays (not usually found on a C-34 but can be on Cat's or Tri's) or large current source charging.

Regardless of current limiting / acceptance you still have Coulombic efficiency and with AGM's you'll still need to put back approx 105%-115% of what was removed in order to attain a full charge..

With the array and use the OP has, he can barely break above 13V in bulk charging. If he is also dipping below 12.0V this is PSOC (partial state of charge) murder to his AGM's...

[RonE]

Thanks for the responses, I am all over the Electrical Systems 101 reads, and your writeups, mainesail are very good. lots of informative stuff. I need to revamp my system, I always figured it wasn't wired properly. I should have inquired before I  made the agm purchase, hopefully I didn't already mess them up...
Ron

[Stu Jackson]

I should have inquired before I  made the agm purchase, hopefully I didn't already mess them up...

Ron,

While you may have ruined them if your system wasn't corrected, as long as you follow the guidelines to keep the new AGMs topped up, you should be fine until you repair the charging stuff.  There are a couple of good AGM articles by Maine Sail in the Elec 101.

Any specific questions, please let us know.

Amazing what POs can do, isn't it?

[2ndwish]

I do realize that discussions of batteries is a bit like religion and don't wish to stir the ire of people with a lot more experience than myself and no I am not the PO in this case, but let's look at the facts here...

1) I suspect from reading Ron's post that he is describing the "loaded" voltage on the battery, from which it is difficult to determine a SOC. If he let the battery rest for an hour, I'd bet the voltage would rise above 11.8V.

2) Most of us use our batteries much the way he does while seasonal cruising. That is, we have undersized alternators and rarely put back full charge when running the engine on a cruise. Some of us carry portable generators ($1000) to better top off our batteries, much to the annoyance of our anchorage neighbors.  I noticed the other day, after a three-day stop, that my batteries (400 AH GC) were approaching 50%. On my cruise home, even after 2 hours of motoring, my 51 A alternator was unable to register 13V at the panel meter. Am I killing my batteries? Well yes and no. Any time you cycle the batteries, you are taking some of their life, but that is what they are for! Would I have been better off not charging them underway and waiting until I returned to shore where I could use my 100A 3 stage charger- I doubt it. Putting some charge back in a depleted battery has got to be better than letting is sit depleted- which is the worst thing you can do for them.

3) I would argue that you have to look at how you use your batteries is a big part of the system you put together. Your batteries start dying the minute they leave the factory. If you treat them very well, avoiding high temperatures, discharges more than 50%, use ideal charging techniques and never leave them discharged, you might get 10-12 years out of them (for AGMs), maybe 8 if they are wet-cells. It is quite typical for most of us to get 6 years out of our wet cells. How many cycles does a typical summer cruiser put on those batteries? 10/year if you are lucky? That's 60 cycles over a typical battery lifetime, 120 for AGMs. Compare that to the chart from page 3 of the data sheet I've attached from Trojan for cycles vs DOD. As you can see at 80% depletion, you get 500 cycles vs 1000 for 50% discharge. Even if I apply mainesail's very useful rule of thumb of degrading this by a factor of 2, Ron's batteries should last 250 cycles, which should provide him many good years of service. If Ron is lucky enough to cruise more than that in a summer, then he should think about investing in hardware to prolong his battery life.

We can spend thousands of dollars on generators, high output alternators, external smart chargers etc, but we will be saving money 5-10 years down the road, assuming the batteries don't fail for some other reason (shorted or open plates) long after the warranty has expired. That said, it is a good idea to make sure you can provide every reasonable source of charge to your house bank (like an undersized alternator) because the one thing that is certain to kill your battery is leaving it discharged for a long period of time. I hate terms like "battery murderer", because we all take life from our batteries as we use them, but that is what they are for. Some do it more quickly than others.
Sorry batteries.

 

[KWKloeber]

Every time anyone asks "what battery do I need? I argue on and on that one needs to do a COMPLETE and proper power budgeting in order for any discussion to be meaningful   It always falls on deaf ears because "we" want quick, simple, down and dirty answers, and don't want to spend money on changing the hardware.  So long as she starts and the alt charges - no need to change unless there's a problem (how many still have OEM 4 AWG battery cables?)

Returning depleted AHs is more often about regulation/sensing, than alt capacity.  Yah can only give 'em what they will take, given the crappy non-adjustable regulation on the OEM alts, higher V demands of specific battery chemistry, internal instead of external sensing, no temp compensation, bla bla bla.  If you're a day/weekend cruiser that may be ok, but if you have high demand the above HAS TO BE part of the equation.

Doesn't make much sense to pony up for a $1k genset, and not first pony up to upgrade the OEM charging system.

KK

[mainesail]

1) I suspect from reading Ron's post that he is describing the "loaded" voltage on the battery, from which it is difficult to determine a SOC. If he let the battery rest for an hour, I'd bet the voltage would rise above 11.8V.

As we all know using voltage is not a good way to determine SOC but it can be decent rough guidance as a "when to charge". Talking specifically about AGM batteries, Lifeline for example, shows discharge vs. voltage & SOC at varying rates in their tech manual.

A healthy 100Ah Lifeline battery hits 50% SOC under a 5A load at 12.15V. This is a loaded voltage at the 20 hour rate when it passes 50% SOC. A 20 hour discharge rate is far steeper than our average discharge rate on cruising boats and this is why our cut off voltage, if using voltage, should be higher than folks usually expect it to be..

Most C-34 owners would have a 400Ah +/- bank not a 100Ah bank so the 20 hour load would now be 20A in order to hit 50% SOC at 12.15V. This is significantly higher than most of us discharge our banks. We discharge closer to an 80 or 100 hour rate so the voltage to hit 50% SOC goes up.

At the typical average house loads we see on boats a 400Ah bank of Lifeline, or similar AGM batteries, will pass 50% SOC somewhere between 12.1V to 12.35V depending upon your avergae loads and the health of the batteries. Taking them to 11.8V loaded, at the typical house loads, is in the range of 70% + DOD.....

I know that taking this type of battery to 11.7V at the 20 hour discharge rate =

Odyssey PC2150 TPPL AGM @ 5A load & 11.7V cut off = 26% SOC

Deka Group 31 AGM @ 5.25A load & 11.7V cut off = 30.2% SOC

Firefly Carbon Foam AGM @ 5.5A load & 11.7V cut off = 25% SOC

Lifeline Group 31 AGM @ 5A load & 11.7V cut off = 28.5% SOC

Northstar TPPL AGM @ 5.25A load & 11.7V cut off = 27% SOC

[2ndwish]

Taking them to 11.8V loaded, at the typical house loads, is in the range of 70% + DOD.....

Mainesail-So assuming that is correct, how many cycles can Ron expect from his AGM batteries at that DoD?

I'm not disagreeing that Ron is not treating as well as he possibly could, but he is not treating them all that differently than most of us do when cruising- we deep cycle them, then run the alternator or solar array or generator to get them as high as we can, given engine noise or sun limitations, but rarely to ~100% SoC. Because he only uses solar, he discharges them deeper than we do, so his AGM max cycles will be fewer, but it might not even be noticeable in the end.

I am going to post another story from this weekend about the dangers of large battery banks and high capacity alternators...stay tuned.

[mainesail]

What he is doing is called deep PSOC cycling and while many do this it is murder on batteries. I think the data speaks for itself when you look at what happens in just 30 PSOC cycles to 11.7V...

Image Courtesy Practical Sailor


This Deka battery started as a 104.5Ah battery (105Ah rated) and after 30 PSOC cycles to 11.7V, and then charged for 1 hour at .46C, the battery lost approx 28% of its Ah capacity in just 30 days of heavy PSOC cycling. By industry standards a deep cycling battery is considered dead when it can no longer deliver 80% of its rated capacity.  How many cycles to dead when you deeply PSOC? Less than 30 for this Deka AGM.....  

Even the premium Lifeline AGM lost 11% in just 30 PSOC cycles.. Unfortunately for sailors lab ratings are not worth the paper they are printed on if you deeply PSOC cycle your bank. Some of us in the industry have been pushing BCI to develop a PSOC cycle test so all batteries could be rated fairly for how they deal with deep cycle abuse. Don't hold your breath!!!

In the real world 90% of my customers are on moorings and I regularly see newly acquired customers getting 2-3 years from premium AGM batteries, without solar. With solar or wind or both and a better alternator system I can bump this to 5-9+ years.

I just walked in the door from a customers boat, doing an AP install, and when I got there this morning (they raced last night) his bank was at 11.9V rested. These are two year old AGM's and they are testing as dead already. Being Lifleline's I will try and re-condition them and perhaps get some life back into them...  

In summary Ron would be lucky to get two years from his bank if he continues to treat it like that (assuming he mooring sails). Again it is not so much cycles as much as how deeply they were discharged, how long they sat discharged, at what temp they sat discharged, and at what DOD they were at while not fully charged.. If charged to 100% weekly this time extends but 11.8V is still going to degrade the bank faster than stopping at 50% SOC.. Most batteries I replace barely even have 100 cycles on them because the owners murder them..

I have an owner of a J-42 who was burning through an $1800.00 bank of Lifeline AGM batteries every 2 years (approx 45 deep cycles). All he had was a super dumb Hitachi 80A alternator and he's on a mooring.....  He's now on year 5 and his Lifeline's tested this spring (May) at 94% of new capacity. That is a major cost savings! How? Solar, temp compensation, proper wiring, regular equalization, he stops discharging at 12.2V, and a new high output alt & regulator with temp sensing. It is looking like he should get 7+ years out of this bank or a total savings of over $4000.00.