Time to change batteries

Coach Dad · July 2019

I haven’t been on this forum for a long time. I’m glad to see it is still going strong.

My off grid system consists of 1880 watts of PV, a Morningstar MPPT 60 controller, a Magnum-MS4024PAE Inverter/Charger, Magnum BMK (Battery Monitor Kit), 8 Sun Xtender AGM 6V 305ah batteries set up as two 24 volt strings to give me 610 ah and a generator. My batteries (and system) can see temperatures from -15F to +95F.

My loads are a 19 cubic foot refrigerator, 55 in TV, 3/4 HP 240V well pump that runs about 20 minutes over a 24 hour period and a few LED lights. I also have an electric coffee maker that only runs when I’m running the generator.

I typically use my system on weekends only, with maybe 5 full weeks a year. So the batteries stay fully charged Monday through Friday.

I almost always turn on the generator in the mornings when making my coffee which always gets the batteries charged to over 90% State of Charge.

I installed my off grid system in 2012, the first set of batteries went in 2016. I replaced them with the same ones and now my 2nd set is on its way out. So I’m getting less than 4 years per set of batteries.

I want to switch from AGM to Flooded this time around with the hopes that these will last longer (even though I don’t what to do the maintenance).

Questions:

Do you see any flaws in my setup?
How much time per week do you spend checking water, SG and other battery maintenance?
How much water do you normally use in a week for the batteries and where do you get it?
Given the possible temperature range my batteries live in (-15F to +95F), would I be able to use an automatic watering system? Probably not.
I’m considering the Trojan SSIG 06 405 as my next set of batteries. How does it compart to the L16 RE that is talked about so much on this forum?

Estragon · July 2019

The system looks reasonably balanced to me. I assume loads (esp fridge) are off during the week? 95°f is pretty warm for batteries, and with that range you'll want to be sure battery temperature is properly monitored with RTS and charging voltage for both charger and controller is properly compensating.

I spend maybe an hour every couple of months checking SG etc. For me, it's time well spent for the extra info it gives me on bank health and catching/remediating problems early.

When new, batteries used maybe a gallon of water in a summer season (~May to Oct). 5 years on, they'll use 2-3 gallons. I buy it at Canadian Tire (a sort of big hardware store).

I probably wouldn't use an automatic system. Adding water isn't that big a deal, so for me the risk of a failed watering system isn't worth taking. It obviously wouldn't be happy at -15°f.

Don't know much about the Trojans.

Estragon · July 2019

BTW, I wouldn't crank up the genny just for coffee unless weather was going to be really gloomy or the bank was quite low (eg 50%). I often make toast in the morning at ~80-85% SOC, and batteries typically float around noon.

Coach Dad · July 2019

Yes, I turn off all the power to the cabin during the week while I'm not there. So the Refrigerator is off.
Just to be crystal clear... The MPPT runs through the charge cycle on a daily basis even when the inverter power is turned off. So the batteries are fully charged and there is no load on them during the week.

Estragon · July 2019

My classic charge controllers have a "skip days" setting so they will go straight to float for 'X' days unless bank hits rebulk voltage. This avoids running a full absorb needlessly every day. They also use "end-amps", which will terminate absorb before the timer runs out if charging current drops below ~1-2% of C, as would be the case for already near full bank. IIRC, my Morningstart PWM controllers adjust absorb time algorithmically but I don't recall the details. Not sure about MS mppt controllers.

Anyway, the general thought is you don't really need a full 2-3hr high-ish voltage daily absorb on an idle bank, as this ages the bank with no real benefit. Just a periodic (eg weekly, or less frequent) full absorb is needed to mix electrolyte occasionally for idle flooded (or not at all for VRLA).

mcgivor · July 2019

Being that the system is unused during the week I would be inclined to shut everything down including the solar, if fully charged, the minor self discharge losses would be negligible in the big picture, with the added security that if nothing is working there is less chance for something to go wrong.
The amount of water flooded batteries need is dependent on how they are used, heavily cycled will require significantly more than lightly cyced. Automatic watering is like automatic anything, more prone to failure, the amount of effort required is not great and it is useful in that it forces the operator to visually see any potential problems, bad connections etcetera.

mike95490 · July 2019

I bought a very expensive watering kit, and out of 43 auto-caps, I had 3 failures on day 1, one continued to fill the battery to overflow, and 2 dribbled water out of the vent holes onto the top of the batteries - happy I was not. I now only dare to use it manually, while watching each cell, it's easier than opening caps and funnels and checking levels with a flashlight.

Coach Dad · July 2019

Thanks to all for your advice....
I'm still unclear about how the Trojan SSIG 06 405 compares to the L16 RE-B... Spec wise they seem ALMOST identical.
Another question: My current AGM batteries are about 12 inches away from the inverter... How far away should the flooded battereis be?

mcgivor · July 2019

Put a beef patty in a bun, call it a hamburger, add lettuce and a slice of tomato, you have a deluxe burger. There have been many adjustments to the initial recipe of lead acid batteries over time, though in reality they are tradeoffs on a basic design which hasn't changed much in over a hundred years.

Estragon · July 2019

One possible concern might be that at 443ah 20hr rating, it's on the high side for an L16 size 6v battery (often 320-370ah). Don't know much about this particular battery, but it may use a higher acid concentration to get the higher capacity, and there may be implications for life expectancy. As Mcgivor said, tradeoffs.

paulcheung · July 2019

If I understand what the Trojan Tech told me before, (I don't know if it has changed, was few years back) The 443 or 428AH signature line was designed for floor cleaning machine etc. It has higher Acid concentration and design to be charge back by steady current like the grid. on the other hand the premium RE line are design with the new smart carbon in the negative plate to prevent sulfation easily. So in solar application I would choose the premium RE line over the signature line.

Coach Dad · July 2019

Estragon said:

One possible concern might be that at 443ah 20hr rating, it's on the high side for an L16 size 6v battery (often 320-370ah). Don't know much about this particular battery, but it may use a higher acid concentration to get the higher capacity, and there may be implications for life expectancy. As Mcgivor said, tradeoffs.

Actually.... The SSIG 06 405 has a 366ah 20hr rating.

Coach Dad · July 2019

paulcheung said:

If I understand what the Trojan Tech told me before, (I don't know if it has changed, was few years back) The 443 or 428AH signature line was designed for floor cleaning machine etc. It has higher Acid concentration and design to be charge back by steady current like the grid. on the other hand the premium RE line are design with the new smart carbon in the negative plate to prevent sulfation easily. So in solar application I would choose the premium RE line over the signature line.

I emailed Trojan and was told the same thing about the Premium RE Line, so I decided to go with the SPRE 06 415.
aka.... Deluxe Cheeseburger with Mushrooms and Onions It has a 377ah 20hr rating.

wellbuilt · July 2019

I’m in a freezing climate , I just stoped burning wood at night this week .
Any way , I use my system about the same way you do .
My panel where covered with snow most of the winter, 31/2 months and I charge with generator .
I’m not in need of water at all from nov to March so it’s a non issue for me.
I leave my system off when I’m not there I just charge the battery’s to full before I leave .
Battery’s are all was full when I come back.
I am up there every week this time of year .
In the winter it is possible for me to get snowed out for 4 to 6 weeks

Marc Kurth · July 2019

Coach Dad, you are getting an unusually short lifespan for that battery, in that application. Are you losing one battery, or all of them? Are you sure that you are staying at the absorb voltage long enough to actually reach 100% charge?

Marc

Dave Angelini · July 2019

Hi Marc, yes you are right that is really short. The boat still floating on the lake?

Coach, you have one of the best AGM guy's here with Marc. Might want to answer all the questions....

Coach Dad · July 2019

Marc Kurth said:

Coach Dad, you are getting an unusually short lifespan for that battery, in that application. Are you losing one battery, or all of them? Are you sure that you are staying at the absorb voltage long enough to actually reach 100% charge?

Marc

Marc,
Yeah... that is why I'm switching over to flooded batteries. I can't afford to keep changing them so often.
Yes... I have the MPPT set to run in Absorb for 2 hours. I typically run the generator Sunday morning during coffee and then leave the cabin for the week. The batteries are typically over 90% SOC with the Generator when I leave. I turn off the inverter (and all power to the cabin). The solar panels/charge controller run all week long 2hr absorb time. Batteries are always fully charged when I come back Friday night. Not sure if I lost one or all, I didn't bother checking since you are not allowed to mix new and old batteries.
Let me know if you have additional questions... I'd like to understand what is going on too.

BB. · July 2019

Measuring the battery voltage, assuming you have several batteries in series, is a quick way to figure out if all your batteries are good/bad (i.e., all the batteries are about the same voltage...). And you measure the batteries and bus voltages under load/charging/resting to see if the system is working correctly or not.

It is possible to have one bad battery in a string--And replace just that battery and get a few years more life out of the bank--Assuming all else is good.

Doing your debugging with the old bank--Helps you understand what happens when things go wrong, and verify that your hardware is working correctly. Also, if there are other issues, you fix them before they damage your replacement bank.

When/if you get flooded cell... Get a voltmeter (if you do not already have one) or AC/DC current clamp meter, and a hydrometer (always rinse with distilled water when you put the hydrometer away--or the float can get sticky). Some places to start looking:

https://www.solar-electric.com/search/?q=hydrometer
https://www.amazon.com/gp/product/B019CY4FB4 (a medium priced AC/DC current clamp meter)

And if you have several strings of batteries batteries in parallel, check out the suggested wiring connections/routing:

http://smartgauge.co.uk/batt_con.html

-Bill

Dave Angelini · July 2019

As Bill said and my comment that I think Marc would agree is absorb should be 3 hours at the correct voltage.

2 Strings of batteries is not a great design. It would have been better to use a 48V inverter and have one string. The floating all week and charging unattended, too often, with no loads, could be part of the analysis on why this happened twice in a short time period. Good Luck

Coach Dad · July 2019

Dave Angelini said:

As Bill said and my comment that I think Marc would agree is absorb should be 3 hours at the correct voltage.

2 Strings of batteries is not a great design. It would have been better to use a 48V inverter and have one string. The floating all week and charging unattended, too often, with no loads, could be part of the analysis on why this happened twice in a short time period. Good Luck

If I was starting over, I would in fact go with a 48V system, and try and find a Charge controller that can run multiple charge programs so I could have a 3hr absorb time when batteries are used, and just float them when they are already at 100% SOC..
Unfortunately I'm limited by the hardware I bought before I knew any better.
1) I have a Morningstar MPPT60. It doesn't give you the option to have multiple charge profiles. So it boils down to absorbing 2 hours per day 7 days a week, or turning off the system completely on Monday and risking that the batteries aren't completely charged. There is an "absorb extension" setting where... If the battery voltage drops below this threshold, the Absorption Extension Time value is used. This doesn't work consistently at all. Sometimes it extends, and sometimes it doesn't.
2) I bought a Magnum 24V inverter before I knew any better. So that is what I'm stuck with. $2400.00 for the inverter, BKM, Remote.

I did the debugging after getting 3 1/2 years out of the first set of batteries... I even had them tested by an expert.

BB. · July 2019

I don't remember--What did the expert/debugging find?

-Bill

Coach Dad · July 2019

BB. said:

I don't remember--What did the expert/debugging find?

-Bill

Funny you should ask this question. This was a sore spot for me at the time and is again now.

The Expert who tested them said they had sulfation and that I should Equalize more often.

For my first set of batteries, the Sun Xtender Manual Version D (dated 7/11)stated: "Conditioning should only be done when the batteries are showing signs of capacity loss...." So that is EXACTLY what I did at the time. That led to sulfation and it was too late.
For my next set of batteries, they updated the manual. Version E (dated 4/14) of the manual said to do a Conditioning it when the Float voltages of series connections show variations. But I deviated a little from that and conditioned them for 2 hours every 45 days. I was checking the voltages every 3 months and they stayed constant until March 2019. Then I tried an 8 hour Conditioning (per the manual). But that wasn't enough and I believe they have sulfated again and it's too late again. I actually did the 8 hr conditioning in April and May as well.... No luck.
Now Sun Xtender has a Version F (dated 2/17) of the manual NOW states to condition them every 3 weeks for 4 hours!!! But I'm not going to get their batteries again only to find another correction in their next version of manual once my batteries are ruined.

In my opinion, due to Sun Xtender's incompetence at getting the manual correct, I went through 2 expensive sets of batteries which became sulfatated. I'm done with them and am now switching to Flooded batteries that I can check SG on and know when to Equalize.

Sorry for the rant... but you asked.

BB. · July 2019

From reading earlier manuals... I always wondered how the S.X. batteries were claimed to be "so different" vs other AGM and even straight FLA batteries. Chemistry is Chemistry???...

From your experience and changes to the manual--They do not sound that different (i.e., sulfation is still an issue, some sort of "soft EQ" done periodically, etc.).

Batteries need to be "forgiving" in solar/off grid systems. Real life cannot be controlled exactly.

I am truly sorry to read about these ongoing issues.

-Bill

Dave Angelini · July 2019

It will be interesting to see Marc Kurth's input on this. I had to use AGM's for someone five years back or so and he told me Full River were hard to beat. Still working just fine.

Even though this sucks Coach, it is better now than in winter

I do wonder if the testing of the bad battery involved a load test? Pretty useless testing if a slow full 24 hour charge is not followed by the recommended load test, or something close.

Coach Dad · July 2019

Thanks for your support Bill and Dave...
The water is under the bridge now... My new Trojan (SPRE 06 415) batteries are on order. I should be getting them in mid-August which should give me enough time to get everything fine tuned before hunting season.

Now on to finding a good Hydrometer. This looks like an informative article... https://toolever.com/51/6-best-hydrometers-for-battery-testing/

Thanks again to all, I appreciate all the advice I got from this thread...

Ralph Day · July 2019

When you do get a good hydrometer, be sure to get a good thermometer for temperature compensation. I have a good digital probe type from a kitchen gear store (works well). That way you can get the real reading in seconds. Cooler than 80F electrolyte, subtract .004 per 10 deg. Warmer than 80F add .004 per 10 deg. Quick and easy, no gimmicks.

Wheelman55 · July 2019

Coach...you can buy them from the UK for cheap. Buy two and you’ll have a spare. https://www.ebay.co.uk/itm/Pro-Hydrovolt-HYDRO-VOLT-Lead-Acid-Battery-Hydrometer-Electrolyte-Tester-/322082591860

Surfpath · August 2019

"Trojan SSIG 06 405 compares to the L16 RE-B... Spec wise they seem ALMOST identical"

I believe these are the same batteries.

I have had a bank of Trojan L16 REB's for 6.5 years now. I hope to make them last another 6 months.

They have had a historical 25-30% DOD (ie. 70-75% SOC in the morning) at ~27degrees C average temps.

One cell on one battery died after 6 years - replaced that battery with two new GC Trojans.

Overall they have delivered as promised. Hope that helps

Marc Kurth · August 2019

Sorry to have bailed out mid-stream!

A lot personal stuff going on (My wife is prepping for a new hip, we installed a whole new aerobic septic system with 1700 feet of drip line, rebuilding the dock, etc.) plus I am in the process of re-orienting my business.I was not involved with this project, so I can only provide my overall opinion after working with Concorde Sun Xtender and Lifeline batteries continuously every day since June of 2009. My little operation sells around 2500 AGM's per year. In general, I am deeply involved in the layout and implementation of projects, including some exotic stuff for industrial agencies and three letter agencies. I dislike backing into someone else's problem project after the fact because I do not have the history.

First: I will categorically state that almost every early Concorde battery failure that we see is from undercharging. Undercharging is the enemy and always has been forever. Undercharging can include too low of an Absorb voltage, too short of an Absorb time, too low of a charge rate and not reaching 100% SOC often enough. Way behind undercharging on the list is high temperature. Overcharging is rare to the point of being almost non-existent.

Second: It is MY opinion that Concorde has gradually ratcheted up their support of “conditioning” because customers are so afraid of “over charging” their batteries, that they undercharge them. MOST people do not read (or perhaps ignore) the fact that Concorde batteries must be charged at the Absorb voltage until they are only drawing one half of one percent of the battery bank C/20 rating. Simply put, 0.50 amps per 100 AH of battery capacity.

Dropping to Float before reaching this point is a form of undercharging and will cause sulfation. Their manual also provides suggested Absorb time settings to be used as a starting point to fine tune. Two hours is minimum for very shallow cycling and four hours for deeper cycling. Remember that “end amps” is the key and that lots of Float time brings strings into balance. We often read the internet megaphone about overcharging AGM’s. Think about a typical 1200 ah bank. At 100% SOC, the entire group of 24 batteries is only drawing 6 amps! I assure you that it will take a very long time to cook them. Especially when the sun goes down with great regularity.

There is much, much more to discuss, but I will say that if our battery banks are charged per the manufacturer’s instructions, equalizing is not required for the first 5-7 years. Yes, it is a slightly destructive process, but less so than sulfation!

OK that was wordy! But go ahead tell me what I missed!

Dave: Oh, you bet the boat is floating running strong! It's a 25 footer but is surprisingly nimble. It takes less than two minutes to lower her into the water and shove off - so we go out every day or two. Sometimes a quick 30 minute cruise can be an attitude corrector!

Can you tell that I'm an old Pan X film kind guy? :-) My boathouse the little one on the right.

Dave Angelini · August 2019

Definitely full blown Panatomic. Really nice shot. Wish I had one on my boat....
Very nice battery demise instructions. Pretty much the same with flooded except the hydrometer crutch

Better go as my nephew is here and wants to go to town. He is playing Thunderstruck at stage level AC DC

Coach Dad · August 2019

Thank you for your insight. Do you work for Concorde?

Your 1st point. You might be right about undercharging, but I don’t see my mistake. If you see something that I’ve been doing wrong here, please help me understand so I can make corrections.

Historically my batteries sat fully charged from Monday (maybe Tuesday on some weeks) through Friday night. To clarify my normal operations. I have 8-6V 305ah batteries set up as a 24 volt 610ah bank. I’m using 1880 watts of PV, with a Morningstar MPPT 60 controller that is set to a 2 hour absorb time Absorb Voltage is 28.6, Float voltage is 26.6V. Eq Voltage is 31.0 and set to Eq for 2 hours every 45 days. See my post on July 9 on this thread for more Equalization details.

I normally use the batteries Friday night through Sunday afternoon. I turn off the power to the cabin on Sunday but the Solar and Charge controller run all week long. On top of that, I run my generator on Sunday mornings while making breakfast. The generator is connected to my Magnum MS4024PAE which has a 110 Amp charger. I can’t ever remember leaving the cabin on Sunday with the batteries at less than 90% State of Charge. If the batteries don’t reach 100% SOC on Sunday, they will get there on Monday, and cycle through 2 hours of absorb voltage on Tues, Wed, Thurs and Friday. So how can they possible be under charged?

Your 2nd point. “Dropping to Float before reaching this point is a form of undercharging and will cause sulfation”. I’m guilty of this.

There are many days where the sun isn’t strong enough for long enough to get fully charged on a Saturday or Sunday. But they certainly are fully changed by Monday or Tuesday. On raining weekends, when I see the batteries dropping below 80% SOC, I’ll start the generator for a hour or so, during these times, I don’t fully charge them. But as stated above, they never go more than 2 days without reaching 100%.

If the batteries are sulfating when sitting below 100% and above 70% SOC for 2 of 7 days, than I contend they are not suited for solar usage. I’ve been using solar for over 7 years and during that time, it’s rained on many days.

Unfortunately for me, when it came to “Conditioning” I’ve followed the manual to the letter for both sets of batteries which I’ve owned. Yes revision F (dated 2/17) added a table for recommended absorb times. This was not included in previous versions of the manual.

I think Concorde really screwed up on the manuals not the batteries.

The Servicing section that they published in version E and F of the manual is ridiculous. They expect you to fully charge the batteries then discharge them until they hit the low voltage disconnect and take a bunch of measurements. I’m guilty of not doing this either.

How long would it take a system that is designed for 2 days of capacity to discharge them to the Low Voltage Disconnect point?
What is “run time”?
They what you to measure and record ripple? Other than recording it, there is nothing to do if you have excessive ripple. Sure I’ll run out and buy an oscilloscope to measure ripple and do nothing with the results.

All in all I was happy with the Sun Xtender batteries while they lasted. But I was disappointed with their life.

Time to change batteries

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