New Off Grid System - Please help me make a battery decision!

Ralph Day

Re: New Off Grid System - Please help me make a battery decision!

In case nobody told you...liquid dish soap before you try to pull. Then get it off your hands

Ralph

stephendv

Re: New Off Grid System - Please help me make a battery decision!

Ralph Day wrote: »

In case nobody told you...liquid dish soap before you try to pull. Then get it off your hands

Funnily enough I learnt that lesson just this morning. Other lessons I learnt:
- If I pull hard enough on the insulation, it will come off
- My car is not a winch. A burnt clutch does not smell good.

icarus

Re: New Off Grid System - Please help me make a battery decision!

Try tying the wire to the bumper of the car!

Seriously, they make and sell wire pulling lube. Don't think dish soap will hurt though.

Tony

audredger

Re: New Off Grid System - Please help me make a battery decision!

Awwwh .... pulling 4/0 builds character

whitestrabbit

Re: New Off Grid System - Please help me make a battery decision!

Well, I ended up buying 8 blemished Deka 8L16s. These are supposedly brand new batteries. Only thing I could tell as far as blemish is the terminals are a little crooked. Couldn't pass up the price for what seems like a decent quality battery. $1200 for 8 including tax or about $137 each + tax. I will see how it goes once we get the solar panels installed in and possibly get 8 more if overnight DOD is too large. Hoping to get the hydro up and running next winter so maybe 8 L16s will be enough. Our creek is still running strong a week after the last rain and 6 days of sun so I think it's a solid power source. Also spoke to a few micro-hydro turbine vendors and they felt we have a good application. You can switch out the nozzles on the turbines as stream flow varies and realistic output for our head/flow seems to be in the range of 5-24kWHrs/day.

I have 8 8L16 370AH Deka’s and 10 205W panels. I use 60 – 100AH a night (3-5KWH). So I think that’s about 70-75%SOC give or take. IMO these batteries are hard to get to 100%SOC so I probably get them to 90 – 95%SOC most every day. We also use about 2-3KWH during the day. That’s 5 – 8KWH total each day.

My XW bulk and absorb voltage is set to 60.5V, the trimetric shows battery voltage of 49.5 with these settings. I have measured .3V drop @20Amps from all the cables combined. What I am getting at is that I have the voltage set high so my SG gets close to full.

Jeffkruse - thanks for the info. Has using the higher bulk & absorb caused any issues? What is the water usage like? Did you ask Deka about this?

The Deka spec linked below indicates charge voltage of 2.35VPC (56.4V) and float of 2.25V (54V).
http://www.mrsolar.com/pdf/MK_Battery/MK8L16.pdf

What do you have your equalize voltage set at?
How long, and how often do you equalize? The XW6048 can only equalize 1 hour max. I asked Xantrex if I can set it to longer than an hour and they said no but I could change the custom bulk/absorb voltages to equalize level temporarily to do a longer equalize. That seems kind of cheesy. Not sure why they don't just put in a timer option for the equalize button.

Just hooked up the new batteries and charging them now at 60.5V. For the next week or so no solar panels so want to make sure they don't discharge below 50% so trying to make sure the AGS is set up properly.

What is your inverter cut out voltage set at?

I know you said you have grid so not sure if you use a generator. Do you use the AGS (automatic generator start) ?
If so, and if you have the time, would be interested to know how you configured the following?

• Start DCV 30 sec
• Start DCV 15 min
• Start DCV 2 hr

Thanks!

whitestrabbit

Re: New Off Grid System - Please help me make a battery decision!

Equalized today @64V for 7 hrs to get baseline for new batteries. Equalize looked pretty good at 5 hrs, but had two cells at 1.255.
Final batt temp was 87 degrees F. Didn't need to add any water but they were bubbling pretty good.

B1 - 1.260, 1.265, 1.265
B2 - 1.265, 1.265, 1.270
B3 - 1.270, 1.270, 1.265
B4 - 1.265, 1.265, 1.270
B5 - 1.265, 1.265, 1.265
B6 - 1.270, 1.265, 1.270
B7 - 1.265, 1.265, 1.265
B8 - 1.270, 1.275, 1.275

My measurements were taken with a hydrometer I bought for $10 at the auto parts store which was the best one they had labeled professional. It's the floating bulb type. I guess I should get one of these $35 ones on our host site.

I did as Xantrex recommended and set the custom bulk/absorb settings to 64V since the Equalize button only equalizes for 1 hr. Again not sure why Xantrex doesn't put a timer on the equalize button that can be custom set. That sure would be nice so that once I know my equalize is ~7 hours I can just set it for 7 hours and press the button rather than having to go mess with the voltage settings.

Cariboocoot

Re: New Off Grid System - Please help me make a battery decision!

I expect Xantrex does that 1 hour limitation because equalizing for 7 hours straight is not a good idea. That could lead to excess water loss and warped plates from all the heat produced internally. Normally you EQ for an hour, check for improvement in SG, and then do it again. You stop when there's no further improvement.

Don't knock the 'cheap' hydrometer; it seems good enough. It's all in how you use it, and you seem to have done it right! Your cells are within 0.010, and chances are it couldn't be any closer.

You might want to turn that EQ Voltage down a tad; 60 should be enough. Others may have a different opinion.

But you've got good baseline data to reference from now on.

whitestrabbit

Re: New Off Grid System - Please help me make a battery decision!

I expect Xantrex does that 1 hour limitation because equalizing for 7 hours straight is not a good idea. That could lead to excess water loss and warped plates from all the heat produced internally. Normally you EQ for an hour, check for improvement in SG, and then do it again. You stop when there's no further improvement.

Does everyone see the time for equalizations over the months/years are consistent as far as time/temp or do they vary alot. For instance I checked every 1-1.5 hours and called it good at 7. Do I really need to check every time I equalize every hour or is it pretty consistent? Especially since my temp was not very high. The problem with the Xantrex button in my experience is that I don't feel like having to set a 60 minute timer. I end up going back 90 minutes later not knowing how long the equalize has stopped for. So instead of 7 straight hours it becomes 1 hr EQ, 20 mins off, 1 hr EQ, 10 mins off, 1 hr EQ, 30 mins off, etc. This doesn't seem ideal.

Also, I know you are supposed to equalize with no loads. I did it with a load of about 300W so the family could watch tv but nothing else. It seemed to work fine. Any issues with this?

Don't knock the 'cheap' hydrometer; it seems good enough. It's all in how you use it, and you seem to have done it right! Your cells are within 0.010, and chances are it couldn't be any closer.

Just ordered a Brady off our host site a few minutes ago! Have to calibrate to my cheapo. Wonder if it's any easier to use... and if I just wasted $37!

Cariboocoot

Re: New Off Grid System - Please help me make a battery decision!

You'll find you don't need to equalize so much if your recharge is good - especially with enough current rate to keep things mixed.

Equalizing with a load can be less than perfect, because some of what you're putting in is going right out again. You may not really be getting your full EQ Voltage at the batteries, as load demands shift and put both Voltage and Amperage off. A 12V system will suffer more from this than a 48V will.

You haven't wasted money on the hydrometer; you've just bought a good quality unit that will be accurate for years. Mine was $5 from Princess Auto and is somewhat suspect as to its quality! But it can do the job with a bit of artistic interpretation.

BB.

Re: New Off Grid System - Please help me make a battery decision!

Also, remember that equalization of flooded cell batteries is done after the battery bank is fully charged--so you are trying to get the last 5-10% difference in cell to cell specific gravity back to matching (over charging some cells to top off other cells in series that are not 100% charged). Assuming you are at the recommended 5% rate of charge (20 hour capacity), then an hour or two should be enough.

Lots of equalization time / energy is hard on the batteries too (cause positive grid corrosion, possible plate erosion, loss of water, etc.).

-Bill

jeffkruse

Re: New Off Grid System - Please help me make a battery decision!

I noticed an error in my post. I set my Bulk/Absorb Voltage to 60.5V and my Trimetric shows 59.5V during the Absorb. I know I have .3V drop @20A in all the wiring. All I can figure is the XW algorithm accounts for the other .7V and that might change with a reduction of current.

I use about a gallon of water every 6 - 8 weeks for the 8 batteries.

My eq is set for 64V but the trimetric shows the batteries only get to 62.1V with the available wattage (about 1000 – 1400W) My EQ can be interrupted by cloud cover because I do it in the afternoon after the batteries have been “charged”.

System2

Re: New Off Grid System - Please help me make a battery decision!

Hi, I have been living off-grid since 1994 and just now I need to get a new battery bank. I currently have the Trojan L16. These have lasted 15+ years. I did not see these on your list. I am leaning toward the Trojan L16RE-B's this time. Does anyone have experience with these??? Thanks...

Cariboocoot

Re: New Off Grid System - Please help me make a battery decision!

lifelady wrote: »

Hi, I have been living off-grid since 1994 and just now I need to get a new battery bank. I currently have the Trojan L16. These have lasted 15+ years. I did not see these on your list. I am leaning toward the Trojan L16RE-B's this time. Does anyone have experience with these??? Thanks...

If you got 15+ years out of your Trojan L16's then:
1). Your system must be perfectly set up
2). Why consider anything else?

Keep in mind the L16 'B' is slightly higher Amp/hrs than the L16 'A' - 50 Amp/hrs more. Before you go with the higher capacity, make sure you have enough PV & controller to handle it; depending on your total bank size 50 Amp/hrs could add up to a significant difference across parallel batteries.

niel

Re: New Off Grid System - Please help me make a battery decision!

lifelady,
it certainly sounds as if you did things right to get that kind of life from your l-16s. as was mentioned if going to the b model that you can charge them within their 10-13% charge range trojan specs.
one more thing to mention and that is for you to be prepared for sticker shock. i'd be curious what you paid per l-16 back then?

Dave Angelini

Re: New Off Grid System - Please help me make a battery decision!

Take a look at Surrette also. My personal experience with L16's over 30 years now is that the Trojans made recently are not what they use to be. Quality control and gas leaks near the terminals. The 2 volt L16 they came up with has my award for new dumb product of the year when you compare with Surrette's
model.

whitestrabbit

Re: New Off Grid System - Please help me make a battery decision!

I currently have the Trojan L16. These have lasted 15+ years. I did not see these on your list.

I got quotes for Deka L16 and Surrette L16 and saw prices for Trojan online but never got a bid. My understanding was Surrette had the reputation for the highest quality/longevity, with Trojan second. Prices showed Surrette highest, Trojan middle, Deka lowest. However, in talking to solar installers and battery distributors, and reading online I found people have Deka L16s in service more than 7 years - the same as many Trojans/Surrettes. The Surrette warranty is better but I don't put much stock in warranties. I read instances online of Surrette not honoring the limited warranty claiming failure was due to improper maintenance. Local installers/distributors indicated their experience was Dekas, Trojans, Surrette L16s were all comparable in years of service for the same installation and maintenance. Don't know how true this is since it's anecdotal evidence, but ultimately for a price of $137 each for the blemished Deka 8L16 I figured I'd take my chances. Local distributor price for Surrette was $299 each. I assume Trojan would be somewhere in the middle.

8 Deka L16 + tax = $1,200
8 Surrette L16 + tax = $2,613

And there is the time value of money aspect.
For the sake of argument, let's assume Dekas last 6 years, Surrette 12 years:
Deka price today = $1,200
Deka replacement bank year 6 @ 3% inflation = $1,200 * 1.03^6 = $1432
Total Deka price for 12 years = $2,632

Surrette price adjusted for Time Value of Money @ 8% Invested Interest
$2,613-$1,200 (Deka Yr 1) = $1413 * 1.08^6 = $2,242 - $1413 = $829 lost investment return
$2,613 + $829 = $3,442 Surrette cost adjusted for time value of money at year 6

Deka's are cheaper by $810 for same 12 years of life based on these assumptions
Of course you can play with these numbers and the life spans aren't guaranteed.
Based on the feedback I got from solar installers, and dealers I'd rather have the cash in my pocket than rely on the more expensive battery lasting 2-3x as long.

Your Trojans lasted 15 years so if I were you I'd buy that exact same battery if possible!

whitestrabbit

Re: New Off Grid System - Please help me make a battery decision!

I should point out my numbers are based on blemished Deka batteries vs unblemished Surrettes. I was quoted $199 for a new Deka 8L16. Here is that comparison.

8 Deka L16 + tax = $1,739
8 Surrette L16 + tax = $2,613

And there is the time value of money aspect.
For the sake of argument, let's assume Dekas last 6 years, Surrette 12 years:
Deka price today = $1,739
Deka replacement bank year 6 @ 3% inflation = $1,739 * 1.03^6 = $2076
Total Deka price for 12 years = $3,815

Surrette price adjusted for Time Value of Money @ 8% Invested Interest
$2,613-$1,739 (Deka Yr 1) = $874 * 1.08^6 = $1,386 - $874 = $512 lost investment return
$2,613 + $512= $3,125 Surrette cost adjusted for time value of money at year 6

Surrette is $690 cheaper

icarus

Re: New Off Grid System - Please help me make a battery decision!

I want to know where you are likely to invest at ~8% (with any security) in the current environment? LOL!

whitestrabbit

Re: New Off Grid System - Please help me make a battery decision!

I want to know where you are likely to invest at ~8% (with any security) in the current environment? LOL!

True enough! 8% return is just about as likely or unlikely as counting on 12 years from a Surrette!

Really, that's the whole problem with trying to select a battery bank is none of the specifications are reliable. I don't recall ever having to make such a large purchase with so little reliable information. Ultimately I guess I chose my battery bank the same way I choose my cars. Choose a decent quality product with as little cash up front as possible and don't rely on the warranty.

My wife and I have owned probably 10 cars in the last 10 years between us. Nine of them were used cars over 5 years old. In 2000 I splurged and bought my wife a shiny new 2000 VW Beetle she dreamed of with a full "warranty". We paid more up front for the supposed security that a warranty and new vehicle offers. The car was in the dealer shop 21 times (no joke) before we sold it. Each time at the dealer was a painful multi-day ordeal, much more so than our private mechanic we've used for years who gets us in and out cheaply in hours anytime with no appointment and 1/3 the cost. The 21st issue was bad rear wheel bearings at 8k miles at 1.5 years old. VW said it was not covered under the 100k mile limited warranty as it was a "wear item". I argued to no avail that I have never had a car with worn out wheel bearings and my cars have mileage up to 160k miles. This car had 8k miles! Dealer wanted $2k to fix the bearings. Got it done for $700 at our mechanic and sold the car immediately at a $10k loss and bought a used Chevy with no warranty that we drove for 3 years with no major issues and sold for $1k less than we bought it. Haven't bought a new car since and probably never will again.

Anyways, I personally have no faith in limited warranties, no offense Surrette. Thus I went for the $137 blemished L16 with a decent reputation. I'd rather keep the cash in my pocket and save myself the frustration of an un-honored warranty.

But, if you have good luck with warranties the Surrette may be the right choice for you. It's clearly a high quality product with a good reputation.

icarus

Re: New Off Grid System - Please help me make a battery decision!

I hear you about warrantees, In my case, I buy nearly everything used so it isn't much of an issue. That said, our 99 Subaru was 1500 miles out of warrantee (bought used) when my good local mechanic suggested the knocking wasn't normal, and it needed an engine. Subaru took one listen and said, yes, installed a new short block, along with a new head. I paid for the timing belt, to preclude having to do it 40k later. 125k miles later and it is still going strong.

On the battery subject. I made the choice to buy the cheaper batteries (T105s vs l-16) as I calculated if the t-105s lasted 5 years, and the l-16s 8, the t-105s would be cheaper per wh over the expected lifespan. (of course if the t-105s quit in 5, but the l-16 lasted 10, then I made the wrong choice,, but calculating the time value of the money, still makes the choice the better one IMHO.

Tony

niel

Re: New Off Grid System - Please help me make a battery decision!

wow!
note to self,
do not buy a vw be it new or used.;)

Dave Angelini

Re: New Off Grid System - Please help me make a battery decision!

My bias on the Surrettes has nothing to do with pricing and I never have to worry about warranty because of the way I use them. If I did have a problem, my dealer would take care of it. That said, I would have to do the labor and move the batteries which is the reason I use Surrettes.

Once had a VW that I painted the engine cherry red and sold it to a hippy. I thought it was on it's last legs but he drove it for years...

Ponytails

Re: New Off Grid System - Please help me make a battery decision!

whitestrabbit wrote: »

Well, I ended up buying 8 blemished Deka 8L16s. These are supposedly brand new batteries. Only thing I could tell as far as blemish is the terminals are a little crooked. Couldn't pass up the price for what seems like a decent quality battery. $1200 for 8 including tax or about $137 each + tax. I will see how it goes once we get the solar panels installed in and possibly get 8 more if overnight DOD is too large. Hoping to get the hydro up and running next winter so maybe 8 L16s will be enough. Our creek is still running strong a week after the last rain and 6 days of sun so I think it's a solid power source. Also spoke to a few micro-hydro turbine vendors and they felt we have a good application. You can switch out the nozzles on the turbines as stream flow varies and realistic output for our head/flow seems to be in the range of 5-24kWHrs/day.



Jeffkruse - thanks for the info. Has using the higher bulk & absorb caused any issues? What is the water usage like? Did you ask Deka about this?

The Deka spec linked below indicates charge voltage of 2.35VPC (56.4V) and float of 2.25V (54V).
http://www.mrsolar.com/pdf/MK_Battery/MK8L16.pdf

What do you have your equalize voltage set at?
How long, and how often do you equalize? The XW6048 can only equalize 1 hour max. I asked Xantrex if I can set it to longer than an hour and they said no but I could change the custom bulk/absorb voltages to equalize level temporarily to do a longer equalize. That seems kind of cheesy. Not sure why they don't just put in a timer option for the equalize button.

Just hooked up the new batteries and charging them now at 60.5V. For the next week or so no solar panels so want to make sure they don't discharge below 50% so trying to make sure the AGS is set up properly.

What is your inverter cut out voltage set at?

I know you said you have grid so not sure if you use a generator. Do you use the AGS (automatic generator start) ?
If so, and if you have the time, would be interested to know how you configured the following?

• Start DCV 30 sec
• Start DCV 15 min
• Start DCV 2 hr

Thanks!

So where or how do you get blemished batteries? or slight defects? I may be interested in checking it out.