Author Topic: New battery bank, what to buy?  (Read 6491 times)

0 Members and 1 Guest are viewing this topic.

Vortechs

  • Newbie
  • *
  • Posts: 45
  • Country: ie
New battery bank, what to buy?
« on: April 27, 2016, 11:38:14 AM »
My battery bank's not holding a charge any more, it's done 11 years so I cant complain. Time to bite the bullet and replace it, but I have no idea what's good these days.

My old bank is 24v, has eight 120 amp/hr Soneshinen's, which would cost 4000 to buy new now - so I'll not be doing that... Been looking at Trojan T105 and Yuasa Pro-Spec, 4 would give me roughly the same capacity. Are these any good, any advice or recommendations? Thanks.


joestue

  • Hero Member
  • *****
  • Posts: 1344
Re: New battery bank, what to buy?
« Reply #1 on: April 27, 2016, 11:02:58 PM »
I was surprised at the Yuasa datasheet listing their batteries as "lead-antimony alloy"

I would be tempted to go with them. you will still have to water them. i wonder how they expect you to do that, they have caps but they are absorbed glass matt batteries.

They are almost the same kilograms per amp hour as the Trojan t105, this is a good thing i suppose. how does it compare to the batteries you have now that have lasted 11 years?


anyhow as you probably know, adding water to an agm battery, there is no provision to mix the electrolyte. diffusion is the only method i can think of, and that's slow. 
« Last Edit: April 27, 2016, 11:14:51 PM by joestue »

Vortechs

  • Newbie
  • *
  • Posts: 45
  • Country: ie
Re: New battery bank, what to buy?
« Reply #2 on: April 28, 2016, 06:29:46 AM »
I didn't realize the Yuasa Pro-Spec's are AGM...

The 8 Sonnenshienen Powerfit Telecom 400, 120AH I have are sealed gel batteries. They were a lucky find in an auction. I have a micro-hydro producing 120 to 400 watts running year round so the batteries have been very well treated. I've never run them lower than 23.5v .

I have a 2.3KW inverter running a whole house- Electric kettle, washing machine, fridge, computers, TV's, power tools etc, so I need a good bank as a buffer.

I would prefer FLA batteries, something you can maintain. I don't mind paying for quality, just don't know what it is these days.

dnix71

  • SuperHero Member
  • ******
  • Posts: 2202
Re: New battery bank, what to buy?
« Reply #3 on: April 29, 2016, 11:33:54 AM »
Find a local Deka or Interstate forklift battery dealer and compare prices. Forklift  "traction" batteries should last longer than any other type of flooded lead acid battery because they have thicker plates and are built to be bounced around.

http://www.ebay.com/itm/24-Volt-Forklift-Battery-600-AH-Reconditioned-Battery-12-100-13-/182080987362 $1500 for a rebuilt with a 1 year warranty. 24v 600ah.

XeonPony

  • Hero Member
  • *****
  • Posts: 679
  • Country: ca
  • Sanity is over rated!
Re: New battery bank, what to buy?
« Reply #4 on: April 29, 2016, 10:06:02 PM »
If you can swing it get a wrecked leaf from a salvage yard, you can sell off the rest of the parts of the car, take the battery pack, you'll need to spend a couple hundred on a BMS but once that is don you can get a super cheap 24KwH Lithium pack!

After seeing 2 ways people have don that I am going to do that my self
Ignorance is not bliss, You may not know there is a semie behind you but you'll still be a hood ornimant!

Nothing fails like prayer, Two hands clasped in work will achieve more in a minute then a billion will in a melenia in prayer. In other words go out and do some real good by helping!

madlabs

  • Hero Member
  • *****
  • Posts: 672
  • Country: us
Re: New battery bank, what to buy?
« Reply #5 on: May 01, 2016, 09:25:02 AM »
Just my .02, so that is what it's worth...

I think to some degree it depends on your usage style. I have 16 cheapo Sam's club golf cart batteries in a series/parallel for 48V. They are all coming up on 8 years old and though they show some signs of age (and have been abused a bit!) they still have at least a couple years left in them.

The thing is that I NEVER let them get below 75% SOC. They get charged daily, if there is sun, great. If not, fire up the genny. The old off grid paradigm was that you should be able to go three days without a charge. If you want to do that you need really good batteries. If you are willing to make sure you keep them charged you can get away with cheaper batteries. I have less $/year invested in my battery bank than any other off grider I know.

Just MHO.

JOnathan

Rob Beckers

  • Full Member
  • ***
  • Posts: 130
  • Country: ca
Re: New battery bank, what to buy?
« Reply #6 on: May 03, 2016, 05:02:18 PM »
Vortechs, the regular T-105 is in essence a golf cart battery (that's how Trojan markets it too), good for maybe 5 - 6 years. If you can swing it, go with the T-105RE. Despite the similarity in name that's a battery for off-grid use and frequent cycling. Good for about 10 years if treated nicely. Very different warranty vs. the T-105 as well.

My personal favourite are Surrette batteries, but I don't know if you can get those on your side of the pond (they are a local brand for us Canadians). People regularly get 12 years out of the 4000-series, and I've personally seen them bounce back from the dead (abuse by customers) more times than I care for. I'm a believer.

-RoB-

Vortechs

  • Newbie
  • *
  • Posts: 45
  • Country: ie
Re: New battery bank, what to buy?
« Reply #7 on: May 05, 2016, 06:57:48 AM »
Thanks for all the suggestions. I'm in a really remote area so dont have a lot of choice unfortunately.

I ended up getting the 4 Trojan T105's, they're so common they're cheaper than anything else comparable. I always treat my batteries really well so hopefully they'll last long enough for me to get my monies worth out of them.

I'm not doing bad so far with batteries. I paid 120 for my present bank in an action 11 years ago, and the scrap value of them now is... 120 :)

Vortechs

  • Newbie
  • *
  • Posts: 45
  • Country: ie
Re: New battery bank, what to buy?
« Reply #8 on: May 06, 2016, 03:52:52 PM »
The batteries arrived today. Pleased with them so far. Will get them hooked up over the weekend.


ontfarmer

  • Full Member
  • ***
  • Posts: 116
  • Country: ca
Re: New battery bank, what to buy?
« Reply #9 on: May 06, 2016, 04:41:06 PM »
You will be happy with them.

Vortechs

  • Newbie
  • *
  • Posts: 45
  • Country: ie
Re: New battery bank, what to buy?
« Reply #10 on: May 14, 2016, 10:59:12 AM »
The new Trojan's are now installed in the battery bank.

What's the best Bulk and Float charge voltage settings for these batteries?

I have a Xantrex C40 charge controller but I cant find the manual.

DamonHD

  • Administrator
  • SuperHero Member
  • *****
  • Posts: 3545
  • Country: gb
    • Earth Notes

madlabs

  • Hero Member
  • *****
  • Posts: 672
  • Country: us
Re: New battery bank, what to buy?
« Reply #12 on: May 14, 2016, 06:45:32 PM »
Here is a link with great battery info: http://batteryuniversity.com/

I have my controller (for golf cart batteries) set for 14.4 and 13.8

Jonathan

Vortechs

  • Newbie
  • *
  • Posts: 45
  • Country: ie
Re: New battery bank, what to buy?
« Reply #13 on: May 15, 2016, 04:16:51 AM »
Thanks, the online manual is much more detailed that the one I had.
For bulk & float charging It says:

Deep-Cycle, Liquid Electrolyte Lead Antimony Battery:
Bulk: 14.6 (29.2) Vdc
Float:13.4 (26.8 ) Vdc
Equalizing Charge to 15.5 (31.0) Vdc or per battery manufacturer.

The Trojan website says:

Charger Voltage Settings for Flooded Batteries:
Daily Charge 14.8 (29.6)   
Float 13.2 (26.4)
Equalize 15.5 (31.0)

Should I use the C40's Automatic Equalization (every 30 days for 2 hours) or Manual ? I've always had sealed gel batteries so never had to do it before.
« Last Edit: May 15, 2016, 07:39:10 AM by Vortechs »

Simen

  • Sr. Member
  • ****
  • Posts: 416
  • Country: no
  • Grimstad, Norway
Re: New battery bank, what to buy?
« Reply #14 on: May 15, 2016, 04:38:29 AM »
Most manufacturers specify the charging voltages at a given temperature - normally at 25C/77F. to compensate for colder climate/bank, it's usual to add 0.005 V per C per 2 V cell, or 0.028 V per 10F per 2 V cell. For hotter climate/bank, subtract. :)

If your charge controller do temperature compensation, it's best to have an external temperature sensor from the controller connected to the bank.
I will accept the rules that you feel necessary to your freedom. I am free, no matter what rules surround me. If I find them tolerable, I tolerate them; if I find them too obnoxious, I break them. I am free because I know that I alone am morally responsible for everything I do. - (R. A. Heinlein)

Rob Beckers

  • Full Member
  • ***
  • Posts: 130
  • Country: ca
Re: New battery bank, what to buy?
« Reply #15 on: May 15, 2016, 10:42:28 AM »
...

The Trojan website says:

Charger Voltage Settings for Flooded Batteries:
Daily Charge 14.8 (29.6)   
Float 13.2 (26.4)
Equalize 15.5 (31.0)

Should I use the C40's Automatic Equalization (every 30 days for 2 hours) or Manual ? I've always had sealed batteries so never had to do it before.

Vortechs, the best investment you can make is to get a decent hydrometer so you can keep an eye on the specific gravity values of each cell (keep a log), in particular after a 100% charge when SG is a great indication of battery health. Personally I love one called "HydroVolt" from a Swiss company named Compaselect; they are cheap, very easy to use and read, no mess, build-in temperature compensation, and very very accurate. They look a little different from the usual 'turkey baster' type, the guy that designed it had a really good idea with this one.

If you keep a log of specific gravity values after a full charge you can see if and when you need to equalize the battery bank. Over time the cells of a bank tend to drift apart, some reach 100% charge a little earlier than others and after weeks or months some cells may be lagging. That is when you equalize. For customers that we know are relatively clueless about batteries I normally set up the charge controller to auto-equalize once in 3 months, just so all the cells get pulled back in line every now and then.

Having a battery log is also extremely helpful if you ever have to make a warranty claim with the manufacturer. Cells sometimes do go bad for no particular reason, and if you can show a log they take you a heck of a lot more serious when you make the claim. I would advise topping up (distilled) water once a month until you have a feel for what they need, and taking SG readings once in two months, and writing those down.

Unless your batteries are in a spot where they see a fairly constant temperature year around, it is important to have a temperature sensor mounted on one of them, and a charge controller that knows how to do auto temperature compensation (as Simen mentioned). The difference can be pretty large: Over here a bank that's outside in an insulated box can see -10C in winter (when it's -30C outside), and for a 24V bank that would take the bulk/absorb Voltage up a full 2.1 Volt!

The Voltages I generally use for flooded Trojan & Rolls/Surrette batteries is a little bit higher than the manufacturer's values. IMO it helps to keep them de-sulphated a little better, and make it more likely for them to see a full 100% charge on a regular basis. The trade-off is slightly higher water use:

Bulk/absorb = 29.8 Volt
Float = 26.3 Volt
Equalize = 31.6 Volt for 2.5 hour

For the absorb time, how long it should keep the batteries in absorb, I use Rolls' equation; Absorb Time = 0.42 x Capacity / Current
Where 'Capacity' is the 20 hour Ah rating of the bank, and 'Current' is the charge current you have available. The result is in hours, and usually quite a bit longer than people expected (yes, with fairly feeble charging sources it can take a long time to get through absorb).

There are other strategies to determine when absorb is over, such as measuring the Amps going in and cutting off when it falls below this 'End Amps' setting, but time is reliable and works well for the most part.

If there is another charging source, such as an inverter that can use a generator to charge the batteries, I set the absorb Voltage lower to save on (fossil) fuels. For those chargers I use 29.4 Volt (as long as there is also solar or wind available to charge!).

Wait with watering the batteries until they are being charged and are bubbling vigorously; that will help overfilling since the acid is already at it largest volume (warm and full of bubbles). Watering them when they are cold and not doing anything runs the risk that acid comes pi$$ing over when they are charging. During an equalize is a great time to water!

To get long life out of your batteries it helps to know how people kill otherwise good batteries in short order (and avoid that). The no. 1 way we see people put new batteries in the grave well before their time is by letting them sit at partial charge for long periods of time. Lead-acid (flooded or AGM) MUST, absolutely MUST see a full 100% charge once in (ideally) two weeks, or once a month at the outset. A FULL charge means going all the way through bulk, absorb, and absorb time until they are as full as they are going to get (an SG of around 1.265 is 'full' for batteries in good state).

The reason for this is in the chemistry: A full battery has lead on the negative and lead-oxide on the positive plate. During discharge both are turned (in part) into lead-sulphate. The dreaded 'sulphating'... This is not a problem because that lead-sulphate is initially in a state where it can readily be turned into lead and lead-oxide again, as long as it's done soon enough! Let it sit, even if that battery is sitting at nearly full, and lead-sulphate grows as crystals, much like the salt-crystals kids grow, they get larger over time. It does no longer reverse as readily in that state, or at all if enough of the plates is covered. Lead-sulphate does not disolve in water or sulpheric acid, and it does not conduct electricity. Those sites of the plates covered in lead-sulphate are dead for the world as far as the battery is concerned. They do not participate any more in the reaction.

By the way, this is also what you are measuring with a hydrometer. The chemical process that produces lead-sulphate uses up sulpheric acid, turning it into water. The less sulpheric acid, the smaller the specific gravity, the nearer it gets to just water (SG = 1). So, if after charging part of that lead-sulphate did not reverse back into acid and lead/lead-oxide it means the SG will not bounce back to that of the straight acid as it was put into the battery, and your SG reading will show this.

The no. 2 reason people euthanize otherwise good batteries is by discharging them completely. It may seem straight forward, but it happens more often than I'd like to see, mostly by accident. There are reasons for this. Some very well-known inverter manufacturers have absolutely dreadful battery cut-off Voltages set out-of-the-box. Way to low, and at a point where they do damage. LVCO (Low Voltage Cut Off) should not be below 22.2 Volt! That corresponds to just about 80% DOD (Depth Of Discharge) under load. Deep-cycle batteries are great at handling anything up to 80% DOD, but not so great once you go beyond. Combine a deep, deep discharge with letting them sit over the winter and you get the picture. Dead batteries (and I had a lady on the phone in tears not all that long ago who did just that, killing a brand-new $10,000 AGM battery bank in the process!).

My suggestion for those with a substantial investment in batteries is to buy a MidNite Solar MNBCM. They are not very expensive, and show the approximate state-of-charge at a glance. They are (nearly) idiot-proof, no training is needed to be able to read them (put a 1A automotive fuse in the positive line before connecting to the batteries so you don't burn the house down!). They are not very accurate, but will give you an idea of "what's left int the tank", to help determine if those 3 loads of laundry are a good idea at that time or not. What makes them worth every penny is that they have a little red LED that comes on when the batteries did not see a 100% charge in the last two weeks. When that LED lights up you know that unless there's lots of sun in the forecast it's time to fire up the generator.

That's it. All you need for a long and happy battery life!
This story got a bit longer than I intended. Hope it helps!

-Rob-


Vortechs

  • Newbie
  • *
  • Posts: 45
  • Country: ie
Re: New battery bank, what to buy?
« Reply #16 on: May 16, 2016, 11:24:57 AM »
Thanks Rob & Simen. I really appreciate the advice.

Just ordered the Compaselect Hydrovolt.

I live on the west coast of Ireland where the temperature range is usually only 0*C to 25*C. My battery box would only see 0 - 20*C as it's in north facing shade.  Do you think it would still be worth my getting the sensor?

I looked at the MidNite Solar MNBCM battery monitor, but I already have a pretty good system set up. I have a big red LED volt meter on the wall in my house that shows me the battery voltage at a glance - I probably look at it 20 times a day. Knowing the float and bulk voltage settings I can see how often the battery reaches a full charge. My dump load is a 600W element in an oil filled radiator also in the house, so I know when the controller is dumping.






DamonHD

  • Administrator
  • SuperHero Member
  • *****
  • Posts: 3545
  • Country: gb
    • Earth Notes
Re: New battery bank, what to buy?
« Reply #17 on: May 16, 2016, 12:14:37 PM »
I took advice to get a remote sensor for my similar-ish size bank.  Why not spend a few percent of the cost of the bank on a sensor to help avoid the bank being ruined on temperature differences between battery and controller, or more positively to help ensure optimum charging?

Since the temperature range you are expecting suggests ~125mV movement in set points, which is about 20% of the usable capacity, measuring the voltage accurately may well not be enough to look after the bank fully.

Rgds

Damon
« Last Edit: May 16, 2016, 12:19:08 PM by DamonHD »

Rob Beckers

  • Full Member
  • ***
  • Posts: 130
  • Country: ca
Re: New battery bank, what to buy?
« Reply #18 on: May 16, 2016, 06:29:30 PM »

I live on the west coast of Ireland where the temperature range is usually only 0*C to 25*C. My battery box would only see 0 - 20*C as it's in north facing shade.  Do you think it would still be worth my getting the sensor?


Hi Vortechs,

Officially the temp coefficient is -4 mV/C (and that's per cell). So, in your case the maximum you could be "off" is 25 x 12 x 0.004 = 1.2 Volt without temperature compensation. In practice this is the outlier for your case, most of the time it won't be that much. If you have a charge controller that can handle a temperature sensor and apply compensation I'd suggest getting a temp sensor. Ad Damon suggests they are cheap enough.

If you happen to have a charge controller that doesn't do temp compensation don't sweat it. I've sold many batteries and controllers without, and the owners are happy with the results, in particular if you keep an eye on the state of your batteries with a hydrometer so you can intervene with an equalize charge if needed (the risk without temp compensation is not overcharging, it's chronic undercharging during the cold part of the year).

In the bigger scheme of battery things there are much, much worse sins than not having temp compensation...

-Rob-

kitestrings

  • Hero Member
  • *****
  • Posts: 700
Re: New battery bank, what to buy?
« Reply #19 on: May 18, 2016, 01:16:57 PM »
Rob's offered some really sound practical advice here, as have others.  Back when I worked on other peoples systems (besides our own) the most common problems seems to be neglect, where a bank was sold to folks who came north for a few months in the summer; and/or being left partially charged in cold temps.  Leaving them unattended and unexercised is not healthy at all for the bank.  The other, and I've fallen victim to this one, is letting the water get too low, particularly in warmer temps and/or under higher loading.  It is just easy to get busy and neglect the routine maintenance.

I would just offer one other thought, which is to keep the connections clean and/or protected.  Particularly with parallel strings if you develop a bad connection it only works the other string to compensate for the added resistance.

I like the looks of this hydrometer that Rob pointed to -  Midnight Solar seems to be marketing one like, or perhaps it is this one(?)  We sprung for a refractometer a few years ago.  Definitely more expensive, but very precise.  I take a few small eye/ear-droppers and a pill organizer to the basement, collect my samples and then test and record the results at the kitchen table.  As I get older the pill organizer might have a second function I suppose.

Good luck,  ~ks

Rob Beckers

  • Full Member
  • ***
  • Posts: 130
  • Country: ca
Re: New battery bank, what to buy?
« Reply #20 on: May 19, 2016, 05:25:10 AM »
Kitestrings, yes, Midnite's hydrometer is indeed the Swiss HydroVolt. If you happen to be north of that border, we also have them, saving yourself the customs/brokerage rip-off of packages crossing the border.

I did compare one to an accurate refractometer, and found the HydroVolt to be absolutely bang on. Really surprising for something that simple to work so well.

At the end of the day, it doesn't matter too much what hydrometer or refractometer people use, as long as they do use one, and make it a habit to take readings on a regular schedule (every 2 months seems about right). For many there's thousands invested in their battery bank, and a hydrometer really is the only way to 'see' what's going on inside (and take action when it is needed).

While I don't live off-grid personally, we do have an electric forklift and I use a hydrometer to keep track of its battery (I'm probably the only one in the world doing that  :o). It alerted me to the fact that SG values were steadily dropping over the months, meaning our charger was not quite topping them off well enough (for one it did not have an equalize function). I swapped out the control board in the charger, adding equalization in the process, did a couple of equalize cycles and all is well again. Without a hydrometer, and actually using it, I would have wondered two years down the road why my forklift batteries were already doing so poorly (and a replacement is about $6K for those batteries).

-RoB-

DamonHD

  • Administrator
  • SuperHero Member
  • *****
  • Posts: 3545
  • Country: gb
    • Earth Notes
Re: New battery bank, what to buy?
« Reply #21 on: May 19, 2016, 10:40:58 AM »
(Some of us are cowards and have sealed batteries so that we don't have to deal with such grown-up monitoring!)

Rob Beckers

  • Full Member
  • ***
  • Posts: 130
  • Country: ca
Re: New battery bank, what to buy?
« Reply #22 on: May 19, 2016, 02:11:27 PM »
DamonHD, nothing to be ashamed about. As with much in life the question of flooded (non-sealed) vs. AGM (sealed)  is a trade-off. It's important though for people to know what trade-offs they are buying into, and I've found that - well - lacking.

In an ideal world we would all have sealed batteries with zero maintenance, and complete disregard for state-of-charge, last time they were charged etc. We're not there yet. For those who wonder about Li-ion, they're an improvement, but not the great solution to all our battery problems either (consider that the Tesla Powerwall, while the cheapest Li-ion battery I've seen so far, is still 3x to 4x the price of lead-acid per kWh of usable storage, and that's without the absolutely needed battery management system for Li-ion).

So, sealed lead-acid batteries (gel or AGM) buy you zero maintenance. You can stick them just about anywhere you want, never any battery fumes. They are more frost-proof vs. flooded lead-acid (to a point). That comes at a price though: They cost nearly twice as much, and last just about half as long as flooded lead-acid. Especially that last part is something to note, this is not a coincidence: With flooded lead-acid you can monitor what's going on inside by measuring the specific gravity, and take action through equalizing when cells start to drift apart or sulphating occurs. With sealed batteries you cannot do that. There's nothing to tell you what's happening inside, and equalizing is a no-no, since it lets the magic juice out (that you can't put back in).

With flooded lead-acid batteries you HAVE to do some maintenance. Water levels should be checked and kept in check (dry plates is very bad!). Specific gravity should be measured and logged, though I dare to say that most off-grid people do not do this (they should though!). The advantage of flooded batteries is that you CAN equalize them when it is needed. It is easier to correct problems than with sealed.

Sealed and flooded lead-acid suffer from the same limitations when it comes to the need for a full 100% charge every couple of weeks. Sealed batteries will sulphate just as much if they are left sitting at partial charge for too long, and now you can't equalize them to undo that. They too can't be discharged too far, 80% DOD really is the limit for both types, or you run the very likely risk of permanent damage.

I know many that have sealed batteries and are very happy with them. They keep a close eye on them, make sure they get charged regularly, and make them last a long and happy life that way. Part of this has to do with properly sizing the battery bank: Too small a bank vs. what is coming in through solar or wind and you're perpetually fighting to keep those batteries charged, making it more likely that they sit too long at partial charge, resulting in sulphating etc.

My 2 cts on sealed batteries...  :D

-Rob-

oztules

  • Hero Member
  • *****
  • Posts: 1469
  • Country: aq
  • Village idiot
Re: New battery bank, what to buy?
« Reply #23 on: May 20, 2016, 03:32:39 PM »
Unless you have to worry about weight or fumes, I still think FLA is the best way to go. Rob has pointed out why, and I agree with him.

The best BMS in the world wont help you when it fails... and it will fail sooner or later, and you cant recover from it with most technologies other than FLA

With FLA you cant recover from stupidity ( what water???...), but mostly can recover from equipment failure ( over charge from fet shorting out etc).

Not sure I like to go 80% DOD, but my solar to bank sizing allows the bank to always recharge each day, and big enough to stay between 0-20% DOD.

My reverse osmosis makes up to 1000l/day of 0-1 ppm water... so I am happy to have a bit of boiling every day to move the acid around the place and avoid striation.

FLA may not be sexy any more, but still the best for of grid applications with few reservations.


................oztules
Flinders Island Australia

thirteen

  • Hero Member
  • *****
  • Posts: 977
  • Country: us
  • Single going totally off grid 1,1, 2013
Re: New battery bank, what to buy?
« Reply #24 on: May 20, 2016, 10:02:03 PM »
Anyone here been involved in salt batteries? I just read a small add for them. ?? 13
MntMnROY 13