Author Topic: Battery advice request  (Read 2574 times)

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Offline Wolvenar

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Battery advice request
« on: December 28, 2013, 10:51:16 AM »
We will need to replace our battery bank very soon here, and such are shopping around.

I have been looking into NiFe batteries because of their super life plus extremely tolerant of abuse.  My reasons for these particular attributes over efficiency and any other drawback are rather simple. Basically because of rapid onset of health issues. I am not sure how long I will be able to deal with heavy jobs, like moving batteries. I don't want to deal with a bank replacement in 4-10 years. I'm sure my wife wont be to happy about dealing with such either.  I'm trying to set this up so its as fool proof as possible. I want to minimize the failure points. Of course I know there will always be light maintenance and maybe the occasional failed component replacement, but the less the better.

Any which way, Rossw brought to my attention they have a very wide voltage range over their charge cycle. Our current inverter has a range of 17 to 31 volt in its manual, however I have seen it's built in charger equalize batteries at 33.4v. I read that the NiFe batteries have a equalizing voltage of over 38v when setup for a 24v configuration.

So my questions are:

Is there any way to use this battery chemistry with this inverter.

Are there any obvious problems these batteries present?

Would Midnight Solar MPPT(s) play nice with this chemistry?







---EDIT---
 

From the owners manual


NiCad and NiFe Batteries

Disadvantages These types of batteries can be used but are not optimized for the DR Inverter for the following reasons:
• Alkaline batteries, such as NiCad and NiFe types, have a nominal cell voltage
of 1.2 volts per cell. Xantrex inverters and battery chargers are optimized for use with lead acid batteries having a nominal 2.0 volts per cell
(that is, 12 cells for a 24-volt
system and 24 cells for a 48-volt system).
The number of cells required in a battery bank for alkaline batteries must, therefore, be adjusted for a 24- and 48-volt system
(i.e, 20 cells for a 24-volt system and 40 cells for a 48-volt system).
• Alkaline batteries require a higher charge voltage to fully recharge, and drop
to a lower voltage


 Another option for 24 volt (only) alkaline battery banks is to use only 19 cells
instead of 20. Fewer cells allow the battery charger to operate more closely to the
settings used for lead-acid batteries. However, the battery voltage will drop to as
low as 18 volts when discharging the batteries.
Consult the battery manufacturer or supplier regarding system requirements and
battery charger settings for alkaline type batteries.


-------------------------------------------------------------------------------


I am not sure of the listed high scale voltage of the DR as an inverter is limited to the chargers max output, or the components voltage limits. Who knows now if i would get a real and informed answer from Schneider Electric (Xantrax) if I were to call them, but I will give it a shot on a weekday.

If so, I will just have to get an answer from the guys at Midnight if the MPPT works well with the NiFe.
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline tomw

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Re: Battery advice request
« Reply #1 on: December 28, 2013, 01:54:49 PM »
Pretty sure the Midnite Classics can do that battery type.

Try asking Ryan next time you see him in IRC.

Tom
Do NOT mistake me for any kind of "expert".

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24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

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Offline tomw

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Re: Battery advice request
« Reply #2 on: December 28, 2013, 02:53:06 PM »
Wolv;

Ryan says:

Quote
Yes should work just fine. We have a lot of flexibility built in so he should be able to tune the algorithm exactly to the batteries liking.

Ryan

Tom
Do NOT mistake me for any kind of "expert".

( ͡° ͜ʖ ͡°)


24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

I thought that they were angels, but much to my surprise, We climbed aboard their starship and headed for the skies

Offline Wolvenar

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Re: Battery advice request
« Reply #3 on: December 29, 2013, 12:51:55 AM »
Great! part of the problem solved.
Thank you Tom and Ryan
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline Solarnewbee

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Re: Battery advice request
« Reply #4 on: April 30, 2016, 07:20:18 PM »

Good Day Wolvenar,

I see this was posted sometime ago but since I have recently shipped my panels to the Philippines I should be ready to order batteries soon. I am curious what you ended up deciding to purchase in the way of a battery bank. I have since decided that lithium batteries of most configurations is over_price so I am stuck with fel, agm etc etc. Any advice from your experience would be appreciated.I am working on Arduino projects to monitor each battery and input output ac and dc current voltages temperatures inverter status and charging. long road to that part but I believe if I can get the microcontroller to read and take actions like cooling, desulphate, equalization (a reason why I have separate banks of batteries). Any thoughts?

one last thing, I'm ADD like crazy some days and my health and long work hours I am seem at a loss as to post my own topic. is there a "post a topic for dummies" on this sight?

Attaching my wiring diagram, bank 1 is squirrely looking and may or may not be wired right. 3000w on front roof 3000w on rear roof nothing but sky. 2017 plan to double panels and batteries.

Thanks for your help,
Solarnewbee
SN

Any day above ground is a day for potential mishaps

Offline rossw

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Re: Battery advice request
« Reply #5 on: April 30, 2016, 09:19:47 PM »
I have since decided that lithium batteries of most configurations is over_price so I am stuck with fel, agm etc etc.

It's easy to think that, if you compare say 300AH LFP with 300AH of lead-acid.
But when you do the numbers and consider that 300AH LFP is approximately the same "useful working capacity" as 1000AH of lead-acid, the equation doesn't look so bad.

Then, factor in LFPs advantages: higher cycle efficiency, "no maintenance", no gas/venting considerations, about 1/5 the volume, about 1/10 the weight, far "stiffer" in use... I am definately happy I went LFP. My only complaint is that I didn't take the plunge earlier, or buy more. A single 300AH LFP bank is out-performing my old 1000AH AGM bank by every metric I have.

Offline Solarnewbee

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Re: Battery advice request
« Reply #6 on: April 30, 2016, 11:34:55 PM »
Rossw

What price range are the lfp's going for here? Where did you buy yours maybe I can afford factory direct Shanghai.

Thanks
Solarnewbee
SN

Any day above ground is a day for potential mishaps

Offline rossw

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Re: Battery advice request
« Reply #7 on: May 01, 2016, 03:06:40 AM »
At the time, I paid about $0.9 USD per amp-hour of cell. (so, nominally 3.2V) - ie, around $270 per 3.2V/300AH prismatic LFP cell.
If you do the maths, that's a little over $4000 USD for a bank that performs similarly to a 1000AH/48V.

Put another way, to be competetive - your AGM cells would have to be $90 or less per 2V/500AH cell.
Last time I priced them, they were more like $400 USD each (which is why I only had second-hand ones).

Offline lighthunter

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Re: Battery advice request
« Reply #8 on: May 01, 2016, 09:11:03 AM »
I agree with ross, buying lead acid of any type makes you think you have a lot of battery because of size and weight. When it comes to performance, LFP just plain works, no disapointments there. Its like having a perfect battery, similar to the gas tank in your car.

Cheers LH
LH

Offline Solarnewbee

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Re: Battery advice request
« Reply #9 on: May 01, 2016, 08:18:49 PM »
Thanks Guys

I have a best price China Alibaba.com is $162-185usd per 200ah battery and door to door shipping to Philippines $825usd so my 12 lot would be $173.5 average X 12 = $2082usd + $825 = $2907usd shipped. Whereas how many Lfp batts do I need. More math so 3,2v 300ah X 4 in series = 12.8v @ 1200ah/4=300ah?? Rossw Help! I am so used to 12v batts with 6 cells add up parallel halve in series. If I can find Lfp batts at affordable ie under $4000usd with shipping that will give me the ah I want. Typhoon and rainy season is my only concern so I want a few days of reserve. Oztules said grab all the panels you can and batteries to meet your nights and crappy periods and all the rest is just noise.

Rossw if I use 8 3.2v 300ah lfp in series to get my 24v (25.6 nominal) to the inverter(setting my PJ to 26v?) what's the ah for just that set?  I would still like 2 batt banks for maintenance and reserve purposes. If I could get 10 years out the batteries thru constant upkeep and attention thru monitoring that would work for my measly veteran pay I may be living off of in the Philippines if desert storm doesn't catch up to me haha.
edit: removed image
Guys maybe in 10 years some older lithium tech will still be in production and lead acid will be a thing of the past. Maybe.

Thanks for y'alls help

Best regards,

SN
SN

Any day above ground is a day for potential mishaps

Offline rossw

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Re: Battery advice request
« Reply #10 on: May 01, 2016, 08:39:22 PM »
Whereas how many Lfp batts do I need. More math so 3,2v 300ah X 4 in series = 12.8v @ 1200ah/4=300ah?? Rossw Help! I am so used to 12v batts with 6 cells add up parallel halve in series.

LFP is nominally 3.2V/cell, so 4 in series is a "12-v equivalent". 8 in series for 24V, and 16 in series for 48V.
Being SLIGHTLY higher in voltage reduces the current slightly - eg, in my old AGM days, 24 series cells gave me almost exactly 48V, so a 1KW load took 23.2 amps from my batteries (including losses).

With my LFP, sitting at 52V, that drops to 21.3 amps. It may not SOUND like much, but it's a 10% drop in current - which is immediately a 10% increase in amp-hours capacity if you stop and think about it!

Running series/parallel with LFP is exactly the same as with lead-acid, except the higher cell voltage means you only need 2/3 the number of cells to get the desired voltage.

Quote
Rossw if I use 8 3.2v 300ah lfp in series to get my 24v (25.6 nominal) to the inverter(setting my PJ to 26v?) what's the ah for just that set?

8 x 300AH cells in series is still only 300AH


Quote
I would still like 2 batt banks for maintenance and reserve purposes.

Yes, that's still a nice idea. For my money though, I'd rather have two banks run permanently in parallel, but wired such that I could (if I needed to) isolate one bank. Two banks in parallel makes it easier to charge them, and reduces the depth of discharge on each, giving you better battery life.


Quote
If I could get 10 years out the batteries thru constant upkeep and attention thru monitoring that would work

10 years from AGM is probably a big ask IMO, unless you really mollycoddle them. It's not impossible, but it's a big ask.

The LFP are pretty much guaranteed to still hold 80% capacity (or better) after 7 years of discharging to 85% DoD (ie, only 15% left in them) EVERY SINGLE DAY. Your typical AGM probably won't last 6 months under those circumstances.

The trick to long life with lead-acid is to not discharge them too deeply, too often. The downside to that is with a bank big enough to only take them down 20-30% DoD (maximum), is a very big, expensive and heavy bank, that will also take a lot of power to charge properly - which means lots of PV (or generator), big wiring, beefy charge controllers etc.

Offline Solarnewbee

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Re: Battery advice request
« Reply #11 on: May 02, 2016, 12:43:07 AM »
Your awesome Ross thanks.

One other thing is will my moot controlled work well together in parallel?

10 years time span I was thinking about lfp's not lead acid. Just got a quote from China factory $176 to $205 per lfp cell depending on pieces needed. 16 cells for 2-24v banks. Prefer 32 but money will determine.

I repaired an HVAC unit for a guy Saturday out on Johns Island SC and he has 34 panels on the roof and no storage but only pays max $79 a month to the light company down from $350 and up in summer. 3800 sqft house, real nice electric bill.

Thanks again!
SN

Any day above ground is a day for potential mishaps

Offline rossw

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Re: Battery advice request
« Reply #12 on: May 02, 2016, 01:58:56 AM »
I repaired an HVAC unit for a guy Saturday out on Johns Island SC and he has 34 panels on the roof and no storage but only pays max $79 a month to the light company down from $350 and up in summer. 3800 sqft house, real nice electric bill.

Everywhere seems to be different, and each contract seems to vary.
Within 3 miles of me, I have people who are getting:
* paid 66c/kWh fed into the grid
* paid 40c/kWh fed into the grid
* paid 6c/kWh fed into the grid
* paid nothing for power fed into the grid but "use their own power first"

And then, various combinations of the above!

If you are getting paid "net metering" it probably makes little difference how you do it.
If you are getting paid for production at one rate, and paid for consumption at another (like many here are) then it changes HUGELY. If you get paid more per kWh you pump into the network (like, 66c/kWh) and only pay 30c/kWh for power you use, then you are FAR better off to export all your power, put off the washing, dishwasher, electric water heating etc, until night time and sell your "expensive" power, then buy it back when it's "cheap".

If you get paid less for your exported power than your consumed power, you're better off using as much of your power as you can - but NOT just putting everything on at once! Especially if you're on time-of-day metering. Ideally, you would use up to but absolutely no more than you produce at any given time (so peak loads around solar noon when you have most power to spare) but spread your loads out over as much of the production time as possible.

It all changes, depending on your arrangements with the electric company.

In some places, and in some cases, you could make a decent amount of money simply using a charger and charging batteries overnight on cheap power, then exporting it again during the next day when they pay you more for it!

Offline oztules

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Re: Battery advice request
« Reply #13 on: May 02, 2016, 06:29:22 AM »
This is where the island has an advantage.

They claim it costs them over a dollar/kwh... small system ( 300 odd services over 1500sqkm, with too many staff, running diesel generators.
The gov subsidises this so it costs us only 28c/kwh

Because of the massive wholesale cost, they have seen their way clear to give one for one.. at all times..
So feed in is 28c and draw at any time is 28c.... this won't change in future I suspect... unlike the mainland where wholesale is very cheap.

..........ozutles
Flinders Island...... Australia

Offline johna

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Re: Battery advice request
« Reply #14 on: May 03, 2016, 03:26:25 PM »
28 for 28 thats how it should be down here on the small island, it would not cost any body anything you can use the old meter's that are in place., but there greed wont let that happen.They would not have a power crisis now if they were not greedy but they have had it so good for so long  they refuse to see the elephant in the room. It will be there total demise.As more and more people realize how easy it is to produce power. It is sooo easy and cheap now thanks to china.( you don't need any gvment subsidy ) and we have the perfect system with only the hydro. If only we had a decent forward thinking poly.like electric Eric.