Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: Pord on September 18, 2017, 12:27:39 PM



Title: Trojan, Crown or Powerline?
Post by: Pord on September 18, 2017, 12:27:39 PM
Afternoon folks

I'm currently putting together an offgrid PV system. I just have the batteries to buy and I would really appreciate your thoughts on which to choose.

The system is 1kw 24v, 4 x 250w panels with Victron kit. I want a battery bank of 200ah minimum, giving us 2 to 3 days hold over (our needs are very low). This will power our static caravan while we build an offgrid house.

This will be my first PV and battery system, so will be something of a trainer set. I've narrowed my choices to:

Trojan T105 (565)
Crown 27DC105 (510)
Powerline T105 AGM (525)
Powerline T105 FLA (490)

Prices are inc VAT and delivered.

Has anyone experience of Powerline (made by Trojan apparently)? Are the AGMs worth the bit extra? Every penny is a prisoner, so any saving is welcome.

One last question - is there a definitive reference book/manual on basic battery maintenance?

Thanks.



Title: Re: Trojan, Crown or Powerline?
Post by: Scruff on September 18, 2017, 12:48:09 PM
Crown CR-220 FLA 6v x4

Are the AGMs worth the bit extra?

Absolutely not. They're non spillable, non serviceable designed for safety on boats and aircraft and found popularity by means of being reassuringly expensive.
Flooded batteries will last 3 times longer. Give you more power per cycle, charge faster and forgive you for over-voltage & over-charge.


One last question - is there a definitive reference book/manual on basic battery maintenance?


Not really but I can write one.

Get battery, charge it to specific gravity 1.275 per cell once every 3 weeks...aim for once every week. Refrain from discharging below 50% state of charge but design the system to use only 10% capacity per day.

Charge to 29.6V + temperature compensation absorption.

When you buy a charger and find it doesn't charge your battery to 1.275 per cell, chuck it in the bin and get something better (have a very large bin on standby). If the charger you are buying doesn't have a 29.6V setpoint don't buy it.

Add water as needed. Never expose the plates to air and only top up electrolyte when the battery is fully charged.

Get a shunted battery monitor for the system that displays state of charge as a percentage.

The end.


Title: Re: Trojan, Crown or Powerline?
Post by: DaveSnafu on September 18, 2017, 07:03:59 PM
What he said.


Title: Re: Trojan, Crown or Powerline?
Post by: offthegridandy on September 18, 2017, 08:16:29 PM
Or here's a place to go and get a lot of homework/reading.  http://batteryuniversity.com/

Andy



Title: Re: Trojan, Crown or Powerline?
Post by: RIT on September 18, 2017, 08:27:48 PM
One thing you do not say is how long you expect to stay in the static caravan or if you expect to continue to use/expand the storage solution once you are able to move into the house.

These values are likely to have a major impact on how much you should invest in the setup.


Title: Re: Trojan, Crown or Powerline?
Post by: Pord on September 19, 2017, 08:53:37 AM
Thanks all.

We reckon we'll be in the static for 2 years. After that we'll either incorporate some of the pv kit into our larger system for the house or use it elsewhere on our site such as a workshop or bothy. These batteries are primarily a shorter rather than longer term purchase.

Has anyone any experience at all of Powerline? On paper the T105 gives best value.


Title: Re: Trojan, Crown or Powerline?
Post by: Scruff on September 19, 2017, 12:44:38 PM
CR-220s are better batteries than T-105s


Title: Re: Trojan, Crown or Powerline?
Post by: Pord on September 19, 2017, 09:54:58 PM
Thank you Scruff, really great to have very definite advice. The CR-220s have been ordered, at a good price too. I'm on target for a sub-1500 1kw system with 220ah battery bank.

To be honest, though, most off your beginner's guide to battery maintenance advice may as well have been written in Urdu. I realise this stuff is second nature to you, but at this stage it's anything but to me. I've come to realise that this is the great challenge to people like me who aspire to (and indeed are living) an offgrid lifestyle. The technology is still frankly intimidating, and seems to require quite a high level of technical knowledge. It reminds me of the early days of computing, compared to now when we switch on a tablet or smartphone and it just works.

Anyway, on to the challenge of not ruining my lovely new battery bank!





Title: Re: Trojan, Crown or Powerline?
Post by: Scruff on September 19, 2017, 10:08:10 PM
If you get a Hydrometer, battery monitor and MorningStar controllers you won't go wrong.

I've not been impressed by Victron, the charger I have from them can't do better than SG 1.255
It's been gathering dust beside a Sterling since I bought it.
Yurp pretty steep learning curve but as long as you are getting the battery to 1.275 every few weeks it'll last a decade.

(https://i1348.photobucket.com/albums/p725/Sir_Liamalot/SG%20-%20SOC_zps3vipvh68.jpg)

I try to avoid inverters as much as possible they're system parasites, do as much as you can with truck power supplies and you'll get a much more efficient system.

Put on a cuppa and dig in here (https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/) and here (http://www.smartgauge.co.uk/technical1.html).

Good hunting!


Title: Re: Trojan, Crown or Powerline?
Post by: Pord on September 20, 2017, 10:26:09 AM
Thanks, very much appreciated!


Title: Re: Trojan, Crown or Powerline?
Post by: Scruff on September 21, 2017, 12:14:20 AM
(https://i.imgur.com/KJusjvJ.jpg?2)

Happy CR-235s
Left to fend for themselves onna 150W panel anna TriStar for a week after a month of touring.
 ;D


Title: Re: Trojan, Crown or Powerline?
Post by: Pord on September 21, 2017, 09:40:18 AM
Sounds like a great thing! But what is the 113? The label suggests % charge...

Crowns arrive today. Had to laugh when the seller asked if I have 'lifting equipment' to get them off the lorry.


Title: Re: Trojan, Crown or Powerline?
Post by: Scruff on September 21, 2017, 10:09:29 AM
I've set the TriMetric to L3 Advanced with auto-reset when fully charged set to off and battery efficiency to 100%. This way I can see the meter drift and puekert compensated efficiency.
There's reasons (http://www.smartgauge.co.uk/sgvahrs.html) that no battery monitor is 100% accurate. This way I can see the drift and compensate for cycle depth and duration with reference to specific gravity, water level, nominal operating temperature, average C-rate, charger CC input, resting voltage, battery age & battery health I know exactly where the battery's at.
113% is % charged so 132Ah replenished after a cycle bottoming @ 55% SOC (-110Ah) over a week (since last full charge). Nought I've tried but MorningStar will get my battery to tippy top SOC.

Which leads me to believe that this "you must charge lead acid 100% every week" is a myth rule of thumb. Absolutely you must charge lead acid every week if you use an off the shelf charger that only gets your battery to SG 1.260. How and ever I've not noticed any deterioration in my cells running up to 6 week deep cycles provided I can get them to SG 1.275 on a semi-regular basis.

My battery is freshly (over)watered too, the electrolyte is weaker and it's less efficient but I'm happy to sacrifice performance for a coupla months so I don't have to water them again until Spring.

I reset the meter manually with a button press when I start a new depletion cycle.
This is a direct-drive sunlight powered post.  8)



Title: Re: Trojan, Crown or Powerline?
Post by: Scruff on September 21, 2017, 10:19:46 AM
Crowns arrive today. Had to laugh when the seller asked if I have 'lifting equipment' to get them off the lorry.

Hmmmm...factory fresh premium lead...

(http://i49.tinypic.com/140jcbs.jpg)

They are heavy lumps get a ratchet strap tail and thread it through the handle loops so you don't have to bend your back to move them.
Charge them before you commission them, then take note of an SG reading for a basline and to make sure the fill level is correct (no electrolyte lost in transit).


Title: Re: Trojan, Crown or Powerline?
Post by: Pord on September 22, 2017, 02:25:31 PM
Thanks Scruff. Batteries are safely ensconced and hydrometer on the way in preparation for the next phase. Give it 20 years and I reckon we'll look back on current batteries the same way we now think about steam power...


Title: Re: Trojan, Crown or Powerline?
Post by: Scruff on September 22, 2017, 11:00:45 PM
Steam's what turns magnetic fields in an awful lottov our power stations to this day.  :ballspin


Title: Re: Trojan, Crown or Powerline?
Post by: Pord on October 10, 2017, 04:03:07 PM
Ach, every step brings unfamiliar territory with a new challenge!  Scruff, can I ask for your further help please? 

I've now had the Crowns for around 2.5 weeks. They came fully charged (I'm informed) and I expected to have the panels and kit all connected by now but unexpected delays means this won't happen for possibly another two weeks.  I went to test the SG yesterday but my brand new hydrometer came out the box broken and the replacement won't be here for a couple of days.  I'm assuming they will gradually lose charge and need a top up soon.  I'm assuming my genny would take way too many hours to charge so would the simplest short term option be an off-the-shelf mains battery charger and a favour from a nearby friend with mains power?  Any suggested make or model to choose/avoid? Presumably I could use either a 6v or 12v model, but I don't yet have battery connectors for the 12v/series option and I was waiting for my electrician to bring those (with relevant knowledge).

Thanks...


Title: Re: Trojan, Crown or Powerline?
Post by: offthegridandy on October 10, 2017, 06:56:59 PM
Hi Pord,

I shouldn't worry to much about the stae if charge (SOC).  If they were delivered fully charge, which is normal and are not connected or in use they shouldn't come to any harm for a few eeeks.  You could check the battery voltage if your conncerned. Just put a accurate voltmeter across each pos and neg terminal ideally you'd expect get 2.2V.

Andy


Title: Re: Trojan, Crown or Powerline?
Post by: splyn on October 11, 2017, 12:29:35 AM
I'm assuming my genny would take way too many hours to charge so would the simplest short term option be an off-the-shelf mains battery charger and a favour from a nearby friend with mains power?

Hmm, that could be a problem. Have you used PVGIS to estimate your PV generation and battery useage? If not you really should as it's a fabulous resource:

http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?lang=en&map=europe (http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?lang=en&map=europe)

Select your location on the map and select the Standalone-PV tab. I entered Aberfoyle, 1000W panel, Discharge cutoff limit (%) set to 20% ( ie. the absolute maximum you'd want to discharge to), 24V 220Ah battery, 1000Wh daily consumption and 82 degrees module inclination (for best winter performance). If your location has any shading issues from local topology, trees etc. (which will be much worse in winter of course) then create and upload a horizon file to improve results.

The results estimate that the batteries will be empty on (ie. 80% discharged) on 30% of days in November and 60% in December! You might need the genset rather more than you'd hoped in winter - especially since you don't want to run the batteries down to 20% then leaving them discharged for days or weeks. You will also need to equalize them periodically which will take many hours on the generator. Good luck.

For those who haven't seen/tried it, there is a beta of a newer version available as well:

http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#DR (http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#DR)

This has two big new features: (a) you can select from 4 different databases (2 in the current version) and (b) you can download the solar insolation data for your location for periods between 2005 and 2016 (varies between databases). That allows you to model your consumption and battery state of choice to get more detail than the summaries provided by the online tools. For instance, you could find out the longest periods when the battery gets little to no charge rather than the average over many years.

Select 'HOURLY DATA', select the year(s), slope and azimuth of the panel, select 'Radiation components' and click 'Download csv' to get hourly data for the whole period.

Now the worse news is that the new version of the tool produces even worse results with the default (PVGIS-CMSAF) database. Selecting OFF-GRID, 5280Wh battery, 20% cutoff and 82 degree slope, click 'Vizualize results' and selecting PDF gave 96% of days in December with the battery empty!


Title: Re: Trojan, Crown or Powerline?
Post by: Scruff on October 11, 2017, 01:31:50 AM
Hi Pord,

I'd expect your 6v batteries to be 6.3V from factory. It's not normal for battery handlers to charge batteries and I believe they'll accept an 8 hour charge as you have them.
They're shipped dry. The handler fills them with acid (sometimes incorrectly) level and specific gravity ought to be checked after first charge completion to verify fidelity.

Battery sellers tell me the batteries are inert after this process as no degenerative cycling has taken place there is no upsetting chemistry inside to be transmuted with electricity. Don't worry about storing them the sellar has had them on the shelf for months. You can find the manufacture date in the code ingraved on top.
Chargers I say morningstar or nought...never met another like 'em. I heart them so much I run them as mains chargers too because I'm tired of wasting money on other brands just to say I found one that's fit for porpoise too so I don't sound biased on the subject.
ProNautic make the best mains charger I've tested and it still only cuts a specific gravity of 1.265

You can make links from drilled copper/aluminium flat bar or just use an old set of jump leads replacing the croc clips with automotive terminals for battery interconnects.


 
Notes on drawing..old draft;
PE to DC Ground Bus ought to be 25mm2 (one size smaller than cable on largest fixture) and system could benefit from a dedicated inverter DC Isolator for service work ie. work on the AC system can be carried out in isolation from an operational 24V system.


Title: Re: Trojan, Crown or Powerline?
Post by: Pord on October 17, 2017, 12:29:09 PM
Thanks gents for such great input (again).

Scruff, really appreciate that advice and the wiring diagram. I'm relieved that the batteries will be ok in storage for a wee while yet. I had to put everything on hold to prepare for the visit by Ophelia, including dismantling my workshop marquee before the storm did it for me...

Splyn, thanks for that. Yes, I have done my calcs and had seen that website, although I used the calculators on Michael Boxwell's Solar Electricity Handbook site (as recommended elsewhere on this very forum). I now need to move beyond the theoretical stage if I'm ever going to get to grips with this stuff, hence doing my calcs, taking the plunge and buying the kit. Something odd about the average daily energy production displayed by the jrc site, though. It calculates a max daily average generated of just 800wh even at the peak month of May, which has an average irradiance value of between 4 and 5 and theoretically should give me an average of 4-5kw production.

Regardless, I'll find out the hard way in good time! What is guaranteed is that I'll have more questions...


Title: Re: Trojan, Crown or Powerline?
Post by: splyn on October 17, 2017, 03:53:44 PM
Something odd about the average daily energy production displayed by the jrc site, though. It calculates a max daily average generated of just 800wh even at the peak month of May, which has an average irradiance value of between 4 and 5 and theoretically should give me an average of 4-5kw production.

The panels won't generate any more energy than is actually used (or wasted) thus the daily generation figure shown will be the lower of the actual total generated each day or the energy consumed plus the energy that can be stored in the battery. Thus in May the panels aren't going to produce more than the 800Wh (that I presume you entered as your daily consumption) given that the batteries are going to be fully charged most of the time.

I assume the simulation doesn't account for battery charging losses.