navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: 1 [2]   Go Down
  Print  
Author Topic: Two battery banks  (Read 3433 times)
camillitech
Hero Member
*****
Offline Offline

Posts: 5403



WWW
« Reply #15 on: January 31, 2016, 07:21:05 PM »


ok it's not perfect, but joining them into one big bank is your best bet





I'm with Woodi, really bad idea mixing different cells, ages and capacity. I've looked after many battery banks at home and work and mixing them always ends in tears. Especially something like Rolls (I bet Trojans are the same) as they like a much higher voltage than others. My main bank sits around 60V much of the time, don't think that would go down well with other types. Certainly one bank is better than two, but if someone has given you half decent bank then you don't want to turn your new good bank into another half decent one.

 The sane thing to would be to sell the half decent one on eBlag, combine it with the money you would save on an extra inverter and buy more PV or a quieter generator  horror (hides from Billi) However, sometimes it's more fun and a lot more interesting to be a little insane  Grin

I already have a spare Outback inverter/charger and really fancy working on Billi's idea of AC coupling into the main system. I'm working on using a spare Tri Star I have and using it LVD mode on the forklift bank. Not read the Outback manual fully yet but it may have similar features to the SI and Victron so may not be necessary. Trouble is that to do anything on an Outback you need a 'Mate' and I'm not for forking out on one of those unless it's going to really improve my system.

Cheers, Paul
Logged

http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
woodi
Full Member
***
Offline Offline

Posts: 119



WWW
« Reply #16 on: January 31, 2016, 07:45:58 PM »

Well the cycle life and general durability of the 2v traction batteries is way above the Trojans - the 2v are 60kg each, and a single 6v trojan is what - 20kg? I'm very nice to the traction batts, so I reckon they'd outlive the Trojans quite considerably.
Selling the Trojans and getting some more PV is probably a sensible proposition if they are worth anything, but part of me can't resist the idea that more storage is a Good Thing, and adding another AC coupled inverter offers the chance to play around. Plus I can always separate the 2 systems, which at some point might be useful as I'm powering 2 separate buildings....
Camilltech makes a good point about voltages. The traction cells have an absorbtion voltage of 30v because of their height, and subjecting the trojans to that would (I assume) end in tears.
« Last Edit: January 31, 2016, 08:01:27 PM by woodi » Logged

8kw PV - 40x80w; 8x100w;13x300w Victron 150/70, 100/50, 100/30 MPPT; 3x Victron Multiplus 24/3000/70; Color Control GX Monitoring; 1000ah@24v traction batteries - 50 tube solar thermal - 3kw Bornay Inclin grid tie/ac coupled wind turbine - wood fuel cooking & heating.
camillitech
Hero Member
*****
Offline Offline

Posts: 5403



WWW
« Reply #17 on: January 31, 2016, 07:58:29 PM »

Well the cycle life and general durability of the 2v traction batteries is way above the Trojans - the 2v are 60kg each, and a single 6v trojan is what - 20kg? I'm very nice to the traction batts, so I reckon they'd outlive the Trojans quite considerably.


That's exactly my point Woodi, charge the forklifts at the Trojan (Rolls) voltage and they'll get fecked or charge the dubious Trojans at the forklift voltage and they'll barely hold a charge. OK, perhaps not so dramatic but you get my gist, DON'T MIX em in the same bank (not that you would). Much more fun to play around with inverters and AC coupling  fingers crossed! probably not sensible but far more exciting  Wink

Cheers, Paul
Logged

http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
billi
Global Moderator
Hero Member
*****
Offline Offline

Posts: 8926



WWW
« Reply #18 on: January 31, 2016, 11:07:03 PM »

no , pairing those 2 different batteries  does not sound right to me ,   what is gained with that idea ? If one weakens the main  bank  of 2 volt tractions cells  that can live beyond 15 years  ( mine are now 13 )  if treated right ( i am  not overprotective  but my system  does seldomly discharge them under 50% )

It does make perfectly sense to me  to create a kind-off back-up generator  with that second battery (that has a shorter cycle life)  to avoid  too often deep discharges of the main Batt bank


We  people  take care of weather forecasts  because of our off grid  lifestyle    and  can switch on  that battery based  back up generator   (or  our main inverters do that automatically )


But i think , i think  i would go the Micro GTI 300-500 watt  idea http://www.aeconversion.de/en/inv350-60.html  ( i mentioned 2 options above)   connected to the Trojan  battery  and feed into my housegrid to take the pressure of the main battery on the AC-out   of the Victrons

It is done and tested that  micro GTI s work on battery power , but as Paul meantioned  , a too deep discharge has to be  avoided ( simple time  perhaps )

This guy  works  a lot with that kind of idea http://www.solarelectrix.de/4_panel_uk.html    of feeding battery into Micro GTinverters


Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
Justme
Hero Member
*****
Offline Offline

Posts: 3530


« Reply #19 on: January 31, 2016, 11:19:43 PM »

Yes they're both FLA and in good condition, but one set are tubular plate and the other aren't.  They are different ages and capacities though, and everything I've ever read tells me that mixing batteries in that way isn't a great idea. Going to go with the inverter feeding the current setup and ac coupling. If nothing else it will be an interesting experiment.

Everything you have read is wrong.

Age & capacity matter not if they are in good condition. All the stuff you read about splitting banks is due to a faulty bat dragging the rest down.

Think about it.

If you cant join banks then you cant have more than one 12v battery in each bank unless its made up of 2v cells. You also could not have say a forklift battery converted from its original voltage to 12 or 24v as you are linking banks in parallel.

Read THIS re split banks. The writer is prob the best source re battery info.

Just for clarity I will say again that this is with the same battery type.

Mixing types would be wrong.
« Last Edit: January 31, 2016, 11:23:11 PM by Justme » Logged

Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
billi
Global Moderator
Hero Member
*****
Offline Offline

Posts: 8926



WWW
« Reply #20 on: January 31, 2016, 11:57:14 PM »

  ... we are not splitting banks here  , more about how to combine   different  batteries together  , but sure  i would be interested in  an answer  of the smartgauge  guy  , if he would recommend to direct parallel a 600 cycle with a 1500 cycle battery
Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
camillitech
Hero Member
*****
Offline Offline

Posts: 5403



WWW
« Reply #21 on: February 01, 2016, 12:03:37 AM »



Just for clarity I will say again that this is with the same battery type.

Mixing types would be wrong.

But the OP quite clearly says in his first post that they are different types.
Logged

http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
oliver90owner
Hero Member
*****
Offline Offline

Posts: 2024


« Reply #22 on: February 01, 2016, 06:51:40 AM »

I've seen that the ah rating for both is 1000.  I've seen that one bank is 24V (so a group of 12 cells).  I've see that one battery is 6V.  I am given the impresion that both banks are equivalent in power, if not quality/durability.  I've also read that the trojan cells weigh around 6-7kg each (6V battery is 'about 20kg') whie t'others are 60kg/cell.

They are not the same.  What is the battery format of the trojans?  Strings of 4 in parallel for the pack to achieve 1000Ah?

As soon as a high current is drawn the cells with the higher internal resistance will deliver less power as their terminal voltage will fall more than the other set..

At a push, if both were really the same type (traction fla or whatever) they would be acceptable in series - yes, at a push.  They are not, and 48V is not an option,  so they are not compatible for secure long term use.

Seems to me that the word 'type' is being used as a convenient term.  They are both lead/acid chemistry, so of the 'same type'?  Would one mix fla with gel, even if both were of that 'type'?  Even as a series bank newer with older is not good - think here of changing one failing battery, of a pair, for a mobility scooter.  Just not the done thing unless for a short term quick fix (err, bodge).
Logged
woodi
Full Member
***
Offline Offline

Posts: 119



WWW
« Reply #23 on: February 01, 2016, 07:59:34 AM »

Ok, for clarity - they are both FLA banks but one is a year old bank of12x 2v tubular plate traction cells - Exide EPZS 1000ah@24v. The other are 8 x fairly regular Trojan 6v 225Ah, (so 2 strings of 900Ah to give 24v @900ah) which are  nearly unused, but approx same age, and have had the odd float to keep them happy. Quick check of specific gravity shows the trojans to be in a marginally better state of charge. 

As Billi says, they have very different cycle lifes and are physically very different beasts. Info about mixing them together is very interesting but I'll let someone else experiment with their two and a half grands worth of battery Smiley
Logged

8kw PV - 40x80w; 8x100w;13x300w Victron 150/70, 100/50, 100/30 MPPT; 3x Victron Multiplus 24/3000/70; Color Control GX Monitoring; 1000ah@24v traction batteries - 50 tube solar thermal - 3kw Bornay Inclin grid tie/ac coupled wind turbine - wood fuel cooking & heating.
billi
Global Moderator
Hero Member
*****
Offline Offline

Posts: 8926



WWW
« Reply #24 on: February 01, 2016, 08:44:05 AM »

.... the  one batt is rated  at C5 1000 ah  capacity ,   the Trojan  900 ah  at C20.......  at C5 that would only be about 650 ah

Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
biff
Global Moderator
Hero Member
*****
Offline Offline

Posts: 11908


An unpaid Navitron volunteer who lives off-grid.


« Reply #25 on: February 01, 2016, 10:37:41 AM »

Hello Woodi, Grin
                 How are ya doing over there.? We are having a right old breeze at the moment and it is set to get going properly around 3ish this afternoon.
   The sun is shining now. We are going to have to get out of the house and move into a tent down the garden because the water is that warm, the house is too comfortable and we want the excitement but,
  maybe we will wait until this after noon till the dance really gets going.
   Years ago, I defeated the laws of physics on this very forum, I mixed a whole clatter of different type batteries, different Ahs, different compositions and different brands, 24cells forklift cells were 850ah and 36 cells were 650ah. I stuck the lot together and hoped for the best. I got the best. Then in the name of science, i boiled them dry for good measure Twice,!!. Now I can excuse myself (no bother to me) on the grounds that I was very ill and batts and things never entered my head for over 6 months,,but,,but the system still kept running till I was able to stand and walk. So down the garden I went and gave them a big long drink of the purest bluestack rain water, which Eleanor said could be full of that Atlantic salt Cry  but,,but They are still going strong and are being pumped full of lovely lecky as i type.
 I was due to make some alterations to the AH recently by adding more to the mix but the bad weather scuppered that. I need a nice calm day and will have to wait a while longer,
 Yes,they are still performing well. These cells would have put in a hard time in their previous job, so that is my experience of mixing 60 cells..However, my voltage is 120vdc and the cells are in series. I still have to add a 48pack at the end,in parallel. wackoold, all in the name of science of course.
 Now, in fairness,, I would not recommend that you do what I have done. I am beginning to sound like my old man, who used to get quite serious when I was young. he would say, " Don,t do what I dii but dii as I tell yee"  especially after a few days consulting with Johnny Walker and Black Label. He only lived till he was 94 and would have taken another 94 if he could have gotten it but that is a totally different story and has nothing at all to do with banks and cells and batteries.
    I will make one quite serious hesitation, if you get my gist, You have some very good stuff and even I would not bring them down to the level of your "Not quite so good stuff"
 Was it Paul who said,"stick them on fleabay"  Yes!!, and use the cash to buy into a new pack like the good ones that you have already.
          Cheers,
                     Biff.
Logged

An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
woodi
Full Member
***
Offline Offline

Posts: 119



WWW
« Reply #26 on: February 01, 2016, 10:49:14 AM »

Still oddly calm here. We're relatively sheltered, but average windspeed hasn't risen above 25mph this morning, and biggest gust has been 43mph. Plenty to keep the power coming though - be a good chance to equalise the batteries, and turn the dump off for an hour. By the looks of the satellite, the storm has gone south a little, so you could be in for a bumpy ride.
My turbine isn't coming down any time soon, as the winch mount broke, so I've to drill out a bit of plate to make a new one. All my previous 'incidents' with turbines have been when taking them down anyway - never had one fail in the air, its always been down to some mishap with winches and/or supports.
Good to hear about the longevity of your batteries - when I got these, it was with the intention that I wouldn't have to do it again for a long time - I try and keep them above 70% at all times, and they've never been below 50%.
Part of me can't resist the lure of more boxes to play with, so not decided what to do yet.
Logged

8kw PV - 40x80w; 8x100w;13x300w Victron 150/70, 100/50, 100/30 MPPT; 3x Victron Multiplus 24/3000/70; Color Control GX Monitoring; 1000ah@24v traction batteries - 50 tube solar thermal - 3kw Bornay Inclin grid tie/ac coupled wind turbine - wood fuel cooking & heating.
Justme
Hero Member
*****
Offline Offline

Posts: 3530


« Reply #27 on: February 01, 2016, 10:59:47 AM »



Just for clarity I will say again that this is with the same battery type.

Mixing types would be wrong.

But the OP quite clearly says in his first post that they are different types.

No he did not.

By types it means FLA or sealed or jell or ect ect. Not if the are dif capacities or 2v cells or ready assembled 2v cells.

He only mentions that one bank is 2v cells & the other 6v batteries. They could be the same type.

Again all the talk of if one is failing & how it will affect the rest, well then you should not even be using it.

Re load sharing, if correctly set up the load will be split proportionately to the capacity.

Logged

Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
DaveSnafu
Full Member
***
Offline Offline

Posts: 247


« Reply #28 on: February 01, 2016, 11:30:11 AM »

Just for clarity, 4 x 6v 225ah batteries in series to make 24v is still only 225ah, thus 2 strings would make 450ah, NOT the 900ah stated, and then as has been pointed out, at trojans rather optimistic rating @c20.
 
Logged

Proven wt2500,24v batteries,running house,navitron solar thermal integrated tank, 10 x 210w eclipse italia pv, wbs,
Pages: 1 [2]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!