4 L16 @ 24v - VS - 8 T105 @ 48v

MrM1
MrM1 Registered Users Posts: 487 ✭✭✭✭
in Old Battery Tech Discussions #1
I am considering upgrading my Conext SW Inverter from 24v to 48v.   I currently have 4 Trojan L16H-AC 435Ah batteries @ 24v.    If I upgrade to the 48v Inverter,  I would consider 8 Trojan T105 225Ah batteries.

The storage capacity is very similar:
4 L16H 435 x 24v = 10,400
8 T105 225 x 48v = 10,800

Yet the batteries are of different size,  Weight,  Plate size, etc.   With the 24v L16 set up I currently have, I know what to expect and how they handle larger loads.  Not great,  but OK. 

Large Loads on the system are:
Fridge compressor = 2.5 kWh per day
1/2 HP well pump = .55 kWh per day
1000 Watt Water Heater Element = .5 kWh per day (but most of the time not on the battery,  only as a diversion)

Wondering how the 8  T105s would preform with these larger loads (especially surge/inrush) compared to the larger L16 size battery format. 
REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #2
    My guess (and it's only a guess) is there won't be a significant difference, unless there's a pinch point (eg undersized 24v inverter DC wiring) in the existing 24v setup. As a % of C, it's about a wash.

    If you can live with the existing setup for now, I'd use it until the L16s die, then upgrade inverter and bank to a 48v bank of 8 x L16s.

    If capacity is otherwise okay and just the surge load is an issue, AGMs might be a consideration.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #3
    Your consumption is not excessively high, if what you have satisfies your needs, it would seem making a change simply to up the voltage would be money wasted, my opinion naturally. The surge issues , I'm assuming the pump, could be because of factors other than the battery voltage, is the pump 120V or 240V? My setup C'S 2524 230 has no issues with surge even with a 2 hp compressor 230V, if using on a split phase at 120V this may be the source of the issues....just some thoughts.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    Large unbalanced 120V loads on a 240V inverter can cause problems. 
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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  • MrM1
    MrM1 Registered Users Posts: 487 ✭✭✭✭
    #5
    Mike the loads are pretty balance.  I have spent hours balancing the various loads like lights on various circuits based on usage and off set to the fridge. 

    The well pump is 240v split on 2 wire and w/ ground
    The Water heater is 240v split on 2 wire w/ ground
    Fridge is 120v on L1  but I off set on L2 with the lights that I leave on more offten

    So the 2 largest loads are balanced and the system is fairly balanced. . 

    Yes I am pretty much happy with the set up.  Works well.  But as Estragon said,  I am kinda kicking this idea around for when the L16s die,  or if someone walks up now and offers me the right price for the L16 battery and 24v Inverter combo

    But if there is no real appreciable difference between 24v 4  x L16s and 48v 8 x T105s as far as handling large start loads  I may just stay where I am.  I suspect the 24v SW will last a long time.   

    I just did not know if there would be a big difference in load handling, life expectancy, etc from one or the other,  or if they would preform pretty much the same.
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion
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