battery bank voltage 130V

Piter
Piter Registered Users Posts: 3 ✭
edited November 2019 in Off Grid Solar & Battery Systems #1
Hi all,
We have a battery bank with 96 cells in serie. Each cell has a 1.3 to 1.4 voltage, then the nominal battery bank voltage is 130V.
On the battery pack, we planned to install 3 ´Flexmax 60´ with an equal load (same number of panels, no shadow...) on each entry of the 3 charger. Then the charge should not be unbalanced.
According to your Flexmax data sheet, it would be possible to use the set up regulation and then have 43V (130/3), each controller would "see" a 43V battery bank.
Is it a configuration that you suggest? Do you see any drawback? Are there any other options, like one charger that would accept to charge 130V, does it exist?
Thank you very much for you help
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,634 admin
    edited November 2019 #2
    Welcome to the forum Piter,

    We are actually not operated by NAWS (Northern Arizona Wind & Sun / www.solar-electric.com)--We are volunteers here that help end users with off grid and other power systems.

    I think you need direct engineering support, I suggest you contact NAWS for help:

    https://www.solar-electric.com/contact

    Regarding your design... First, I would be very careful with the controllers/fusing/circuit breakers/system interconnects)... The standard MPPT solar charge controllers assume that the negative lead to the controller is "ground" referenced. When you have 3 controllers charging your single string of "cells", Controller A will be at Zero and 43 volts, Controller B will be at 43 volts and 86 volts with respect to ground, and Controller C will be at 86 and 129 volts with respect to ground. There are potentially many issues internal to the controller (its own "internal ground" references, and interconnects to other controllers, spacing/bypass capacitors, etc.) that you do need an engineer to answer (NAWS or even Outback through NAWS).

    And there is fuses/breakers on the battery lines to the charge controllers... Normally, with ground referenced connections (negative bus connected to safety/equipment ground), there is no fuse/breaker required on the negative battery bus to Solar Controller... With controllers B and C, these battery "negative" connects are not at Zero/Ground potential, and they need to be fused/breaker protected.

    And you will have some programming questions... It sounds like you are not using Lead Acid cells, but some sort of, possibly, Nickle based cell--So, the charging parameters will have to be altered to proper charging/good battery life (most likely).

    Please contact NAWS directly, and they should be able to help you move forward.

    Sincerely,
    -Bill "volunteer moderator" B. 
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
    If you are using NiFe cells, I can help with some experience in that area.
    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

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Piter
    Piter Registered Users Posts: 3 ✭
    #4
    Thank you very much for your detailed answer BB. 
    I am waiting an answer from Outback conerning their chargers.

    I understand it would be easier/safer with a charger that would allow 130V but I do not find any that charger more than 96V. Do you know if such a product exist? I suppose I am not the only one in this situation...

    Thank you
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #5
    https://www.sigineer.com/product/high-voltage-96v-120v-192v-216v-240v-384v-mppt-solar-charge-controller-50a-60a-80a-100a-output/

    I know nothing about this, but looks like it may do what you want?
    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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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,910 ✭✭✭✭✭✭
    #6
    Drawbacks?  Plenty!
    Building a battery for offgrid that can't easily be replaced.
    Charge electronics failure resulting in fire especially with high voltage.
    High voltage tends to not have good surge capability unless special care is take in design. Most I have seen are average, not great for pumping and compressors.

    If you had insurance it might be void or questioned on if this meets UL or is listed?
    What is the battery chemistry BTW?
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,634 admin
    #7
    I think he is out of central or southern Mexico... So UL/NRTL may be of lesser issue for him.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    #8
    If you can find a Midnite Solar Classic 250KS 250VDC MPPT Charge Controller It will charge up to 120 volt battery banks.
    http://www.midnitesolar.com/images/classicFrontPage/graphs.php

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Piter
    Piter Registered Users Posts: 3 ✭
    #9
    Thanks all for help.
    Midinte did some years back so no way to get someting new, but Sigineer has a solution. I will investigate with them.

    To answer to Dave, the batteries are níquel-Cadmio. But we have no choice concerning the type and the voltage, there are already on site...
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  • mathias
    mathias Registered Users Posts: 31 ✭✭
    #10
    If batteries are on site, would it be possible to rewire them in 2 or 3 parallels strings ? And get to a more common voltage. Would make finding controller and inverter much easier, and probably cheaper...

    Mat
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  • MarkC
    MarkC Solar Expert Posts: 212 ✭✭✭
    #11
    Piter said:
    Thanks all for help.
    Midinte did some years back so no way to get someting new, but Sigineer has a solution. I will investigate with them.

    To answer to Dave, the batteries are níquel-Cadmio. But we have no choice concerning the type and the voltage, there are already on site...
    Although Midnite stopped selling the KS at one point, they have offered the KS model twice over the last few years, with a warranty.  They told me at the time that they took old stock, tested them out and put them out for sale at a very reduced price.  I did not pay any attention to the last offering, however it was within the last year (my memory does not always serve me precisely however!).  I bought one during the first offering (~3 years ago) to use with a APC SMX 120 VDC system.  It has worked fine, although I've actually been using it for a 48 VDC system.  
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
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  • KenMorgan
    KenMorgan Registered Users Posts: 92 ✭✭
    #12
    Estragon said:
    https://www.sigineer.com/product/high-voltage-96v-120v-192v-216v-240v-384v-mppt-solar-charge-controller-50a-60a-80a-100a-output/

    I know nothing about this, but looks like it may do what you want?

    that looks exactly like the POS chineese charger my friend just bought in a premade chicom standalone solar kit...colors, shape, wording are all identical.  he asked me to "setup" the unit after he wires it.  Ha ha ha yeah....  typical chicom no manual included.  will get back and let you know what its like after I figure it out.
    70kw LiFePo4 battery bank, 18 JA solar 200 watt panels, 20 sharp 200 watt panels,  morningstar controller(s) and a magnum 4448 inverter with all the usual junk that goes with it. 
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