Looking for complicated battery wiring diagram.

soloronesolorone Solar Expert Posts: 250 ✭✭✭
I have spent hours on hard drives looking for a lost battery wiring diagram that was posted on this forum years ago. It was from a sailboat site.

It was complicated with several crossovers and said to be the very best way to balance batteries and equal out loads and charging. I wanted to give it a try.  Thanks if anyone remembers it.  Cheers.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,518 admin
    In general, I am not a fan of "crossover" connections to balance cells/batteries in series/parallel connections.

    This is the site we generally suggest for understanding how to parallel strings of batteries:

    http://smartgauge.co.uk/batt_con.html

    When you don't use cross connections for cells, you can use your DMM to measure the voltage of each cell/battery directly and check their health. When you parallel cross connect each group of batteries/cells, then they all have a shared single voltage. In a properly working battery bank, cross connects don't help anything (they do not pass current) if everything is OK. And if you have a failed cell (open or shorted), the cross connects do not "recover" any capacity... The bad cell/battery is still bad.

    With simple connect in series, then take all series string and connect in parallel the strings--Makes it easier to quickly measure current flow in each string when using a DC Current Clamp DMM.

    For all I have typed above... With Li Ion batteries, they parallel groups of cells, then connect them in series. My belief is that this is done to "cheap out" on BMS (battery management system) wiring connections and make it easier to balance a single group of cells, vs a bunch of individual cells.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • soloronesolorone Solar Expert Posts: 250 ✭✭✭
    Well, thanks for the info, I hadn't considered the disadvantage of not being able to check cell health, but then I am a big user of hydrometers. That drawing has been nagging at me for many years and I could not find it during my last rebuild 5 years. Just thought I might give it a try. Cheers and thanks for your time. Can we get someone to remove my post as it is wasted space?
  • BB.BB. Super Moderators, Administrators Posts: 29,518 admin
    Posts are here for now, and for the future reader. I have no problem with your post and question.

    We get a fair number of questions about cross connecting batteries and the best way to do that.

    The hydrometer is great for flooded cells--For sealed cells, voltage is the only quick method of looking at health. And given hydrometers ar a bit more "fussy" to use--The DMM and Current Clamp DMM/Measurements are the easiest and quickest. And a hydrometer is best for gold measurement of FLA state of charge.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jonrjonr Solar Expert Posts: 1,298 ✭✭✭✭
    edited September 8 #5
    It's easy to show that cross connects typically reduce the differences cause by cells that are never perfectly matched.  More effective is to use series balancers (eg, HA-01).   Or spend a little time measuring the batteries and arranging them in a more optimal way (than the usual random assignment).   You want all cells in a series string to have the same capacity.   

    I am available for custom hardware/firmware development

  • Dave AngeliniDave Angelini Solar Expert Posts: 4,665 ✭✭✭✭✭
    Maybe the OP is thinking of the way sailboats use multiple battery systems on 1 , 2, or both switch. Some even use more and we had 3 different battery systems on our boat. They all could start the diesel and they all were isolated or could be paralleled. 

    We do the same now offgrid but with completely isolated inverters with there own battery. Some of my clients have wanted 3 systems for winter with one being not connected to protect from lightning. Pretty easy now with LFP to just let it sit there if the environment is right.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BB.BB. Super Moderators, Administrators Posts: 29,518 admin
    If looking into redundant power systems... That is an option.

    In my humble opinion, you have to be willing to pay the price and do the maintenance (understand how to test and maintain a redundant power system). I have designed redundant computer systems that run on -48 VDC (telecom systems). It is not trivial, and the complexity of redundant systems does make for new wild and wonderful ways to fail.

    Dave here has lots of experience in power/electronics/off grid power systems. It would be interesting to hear more of his take on redundancy vs a single system with onsite spares.

    I understand that when the US Coast Guard goes for redundancy--It is with 3 fully independent/redundant power systems (lighthouses and such). 

    Having two systems (such as an RV or Boat) so that you can run the house power and any over discharge/failure will not affect the starting battery/radio systems/etc... It is a good thing. You don't get stranded if somebody leaves the loads running on the house system and kills the battery bank--Because you still have the system to start/run the vehicle side of things.

    For a standard off grid home--I am more towards the single system (not multiple battery banks--That have to be managed/charged/etc.). The backup to solar, for me, is probably two or more gensets. A smaller manual start genset (like a Honda eu2000i - 4000 series family that can charge the bank and run the home in bad weather and/or if there is a system failure... And a larger genset (usually less fuel efficient) that is both a backup genset--And a larger genset for running shop tools/fire pumps/etc. when needed--And you don't have to "over design" the basic off grid solar power system to run these "few times a year" loads. Even picking the fuel type has pluses and minuses (gasoline ages pretty quickly. Diesel not quite as fast, longer life engines, more efficient burning of fuel--In terms of volume. Propane stores forever, more gallons per kWatt--less energy dense fuel. If subfreezing weather--Diesel and Propane have their cold weather problems).

    Similar issues with hot/cold weather for various battery chemistries.

    However--In the end, the system has to meet your needs--Not what I think your needs maybe (in my every be it so humble opinion) o:) .

    I always suggest doing several paper designs first and figure out what will be the best/optimum/most cost effective solution for your needs.

    There are always many ways to solve a problem... And until you have explored them in depth, it is not always obvious until you have done the research.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,665 ✭✭✭✭✭
    Well said Bill.

     The fastest way to solve/explore power problems, is to lose power days away from any help. This usually happens at night in winter.

     For myself, and many offshore sailors it was the challenge to always have at least 3 ways to solve a major problem. This now translates to the tropics and life in the rural north (Alaska) for offgrid 24/7.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Marc KurthMarc Kurth Solar Expert Posts: 476 ✭✭✭✭
    edited September 8 #9
    Single strings have an advantage that many people do not consider. Some of my blue water customers setup for 24v on their inverters using smaller 2v cells. Loss of a single cell means losing 1/12 of their capacity and reprogramming for a nominal 22v system. A friend of mine was a serious solo sailor (Morro Bay, CA to Fiji) and taught me a lot about redundancy.
    I always have more questions than answers. That's the nature of life.
  • softdownsoftdown Solar Expert Posts: 2,414 ✭✭✭✭
    "This usually happens at night in winter." You left out the blowing snow I think.

    "the complexity of redundant systems does make for new wild and wonderful ways to fail." Yes - keeping one system maintained is likely enough for most. 

    Any older optimists around?
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • softdownsoftdown Solar Expert Posts: 2,414 ✭✭✭✭
    "Even picking the fuel type has pluses and minuses (gasoline ages pretty quickly. Diesel not quite as fast, longer life engines, more efficient burning of fuel--In terms of volume. Propane stores forever, more gallons per kWatt--less energy dense fuel. If subfreezing weather--Diesel and Propane have their cold weather problems)."

    Here is a list of stations that sell ethanol free gasoline in Colorado. But the organization is nation wide with just a little sleuthing. Combine ethanol free gas with a good preservative like PRI-G and store it properly (cool and dark) - I think gasoline should usually be OK for at least a decade. The keys being ethanol free and a good preservative. https://www.pure-gas.org/index.jsp?printable&nocopy=true&stateprov=CO&fbclid=IwAR1x55LVxv7QVJZhLlGnxbVkOxp70J3r26C29uThymifeKdEH0K1qDuoK-8

    There is PRI-D for diesel. I used this on my 180 gallons of diesel which promises to last for a century at my usage rate. We. shall. see. 

    Shame that propane has about 20% less energy than gasoline. Gas is about 15% lower than diesel. One can mix some kerosene with diesel to make it cold weather friendlier. Don't use too much kerosene - it lacks the lubricity of diesel. People used to commonly use gasoline but there are rumors of risks in modern diesel injectors.

    Sophistication = Delicate and failure prone it seems. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 29,518 admin
    edited September 8 #12
    One of the issues I have seen with diesel is that as you use the fuel--The tank brings in air and moisture--Which can cause algae to grow in the water/diesel boundary. So you see a lot of recommendations to keep your diesel storage tank full (which seems to negate the buy in bulk and use fuel locally over a longer period of time).

    https://www.offthegridnews.com/how-to-2/the-key-to-long-term-diesel-and-gas-storage/

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,665 ✭✭✭✭✭
    edited September 8 #13
    The rule of 3 again on a boat is at least 3 different tanks for fuel and water for Blue Water cruising. Algae is a major source of headaches and a prime cause for boats on the rocks/beach.
    softdown said:
    "This usually happens at night in winter." You left out the blowing snow I think.

    "the complexity of redundant systems does make for new wild and wonderful ways to fail." Yes - keeping one system maintained is likely enough for most. 

    Any older optimists around?
    Yes I did leave out the snow, ice, roads washed, out along with fire and a few others. It is also the human requirements. I have a few that will be happy to use candles, and a wood stove for months without power. A few that have just given me a blank check and said make it happen. Even here in the Sierra there are a few that just can't deal with a failure in winter and so redundant systems work very well. 

    The purpose of a well designed redundant system is to make up for human frailties along with equipment failures. They are not new ways to fail if the user has been given the knowledge.

    Older optimists are very rare in my opinion.
    The old saying about the difference between an optimist and the pessimist is the pessimist has more data. ;)
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • softdownsoftdown Solar Expert Posts: 2,414 ✭✭✭✭
    edited September 8 #14
    There are almost 15,000 ethanol free sources in the US and Canada. Notably - only 20 in Communi, I mean California. One in Sacramento - we have some members in that area. Nebraska has over 10 times as many ethanol free stations as Communi, I mean California. 

    https://www.pure-gas.org/index.jsp?stateprov

    I'm pulling out of storing so much diesel in favor of ethanol free gasoline. Which reminds me of a question I have been wanting to ask - look for a Prius comment soon if curious. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • softdownsoftdown Solar Expert Posts: 2,414 ✭✭✭✭
    http://smartgauge.co.uk/batt_con.html

    While it is common sense for the electrically inclined, it would be helpful for many if they also showed these connections for batteries connected in serial (48 volt config). The first time I acted on their diagram, I was so intent of following the directions that I made a huge 12 volt battery bank. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • softdownsoftdown Solar Expert Posts: 2,414 ✭✭✭✭
    softdown said:
    http://smartgauge.co.uk/batt_con.html

    While it is common sense for the electrically inclined, it would be helpful for many if they also showed these connections for batteries connected in serial (48 volt config). The first time I acted on their diagram, I was so intent of following the directions that I made a huge 12 volt battery bank. 
    Since there is only one way to get an accurate reading from a 48 volt bank, it may seem there is only one way to "cable up" a 48 volt bank. I'm sure not going to experiment with that particular equation. As BB indicated, there are possible issues with cables running all over the place. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,665 ✭✭✭✭✭
    There was a guy on here who made a 96V battery and it actually turned on an XW6048, for some time :#
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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