Where is the cheapest place to buy lithium batteries right now?

Discussion in 'OnBoard Electronics & Controls' started by DennisRB, Nov 1, 2014.

  1. gonzo
    Joined: Aug 2002
    Posts: 14,163
    Likes: 546, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The reason for testing at 80C is to mimic aging. It gives results that are consistent with several years of use. Good battery charge management, regardless of battery type, is what makes a system efficient.
     
  2. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 123, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    Good battery charge management...? You mean appropriate charge voltage regulation...

    With such low internal resistance, the lifepo4 cells heat up very little with even rather large charge and discharge currents. With a 700ah bank, you can basically do whatever you want to them in practical terms. That is, on a typical recreational boat, 150amps from an alternator, 300amps from 2 engines, full charge current from a 2Kw solar array, etc none of this is any problem at all... If you could, in pracitcal terms you can't, you could potentially punch in 700amps into a 700ah bank without any heat or other issue. Same goes for large discharge loads such as the compressor, 3kw inverter, or other large 12v loads... Lithium is the future, until the carbon batteries take off, and you don't need any ******** bms provided you understand what kills them, and how to configure your system so it minimises the risk of harmful unintentional cell voltages.

    The problem arises from the lead acid legacy equipment we have. Such as an engine alternator for example. These are typically regulated at 14.8v or thereabouts which is designed this way for connection to a lead acid battery. This is way too high for a lithium bank and if you connect this to your bank, you will kill it pretty quickly with lengthy run periods when already fully charged. Hence the bms takes care of it for you... Or you can take care of it yourself, by limiting the output voltage of your alternator, my solution was to simply put a schotky diode in line with it, which carries an inherent 1.2v voltage drop across it, mounted through an aluminium heat sink to dissipate the 48w of heat generated by it. Programmable solar Regulators can be set to whatever output you choose, make sure it can't hold the voltage above 3.4v per cell or 13.6v nominal battery, and you don't need other bells and whistles to 'manage' it for you. Set the LV cutoff at 3v per cell, or 12v nominal, and you have made it impossible to over voltage or undervoltage your bank. Therefore it's effectively managed...
     
  3. BertKu
    Joined: May 2009
    Posts: 2,478
    Likes: 42, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi Gonzo, I know you mean it well, but you must tell me whether a sophisticated Management system does it better than I do it at present.
    a) first at all, each 3.35 Volt set of 10 batteries parallel are monitored by a cheap simple very low current consuming LED , a couple of diodes , high value resistors and 2 transistors which only consumes micro Amps when system is switched on. As soon the voltage drops below 2,3 - 2,5 Volt, depending on ambient temperature -10 (not in a million years happened here) and 35 degrees C occasionally once per 10 years. the red LED comes on and I know my one battery bank is a problem.
    b) I am charging 1C, i.e. my batteries does not get hot, but the lab likes to push the limits and charge at 5 or 10 C, then a sophisticated battery charger is needed, not at my charging levels.
    c) I charge each bank until full and then jumps to the next bank. I have time, you youngsters like to have done everything within seconds.
    Why is an expensive sophisticated charger doing a better job. I love to learn.
    Bert
     
  4. BertKu
    Joined: May 2009
    Posts: 2,478
    Likes: 42, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    It does not help to have a good management system looking after the batteries, when the user has inefficient loads. The overall system is also then not very efficient. Bert
     
  5. gonzo
    Joined: Aug 2002
    Posts: 14,163
    Likes: 546, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Actually, new batteries can take 15C charge with no problem. One important item on charge management, also for lead/acid, is temperature sensors that allow charging at the maximum safe rate. I agree that undercharging will not overheat batteries. However, that is not an efficient way of using batteries. That is like saying that new efficient diesels are worthless because engines from the 1930's run fine as long as you keep on feeding them fuel and oil. If we are discussing efficient use of materials and resources, management is very important.
     
  6. BertKu
    Joined: May 2009
    Posts: 2,478
    Likes: 42, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi Gonzo, I am not going to argue with you and capitulate. Although it is a well known fact that if a battery is slowly charged until full, it has a longer lifetime. I have here NiCd batteries which are 42 years old and still in use (VARTA). I had to short circuit them some time ago to reduce the memory effect. But I charge them at a reasonable rate. In the same way I am charging my LiFeP04 batteries, also in a slow mode. Why should we charge them fast, when I have the time. You can argue, it cost more to have the 87% switch mode power-supply switched on, true, you are correct. Or the solar panels have to be standing outside a little longer. That does not worry me. I will over the week-end draw my Management Low Voltage Control system out. Let see what comment I will get.
    Bert
     
  7. gonzo
    Joined: Aug 2002
    Posts: 14,163
    Likes: 546, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I am talking about efficiency. That means that if an engine is run to charge the batteries, it should provide the maximum charge possible. Fast charge in Li batteries is very different from what happens in lead/acid types. The only reason to spend money on them is the capacity to fast charge and still have a long life. If you plan on slow charge, lead/acid will be more economical.
     
  8. WestVanHan
    Joined: Aug 2009
    Posts: 1,374
    Likes: 56, Points: 0, Legacy Rep: 746
    Location: Vancouver

    WestVanHan Not a Senior Member

    I know you want to keep things as they are,but I'd suggest having a peek at the small Kubota diesels-1.5 hours on a litre of diesel at half power,maybe run half an hour a day or even rarely if the solar is taking care of things.

    Electric clutched belt to whatever 150 amp alternator you need to charge the lithiums, and another to the dive compressor.
    You're happy with the DC fridge and freezer,else you could run a reefer compressor as well.Waste heat for hot water.
    Easily silenced.

    Like this but build your own:
    http://www.nextgenerationpower.com/3kwmarine.html
     
  9. DennisRB
    Joined: Sep 2004
    Posts: 1,268
    Likes: 25, Points: 48, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

    WestVanHan. I had one of those on my old boat! It was great. It was hooked up to a large frame 150A alt and the cooling system gave me hot water. It only used 0.7L per hour average. One of those joined to a compressor and watermaker would be great. Def a good idea from a ground up build. But I am not sure I want to install one on this boat.

    Groper. I was also thinking of a diode to limit voltage from the Alt. However it might be just as easy to have it stop charging totally once the pre set voltage has been reached, with some form of hysteresis. Have you read that once lithiums are full you should totally stop charging rather than hold it (float) it at the pre set max voltage? I read its not good to do this, and its best to discharge the batteries a little before resuming charging. One other thing that may be of importance is current limiting of the alts. With a lithium bank they will be pumping out so much current they will be likely to live a short life.
     
  10. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 123, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    Yes you could do that, however if the voltage is set to no more than 3.4v per cell, or 13.6v nominal, you won't need to switch the charging off- the current will stop flowing as the cell voltage equals the charge voltage. No potential difference means no current. This approach doesn't work efficiently with lead acid as the internal resistance is higher and needs a greater potential difference to get the battery topped off in a reasonable timeframe.
    The key to longevity with the lifepo4 is not to try and achieve 100% charge, just take them to 95% or approx 3.4v per cell, and not let them go below 25% DoD. Going outside this range will reduce your battery life. Occasionally you may wish to top end balance them, which would involve holding them at 3.65v per cell for a couple of hours. You could do this via your programmable solar regulator periodically, however some of the guys running them in caravans and motor homes as house banks have not had to balance them for in excess of 12 month intervals...
    The alternators should look after themselves, yes they will push out their max current as the resistance is very low, but the regulator should prevent them burning out.
     
  11. Timothy
    Joined: Oct 2004
    Posts: 307
    Likes: 15, Points: 18, Legacy Rep: 202
    Location: canada

    Timothy Senior Member

    Funny I also had a Kubota but with a 200 amp Balmar. I got rid of it after I installed 4 semi flexible cheap Chinese solar panels and a controller I got from ebay. I still have a 200 amp Balmar on the main engine that has a field disconnect but I have as yet had the need to use it after a seasons sailing. The panels take care of my fridge a separate freezer all my house needs as well as my autopilot. I doubt they would be up to making hot water , running a water maker or a dive compressor,but still I rate them as on of the best improvements to my cruising lifestyle in 30 years. If Lithium ion batteries come down in price then cruising and living at anchor is about to become even better.
     
  12. BertKu
    Joined: May 2009
    Posts: 2,478
    Likes: 42, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    Like anything in life, one has advantages and disadvantages. I made an inexpensive BMS with some transistors and LED's. I personally don't like a BMS cutting my batteries out, at a time one needs them the most. All what I need is some indication whether a group of parallel connected LiFeP04 batteries has fallen below 3 Volt. This is what the circuit is given me.

    1) the cost is low about 2 - 3 dollars in components from the right company.

    2) A disadvantage, if there is a short in the 4 meter wiring and the fuse blows, one circuit is no longer functioning properly anymore. However, I gamble that should I get a short in my 4 meter wiring from battery to my steering wheel console, more than 1 fuse will have been blown and that is noticeable on the console. I dare don't have wires, without being protected by a fuse.

    3) One can only use high bright mcd LED's. I used 12.000 and 17.000 mcd

    4) Red has a lower voltage across the LED than green, and this system is based on that fact. Because green LED's need between 2.5 and 3 Volt to function versus the red LED at 1.7 - 2 Volt, I utilize that fact. If the battery has dropped below 3 Volt, the green LED will become a high resistance and the RED LED will come on, as there is still sufficient Voltage to let it come on. If the battery is so flat that even the red LED does no longer come on, I must be sleeping at the steering wheel for a long time.

    5) It uses only approx 1 milliAmpere and it means, that it take 5 years before it has drained the battery. I hope I have re-charged the battery before that time.

    Working.
    If the battery falls below 3 Volt. The green LED closes up (the 0.5 Volt + green LED needs more than 2,7 Volt) and the first transistor close down. This allows via the 18 Kilo Ohm resistor to open up the 2nd transistor BC 337-40 , which in turn switch the red LED on. If I am not satisfied with the brightness of the RED LED, I can reduce the 2700 Ohm to a lower value, let say 560 or 680 Ohm.
    The 270 Kilo Ohm resistor ensures, that if the green LED is off, that the leakage current does not play havoc with the system and closes the first BC337-40 transistor properly.

    The circuit is slightly temperature dependent. i.e. at minus 10 degrees or plus 40 degrees Celsius, one may have to use maybe different resistor values.

    Yes, it is a simple BMS and it has a lifetime of 25 years at least.

    If I ever move onto 24 or 36 Volt. It is not a problem to extend the circuit by another 4 or 8.

    Well Gonzo, you may now crap all over me. Bert
     

    Attached Files:

    • BMS1.jpg
      BMS1.jpg
      File size:
      126.4 KB
      Views:
      169
    • 101.jpg
      101.jpg
      File size:
      224.1 KB
      Views:
      145
    Last edited: Nov 8, 2014
  13. gonzo
    Joined: Aug 2002
    Posts: 14,163
    Likes: 546, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I think that if only a slow charge is available, lead/acid batteries are adequate at a lower cost. I am not "crapping" on anyone, but attempting to have an intelligent discussion. It is relatively simple to do a power requirement audit and a charging power available. Then use those numbers to calculate the type and number of batteries needed. Any system may work, but the best will be the one that matches the equipment, resources and provides the necessary power.
     
  14. BertKu
    Joined: May 2009
    Posts: 2,478
    Likes: 42, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    Good morning Gonzo, please have a nice warm cup of coffee and have a good laugh about what I have to say now. Some years ago I bought plans from New Zealand to build a hull and to enable me to build it on my yard and move it in and out through my gate. I was planning to reduce it by 10 – 20% to make sure it was able to move through my gate. All forum members told me in no uncertain terms that that was not the correct route to take. Thus I listen to your guys and bought a seaworthy hull with good buoyancy. Then after calculating all my needs, I made with blood and hard work and sometimes tears in my eyes, an extension to the transom , to get more buoyancy. I need 25KWh to enable for me, to be comfortable on the sea, Now you are telling me I must fill that flipping hull with lead, so it can sink to the bottom of the sea !!. 25 KWh means a cool 800 kg lead. Now you understand why we exploring lithium batteries. I have now 100kg,, but the majority are deep cycling Lead acid batteries and 40 lithium , just to get the experience, with the hope that prices and weight would have come down. I love to chat to you over a cup coffee, as you seem to be a knowledgeable forum member. Every time I fly to Europe, I have a chat to a forum member. , Amsterdam, Norway, Belgium. Pity that the cruise boat with the 4000 guests refused to stop in Croatia, thus I had a phone call with CDK, while passing his house. But this time I am flying to the UK Channel Islands soon and Milwaukee is unfortunately too far, just to pop over. Pity, I love to chat to learn from knowledgeable people.
    Bert
     

    Attached Files:

    • 001.jpg
      001.jpg
      File size:
      224.2 KB
      Views:
      148
    • 000.jpg
      000.jpg
      File size:
      197.3 KB
      Views:
      115
    • 004.jpg
      004.jpg
      File size:
      225.7 KB
      Views:
      176
    • 006.jpg
      006.jpg
      File size:
      249.8 KB
      Views:
      115

  15. BertKu
    Joined: May 2009
    Posts: 2,478
    Likes: 42, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.