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  1. #321
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    Default Re: Lithium vs Lead Acid

    In the absence of a smart BMS, how do you I know the voltage of individual lifepo4 cells without disconnecting them from a battery bank?

  2. #322
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    Default Re: Lithium vs Lead Acid

    Another LiFePO4 battery to consider is the Enertec. I have just installed a 200Ah into my off-road caravan - we do a lot of remote travel without access to AC power. I did not have to change my Ctek D250S DC/DC charger but decided to upgrade to the D250SE which has a lithium programme. We have had issues with power on our travels before so want the maximum capacity available when recharging - which the lithium programme on the D250SE will provide which the D250S will not. I also went for the Ctek PRO25S charger for AC/DC. We are about to go on two trips over the next couple of months so looking forward to seeing how the batteries perform. Good luck - I think the lithium is the way to go and will pay for itself over the extended life of the battery and better performance.

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  4. #323
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by VVTi View Post
    In the absence of a smart BMS, how do you I know the voltage of individual lifepo4 cells without disconnecting them from a battery bank?
    This is going to seem obvious but here goes with a voltmeter measure the first cell (A), then the first cell plus the second (B), first cell plus second and third (C) and then the entire battery (D). So A = first cell's voltage, B-A= second cell, C-B = third cell and D-C = fourth cell.

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  6. #324
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by River Rat View Post
    This is going to seem obvious but here goes with a voltmeter measure the first cell (A), then the first cell plus the second (B), first cell plus second and third (C) and then the entire battery (D). So A = first cell's voltage, B-A= second cell, C-B = third cell and D-C = fourth cell.
    Thanks although seems tedious. I think it's in my best interest (and the cells!) to get a smart BMS.

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  8. #325
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    Default Re: Lithium vs Lead Acid

    My opinion, for what it is worth.

    If you have to start manually worrying about and managing individual cells.

    The benefits aren't worth the bother or risk.
    The technology you are using is not suitable for a critical application.
    Spend the money and buy something decent.

    When overlanding or glamping you have many much more important things to worry about than looking after cells. Your aux battery system should be fire and forget, reliable and easy to fix.

    Likewise a home Solar system. SWAMBO will be mighty upset if their is no power and the Woolies quiches thaw, or the kids cant watch YouTube.
    Cheers

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  10. #326
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    Default Re: Lithium vs Lead Acid

    It's these aspects that make a little hesitant about general usage of aftermarket DIY Lithium based system.

    For the vast majority it is go big or go home. (Buy decent proven commercial products like Jeremy Franklin two posts up)

    Enthusiast and able - fine, different story.
    Last edited by Fluffy; 2021/04/26 at 10:35 AM.
    Cheers

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  12. #327
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by Fluffy View Post
    It's these aspects that make a little hesitant about general usage of aftermarket DIY Lithium based system.

    For the vast majority it is go big or go home. (Buy decent proven commercial products like Jeremy Franklin two posts up
    Perhaps we can add Probe as well as they also started selling them 4 months ago.

  13. #328
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by VVTi View Post
    In the absence of a smart BMS, how do you I know the voltage of individual lifepo4 cells without disconnecting them from a battery bank?
    I used to measure each cell, cause I had a BMS that could not give me the individual cell voltages.

    Problem is, by the time the inverter has switched off, your first warning, you got the voltage meter in hand after searching for it, opened the battery box to get to the cells cause a cell/s spiked above 3.65v, and your start measuring each cell, the cell that causes the drama has dropped back to acceptable volts.



    Recently me and a group of others have been looking into buying lithium cells direct from China, the 280ah ones.
    FIWIW, to get the cells landed in Cpt harbor, easy as pie.
    To get it out of CPT harbor to an address other side of the fences ... whole new very expensive ballgame.


    We can pay >$75 per 280ah cell or $119 per cell with reports accompanying every per cell. All depends on the quality we want, and from whom we buy.

    So methinks when there are very very cheap lithium batteries on offer that I'm not convinced that there are using A Grade cells in that bank.
    So one would get different level cells which makes balancing a challenge.

    Furthermore, to make it even worse, a BMS with said cells that cannot at least show you at the Min/Max cell voltages as well as the min/max cell no's ... naa, just get a BMS that at least has Bluetooth capabilities to be able to see each cells voltages, with software that allows you to access said BMS.

    I also agree with Fluffy, DIY, if that is your thing, go for it!
    If not, get a brand name ... just do it.

    Sukkling with unbalanced cheap cells and a cheap BMS that has no functionality like basic Bluetooth and the software to match, can cause one immense headaches not to mention the risk of the inverter forced to switch off because the BMS disconnects the bank due to unbalanced cells ... I have said T-Shirts.

    It looks like this when you can view all 16 cells, "B" are the cells being balance. Pic is from a live operating system.
    Attached Images Attached Images  
    Last edited by the_terrible_triplett; 2021/04/26 at 01:56 PM.
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  15. #329
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by Jeremy Franklin View Post
    Another LiFePO4 battery to consider is the Enertec.
    I tried to search for this without luck, please provide link. How does this compare to the Mecer or Vision Lifepo4 in terms of performance and price?

  16. #330
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    Default Re: Lithium vs Lead Acid

    Enertec is now R12660 for a 100Ah. 5 year warranty. > 2000 cycles up to 80% DOD.

  17. #331
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by VVTi View Post
    I tried to search for this without luck, please provide link. How does this compare to the Mecer or Vision Lifepo4 in terms of performance and price?
    I would also like to know.

    Remember the Mecer is 2nd life and cannot be connected in parallel.
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  18. #332
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by BruceHun View Post
    I would also like to know.

    Remember the Mecer is 2nd life and cannot be connected in parallel.
    See my post just before yours.

  19. #333
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    Default Re: Lithium vs Lead Acid

    It is not really required to have a bluetooth enabled BMS. That is expensive. You do get good cheap cell testers. What I have found is that while charging, the cells go out of balance. When I stop charging they stay out of balance for a loong time. As soon as you put a load on them they balance very fast.
    Quote Originally Posted by the_terrible_triplett View Post
    I used to measure each cell, cause I had a BMS that could not give me the individual cell voltages.

    Problem is, by the time the inverter has switched off, your first warning, you got the voltage meter in hand after searching for it, opened the battery box to get to the cells cause a cell/s spiked above 3.65v, and your start measuring each cell, the cell that causes the drama has dropped back to acceptable volts.



    Recently me and a group of others have been looking into buying lithium cells direct from China, the 280ah ones.
    FIWIW, to get the cells landed in Cpt harbor, easy as pie.
    To get it out of CPT harbor to an address other side of the fences ... whole new very expensive ballgame.


    We can pay >$75 per 280ah cell or $119 per cell with reports accompanying every per cell. All depends on the quality we want, and from whom we buy.

    So methinks when there are very very cheap lithium batteries on offer that I'm not convinced that there are using A Grade cells in that bank.
    So one would get different level cells which makes balancing a challenge.

    Furthermore, to make it even worse, a BMS with said cells that cannot at least show you at the Min/Max cell voltages as well as the min/max cell no's ... naa, just get a BMS that at least has Bluetooth capabilities to be able to see each cells voltages, with software that allows you to access said BMS.

    I also agree with Fluffy, DIY, if that is your thing, go for it!
    If not, get a brand name ... just do it.

    Sukkling with unbalanced cheap cells and a cheap BMS that has no functionality like basic Bluetooth and the software to match, can cause one immense headaches not to mention the risk of the inverter forced to switch off because the BMS disconnects the bank due to unbalanced cells ... I have said T-Shirts.

    It looks like this when you can view all 16 cells, "B" are the cells being balance. Pic is from a live operating system.
    2002 Discovery td5

  20. #334
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by Nambro View Post
    It is not really required to have a bluetooth enabled BMS. That is expensive. You do get good cheap cell testers. What I have found is that while charging, the cells go out of balance. When I stop charging they stay out of balance for a loong time. As soon as you put a load on them they balance very fast.
    They are <R3500, the ones I bought, landed in my hand via airfreight. In bulk even cheaper.

    Yes, the loads do help a LOT with balancing, the top balancing, when the SOC is >95%, is the bastard I found, when charging and no loads.

    I balance the cells top, help the BMS to "catch up" by using 2 x brake bulbs on the cells that shoot out, till the start "behaving".
    To hasten the process, I drop the bank down to a SOC of 30%, even 20%, to recharge again till the top balancing is sorted.

    Takes a few days. then it stays in line as the BMS can handle it all.
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  21. #335
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    Default Re: Lithium vs Lead Acid

    In addition to a BMS I add these as well:

    https://lithiumbatteriessa.co.za/col...ctive-balancer

    After many hours of monitoring, charging and discharging I can say they work fairly well.
    Donít blame yourself over past mistakes. Itís like driving down the N1 while looking in the rear view mirror only.

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  23. #336
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    Default Re: Lithium vs Lead Acid

    Ja, so leer ons vinnig.
    Quote Originally Posted by Dungbeetle View Post
    In addition to a BMS I add these as well:

    https://lithiumbatteriessa.co.za/col...ctive-balancer

    After many hours of monitoring, charging and discharging I can say they work fairly well.
    2002 Discovery td5

  24. #337
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by Dungbeetle View Post
    In addition to a BMS I add these as well:

    https://lithiumbatteriessa.co.za/col...ctive-balancer

    After many hours of monitoring, charging and discharging I can say they work fairly well.
    I agree, if your BMS balances at say 30mA, it WILL help.

    But, here is the thing. Once the cells are balanced, you don't need that added complexity.

    BMS + Active balancer = 2 x brake light bulbs and BMS that can show you each cells voltages.
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    Saw this in a pub - no idea why the wife does not see it so:
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  25. #338
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    Default Re: Lithium vs Lead Acid

    Quote Originally Posted by the_terrible_triplett View Post
    I agree, if your BMS balances at say 30mA, it WILL help.

    But, here is the thing. Once the cells are balanced, you don't need that added complexity.
    ....
    With the set I did all the testing on the particular BMS only does top balancing and only start balancing once some cells go above 3.5V. I found that when you cycle the set a few times between 30-80% some cells do go out. I did check for any small voltage drop issues between cell connections, none, so I attribute the problem to slight internal resistance differences between cells. After adding a constant active balancer no issues at all. Plus I do not have to fiddle.
    Last edited by Dungbeetle; 2021/04/30 at 08:46 AM.
    Donít blame yourself over past mistakes. Itís like driving down the N1 while looking in the rear view mirror only.

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  27. #339
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    Default Re: Lithium vs Lead Acid

    I'm gaining a lot of knowledge by reading the info here, never imagined it could get this involved. I'm wondering whether it's necessary to worry about all of this or if it's more of a hobby at this level.

    My DIY Lifepo4's with non Bluetooth BMS are working great, just returned from 14 days off-grid camping charging from solar and directly from vehicle alternator (the big no no), and all ran perfectly, - the envy of my fellow campers battling with lead acids. I had extra battery capacity at all times running two fridges, one as a freezer and the other as a fridge. Two lifepo4, 120 AH units. They are easely portable, I sometimes charge and/or use them in parallel, mostly individually, depending on the camping situation.

    If camping in one spot for a reasonable time I'll have both fridges at the campsite on a single battery recharging via solar and deplete that unit to around 20%, then by that time usually an opportunity arises for a game drive or a trip with the vehicle at which stage I'll put the 20% battery in the vehicle to charge and a fuller battery at the campsite/trailer. After a longish drive the empty battery is near full again and I then swap it out again as needed.

    If not going on drives at all I just run them in parallel for charge on solar, - that scenario is rare for me though.

    Hope I never have balancing issues, but so far so good. Must say, the little coulomb meters to see the exact state of charge of each unit are a game changer to manage the batteries usage.
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  29. #340
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    Default Re: Lithium vs Lead Acid

    The 1st time I see some lithium must not be charged for longer than 8 hours.
    Does this imply not to use a too low current charging system?
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