LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[ReneJK]

Renogy 50A B2B vs Sterling 60A B2B

I was literally just about to hit the 'buy' button for Sterling 60A B2B w/ remote display (costs total incl shipping £310 = approx $350) when I saw the Renogy being announced here

Since I plan to use the Sterling as in the picture below , can someone shoot any holes in it for me or let me know what the advantages of the Renogy over the Sterling would be ?

I dont believe I would use the MPPT function of the Renogy as I plan to put the PWM's of the smaller solar I have and also the wind generator , on my AGM's and let the Sterling do the LFP charging

[john61ct]

Bottom balancing is best if you regularly draw your bank down to **very** low SoC, in effect ensuring you can discharge as deep as possible without an imbalance "blocking" you via the BMS per-cell protection.

It also **requires** you to regularly go down that low, balancing must be manual, and

more frequently than you would need to just doing capacity benchmarking.

IMO less convenient, a bit risky, and better to have a bit larger bank and not go to such low discharge levels.

______
Whereas top-balancing is usually automated, can be done as a part of every single charge cycle, and ensures that your usage can get as close to 100% as possible without an imbalance "blocking" you via the BMS per-cell protection.

In reality, it doesn't matter much which you choose as long as you do it consistently - no point to doing both of course nor balancing in the middle ranges.

Although there are balancing gadgets that could be used 24*7 while cycling at all points of SoC, never heard of anyone doing it that way, would probably waste a fair bit of stored energy.

[john61ct]

Originally Posted by newhaul

we covered all of this

Exactly, yet you still keep asking the same Qs as if you've forgotten

User-custom setpoint adjustability is a very different feature from just presenting a canned list of choices. Adjusting the Absorb Hold Time is also critical in many cases.

> Not sure why you want to derate output on the alternator charging

Already covered at length in several threads.




A vendor stating "rated for marine installation" means little compared to testing for IP certification.

As does a warranty that is not written down, subject to their whim if a systemic fault emerges causing return %s to rise one day.

> As to the VSR/ACR functionality built-in rather than having to buy that as well

As stated I've no interest in the coming new model, but if they've now added that, great, but it is still missing from the better-value models that are currently available.

I have already referenced this thread dozens of times in each of dozens of other forums. And please stop telling me how to write my posts.

[newhaul]

Originally Posted by ReneJK

Renogy 50A B2B vs Sterling 60A B2B

I was literally just about to hit the 'buy' button for Sterling 60A B2B w/ remote display (costs total incl shipping £310 = approx $350) when I saw the Renogy being announced here

Since I plan to use the Sterling as in the picture below , can someone shoot any holes in it for me or let me know what the advantages of the Renogy over the Sterling would be ?

I dont believe I would use the MPPT function of the Renogy as I plan to put the PWM's of the smaller solar I have and also the wind generator , on my AGM's and let the Sterling do the LFP charging

if you really want to use PWM controllers then spend the extra money . However with the renogy unit the mppt controller will charge both banks . And we all know that mppt controllers are between 25% and 35% more efficient . Save some money and harvest more power in the process . Sounds good to me.

[newhaul]

Originally Posted by john61ct

Exactly, yet you still keep asking the same Qs as if you've forgotten

User-custom setpoint adjustability is a very different feature from just presenting a canned list of choices. Adjusting the Absorb Hold Time is also critical in many cases.

> Not sure why you want to derate output on the alternator charging

Already covered at length in several threads.




A vendor stating "rated for marine installation" means little compared to testing for IP certification.

As does a warranty that is not written down, subject to their whim if a systemic fault emerges causing return %s to rise one day.

> As to the VSR/ACR functionality built-in rather than having to buy that as well

As stated I've no interest in the coming new model, but if they've now added that, great, but it is still missing from the better-value models that are currently available.

I have already referenced this thread dozens of times in each of dozens of other forums. And please stop telling me how to write my posts.

then get some actual real world experience

[ReneJK]

Originally Posted by newhaul

if you really want to use PWM controllers then spend the extra money . However with the renogy unit the mppt controller will charge both banks . And we all know that mppt controllers are between 25% and 35% more efficient . Save some money and harvest more power in the process . Sounds good to me.

its not just the Solar PWM also the wind generator , the 40A 'old' battery charger without LFP setting (has gel setting) and 2x alternators that I dont have to buy external regulators for , I know I'll loose some LFP charge capacity from the alternators but it seems like a good affordable 'middle ground' solution to me ? I can still get some usage out of them without having to throw them out for relatively affordable price

[evm1024]

Originally Posted by john61ct

SNIP %<

I have already referenced this thread dozens of times in each of dozens of other forums. And please stop telling me how to write my posts.

I've read every post in this thread over the life of the thread. I read this thread to get insights from others who have experience with LiFePO4 installations. Of course that is just me.

I barely have time to post on this forum and yet I cannot fathom how others have time to post on DOZENS of other forums and actually have time gain direct experience with LiFePO4.

I for one value the opinions of someone who has direct experience with something and has read the manual and tried to use the device over someone who has ONLY used Google as the basis for their opinions.

Google lookups are valuable but should never be passed off as "real" expert opinion.

From my reading of the forum rules we are are allowed (within the limits of the forum rules) to state our opinions and post as we see fit. And with that said:

Personally, I feel that when we give opinions or advise or state requirements we owe it to other forum members, especially those who are seeking advise, to explain the basis for our opinion, advise or requirements.

If we have only done a bit of Googling, that fine. Say so. If we are writing a book on the topic - say so again. If we have direct experience, again say so.

[john61ct]

Originally Posted by ReneJK

its not just the Solar PWM also the wind generator , the 40A 'old' battery charger without LFP setting (has gel setting) and 2x alternators that I dont have to buy external regulators for , I know I'll loose some LFP charge capacity from the alternators but it seems like a good affordable 'middle ground' solution to me ? I can still get some usage out of them without having to throw them out for relatively affordable price

Yes, you can visualize the Sterling as a "front end" filter for your bank, even make that the only charge source that directly feeds it.

Then no further infrastructure upgrades are required to get precisely the charge profile you want, from any old charge source.

Works especially well for portable packs that have multiple purposes, ratio of one B2B per 200-300Ah, can even be made into an integrated portable power pack for use in an off-grid home or on extended road trips.

[Cpt Pat]

Originally Posted by john61ct

Bottom balancing is best if you regularly draw your bank down to **very** low SoC, in effect ensuring you can discharge as deep as possible without an imbalance "blocking" you via the BMS per-cell protection.

It also **requires** you to regularly go down that low, balancing must be manual, and

more frequently than you would need to just doing capacity benchmarking.

IMO less convenient, a bit risky, and better to have a bit larger bank and not go to such low discharge levels.

______
Whereas top-balancing is usually automated, can be done as a part of every single charge cycle, and ensures that your usage can get as close to 100% as possible without an imbalance "blocking" you via the BMS per-cell protection.

In reality, it doesn't matter much which you choose as long as you do it consistently - no point to doing both of course nor balancing in the middle ranges.

Although there are balancing gadgets that could be used 24*7 while cycling at all points of SoC, never heard of anyone doing it that way, would probably waste a fair bit of stored energy.

I endorse the above. Except for manual testing, I never discharge below 20% SoC, and since that SoC is above the "knees" in the curve, I never see more than a few millivolts of imbalance between cells at the 20% SoC discharge termination threshold (resting voltage us 12.90 volts for my 4S pack). And the same holds for charge termination: I never charge above 80% SoC except when manually calibrating my SoC monitor/coulomb counter. The cell voltages there too are within millivolts at 80% SoC (resting voltage is !3.30 volts).

It appears to me that cell balancing is just an academic exercise when one has quality cells and uses those cells conservatively at fractional C charge and discharge rates. The trouble arises when one wants to operate at the factory rating extremes (10-90% SoC, and factory maximum charge and discharge rates). I appreciate the temptation to do so: you only want to run your engine a short while charging at (for example) a 1.0 C rate to conserve dead dinosaurs, and you want your money's worth out of the pack by drawing it down below 20% SoC. You also don't want to pay for more battery than you are using (even tough you were forced to do that with lead-acids), and for those racers who cut the end off their toothbrush to save weight - you don't want added battery weight. But the engineering complications seem to grow exponentially as you approach the rating maximums. I urge chilling out with renewable energy sources and staying off "the knees" of the charge/discharge curve. If you run your batteries like you'd drive your car in a race - they won't last long. Maybe I'm just not a "Type A" personality (which I suppose explains why I cruse and don't race).

It's your bank, use it as you choose. There's no judgment here. But I just shrug over the discussions of cell balancing since cell top balancers set even as low as 3.50 volts per cell would never activate in my sub-fractional C implementation where I never charge at a rate above 0.15 C. Charging terminates when my cells are at 3.45 volts per cell while charging. The price I pay for that is the need for patience.

[Inkog]

Originally Posted by ReneJK

Renogy 50A B2B vs Sterling 60A B2B

I was literally just about to hit the 'buy' button for Sterling 60A B2B w/ remote display (costs total incl shipping £310 = approx $350) when I saw the Renogy being announced here

Since I plan to use the Sterling as in the picture below , can someone shoot any holes in it for me or let me know what the advantages of the Renogy over the Sterling would be ?

I dont believe I would use the MPPT function of the Renogy as I plan to put the PWM's of the smaller solar I have and also the wind generator , on my AGM's and let the Sterling do the LFP charging

I have the Sterling 60A in my RV and I personally wouldn't recommend it. I never see over 50A going into my bank and it often goes into "half-power" mode due to over heating in <90* temps. This effectively puts my average output to around 35A. I have a high-output 240A alternator designed for AGM that reads ~14.1V at the Sterling (with voltage drop) and the sterling seemingly sweats to correct to 14.4v that I have configured for charging my LiFePo bank. The fan constantly runs, and sounds and feels like a hair dryer. I couldn't imaging how the thing would run in an engine room in temps above 90*

[ReneJK]

Originally Posted by Inkog

I have the Sterling 60A in my RV and I personally wouldn't recommend it. I never see over 50A going into my bank and it often goes into "half-power" mode due to over heating in <90* temps. This effectively puts my average output to around 35A. I have a high-output 240A alternator designed for AGM that reads ~14.1V at the Sterling (with voltage drop) and the sterling seemingly sweats to correct to 14.4v that I have configured for charging my LiFePo bank. The fan constantly runs, and sounds and feels like a hair dryer. I couldn't imaging how the thing would run in an engine room in temps above 90*

thanks , exactly the kind of input I am looking for

I wasnt planning to put it inside the engine room but close to the LFP bank away from the engine heat

so aside from the heat protection & reducing amps , it does work albeit not at the 60A's ?

[Inkog]

Originally Posted by ReneJK

thanks , exactly the kind of input I am looking for

I wasnt planning to put it inside the engine room but close to the LFP bank away from the engine heat

so aside from the heat protection & reducing amps , it does work albeit not at the 60A's ?

Sure it works, but I expected much better performance out of a 60A B2B. I could have saved a ton of money going with the 40A Renogy, and it runs silent. (the Sterling is LOUD) Although, no one knows yet how the Renogy will perform over time. The Renogy B2B is a rebranded Chinese device. Dometic sells the exact same device in Europe.

[Delfin]

Originally Posted by Inkog

I have the Sterling 60A in my RV and I personally wouldn't recommend it. I never see over 50A going into my bank and it often goes into "half-power" mode due to over heating in <90* temps. This effectively puts my average output to around 35A. I have a high-output 240A alternator designed for AGM that reads ~14.1V at the Sterling (with voltage drop) and the sterling seemingly sweats to correct to 14.4v that I have configured for charging my LiFePo bank. The fan constantly runs, and sounds and feels like a hair dryer. I couldn't imaging how the thing would run in an engine room in temps above 90*

While I haven't seen a heat related drop in output, the 3 x 30 amp 24v Sterling's say they are putting out 30 amps each, but I can only measure 25.

[tanglewood]

I guess I just don't understand a power system design that takes 220A of alternator capacity and reduces it down to 40, or 50, or 60A (doesn't matter which). To me, priority one would be directing full alternator output to LFP charging and house loads, regulated as needed for continuous duty. For the cost of the Sterling plus the Blue Seas disconnect you could install a single Wakespeed or Balmar regulator and have a power system with 220A capacity rather than 60A.

[Inkog]

Originally Posted by tanglewood

I guess I just don't understand a power system design that takes 220A of alternator capacity and reduces it down to 40, or 50, or 60A (doesn't matter which). To me, priority one would be directing full alternator output to LFP charging and house loads, regulated as needed for continuous duty. For the cost of the Sterling plus the Blue Seas disconnect you could install a single Wakespeed or Balmar regulator and have a power system with 220A capacity rather than 60A.

You have to consider maximum charge rate. The recommended charge rate of LiFePo is 0.5C, or half their capacity. If you have 400Ah bank, then you can charge them at 200A no problem. Your 220A alternator wont like that, but you can do it. This is another reason one would want to limit the current.

I have a 200Ah bank in my RV. The bank will take 100A charge no problem, but I also have 50A of solar. In my case I want to limit alternator output so I don't have to worry about overcharging while driving my RV while its sunny. 50A B2B + 50A Solar = the 100A max my bank likes. I designed my system to be worry free. This way I can let my mom or girlfriend drive my van and I don't have to worry that she'll fry my nice batteries.