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Yes, this is precisely why you need heavy wires for long runs - such as between panels and the charge controller. The wires on the BMS in question in this thread can be much lighter if they are kept very short.

The temperature rise on very short wires can also be drastically reduced by heat sinking effects of that they are connected to. That is why I cut mine back to about 2 inches. The 4 wires were originally about 6 inches long on each side.

Length matters (that's what she said) ?? Seriously, wire resistance and voltage drop increases linearly with length. It's not just about diameter and cross sectional area. The only time wire cross sectional area alone matters is when you are concerned about wire heating. This is why wire gauge...

Thanks Steve, Your statement "Charge on the other hand IS affected [by low temperature], it slows and takes longer" matches my 25+ years of experience with Li-Poly batteries. It is clearly also true of LFP cells (although perhaps to a lesser degree). Cold Lithium cells have a higher internal...

Thanks - that is basically what I was looking for.

Pushing the voltage up to 3.5v/cell is not an option because of the capacity mismatch on these commodity cells. Even with top balancing limited to 3.35v or above, the lower capacity cell(s) rather quickly exceed their maximum safe voltage when left on a float charge of a level that high. I'll...

I know that when program 32 is set to "Auto", the bulk charge voltage setting is ignored. When set to manual it does not drop to float until the timer runs out. The timer starts when the float voltage is achieved. This came up in another topic awhile back which you might remember.

Yes - I'm talking about current at bulk/absorb CV and a relatively high SOC - 80% for example. There is plenty of current available, which can be easily demonstrated by increasing the charge voltage. It's not a limitation on the input. Below bulk/absorb voltage the charger is in CC mode so...

I know this thread is almost a month old now, but I believe that setting program 26 (bulk) to 57.6 volts is either pointless or dangerous - depending on what program 32 is set to. If program 32 is set to "Auto" then the unit ignores the bulk setting (#26) and always only charges to a max CV of...

By reduced charge acceptance I mean lower current draw at the same voltage than what is seen when the battery is warmer and at the same SOC. Absorption voltage - or bulk charge voltage - as it is called on my LV5048 is typically set to no more than 54.4v (16S).

This is my first winter with LifePO4 batteries and I've noticed that cold cells seem to have much reduced charge acceptance. I suspect it is because the internal resistance is higher at colder temperatures. This makes them difficult to charge quickly - which is a must with the short winter days...

About 20 years ago I read Ray Kurzweil's The Age of Spiritual Machines and was fascinated by it. I thought it was the answer to immortality. All I had to do was live long enough to see the singularity and I could download my consciousness into a machine and I could live an eternal productive and...

I bought 20 of the 100 watt Rich Solar poly panels last spring. Some of them developed faint "snail trails" over the summer, but as best as I can tell the output has not been affected. One of my panels did come with a bad solder connection of a wire to the diodes. The wire had actually pulled...

Well, this was in direct response to a highlighted statement made in the original post. That's why I asked the question here... "⚠️ When discharging/charging cells for top/bottom balancing and after assembly, remember to "FIX" or "Clamp" the cells together. They will expand & contract up to...

I have a question on clamping cells together. This seems to be a point of contention for some folks. Slight cell swelling/bloating is a result of internal out-gassing which I think is normal to a certain extent when under load. I don't think that clamping cells together under pressure will...

I'm skeptical about capacity numbers like this being actually measured. This is a time and energy intensive process which would add greatly to the cost of the cells. I'd be very interested to know if anyone was able to verify the accuracy of these numbers once they receive their cells.

MPP Solar WiFi Module I'm going to answer my own question here for the benefit of others who might be wondering the same thing... I went ahead and purchased the MPP Solar WiFi module by emailing mppsolar directly. The Price was $70 + $4 Fedex shipping that got is delivered to the US from Taiwan...

I recently discovered that my cell balance problem is really caused by one of my cells having lower capacity than the others. Cells with mismatched capacity can not be properly balanced. It reaches full charge before the others and the voltage goes dangerously high. If I try to top balance, the...

Because LifePO4 have such a flat discharge curve, you can't really balance based upon cell voltage in the 10% to 90% SOC range. If you have cells with only a moderately small difference in their state of charge, you probably don't see any noticeable difference in their voltage. That basically...

No balancer will do much when you are on the flat part of the discharge curve. You have to get the voltage on all cells up to 3.5v or higher in order for small differences in the state of charge of each cell to be seen in their voltage. Then the balancer can do something useful.

The thing that will probably help the most to get to full charge quickly without having a few cells go higher and trip the BMS cell protection is to try to get a better top balance. In order do do this you need to hold a high state of charge (~3.5v/cell or higher) for an extended period of time...

I'm new to these MPPsolar units also. I don't actually have any experience with the LV2424 - I just looked up the manual and compared it to the LV5048 manual. When I mentioned going as high as 29.2 volts, I wasn't thinking float or bulk specifically - just how high you could go and not exceed...

I see this thread is several months old, but - Did you ever figure out how to clear that alarm code? How do you feel about the wifi module and the app? Is it worth the money? I see the app itself has poor reviews on the Play Store. I guess the other option is using a Raspbery Pi and setting up a...

In comparing the manuals for the LV2424 and LV5048 it appears that quite a few of settings are different between the two. The LV2424 seems to have no setting for bulk charging time like the LV5048 has (program setting 32). Perhaps it judges when to switch from bulk back down to float...

I was able to reduce the voltage difference between cells at high SOC (3.5v/cell) by putting the LV5048 in utility charging mode so that it would hold that voltage for an extended period of time. That allowed me to use a resistor and a seperate power supply to force the cells to the same...

This sounds familiar. If I don't charge above 54v, the cells all stay nice and balanced - even under fairly heavy charge/discharge current. However, if I try to push it much higher the cell voltages start to scatter. I set the bulk mode to "manual" today and set the timer to 180 minutes. Bulk...

I have my BMS set to only balance if cell voltage is above 3.35 volts. I tried setting it to 3.4 volts, but the voltage drops below 3.4 volts so quickly after charge termination that it doesn't have enough time to do anything. Also - my BMS will only go into balance mode if charge/discharge...

In reading that thread, your testing seems to indicate that the discharge curve of LifePO4 cells is so flat, that paralleling them - or any other means of equalizing cell voltages is not very effective. That begs the question - how to you equalize SOC accurately? The standard recommendation is...

Ok, I understand that lead-acid works that way. You have to apply a higher voltage to get it to absorb that last few percent of capacity. Forcing in that last little bit of remaining capacity is inefficient and ends up generating heat. A large Lead-acid battery does not seem to be harmed by this...

I have found it impossible to get a rest cell voltage that high (3.65v) without applying significantly higher (potentially battery degrading) voltage during charging. 3.65v is not a real sustainable cell voltage anyway. As soon as you apply any small load - even a cell balancer, the voltage...

The reason for not going into bulk mode appears to be the "auto" bulk charge mode. I didn't understand how it works (or actually doesn't). Thanks to Mtour I think I understand that now. (Too bad the MPP Solar manual doesn't explain that) As far as proper cell balance is concerned, I've actually...

This is making more and more sense. I believe the capacity of the battery would also affect the proper absorption timer setting. What is the capacity of your battery? My cells are 150Ah. I'll try your 54.4v bulk/absorption setting with a shorter timer setting, and then slowly work my way up to...

Th That is good information. It sounds like automatic mode basically never goes into bulk absorption mode. I will try using the manual bulk timer and starting off with a short time period. I will then gradually increase the timer setting - watching to make sure I'm not overcharging. Does that...

Why do you think the MPP is malfunctioning? I'm not sure I understand. The battery cells seems well balanced. Up to about 98% SOC the voltages track very closely. At that point - "the upper knee" - the voltages will start to diverge. I spent quite a bit of time trying to top balance the cells...

I have pushed the float voltage a little higher, but if I do several of the cells will hit the BMS limit (3.65v) due to cell voltages diverging at full SOC. That results in the BMS cutting off to protect those cells. So, I can't go much higher on the float voltage. I think what is needed is a...