Correct, it will take amps until it is full. This is for an RV. Right? I'm assuming this is the duration of absorption charging, after which is will enter float charging. I'm not finding anything so far. It's possible you're getting voltage drop when the charger kicks on and it's shutting off as it thinks the starter battery is under voltage. The internal resistance of this battery is "<30 milliohms". And throughout all that, the battery monitoring screen records no incoming current (which it knows how to do - tested that with the AC-DC charger earlier). Obviously, a solar controller is is a lot more complex than an alternator, but this one doesn't understand anything about LFP batteries. When the battery was assembled the cells would have been ballanced, the ballancing the BMS dose at 14.4V is at extremely low current values which some meters may not be able to detect and definitely not the controller display. At that point you're not reading the battery, you're reading the alternator, even at the battery terminals. It had 67W to work with. Click here to remove banner ads from this forum. The BMS I have has a recommended input of 28.8V (24V nominal system ) constant voltage which is in the ballance regon, I however use 28.0V to avoid unnecessary time in that regon, the actual battery voltage never goes over 27.4V before transition to float 27V. You can buy ones that go as low as 0.75A, yet they still charge a battery because they are outputting 14+ volts. [EDIT: I'm wrong, it totally has load connections, but I'm probably never going to use them.] 2018 3500 EXT Camper Conversion in CT (TX for now due to Covid). I guess my misunderstanding may result from not understanding solar controllers, or maybe LFP batteries. The amperage the controller is outputting is moot if the voltage isn't high enough. It has to significantly exceed the battery's voltage. As to your question for me. Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total. I specifically have my solar charger set to not attempt to charge the batteries unless they fall below 13.2 right now because my batteries are not really being used. It just feels like the controller is misbehaving. Note: The values above are based on the manufacturers suggestions, I personally would choose lower values to extend life expectancy. Provided the current is sufficient the voltage will gradually rise to the pre set absorb voltage. It said it was in Boost mode, and that's configured for 14.4V. If you read the battery before starting it, it will say 12.6V. I own six total, but I'm just testing with three. But elsewhere I have read that that will kill a lithium battery. You have a full battery. The system seems to be performing but the batteries will not accept anything over 13.2-13.3 volts - which leads us to believe it is the BMS locking out. So, for a proper test, I should run a load on this battery for a while and try my testing again, tomorrow? The very end of the charge cycle when it's very nearly full? That would cause input power to your battery to exceed your solar power, which is impossible. The reason a battery is not floated at absorb voltage is that it shortens the life of the battery. CH1, the house battery, shows at 13.0V (which agrees with the multimeter at the bussbars and with the battery monitoring screen), CH2, solar, shows as 0V (which makes sense, since there's nothing hooked up there), CH3, van battery/alternator, shows at 14.4V - which agrees to the multimeter reading at the van battery terminals, CH3 then goes to "blinking" (which, according to the manual, means it's recognized, but not used to charge) - and then the charger turns itself off. That should give you about 12 charging amps. With a DIY bank it's possible to monitor individual cells to visually see what's going on, however with a packaged bank this is not possible. It claims to be in Boost mode, but that makes no sense given the low voltage. I'm new to the lithium battery world and have looked over other forum posts and google but not sure of the answer. We did all of our tests with no load as stated in our last comment. Were a community forum dedicated to Promaster enthusiasts to discuss mods, camper conversions, diesel, fuel economy, reviews and more! I don't just want to know what settings to use; I want to understand what these things mean. A car battery is 12.6V. Looking at the following graph from Battery University, the voltage only increases during the bulk charging phase, and stays flat during the saturation (absorption) phase. With a controller that is programmable, the end amps would be set much higher value in order to prevent it from having any part of the termination of absorption, which is just a function of a controller designed for lead acid batteries. But why is it only outputting 13.4V? You're only getting 53 watts from your 300 watts of panels. I image your charger is waiting for the battery to fall below some trigger voltage before charging it back up. Any thoughts you could add about how that works would be greatly appreciated. It's been charging for an hour. Internally, it manages what it actually uses, and whether it truly "floats" at all. Why did you replace the AGM batteries after just a year of use? Like 13.16. What do you mean by, "Batteries dictate the charging voltage which the controller is stepping down to."? One benefit in Baja is I have them Stacked and basically hidden (hopefully) from any potential burgleritos that might want to steal my batteries. 3.9 amps is only a 2.29% charge rate. And how long is it? . Or is it always at 13.2 3? The charging requirements are very different from that of lead acid where cell voltage differential is of less concern, with Lifepo4 it's very important to keep the cell voltages close to one another. There is a small international airport just outside San Felipe but I'm not worried about the border. The manufacturer of a sealed battery has no knowledge of what the end users abilities or knowledge, so they supply a recommended set of values. I'm not really sure what this feature is for. It's the voltage that forces the current to flow in a certain direction, from high voltage to low. When your alternator runs, it's putting 14+ volts on the battery because that's the only way to get current to flow into it. As it is approaching full, I'd relax and see what happens on a sunny day. I set this value to 14.5, and the reconnect to 14.3, but I have no idea if that's right. Please contact Victron and ask for their recommendation on the absorption time based on the their controller model. The rest of the settings relate to the load terminals or boost and equalization which are taken care of by the lowest value of 9V so should never occur. Lithium doesn't like to be trickle charged.But..as most systems have loads attached to the batteries, you want a voltage to use to prevent discharge of the batteries. It may sound obtuse, but you will see, with experience, that's the way it works. Regarding float voltage, you never mentioned the reasoning behind your recommendation. After 6 months of daily discharge of ~25%, I reset it to 28.8V to see how in ballance the cells were, there was negligible change. So the voltage drops as needed. It also shows CH3 (the van battery input source) available, but not charging (CH3 is flashing in the display, and that's apparently what that means according to the manual). However there is a maximum amount of amps that can be applied to a battery determined by the Battery chemistry, size and voltage. I leave a 2 panel maintenance array running to keep them topped off. The whole puzzle of what's going on just doesn't fit together. If you can't get rid of the float stage, please track the float charging current and make sure it's small enough to not over charge the battery. It was partly cloudy. At least it's not behaving how I expected. Or will it always be lower than that? If the battery is sitting at 13.4 volts the charge controller is going to supply charging voltage which when connected to the battery will basically be a bit higher than the batteries voltage. I'm not an expert on lithium batteries but I'd guess they are sitting at 13.4 and the small amount of current isn't sufficient to charge them very fast. All it has is a list of voltages you configure, and some preset ones for Sealed, AGM, and Flooded. The nature of the beast. Thanks all for the feedback, that's all really good helpful stuff in trying to wrap my arms around this. Ignition off will lead to the unit not charging off the van battery no matter what (and turns the charging off about a couple seconds later, as opposed to the minute or two the charger might otherwise take when it detects van voltage dropping on engine shutoff - something that might come in handy if trying to get a bit of charging in on short intermittent trips). This morning I created a custom profile and didnt see much difference. Boost charging voltage - Is this the same as "Absorption"? Is this not charging fully something new or has it been doing it from the start? That's where the 'float' voltage comes in: configure it to the value the batteries aren't loaded, for LiFePO4 about 3,35V per cell = 13,4V. Hard to beat AGM's so get a fresh set. The battery reads 13.2 volts. Small differences in voltage may be within the tolerances of the meters in use, though the voltage on the charge controller should represent what it's putting out. According to Renogy my charge voltage is 14.4, cut off is 14.6 but it doesn't say if you should have a float voltage. Charging limit voltage - I set this to 14.4. With our Li batteries, we would recommend setting the charging voltage to 14.4 0.2V, the float voltage must be set to the same voltage as our batteries do not require a floating stage. Here is a photo of all of the settings the controller lists in the manual: First off. "Connected each isolated battery via jumper cables to Ford E350 6.7 diesel Super Duty. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Hi Dave, Yep, I've been using AGM batteries myself for years. 4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset. I believe if the battery goes below the "Low voltage disconnect voltage", it will cutoff the load, and only reconnect when the battery is back above the reconnect voltage. @Raj174 Interesting. The higher the charging amperage the higher it will push the voltage of the battery. That's why they don't know their own specs, because which particular cells and BMS you have depends entirely on which Chinese warehouse overstock they bought and slapped their name on. Just wondering if your battery monitor's SOC is properly calibrated to your battery bank. Forgot to hit post comment. EDIT: I just found some of the deeper monitor screens of the meter, specifically for the battery. That is my guess by your picture post. Sign in or register to get started. Boost reconnect charging voltage - Really not sure on this one. reading above comments, I have to warn you, DO NOT treat your battery like AGM or flooded, lithium ion has a much lower full voltage value. I really want to understand this stuff and not just make changes without understanding them. House battery is under 13.3V - which mine now is, I've got it down to 13.0. What is the lowest voltage that you have seen in the batteries? The ideal charging profile for lithium battery is keeping the constant current stage (fast charge) until the battery is reaching 100%, which means when the battery charging voltage reaches the absorption (boost) voltage set point, the battery is almost fully charged. DMT-1250 shows that with the engine running, there's plenty of voltage from the van battery. Good years are sweet! The thing is, my model of controller doesn't even have load connections. That's not really applicable with Lithium batteries, so maybe I don't know as much as I need to. At that voltage, the battery is 90 to 95% full. I would expect it to read 14.4V immediately. I don't see why that should be the case with the settings I chose. LFP batteries do not like sitting at 100% state of charge, 90% SOC is the max generally preferred. We cannot get batteries to take more than a 13.3 volt charge. I'm NOT a lithium battery expert, far from it, but one of the advantages of lithium batteries is that they are VERY efficient, They don't require the much higher voltage you see with lead acid batteries. And then reconnect when it's equal to or lower than the "Over voltage reconnect voltage". Please help with my Victron SmartSolar MPPT 150/35. Plug a huge draw into your inverter and watch the battery start taking charge once its no longer full. FORMER caretaker of the Backroader 159" wb - Looking at options for building out a 4 seater full bunk bed layout. The charge controller's actual output is still 14.4 volts, but the load that the battery is putting on it is dragging the voltage down. It doesn't want to receive any more than that. The image is not the charging curve for lifepo4, which is what you have. The lower the charging amps the longer it will take to reach absorb voltage. Seems pointless to bother with these settings, but I set them at rational values. Will the AC-DC charger reach 100% SOC before dropping into float? Here is the curve for a 180 Ah prysmatic cell, note the current relationship to voltage, this is for a single cell, multiply by 4 for 12V nominal. Toggle Comment visibility. You use maybe 5% charge to start your engine, and then the alternator starts charging it. Discharging limit voltage - Seems like it might be for the load again. Yet even after 2 hours of leaving it running (with untilted panels) in the mixed sun and clouds, a multimeter at the terminals never read more than that 13.2. In other words, when you set 14.4V on a charge controller, it actually means "14.4V or the voltage needed to limit power output to the available input power, whichever is lower". So that would indicate that the PV input power is to low to drive the battery voltage up faster. I figure this is the absolute highest voltage the controller will send to the batteries. We have trouble shot everything and wondering if anyone else has had this problem? Over voltage disconnect voltage - I'm guessing this means that if the controller will disconnect if the detected battery voltage is higher than the value. And there's a recognized input coming from the van battery (and/or solar, but I don't have any solar hooked up yet) that's above its start-up threshold - which it is (mine is delivering 14.4 and up, vs. the 13.2V start-up cutoff). All batteries have some resistance to charging, and LFP batteries are no exception. It's high because lead acid batteries have a lot of internal resistance and all that. Probably could get away without it but I feel better with it. Since there is very little useful capacity over 3.400V per cell there is little point in reaching that value. So why are you only getting one amp from your panel(s)? > I would expect it to read 14.4V immediately. Only when disconnecting the panels would I expect it to read the battery's voltage itself, since the controller would no longer be outputting anything. If one cell becomes higher or lower it will modulate the current to ensure they are within parameters, sometimes actually cutting the charging altogether to allow stabilization then resuming, this occurs at the knee of the charging curve where minor imbalances occur for the most part. Example, if a battery is at a lower state of charge and the maximum amperage is applied, the voltage will go to absorb voltage almost immediately and stay there until absorb is finished. The Fora platform includes forum software by XenForo. Press J to jump to the feed. Yes? The battery will take constant current until the voltage reaches the absorb set point and then because the voltage will no longer rise, the amperage will begin to slowly drop while the voltage remains constant. I was getting some direct sun. Under voltage warning - I'm assuming this means it will audibly beep and turn on the warning LED if the voltage drops below this value, giving you a chance to deal with the issue. I could set it to 14.2, but that didn't change the behavior of the controller. Let's assume the battery voltage is 13.4V, that value is in the 90-95% fully charged regon, without knowing exactly what the BMS is programed to do, it is very likely it is purposely reducing current for the final few percentage points, there are hundreds of cells which need a very controled current to prevent individual cell runaway. This is roughly a 24 hour period. Source: https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries. Most modern MPPT chargers (or pwm) DO NOT have an LI setting and must be programmed manually. 1500W, 6 Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS, "we go where power lines don't" Sierra Nevada mountain area, https://forum.solar-electric.com/discussion/comment/396656#Comment_396656, https://forum.solar-electric.com/discussion/comment/396661#Comment_396661, https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries, https://forum.solar-electric.com/discussion/comment/396670#Comment_396670, https://forum.solar-electric.com/discussion/comment/396654#Comment_396654, https://forum.solar-electric.com/discussion/comment/396675#Comment_396675, https://forum.solar-electric.com/discussion/comment/396680#Comment_396680. Hopefully it will raise the battery voltage 1 or 2 tenths of a volt. The current should be at maximum until almost fully charged, it should then cascade to very low values as it approaches the terminal voltage set-point, 14.4V in your case. If it were truly charging the battery, then the voltage would be higher when charging than idle, but they are both the same. In short, It's "charging" right now, but my multimeter only reads 13.2V on the battery. Not a bad life and as I remember, some of my best years. ", The Forum has been moved to support.renogy.com, Lithium 170 ah Batteries not charging completely. Batteries dictate the charging voltage which the controller is stepping down to. This subreddit is for you! Voltage, up to the absorb voltage is available but the battery doesn't instantly jump to absorb voltage. The controller meter says 13.4V. Renogy gives a cut-off current, so to stop charging after that. It depends largely on the controller, if automatically 2% as the Schneider is, based on battery capacity, the capacity programed into the controller would be less than actual, to ensure a quick transition to float, technically ending the charging. That's what it needs to put out in order to get current to flow into the battery. Then you should see substantial current . Now, if I used the same settings but I connected a flooded battery, there's no way it would have charged it. It says nothing about float, and my research says that it's just supposed to be the same as the charging voltage. Well I missed out on a lot of much more detailed explanation on lithium batteries than I could give. If the voltage were high enough, the battery would receive a charge, regardless of the amount of current. I am available for custom hardware/firmware development. It defaulted to 13.2. That and the fact that I can leave them for 3 months in the summer without needing to check electrolyte. Press question mark to learn the rest of the keyboard shortcuts. It seems like the voltage it must drop to in order to go back into boost/absorption mode? Plenty of Baja Sea of Cortezsunshine. And you are charging with 5A. Still love it here but a bit more work than normal. I also didn't realize the battery could prevent the controller from stepping up the voltage. Well, riddle solved. If a charge of half that amount is applied to the same battery, the voltage will rise, but take much more time to reach absorb voltage. It looks like you're new here. I'd assume the same is true of lithium batteries, so how can it be charging the battery at only 13.4V? @littleharbor2 Yes and no, there is no absorption to speak of with Lifepo4 , the voltage for both bulk and absorbtion are set at the same value, with a very short time set for absorption to satisfy the needs of the controller, end amps really don't come into play. Generally based on a timed end point or a percentage of Ah. Your not really suposed to top them off either, 90% full is plenty and increases the battery cycle life when it comes to LI . Also, I recommend the float voltage be set at 13.4 volts. You can shut down the controller then reconnect the next time the sun is overhead and shining brightly on your panels. Float charging voltage - Like I said above, I've read it's supposed to be the same as the main charging voltage, so I set it to 14.4V. Very comforting to hit that inverter bypass and a different set of batteries and inverter come on. Our entire system is Renogy. I saw the another as high as 5 amps, but the voltage was still only 13.2 at the battery. I have two concerns at this point, first is the Renogy battery doesn't have output contacts from the BMS so I do not know how to trigger the Multiplus to turn the charger off after the battery is fully charged if I don't want to use a float voltage such as when in storage and what triggers the charger to charge again if the battery does need "topped off". Calibration needed? Besides that would a useless and quite lame thing to do. I don't understand all of these settings. I'm a little confused if it's the charger not charging properly, or if the battery is meant to have a full charge state at 13.6V. "All the theroy related to lead acid is not applicable, useful perhaps in basic understanding, but definitely not applicable to lithium batteries and their very different needs.". I just setup my controller and such last night and got my Renogy lithium battery today. I'm just not understanding why that was the case. Couldn't do that with flooded batteries. The controller was supposedly in Boost (absorb) mode, but the voltage was less than a traditional float charge by almost half a volt. Anything Solar Do It Yourself! It won't let me set it to 14.4; it gives me a parameter error. I'd assume that amperage reading in the middle indicates that it's putting 3.9A into the battery, but maybe that only means what's available. If you know who closes the border it wouldn't last 24 hours. That is much safer. I'm curious what Renogy says it should be. And why doesn't it read 14.4V since that's what I configured it to output? I guess I didn't expect them to send me a battery with such a high SoC. If the voltage were 14.4 with 0.5A, it works still charge the battery, albeit very slowly. Batteries are only 2 months old. That seems backwards to me. Regarding the float voltage, what's the reason to lower it? I expect you need a more precise volt meter. 2.1 KwSuntech 175 mono,Classic 200, TraceSW 4024 ( 15 years old but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 460 Ah. This is why Tesla insists on fire cabinets and special chargers designed for LI batteries. Are you building a solar system for your house? This also seem to be the general consensus wit of grid users of lifepo4 prysmatic cells which may differ from your battery if it uses hundreds of small cells though I do have my doubts. If you've mentioned what panel you are using I missed it. Blue smart IP65 12V 10A and Lifepo4. If it were a simpler design, the RPM of the alternator is what determines the voltage. If the internal BMS manages what they battery takes in, why lower the voltage at all? One manufacturer of a battery system states that if the charge settings are set at 3.600V per cell, rather than 3.400V, the warranty is reduced from 10 to 5 years, there is also a maximum discharge parameter of 20% SOC involved. We had a really bad winter weatherwise and 2 years of month long, smokey wildfires. In essence you would be fooling the controller into believing it is charging a lead acid battery.