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 > Your search for posts made by 'BFL13' found 1246 matches.

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RE: LFP on Shore Power with Inverter/charger?

"If you want to measure your battery capacity, charge your battery full, turn on a load (the current doesn't really matter) and then run until the BMS cuts off. Look at your battery monitor to see how many Ah came out, and that is your capacity" That makes sense, kind of like my "new plan". It would not quite work with my Trimetric of course, since it gets its 12v from the battery being monitored. When the BMS cuts off the battery, the Trimetric display would go black. Have to take the AH reading just before the BMS shut things down. Have to know when that is about to happen. time2roll is going to try to camp the same as now using his voltmeter as the only monitor he needs. I like Itinerant1's approach. He must have done a whole bunch of math before getting his set-up. His 500AH bank was not chosen at random, nor his amount of solar. He figured his daily AH usage and the various rates. He is thus able to do it all, staying above the lower knee, and get his cycles worth of LFP without having to use high rates. He monitors it all like crazy to make sure it is working like it is supposed to. He "adjusts" his solar so it can keep up by moving North and South as required as well as keeping in comfortable climates. None of that happened by trial and error--he did some math first. time2roll has the luxury of being able to do some trial and error, not being a full-timer. He can get a monitor later if needed. Anyway, you LFP guys can figure out how to play it each to his own.
BFL13 04/19/21 11:25am Tech Issues
RE: LFP on Shore Power with Inverter/charger?

BB says the surface charge voltage 14.4 -14.6v when the batt is fully charged and is at Vabs drops to 13.6 when that surface charge is gone and the batt is resting at full 100% SOC. FWC says it drops to 13.2-13.3 but that is under a load, as though somehow the 13.6 was still with a surface charge and now all the surface charge is gone, but he did not say that the batt is still full. Not clear what he really means by that. My new plan (see earlier post) is to never mind what the capacity is of the LFP you just got. Find out the AH allowance you can have with it, and pretend that is the capacity. Use the AH counting monitor to keep track of what's left of your allowance while camping and recharge as required. BTW, FWC, you know darn well where that 113AH came from. That was from saying the 1536 Wh was correct. You said that 1536 was fictional, but the 120AH is correct. You never said why to believe that AH number and not the Wh number. Also "nominal" is in English, so we know what it means. It happens that FLA and AGMs both use nominal voltages , 12v and 6v, eg, while LFPs use 12.8v as "nominal" No problem. We don't use "12v" when using the resting voltage vs SOC tables for those batts either. We use whatever the batt specs say is the resting voltage at 100%. Many FLAs use 12.7 as "full" while AGMs use 13.0 as full. No problem. eg my AGMs were 12.4 as 50% while my 6s were 12.1 as 50% (it stayed at 0.3 diff for that range of SOCs) AH count still works. Just means use the right voltage for that battery as your cross-check when "matching". With LFPs it seems you can't believe the Wh or the AH ratings to use with your monitor and you can't really match the voltage with the AH count to do cross checks. Apparently all you have is your AH counter to go by. So my new plan is to use your "allowance" (as described earlier) and use that as your "capacity" never mind what the real capacity might be in the strange LFP wonder-world of inconsistent numbers. YMMV (and no doubt does! :) )
BFL13 04/19/21 08:43am Tech Issues
RE: LFP on Shore Power with Inverter/charger?

How's this for a plan then?---- FWC was careful by saying, "the resting voltage is 13.2-13.3 " He did NOT say that was the "full resting voltage". He did say that as soon as a load is applied to a full LFP, the voltage drops to 13.3. So 13.3v means anywhere from 99-89% SOC in effect. Then the voltage/SOC table time2roll posted (from BB's) could be used (except very difficult to get proper voltage with the temperature making that so sensitive, per FWC's note on that) Then time2roll makes a very important point--you can see where the lower knee starts by watching your voltmeter. How to use your AH counting monitor or smart shunt? 1. You get the battery as full as you can using its charging specs and guide for that. 2. Pick a number for your amps draw since Peukert is near 1 (FWC again) say 10 amps and hold that constant as you can while your AH counter counts down and you keep an eye on the voltage. 3. When voltage starts to drop off, stop! Now you have your AH "allowance" that you can operate within. Using a variety of amp draws while camping, you still have the same total allowance. ( which is why the 20 hr rate doesn't really matter with Peukert at 1) What do you enter as your "full" capacity on the monitor? Doesn't matter as long as it is more than your "allowance". Set your low voltage alarm at that voltage you saw where it started to drop off. While camping, you can watch the AH counter count down and remember your allowance. You can do the math in your head to tell when you are half way down or three quarters the way down, etc. OR, if you make your AH allowance your "full" entry on the monitor, and it reads your percentage SOC, you can use that. Just remember to zero/sync the monitor whenever you get the chance when the batt is as full as you can get it. TA DA! Is that what you LFP guys do? ( Itinerant1 has a more complicated monitoring system that does include some cross-checking, but I am wondering what LFP guys with a simple system do) jaycocreek is looking for suggestions and I suspect time2roll is suspecting he will now need more than just his voltmeter too, so over to you LFP guys on what to do----
BFL13 04/19/21 06:59am Tech Issues
RE: LFP on Shore Power with Inverter/charger?

Yes, I did not state very well how my 10hr test is run. I actually use a 50% "marker" like SG or resting voltage /SOC or both. when I get to that marker, I note the AH count. if I hit the marker '"early" (usually happens) then if that is at 9 hours, I know the battery is 90% of its rating. So with a brand new battery starting full, it ought to go to half its rating in 10 hrs. I would still need the marker. The flatter voltage/SOC just means being more careful to get the real resting voltage. Running a few of these tests, you get an idea of what loaded voltage will be at the 50% marker that will bounce back after to the real resting voltage by next day. At first you can overshoot or under shoot. If you under shoot you can just restart the load, but overshooting is hard to calculate from.
BFL13 04/18/21 09:53pm Tech Issues
RE: LFP on Shore Power with Inverter/charger?

PS the resting or 'nominal' voltage of LiFePO4 is NOT 13.6V. The resting voltage is 13.2 - 13.3 and the 'nominal' voltage is 12.8V. BB says 13.6 is "full" and 13.3 is more like 90%, but whatever. Everyone seems to agree that 10v is "depleted". They should agree on "full" too. Why don't they? I know different brands of FLA and AGM don't agree, but they do give out their own tables so you can use the right numbers for what battery you have.
BFL13 04/18/21 09:23pm Tech Issues
RE: LFP on Shore Power with Inverter/charger?

IMO that does not pin the thing down---nailing Jello to the wall and all that. It is all too wishy-washy for me. If I had one, I would get it as full as I could (won't take any more amps) and then run one of my capacity tests. If I assumed 120AH is full, I would run it down at 6 amps for 10 hrs and note the Trimetric monitor's AH counter. If it came to 60 AH in 10 hrs I would say it is indeed a 120AH batt. If it came to 55 AH, I would say it is a 110 AH batt. Whatever it came to, I would use that as my capacity for monitoring it. ( I might have to run another test at 5.5 amps to be accurate) I would adjust the capacity for temperature like I do now, so I have a pretty good idea what I have in the bank while camping. At least I would feel like I have a real number. I don't like how you can't measure an AGM with an hydrometer, but at least you can use the AH count and compare that with voltage to see if they "match". LFPs are even worse it seems! Now you can do the AH count, but can't easily "match" that to a voltage. Phooey. I like to cross check to verify meters and gauges. You guys can sort it all out to suit yourselves, which is how it is supposed to be. Meanwhile, I can keep on with my Fred Flintstone methods. :)
BFL13 04/18/21 09:18pm Tech Issues
RE: LFP on Shore Power with Inverter/charger?

You would want to enter 120Ah for your 120Ah battery, as it states clearly in the spec sheet. FWC, the spec sheet says 120AH "nominal" It gives the capacity as 1536 Wh without saying, "nominal". It says the 12.8v is "nominal". So why do you believe the "real" capacity is 120AH? If it is, then the Wh figure is wrong AFAIK. (13.6 is full, not 12.8) Do you believe or know that they measured its capacity as 120AH first, then derived that 1536 Wh figure afterwards from the nominal 12.8 voltage? If so, how do you think they got that 120AH? By running it at 120a for 1 hour? Or how? The usual 20 hr rate test ends at 10.5a but these batts are "depleted" at 10a. Not sure that works. Be very interested in your explanation, thanks.
BFL13 04/18/21 08:40pm Tech Issues
RE: LFP on Shore Power with Inverter/charger?

IMO the 120AH capacity entry is too high, being based on the 12.8v instead of 13.6v With the capacity too high, when it gets down to say 30% in its mind, you will be lower than that. I don't know how low you would ever go so that would put you "too low". I see the video shows how you can set "alarms". I don't know how you get the alarm if you are not watching the cell phone or what you do there. I would use 113AH as mentioned to be on the safe side. I know the BMS will shut it down at 10v, but then you lose all 12v, which might be a problem or not until you get it going again. I guess you could set the alarm for before it got that low. Combined with using a lower AH capacity like 113AH , that should keep you in the clear?
BFL13 04/18/21 03:41pm Tech Issues
RE: LFP on Shore Power with Inverter/charger?

Makes sense to me. How can you tell you are still above 50% SOC? What settings are you using for "full"? Is that with the smart shunt? The Video here shows how to set it up including the full capacity. scroll down to the video. http://www.wegosolar.com/products.php?product=SMART-SHUNT-Victron-Energy-all-in-one-battery-Monitor
BFL13 04/18/21 02:38pm Tech Issues
RE: LFP on Shore Power with Inverter/charger?

https://www.lynxbattery.com/lithiumbatteriesrv They say the 120AH is "nominal" so the real 20hr rate capacity could be that 113AH IF they are full at resting 13.6v like the BBs. I don't know. You could get the battery as full as it can get, and wait till next day to get the resting voltage, and divide the 1536 by that to get the AH to use as "full" with a monitor. The charging voltage is 30a, which would be their recommended for long life I suppose. You can use higher amp charging to save gen time if that is more important than max lifetime cycles. Their sales blurb says "four times the power", but it is clear that they mean "energy" , not "power". Their Forbes link guy has a "power density" notion and an "energy density" idea too. He has the energy density being what saves weight (correct) and that is what the blurb probably means by "four times---". Tried to make sense of that before, but since the LFP is only 1/3 the weight of an AGM same AH, it is hard to follow. Might not include casing and BMS etc, just the cells? EDIT--105AH AGM =66 lbs. Lynx 120AH = 35 lbs so where is the energy density "four times" ? It is only half the weight. (another thing we are not supposed to ask about? ) "Power density" seems to be like CCA the way he uses it, so he just means higher power density means more power (I guess) Near as I can tell, you are not supposed to worry about all that, and just use the battery, but stay above that lower knee, playing it safe by staying higher above the lower knee, since your monitor is only going to be a rough guide to the SOC. ? YMMV.
BFL13 04/18/21 01:21pm Tech Issues
RE: LFP on Shore Power with Inverter/charger?

Steve, thanks for the clarification. I was using CCA because it is the only thing I can think of with battery ratings that are a measure of its power. FWC said a battery's power is its max current at its nominal voltage (if I got that right) so 800CCA is twice the power of 400CCA. I don't know where an RVer cares about power as such. Ads saying a battery has "twice the power" got me wondering what that is supposed to mean. Seems to be "Sales" talk. ? That Odyssey 31 hybrid battery that allows a high draw makes that claim, and ISTR LFP ads saying that too. Another puzzle is how they do AH with LFPs, but that only matters to those who operate them trying to keep track of usage while camping if they even do that. EG, The blurbs say don't use Peukert, but still say the LFP is 100AH because they ran it down at 100 amps in 1 hour so that is 100AH. Then they sort of dance around saying it also takes 20 hours to run it down at 5 amps, so that is 100AH at the 20 hr rate. But no Peukert here folks! :) It makes your head spin. Then they start in with the Wh, but use the 12.8 nominal voltage to get the AH. OR----did they get the AH first and then invent the Wh???? In the previous example, it was 1536 Wh and 120 AH at 12.8v The battery is full at 13.6v so that is where you have to start. Either: A. the battery is really 1536/13.6 = 113AH , or B. the battery is really 120AH so x 13.6 = 1632 Wh Which is it? If you are monitoring by Wh usage or AH usage, I would think that is important for setting up your monitor. Not a clue. so Steve, what are you going to do for operating your "280AH" battery for setting up a monitor? Just curious on my part, but other LFPers might be interested. ?
BFL13 04/18/21 11:41am Tech Issues
RE: On the road, battery and charging problems

Hard to follow what is going on, but I hope you know that your charger is not working right, or it is not being left on long enough to bring up the battery voltage to 14.4v. Also you need to be charging at a 20% rate while getting the batts to that 14.4v (forget that 15a nonsense!) Once at 14.4v the AGMs have to stay at that voltage until amps taper to 0.5a/100AH. So you need an ammeter to know when that is. Read the AGM charging guide here--5.2.2 -it also applies to yours. https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf
BFL13 04/17/21 04:51pm Tech Issues
RE: Inverter

https://www.boatandrvaccessories.com/products/powermax-pm3-60lk-12-volts-60-amp-power-converter-battery-charger-w-led-light https://powermaxconverters.com/wp-content/uploads/2021/04/PM3-Owners-Manual.pdf
BFL13 04/17/21 07:31am Tech Issues
RE: LFP on Shore Power with Inverter/charger?

On my battery spec sheet it says (energy-1536 watt hours) but that really doesn't matter to me because I prefer knowing the amp hours over the watt hours,makes it easier for us dummies..lol Right. 1536/12.8 = 120AH but that 12.8 is "nominal" so you need the "real" voltage to get the "real" AH and the AHs could be any darned thing! Eg, if 13.6v is "full", then 1536/13.6 = 113AH So if you had a Trimetric monitor that wants your "AH capacity when full" to be entered so it can keep track from there, you would enter 113, not that 120. Not a clue what your smart shunt wants! You can fight that out with your monitors and meters, but it has to be tough being an AH man in that strange world. Rather you than me! :)
BFL13 04/15/21 11:18am Tech Issues
RE: On the road, battery and charging problems

Looks like your converter was not working even before you left. Suspect blown reverse polarity fuses from a mistake when installing the new batteries. Easy to check and fix. When you isolated the batteries to check them and the "monitor" did not change when you charged the batts, that could mean the monitor is also isolated. You need your own digital multimeter set to voltage to put on the batteries directly.
BFL13 04/15/21 10:43am Tech Issues
RE: LFP on Shore Power with Inverter/charger?

Ok one last shot at it. IMO Steve has it wrong by saying "power" has a time component. AFAIK Watts is "power" and no time, while Wh is the "energy", which is over time. Watts = volts x amps, and the amps might be said to have a time component with its definition of Coulombs per second, but I don't think that is a time component in "power". "Capacity" in Wh or AH is clear enough( 200AH vs 100AH at a given rate), and "twice the power" if that means 800 CCA vs 400 CCA. IMO people are mixing up "power" with "capacity". Should be simple enough to clear that up and end this!
BFL13 04/15/21 08:47am Tech Issues
RE: LFP on Shore Power with Inverter/charger?

My plan is to stick with AH and camp same as I always have. You guys can sort out the rest of it. We need a new topic! This thread is dead.
BFL13 04/14/21 08:19pm Tech Issues
RE: LFP on Shore Power with Inverter/charger?

Steve, IMO you are mixing up power and energy now. Based on what DrewE and FWC said here (scroll down) I think I have it right that CCA is power and how long the batt can keep cranking is to do with its energy. ("Capacity" should be its energy IMO. Not sure you should say "reserve power" either. Maybe somebody can sort that out) https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30219738/srt/pd/pging/1.cfm FWC's second para relates to my previous notion too, a low power batt with lots of energy like a deep cycle.
BFL13 04/13/21 07:26pm Tech Issues
RE: 12 volt only refrigerator

Seems like a typo thing. Lots of new RVs with 120v only fridge (called "residential"). On that, don't know if they give you a choice of a two-way instead on a new one.
BFL13 04/12/21 07:55pm Tech Issues
RE: Converter wiring question

Hot and ground apply to the 120v input side of the converter. There, white is neutral, ground is green, and black is hot. On the 12v DC output side, white is negative and the other colour is positive (blue in some converter models). White is return on 120v wiring but hot on 12v wiring. That is what has me confused. No. In RVs, DC white is always negative, if the other colour is black or blue or whatever. If the two DC wires are red and black, then now black is negative and red is positive. The output DC wires of the converter do not connect to the "converter"! (ok, they do, but at the inner end) They go the the DC fuse panel which has some lugs on it to take converter 12 v and battery 12v. If the battery wires to those DC fuse panel lugs are red and white, put the converter's white to the neg lug with battery white neg and put the converter's black to the battery's red on the pos lug . DC wires do not have a "hot".
BFL13 04/12/21 06:44pm Tech Issues
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