You do not need a BMS for a 4S system. Would be complete waste of money as is using lithium in your application.
The BMS will never turn on, last thing you want to do is fully charge a Lithium battery which is required for a BMS to even turn itself on. Just float them at 13.8 volts. and set your Inverter to trip off-line at 11.5 volts.I can see the logic in not using a BMS in a 4S system but it would be easy and ensure pack stays balanced. A BMS that small is cheap.
I have no clue where you came up with that? A good higher end FLA like a Trojan Industrial or a Rolls 4000 or 5000 series has the exact same usable capacity of 80% capacity. However will live a lot longer than any Lithium battery. You would have to be pretty gullible to think otherwise. CALB, Winston, GBS if you could get a Chi-Com manufacture to honor a 1 year warranty tells you how long they will last. Trojan Industrial has a 10 year warranty with first 3 years full replacement plus 7 years prorated for 10 year total. Rolls 4000 and 5000 same 10 year warranty Trojan offers. Either cost 1/3 what Lithium cost and will last 5 times longer.I respectfully disagree that lithium is a waste of money for a RV house battery. To get the same 400AH capacity, you would need almost 800Ah in FLA and deal with the off gassing, maintenance and smell. I won't even get into the space required for a 800AH FLA 12v system.
It your batteries are gassing excesively would tell you the voltage is set too highYou disagree that FLA's have off-gassing, maintenance and smells?
I never said anything otherwise now did I? What I said is both have the same usable capacity at 80% DOD. At 80% DOD, which would be a very rare event unless the owner is DIY and clueless, Trojan Industrial line still has twice the cycle and calendar life than Chi-Com LiFeP04.You can't argue that discharging past 50% will shorten the life of a FLA.
Rolls is to Rail Road and Marine as Trojan is to Golf Cart and Floor Sweeper machines. They have been around a long long time. The 5000 series carries 10 year warranty. Both Trojan and Rolls are 100% made in the USA.I just saw the Rolls have a 7 year warranty, that is very impressive. I haven't heard of them till now. I have experience in traditional Trojan 12v FLA and they only provide ~3 years service in golf carts.
While FLA are proven technology, I'd much rather prefer a sealed battery in my camper. I see Trojan has high capacity 250Ah 12v AGM's but they only have a 1 year warranty. Any thoughts on a quality AGM with at least 250Ah size and a great warranty? I could parallel two for a 500Ah pack in the future.
Completely meaningless.You do NOT PRICE BATTERIES based on AH because it tells you NOTHING. Your base battery cost on Watt Hour Capacity.Not quite $0.85 per amp hour but the cells we have are about $0.875 per amp hour now on eBay:
Well I am hear to tell you is it is common practice to run at 24 volts, and a few 48 volt systems. But be warned going to a higher voltage eliminates your prime power source, the 12 volt alternator to recharge your batteries whenever engine is running. Pretty much means you would need a generator.I have considered the idea of a higher-voltage RV battery, but specifically to make 120 V AC integration better in a motorhome:
Sure, but you got caught in a 12 volt box. There are two applications that demand 24 volts and once in a while 48 volts.In fixed solar installations, sure, but in an RV?
Sure, but we're discussing an RV, and one that is unlikely (I would guess) to have a massive solar installation and will almost certainly have a 12 volt automotive charging system.
Brian I think you are overlooking some things. 24 and 48 volt super high efficiency air conditioners like Truckers, Off-Griders and Telecom use. I agree with your POV. If all you need is lighting, some entertainment like a TV/Radio/AV and low power devices 12 volts is just fine. But you have people who insist on electric cooking, refrigeration, and the impossible air conditioning requires a lot of power that a 12 volts is just not capable of doing safely, efficiently, and economically. How many 12 volt EV's do you see. Only a DIY would be that foolish. If the owner refuses to consider using propane for high energy requirements, you have limited your options and have to get creative.Sure, but we're discussing an RV, and one that is unlikely (I would guess) to have a massive solar installation and will almost certainly have a 12 volt automotive charging system. Carrying a generator just because the system wasn't properly set up to charge from the vehicle would be silly, and doing without power is not reasonable.
All good batteries, but there are more of equal quality and better. You mentioned Lifeline made by Concorde but they make even a better AGM in a much wider range of capacities and voltages called Sun Extender. All those mentioned are on the same boat as lithium with a worthless 1 year warranty. Another manufacture of high quality AGM batteries is Fullriver and carry a 7-year warranty. You can hammer them with 80% DOD with no problems in an RV application.in the US market, stick to Lifeline, Odyssey and Lifeline.
Well you can wait for guesses or calculate it yourself pretty easily. Most of the AGM batteries you are interested in specify Internal Resistance. For example a Fullriver DC400-6; a 6-volt 400 AH AGM specifies Ri = .0016 Ohms. It would take 2 in series for 12 volts thus total Ri = 2 x .0016 Ohms = .0032 Ohms.1. Voltage sag under load falsely hitting low voltage cutoff on inverter reducing house battery usage, even with a fully charged battery. Especially apparent if running microwave or aircon. This wouldn't happen using LFP pack as lithium doesn't experience voltage sag nearly as bad.
I tried to tell you that in PM's but you were not having any part of AGM out performing LFP. Amp Hour per Amp Hour, AGM out performs Lithium with respect to high current. I had to have you discover it for yourself. The math does not lie.LFP Ri is double some AGM batteries. I didn't expect that.
They cannot and is of no concern for scum bag spammer. LiPo is the last thing you want for a house battery or any application requiring long life as LiPo only have roughly 100 cycles in them. LiPo's are used in RC aircraft where C-Rates run 20C or greater continuous. Extremely dangerous lithium batteries notorious for catching fire.If LiPo, how can they be made to work at 12V for a House bank?
Stricter yes like NEC, and for good reason. Easy to hop out of an RV or EV on fire. Not so easy on a plane or boat.Wire size calculations in aircraft get even crazier.
I was wondering how long it would take you to realize that. I would not have an RV without propane to do the cooking, heating, refrigeration, and generator. That is why many come with Propane Tanks. Batteries are for lights and entertainment.Looking at heating for hot water and even the van air, I may need to abandon the want for an all electric camper and add propane to the requirements list.
I never charge 4S LFP higher than 14V, usually 13.8V.
Under load stays around 13.1-2 cutoff at 12V.
Avoid the shoulders, gain longevity, no need to balance.
This part I do not fully agree with. LFP are drop in replacements for Pb, and no changes are required. However Chi-Com LFP batteries do not have the high C-Rates of a good lead acid, and there is no contest against AGM will run circles around any Chi-Com LFP. A Chi-Com LFP internal resistance is 2 to 3 times higher than than a Pb battery of same AH capacity. You can take say a 55 AH Optima Red Top and put it up against a 100 AH CALB, and the Optima will outperform the LFP with respect to voltage sag by a large margin. To get really low Ri would require you to buy a quality LFP cell from reputable manufactures like A123 Systems or LG Chem, but you will pay up some 400% to get them if they were available.Never came across a load wasn't just fine with that, much less V sag than lead for winches, huge inverters etc.
Most companies building Class B and C motorhomes using the ProMaster went with the gas engine from the beginning, presumably for cost savings. All manufacturers have had challenges getting diesel engines approved
Correct and the EPA made damn sure Diesel in the USA would be higher by making refineries refine diesel more than other countries. All done to discourage deisel fuel use by design. That means the EPA does not care about efficiency and want to punish the citizens.Partially because diesel fuel is much cheaper then petrol (gasoline) in most other countries.
Also EPA restrictions installed for US market diesels makes them very complicated engines and expensive to fix. Example is DEF or diesel exhaust fluid and the regen system. Run out of DEF and you cannot just add more and drive, it needs reset by the dealer to even start the engine again in some cases.