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Old 01-12-2021, 04:52 PM   #1
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Default Battery Analysis... Thoughts?

This was posted on another RV forum, but there really wasn't a lot of technical response. I've noticed there's a ton of electrical expertise on this forum, and I'm wondering what y'all think. I apologize for the length. I'd be interested in impressions even if you only watch a portion. Information or infomercial?

It's a cost/benefit comparison between lithium and lead-acid batteries. Bottom line conclusion was if you go lead-acid, go cheap, but lithium provides the cheapest power over the long term.

I'm not trained in electrical systems, so some of the frequently used terminology went over my head, like "puchrative (sp?) losses" and "voltage sag." Trying to learn...

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Old 01-12-2021, 05:39 PM   #2
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Adding just a 100ah lithium battery (Battleborn) inside a Chevy Roadtrek has made a world of difference in electrical capability and I certainly recommend it. Were I to install it outside I would be interested in the heated version.

I have five Battleborn batteries in two RVs and have had no problems with them over the past two-three years. Using a generator it charges to 100% in much less than an hour. Charging time is the greatest advantage of a lithium system.
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Old 01-12-2021, 05:44 PM   #3
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Peukert's law mathematically describes the observation that the more power you try and get from a lead acid battery, the less it will give you.

This is a real problem for RVers, because unless you use only a a tiny trickle (<10A for a dual 100A bank) from your lead acid batteries you will not get the rated capacity. From the testing described in the video it sounds like even at this very slow rate all of the tested AGM and lead acid batteries failed to deliver their rated capacity, and some were quite a bit below their rated capacity.

If you use an inverter lead acid batteries are even worse. The voltage sags considerably when serving a load. To keep the power draw constant the inverter increases the current draw which worsens the Peukert effect.

I upgraded from two 100A AGM batteries to two Battleborn LiFEPo4 100A batteries. The difference is absolutely amazing. Same total amp-hour rating, but more like triple the usable capacity for normal RV loads, and 6x+ the capacity for running my AC unit or convection oven. Almost no voltage sag so the current draw is smaller. They can be discharged almost all the way without damage, and when you charge them they accept far higher charging currents right up to full charge so you can fill them up in very little time.

When I was considering the upgrade I read a lot of criticisms and warnings of using LiFEPo4 batteries for RV applications. After the install I performed quite a few tests to see how they performed in terms of current draw on the alternator, alternator temperature rise during high-current charging, the need for different charging voltages, and other parameters. My conclusion is that for a smaller LiFEPo4 bank, like my 200A one, these concerns are way overblown. You do need to have a LiFEPo4 capable converter/charger and solar controller (if you have solar), but there is absolutely no need for a DC-DC converter (at least with the Promaster chassis).

The one criticism that I would emphasize however is their cold-weather susceptibility. You need to have a plan for how to keep them safe if you live in a place that sees temperatures below -4 degrees F. Thought they don't say anything about this on their website I saw an Battleborn advertisement the other day in an Escapees magazine claiming their newest batteries now have an internal heating element. If you had these then you could keep your batteries safe by just plugging in the RV whenever the temperature might fall below -4 degrees. As it is, I took the precaution this winter of swapping back to my AGM batteries. This works ok since I don't think I will need the AC until it warms back up.

If you are on the fence about Battleborn batteries I would encourage you to go for it. It is a huge upgrade.
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Old 01-12-2021, 05:51 PM   #4
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"I've noticed there's a ton of electrical expertise on this forum"

Yes, but that does not include me, but still:

"Bottom line conclusion was if you go lead-acid, go cheap, but lithium provides the cheapest power over the long term."

This is understood and has been for 'years'? But that conclusion again is 'cost'. For example, recently here there was a discussion of least cost amp hours - 2 six volt flooded batteries was the answer. Point is, you have to water them. Not watering may very well be worth the extra cost.

"voltage sag", love it - my primary battery monitor.
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Old 01-12-2021, 05:56 PM   #5
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I didn't watch past the first 30 seconds. When it has to do with a Battleborn comparison and includes a disclaimer about including a paid promotion, I am out of there. There are probably dozens of similar videos all over the place, so I would expect this to be the same.


The lithium drop in batteries have limited history, so far, of maybe 3 years, so we really don't know if they will reach anything near the claimed life at this point. They are claimed to not need better charging, and no float charging and we don't know if and how much that would make a difference.


Battleborn also used to say they didn't need heaters, and they have severely reduced their recommended charging rates, so still a pretty fluid set of rules, I think.


My personal opinion is if you want go cheap without upgrading not very good equipment, use Walmart wet cells and consider them disposable. If you have pretty good charging then inexpensive AGMs or higher end wet cells. If you take good care of you batteries with good equipment and monitoring, go for the good AGMs. Lithium, for me, would not include drop ins, but might include fully integrated systems like the OEMs are using in some cases, as long as I had a warm place to store and park the RV.
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Old 01-12-2021, 07:15 PM   #6
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It seems some federal campgrounds are reducing generator hours to morning and evening blocks of two hours each. A lead acid battery bank cannot reach 100% by generator in that time. Lithium works very well with those restricted hours.

That is also a case for solar capability.
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Old 01-12-2021, 08:31 PM   #7
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I'm going on 6 years now with my lithium ion 800ah battery bank so I guess I have the history. Still performing nicely. I would never consider lead acid considering the many advantages. Maybe up to 200-400ah you may not see all those advantages. But in excess of 400ah weight and space become a major consideration as well as a need for faster charging. Self-heating or external heating when you have high capacity off the lithium batteries themselves expends few amp hours. Long-term you should have heated storage space or shore power of 15a if you are in a 24/7 -4F climate. My advantage? All electrica with no propane and I can boondock park at least four days without running any internal combustion engine and still have 115AC service with all outlets and electrical equipment usable 24/7 as if I did have shore power.

I do recommend a second alternator. It is way more convenient than an Onan and can charge much, much faster. Advantage or not, I've found solar is not needed with 800ah of lithium batteries especially with a second alternator. Solar becomes a negligible contributor. You can only get so much solar on a B roof and people are finding that real estate has better use for storage, kayaks, decks, skylights, antennas and such.
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Old 01-12-2021, 08:46 PM   #8
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get the battery(ies) you need for the power you consume


were I to get a lithium it would be wasted money- I don;t need that capacity, propane does the heavy lifting for energy us off grid


I know that with my 1 battery and a briefcase solar cell kicked to follow the sun, I am good for 5 or 6 days at typical energy use- led lights and dc native TV. no inverter ( so no microwave or A/C)
got a genny- have never used used it camping!
the costco battery is edging on 6 years and is fine- i treat it nice.



if you have heavy energy needs a lithium is probably the best choice, define heavy first



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Old 01-12-2021, 09:33 PM   #9
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Quote:
Originally Posted by Jon in AZ View Post
This was posted on another RV forum, but there really wasn't a lot of technical response. I've noticed there's a ton of electrical expertise on this forum, and I'm wondering what y'all think. I apologize for the length. I'd be interested in impressions even if you only watch a portion. Information or infomercial?
Infomercial

There are two lead acid battery capacity ratings. They are:

AMPERE HOUR (Ah) The amount of current expressed in amps that a battery can deliver at 80 F, multiplied by hours it can deliver the current without falling below 1.75 volts per cell (10.5V on a 12-volt battery).

RESERVE CAPACITY (RC) The amount of time expressed in minutes that a battery is capable of delivering 25 amps of power at a temperature of 80F without falling below 1.75 volts per cell (the equivalent of 10.5V on a 12-volt battery).

If you're going to claim that a battery doesn't meet the manufacturers rating then at the very least do the actual, recognized tests. The posted video appears to show a made-up meaningless test using inappropriately high cut-off voltages (12.2V & 11.8V) favorable to the Battle Born battery. Lead acid battery rating tests are to 10.5V as described above.
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Old 01-17-2021, 07:29 PM   #10
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Infomercial. Battleborn is doing a good online marketing effort that includes a lot of "influencers". That doesn't mean it doesn't produce a good product or have legitimate satisfied customers, just that you should be cautious with the information you see.

I think its pretty obvious there is no right answer for everyone to the question of whether lithiums, agms or flooded lead acid are best. It depends on how you are going to use them and for how long as well as how much money you have to spend. FOr instance, it may be that lithiums will outlast AGM's with your uses, but that assumes you will still own the RV when the AGM's need to be replaced.

I don't think planning to run AC for long periods off batteries while boondocking is realistic with AGM's. But I am not sure it is realistic with lithiums either. It is clearly not realistic to compare AGM's and Lithiums based on equivalent AH ratings. But it is also misleading to suggest AGM's can't be drawn down below 50% as this video does.
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Old 01-17-2021, 11:06 PM   #11
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I’m happy with Battleborn, so far, but you need to realize that the test bench in the background in the video is probably in the Battleborn facility in Reno.

Glad to see Battleborn batteries can have a heater.
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Old 01-18-2021, 02:44 PM   #12
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Thank you to all who took time to school an electrical novice. I have a little better understanding of Peukert’s Law and voltage sag. I guess that’s related to the reason you always check the voltage when the battery is at rest to get the most accurate estimate of its state of charge. Thank you for drawing my attention to the ways in which the test parameters were essentially rigged to favor lithium.

For now our power requirements are pretty modest. LP provides all our high energy functions (cooking, space heating, and refrigeration), so our 2@6V FLA seem to do the job adequately for lights, monitors, fridge controls, limited furnace use, power bed & awning. Sure hate the weight and low power density, but it is what it is. I’d never recoup the initial cost of lithium, since we’re still working and only use the camper maybe 20 nights in a good year.

Someday I’d like to have 12V refrigeration, either in one of our current RVs or another we haven’t met yet. Whatever it is will be small and lightweight, so lithium seems like it might be part of the equation at that point. Hope they continue to decline in price and increase in drop-in convenience. Meanwhile I will keep learning.
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Old 01-18-2021, 03:25 PM   #13
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We have a solar panel producing @1KWH per day that pretty much keeps up with the refrigerator. But we have lots of battery storage to save the power for when its needed.
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Old 01-18-2021, 04:11 PM   #14
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DC frigs are not all the difficult to support. There are lots of users that do it with 200ah of lead acid batteries and 2-300watts of solar.


Sun conditions have to be horrible to not be able to keep up unless you use a lot of other power or don't have propane for the big heat type issues.


Most systems will also charge at 50 amps or more from the alternator so a days power in one our of running or driving in and emergency recovery.
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