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Old 03-22-2022, 11:37 AM   #21
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Quote:
Originally Posted by BCam View Post
I've seen several references to these and have been intrigued. I checked out the link you gave, plus the specs on the Firefly 12VG31 (https://webstore.totalbattery.com/Fi...1-p/12vg31.htm) and have the following comments:

1. One advantage LiFePO4 batteries have is weight. From what I can see, the carbon foam battery weight is comparable to, or at least not dramatically less than AGMs (and more than LiFePO4s).

2. They also seem to be in the same price range as premium LiFePO4 batteries like Battle Borns.

3. I can't find an amp hours spec, just 720 CCA, which isn't important for house batteries.

4. For what it's worth, there are zero reviews.

Based on the above, I'd still go for the LiFePO4s.
Not disputing anything you stated above BCam, just introducing the 'option' of Carbon Foam since many people don't have either the resources to move to something along the lines of Lithium (along with all the upgrades needed to run them), or a formidable shop to take on the project. The Carbon foam (for just a little more $'s than AGM) can provide some measurable improvements compared to AGM; 3X lifecycles than the AGM's, and up to 40% more AMP/HR - and that's significant when your goal is to "just replace a Battery".
In a nut shell, there definitely is a place in the market for these batteries - They have become very popular in the Marine industry.
BTW you can find many practical positive reviews on the Carbon Foam batteries; hit up some of the marine forums.

Some additional info just for context:

https://www.coastalclimatecontrol.co...G6AippvfQpd9tI

https://www.coastalclimatecontrol.co...G6AippvfQpd9tI

https://www.fisheriessupply.com/marine-battery-types

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Old 03-22-2022, 11:46 AM   #22
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@pbwebb3
If you need to replace your charger and you’re going the LiFePO4 route, this Progressive Dyaminics charger in the 9100 series was the one suggested by Battleborn when I purchased my first Li battery. The “L” designation on the chargers signifies a lithium charging profile. Mine was a 30 amp charger, but they go from 30, 45, 60, to 80 amps.
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Old 03-23-2022, 11:10 AM   #23
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I traded DM with a builder in IG, but deleted the thread
Short Version: he built a 560 ah system for about $1,200
including the bmg or whatever it is called
in use for a year, no problems
lots of info around coming mainstream, poke around a bit
IMHO
it is all about the Amp hours and how to recharge
more amp hours leaves you wiggle room if not driving or in the shade

no relation, just googled this guy
https://cargovanconversion.com/build...thium-battery/

best to you

send pics

PS
i have two 100ah Mity max from amazon $400 each
400 watts solar
run lights, laptop, air frier (LOL) fridge and fan for heater
no issues
I use my gennyy for the Microwave
i use the inverter for the air frier

FWIW
i use a small air frier for bacon
i can prepare breaky and not stink up rig
bacon done by the time i get food done and on the plate
i use an extension cord and put it outside
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Old 03-23-2022, 09:57 PM   #24
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Originally Posted by Scalf77 View Post

That's a hell of an article. Wow. Thanks.
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Old 03-25-2022, 07:47 AM   #25
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So there really isn't a truly "drop in compatible Lithium solution". Charge profiles for a lead acid battery are not the same as charge profiles for a LiFePO4 batteries. Now that really isn't a lot different from wet cell batteries to AGM or GEL. Sure, they would work with a wet cell profile, but they were not the profile the battery manufactures specified. So, we might ask, what is the big deal.

The problem is life span of your battery. We have all heard the number of cycles that you get if you only do a 50% discharge. Those numbers come from testing the battery manufacturers do. To be sure that testing is done with very controlled environments, it is also done with equipment that will provide the parameters that they specify for their battery. They also control the discharge rate, something that really is not seen in real world use. So, what happens if you don't match up to the battery manufacture charge profiles? Simply put you will not reach the expected lifecycles for your given battery. To be honest you probably can't every reach those numbers, because of all the other variables that come into play.

When we upgrade to Lithium, we face much the same problem. The original message was some very specific charge profiles. The cost of lithium batteries was a big hurdle into the entry into wider Lithium use in RV's. While the manufactures could control their cost, the cost of upgrading to equipment that could support Lithium was an even bigger hurdle, and more importantly one they could not control. Well, they could, by changing the specified parameters for their batteries. Accepting profiles that weren't perfect, allowed them better market entry. The big issue again is expected life cycles. Many of us can remember early numbers being 5000 life cycles at 80% DOD, now most manufactures have brought that down to 3000.

pbwebb3 didn't really specify what actual equipment he had, but capnkurt did gives us his setup. First, we can use the PD9100 with charge wizard. The charge wizard will bring the charge voltage up to 14.4 volts, this meets the charge voltage for most lithium batteries. When the unit reaches about 90% charge it then drops the voltage to 13.8 volts, this really is too low for a proper charge voltage. Eventually it then drops into a float voltage that meets the specified float voltage of Lithium (Lithium doesn't need a float voltage) So it really is a voltage that is low enough it won't harm the battery.
The PD 9100 also once in storage mode or extended float, the unit will go into boost mode (14.4) every 21 hours. They call this equalize mode, even though it isn't a equalize voltage for standard batteries. Lithium batteries don't require or want a equalize mode.

I will be upfront and say I don’t specifically think the PD9100 with charge wizard is a very good charger for AGM batteries. It goes without saying that I don’t think it is great for Lithium. But a Progressive Dynamics representative told the OP that it would work fine with Lithium. To be clear, they do sell a Lithium version. We also have capnkurt usage data (admittedly he doesn’t plug-in much anymore) The key to the PD9100 profile is that it goes to 13.8 volts after reaching 90% full. Most three stage chargers would consider this the absorption stage and would stay at 14.4 volts while they eventually taper down the current. This is an important stage for an AGM battery (one of the reasons I don’t like it as a AGM charger) But this is actually good for a lithium battery, The absorption stage needs to be short when using a three stage charger on a lithium battery. The fact that they set the voltage so low, would pretty much make very short. While this may cause your battery to not be fully charged, it won’t cause an overcharge, that would be worse.
Now we move to the alternator, as stated there have been concerns over burning up alternators when using an alternator straight to charge a lithium battery. This is still a concern, but generally this has been demonstrated when we have an alternator to lithium set up. If we are to drop a Lithium as a house battery into one of our vans, we will generally be putting a Lithium and AGM or wet cell in parallel. This may be enough to help eliminate the alternators burning up. Even then, the problem was seen at idle conditions. Large lithium loads draw more than a comparable wet acid battery, so at idle the cooling is not adequate to prevent the alternator from overheating.

Now looking at capnlurts rig we can see that it has an old surepower diode-based isolator. We can surmise that the two batteries in parallel might prevent the possible alternator burn out. The possible voltage drop over the diode limits the charging voltage of the Lithium battery bank. That is somewhat driven by the where the sense control is on the system. I also know of another forum member that just uses a straight ACR between the two systems. He has reported no problems, but also with a consistent message of the battery is undercharged. I have also seen people on the web happily mixing the two battery types, they give out a bunch of supporting data on how great it is. They also leave some out, or don’t go into details.

For capnkurt, he was able to drop in a lithium battery bank and see no problems, or perceived problems. We can assume the weaker charge parameters are going to result in less life cycles. He also tends not to get a full charge in the lithium battery. So maybe he charges 80% to full range of his bank, can still safely discharge to 20%, still giving him 60% of great usable capacity. Lithium voltage drops are minimal compared to AGM, so you have a full range of 60%. Depending on his electrical usage model, the van may die before his new house battery, so all is good.

So then, who is right and who is wrong. Capnkurt is a happy drop in lithium battery user, the people like me that tell you shouldn’t just drop it in. The answer is both. Certainly, Capnkurt is happy that he didn’t follow my advice. And I am still sure I gave him the correct advice. As someone who is relatively knowledgably in this area I would still stand by that general advice. And to be clear Capnkurt’s model is simple, there was no solar, no inverter usage.
If I am giving out advice, I would generally want to error on the side of caution. Because what works for one setup, may not work well in others. Throw in a bunch of cheap lithium batteries into the mix, BMS discharge rates and you get a lot of unhappy people. I try to recommend things that I am confident will work, or that I have tried myself.

I was a pretty strong supporter of the carbon foam battery, I installed a few firefly’s in some rental vans. The 20 hour amp hour rating is 116 or 120, depends on what version of the specification. I would say at this time with the price of decent lithium batteries coming down, that I would move right to that solution. While both batteries support an 80% DOD, the Lithium still holds up the voltage much better to the end. With 80% DOD on the firefly some voltage sensitive equipment may not work as well. The partial SOC charging was a big technical point for the Firefly, it did loose some capacity if not fully charged but would recover it after a couple of full charges. Lithium does not, although I have seen a few lithium battery manufacturers that still recommend a good high current charge once a month.

greg
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Old 03-25-2022, 07:53 AM   #26
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Greg- Thanks for a complete and well thought out post.
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Old 03-25-2022, 12:03 PM   #27
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Yes, thanks Greg for the informative post.
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Old 03-25-2022, 09:33 PM   #28
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Great informative post Greg. To be clear, I did not talk with Progressive Dynamics. They state acceptable charging of lithium batteries on their website.

https://www.progressivedyn.com/rv/ch...echarge-curves
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Old 03-26-2022, 07:14 AM   #29
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Great informative post Greg. To be clear, I did not talk with Progressive Dynamics. They state acceptable charging of lithium batteries on their website.
I apologize for misrepresenting your initial post.

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Old 03-26-2022, 07:36 PM   #30
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I apologize for misrepresenting your initial post.

greg
Ha! No worries!
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