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 > Your search for posts made by 'Freep' found 42 matches.

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RE: LiFePo4 vs Lead Acid...Some points of interest.

Moot Point vs. Mute Point Moot means unimportant or not worth talking about. Mute means completely silent. Moot and mute might seem like similar words at first glance, but they are pronounced differently. Mute rhymes with cute, whereas moot rhymes with boot. Nevertheless, some people still mishear the phrase moot point as mute point. But don’t let that confuse you. The correct phrase is moot point, not mute point.
Freep 04/14/21 08:14am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

So 3 tons, who told you that the Xantrex LinkLite SOC meter wasn't accurate and the Victron is? From everything I can see, all three products do the same thing with regard to determining state of charge. What am I missing? Edit: Do you think it would be more accurate if it counted Ahrs?
Freep 04/13/21 05:11pm Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

3 tons, This is the response I got: ************************** First, counting coulombs is counting coulombs, and what the source/destination is makes no difference. Secondly, "computing SOC with LFP..." this sounds like its based on voltage instead of coulomb counting... the non-counting meters have only the current voltage to look up (estimate) the SoC. And this of course differs based on type of battery chemistry. ************************** This confirms what I thought. Since the Victron Smart Shunt and the AiLi meter are both counting coulombs they should be equivalent as far as reporting of SOC is concerned. You're just getting bluetooth connectivity and some other bells and whistles with the Victron Smart Shunt.
Freep 04/13/21 01:08pm Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

I agree that it needs to be considered, but so long as the alternator capacity pencils out it to say 30% for continuous down the road charging it can be doable - just another data point in the vagaries of one’s considerations - in my anecdotal scenario I see no necessity to bother with the alternator because harvest has proven sufficient and swift - this, yet a third option worth one’s consideration... I hear you. I've got 600 watts of solar and I'm seriously considering getting rid of my generator. I could just use the engine for a quick charge if I needed it. I never run the gen for more than an hour these days anyway and even that is rare. Why drag a generator around?
Freep 04/13/21 11:55am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

“ But a cheap coulomb counter is fine with me because it's an inherently unnecessary device.” Ok, but for clarity it should be noted here that a meter that only counts coulombs is not structly compatible with LFP, though it may be fine above 50% SOC - in practical terms with LFP, SOC only begins to get important below 50%... As has been already noted here several times, computing SOC with LFP requires a sophisticated algorithm including a ‘look-up’ ledger which is necessary when below a 50% SOC...This is due to the extremely flat voltage curve characteristics of LFP, and why (as previously stated) I had to ditch my former meter... This is interesting. There are a lot of people using the AiLi for their LFPs over at and I've never heard this before. I'll go ask the gurus over there and see if I can get some clarity. I've been using it for almost a year now and it has usually agreed with the BMS on SOC. Edit: To be clear, a Coulomb counter does not rely on voltage.
Freep 04/13/21 11:22am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

How would a coulomb counter risk the battery? I'm not saying your specific installation is risking your battery. I'm saying, from what I've learned from others, that you can't just drop in an a DIY LFP battery and expect it to charge from your alternator without making some changes. I could be wrong here, but my recollection is that the LFP will cause most alternators to overheat trying to keep up with the electrical load of the LFP because it will take as much current as you can give it. This could also result in a fire with overheated wire from the alternator to the battery. Edit: I forgot to add the risk to the battery in the above scenarios. Who knows what kind of horrible electrical surges you might get from a failing alternator, plus a fire risks everything.
Freep 04/13/21 10:53am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

“ You definitely need a DC-DC charger for charging from your alternator.” Not necessarily...With 440w of solar and a single 200a/h LFP, I neutered the 7pin plug charging wire as being unnecessary - Harvest swiftly handles everything...And even with the alternator, so long as the amps are kept at a reasonable level for continuous charging (depending on battery C rate and alternator output), of say 25-30% you should not have an issue... BTW, Victron smart shunts may be a bit pricier (than the China stuff), but so then is your LFP Battery investment, right?? 3 tons I got rid of the 7 pin a long time ago so I could charge the battery and run the fridge while driving. I'm running 6 gauge from the alternator to the camper. This was pre LFP. You're making me smile here. On one hand you're fine with risking your battery and alternator(to save money?) but then raise the spectre of damaging your expensive battery by using a cheaper coulomb counter. To each his own, man. But a cheap coulomb counter is fine with me because it's an inherently unnecessary device. It's just a convenience. If Victron had their smart shunt at half the price I probably would have bought it, but $200 for a fancy coulomb counter is just not a value to me. I'm glad it is for you. If I had unlimited funds I'd be all Victron all the time -- except for the battery. It's too much fun rolling my own.
Freep 04/13/21 10:07am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

I'm not sure what you mean by high quality deep cycle batteries, but I paid $74 apiece for my 2 GC batterers from Sam's Club 14 years ago and they are still doing fine and I only dry camp. If they failed tomorrow I can still buy them for $90 apiece, so I don't see a cost comparison that is close yet. I understand the weight is a lot less as well as the foot print and in time with all the EV's coming out they may be cheaper. If you're comparing batteries by the number of batteries and price, then you probably have the batteries that are best suited to you.
Freep 04/13/21 09:55am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

... to allow for cell balancing - this is where a LiFePo4 compatible smart meter is helpful (like a Victron Smart shunt, BMV 712 or equivalent) as you can watch the voltage and current balancing act work it’s mojo...Having said that, due to LFP’s wide breadth of usable operating range, there’s really little need to fully charge a LFP except for an occasional BMS cell balancing which also allows for SOC meter re-sync. If building your own pack I would highly recommend the overkillsolar BMS with bluetooth. This way you can easily check on the state of your battery with your smart phone or tablet. Also the Victron Smart Shunts are pretty expensive for what they do. I would recommend the AiLi current meter which is only $44 now on Amazon. The downside to the Aili is that it doesn't communicate with my other Victron products and it has no bluetooth capabilities, but I'm fine with that. I can see all the information about the battery from the BMS app.
Freep 04/13/21 08:53am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

You definitely need a DC-DC charger for charging from your alternator. The LFP batteries will take as much as the alternator can give and will shorten the life of most alternators. Sometimes very quickly. For solar, you need a charge controller anyway and it's best to use an MPPT charger. For shore charging, most of the newer converter chargers have a lithium setting. I had to upgrade my Power Dynamics Mighty Mini to charge the LFP battery. If you have a new camper everything should be LFP capable, except for the DC-DC controller. Those are usually not included in campers. And also if you have an LFP battery you are going to want an inverter. That was the very last thing I bought. I kept convincing myself I didn't need one but now that I have it I feel foolish for resisting getting one. It's really nice having a bunch of home cooked meals ready to reheat in the microwave and being able to do it without firing up the generator. It also makes every day living so much easier in my rig, which was already wired for AC. On those trips where it has been mostly overcast and we've been using more juice than we made, we can fire up the generator and take a hike for an hour and come back to a battery that has an additional 50AH in it. But I haven't had that happen since I upgraded my panels.
Freep 04/13/21 08:43am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

for making your own you can build a 280 usable AH for about 600 bucks now. to get that in deep cycles batteries you probably over 1000 for high quality and about the same in cheep on sale (these prices are CDN). other advantages besides price now days is weight that would be about 46LB and it would give me more capacity than the 240lbs of 6V I have now that only have 235AH usable. also the size, this one Li battery is the side of one of the 6V batteries. so 1/6th the weight and 1/4 the size. Steve They're selling cells with 310 AH now with the same dimensions as the 280s.
Freep 04/13/21 06:17am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

Jaycocreek, throw a solar panel or two on the roof and you won't need to run the generator very often, if at all. I don't even plug my TC into shore power at home anymore unless I've put a cover on it.
Freep 04/11/21 04:30pm Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

OK and still in all practical use the LFP is so much better than the dinosaur FLA. FLA has no advantage except on initial price for small capacity applications. Initial price is made up for with higher energy density, more usable energy storage due to true deep discharging capability and long battery life. Also prices are dropping fast and DIY packs are pretty easy and fun to make. One downside to LFP is cold weather charging, but this can be mitigated with an insulated box and a small heater. Some people may get a little religious about battery chemistries but the main selling points for me are lower weight, higher energy density, longer life and high charge and discharge rates. When something comes along that outperforms LFP on any of those attributes, I'll be preparing to move to the new chemistry. Edit: For example, I went from 100ah of FLA(50 ah usable) to 200ah of AGM(100 ah usable) to 271 ah LFP(216 usable). Plus I saved enough space going from AGM to LFP that I was able to add an inverter and can now run the microwave without using the generator.
Freep 04/07/21 10:53am Tech Issues
RE: mounting my solar panels

I know you already got the panels but you will likely need more. I have 600 watts of panels(4x150) on my truck camper and I'm thinking about adding another 300. When picking solar panels for your rig figure out how much space you can use, then pick panels of the largest dimension you can fit in the space with the highest density of wattage per square foot. Those panels will last 20 years, don't go cheap.
Freep 04/06/21 01:40pm Tech Issues
RE: Internet for 4 months

I use an LTE modem and put a cell phone sim card in it. The cell phone has an unlimited plan which is cheaper than hotspot plans. The following site has some good information on those devices. I also have two external antennas mounted on the roof of my camper which increases the signal. If you know you're going to be stationary for months it might make sense to sign up with Starlink One other tip. It's a good idea to use an ad scrubber like Pi-hole and/or a custom hosts file( to keep from downloading ads, many of which are video these days.
Freep 04/06/21 01:31pm Tech Issues
RE: How to build a LiFePo4 battery bank.

For those on a budget, these weed grade B cell and the author did make "studs" to use on the screw in terminals that were not in the best of shape. Cheap fix ! For any of the prismatic cells I highly recommend installing studs and securing them with loctite. The aluminum they use for those terminals is VERY soft and it's easy to strip them out. Even with the studs you want to be careful not to over torque.
Freep 04/06/21 12:54pm Do It Yourself Modifications and Upgrades (DIY)
RE: How to build a LiFePo4 battery bank.

There's a guy over on DIYsolarfoum who is selling a bunch of 700AH Winston batteries his company bought and then realized weren't right for their project and now they're trying to get them off the books. I'd buy 4 if I had room in my battery compartment and sell my current 271ah pack. These batteries can charge well below freezing. I have no financial interest in these cells or DIYSolarForum. I just hope someone is able to take advantage of a good deal.
Freep 04/06/21 12:42pm Do It Yourself Modifications and Upgrades (DIY)
RE: LiFePo4 vs Lead Acid...Some points of interest.

To be clear, 1C means the battery can be charged to 100% in 1 hour. 2C would be 100% in 30 minutes. .5 C means 100% in 2 hours, etc... LiFePo4 cells in general can be charged to 80% capacity in 15 minutes. Whether the manufacturer rates them to that level depends on specific characteristics of that particular product.
Freep 04/06/21 12:32pm Tech Issues
RE: generator and alternator charging at the same time

As the battery voltage rises from being charged, amps will start to taper from the lowest voltage charger of the three until amps get to zero when the voltages are the same, then amps will be tapering on the next highest voltage charger until battery voltage rises to its voltage, and now only the highest voltage charger is supplying amps (to its current limit). Keep in mind that with LiFePo4 batteries the charging curve is mostly flat. So your battery will stay at 3.3v for a very long time until it hits the knees and then it will shoot up. This is why a BMS is critical. Also LFP batteries in general will take a 1C charge, though some take 3C. So it's not really a taper. It's more like a firehose and then suddenly(from a voltage perspective) your battery is full.
Freep 04/06/21 11:38am Tech Issues
RE: LiFePo4 vs Lead Acid...Some points of interest.

Though my system is a bit smaller than your’s (@200a/h LFP, 440w solar), the charge recovery advantage is substantial, and peak harvest times are considerably exploited - this attribute is pretty much a ‘settled science’ (per the principle of Occam’s razor...) and likely why NASA chose a Lithium variant for Mars Opportunity Rover’s energy reservoir...JMO 3 tons, in HarvestVille Central (e.g. the high NV Desert) Yeah I'm so happy with LFP and solar that I'm seriously considering getting rid of the generator and replacing that space with eight of those Winston cells for 1400 ah(or 16.8 Kilowatts). Two big problems with that, justifying it with my wife and timing. It's the wrong time of year for a big project like that. If this were the end of fall, I'd probably pull the trigger.
Freep 04/06/21 11:03am Tech Issues
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