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Reisender

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Posted: 11/10/21 08:10am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

More idle thoughts:

You could stash the LFP and its inverter in the tow vehicle. Run the extension cord from it to the trailer shore power cord.

Note the 45 minutes won't put many AH back in even doing 50-80s.
Say you have a 60 amp charger and you are down 100AH /50%. 45 minutes will get you 45AH (minus a few for heat) so you are now at 145AH and you used 100 the first day, so by next day you are down another 100 to 45AH remaining.

Conserving to 50AH a day means you are down to 150/ 75% and where Bulk ends so your 60 amps will taper from the start doing the 75-90 so it will take longer. ( You don't do past 90 on generator on low amps and waste a lot of gen fuel for little return.) So you only are back to 180AH- restored 30AH of that 50. Next day you are down another 50 to 130AH and so on.

You could splurge the first day to get down to 50% and then do 50-90s. but in any case you will be running the gen for a couple hours a day or even longer depending, so you will need lots of propane or gasoline for it. Doesn't help if they are LFP--an AH is an AH no matter where it came from.

Having an EV for a TV you can plug into is very interesting--IMO that is the way to go if available. Nobody cares about efficiency while camping. You just want to get to tomorrow without freezing in the dark.


True. But it depends on how far your recharge point is for the EV. You are from BC so you know we are kinda blessed with charge infrastructure here and it’s growing super fast as well. But to make it worth while one would have to be camped within 30 or 40 kilometres of a fast charger. Totally possible but not a given. In that case your car is your fuel carrier. The other thing is getting the power to the RV. With something like the Ford Lightning that’s easy as it has a built in 7.2 KW inverter for operating power tools. Just plug in the RV. But for those of us towing with an EV SUV we are relegated to the 7 pin plug or small inverter and battery charger. This is super inefficient as the car has to be “on” which uses about 200 watts just for “housekeeping”. Etc.

Anyway, using the Tesla as a big battery is at best a back up plan. Leaning more to a little champion 2000 watt propane generator at this point. Probably 45 minutes to an hour of operation per day would do it.

pianotuna

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Posted: 11/10/21 08:51am Link  |  Quote  |  Print  |  Notify Moderator

Reisender wrote:

You are from BC so you know we are kinda blessed with charge infrastructure here and it’s growing super fast as well.


three years ago there were 37 charge points in Regina. Over 1/2 were free to use.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

StirCrazy

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Posted: 11/10/21 09:06am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

BFL13,

Given that SiO2 can do 4C continuously, and can be taken to 0% state of charge, why would you suggest that it takes 2 SiO2 to equal 1 LiFePo4?


because while they can go to 0 state of charge a lot more than a normal floded battery it is not a free reign to do it as it still damages the SIO2 and they can only do it so many times. the manufacturs still recomend staying in the top 50% state of charge to get the advertised cycles. I look at SIO2 as a normal battery that can take abuse if you neglect it now as one to try use like a LFP battery for cold wether. they still have lower cycles , cold weather capacity drop off and all the other issues asocialted with flooded batteries but they have a better ability to handle ocasional deep discharge to 0 and have a higher discharge capacity, but for some reason a lower charging capacity...

but I think it might take two LFP batteries to replace the discharge of the SIO2, not because the LFP cells cant handle it but because the adverage BMS is set at a 1C discharge and I dont think that will be enough for a microwave. the bonus side is with two LFP you will get 180 AH of usable power aposed to the 50-60AH from one SIO2 and you can discharge a lot more before your inverter will start giving the low voltage alarm.


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BFL13

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Posted: 11/10/21 09:20am Link  |  Quote  |  Print  |  Notify Moderator

No clue about EVs. Can you use a DC-DC charger instead of the 7-pin like you can with a gasser? The limit with those is the alternator amps vs the DC-DC input so not to over-task the alternator. What happens with an EV?

Watch the gen VA vs the input for the charger. A 2000w does 1600VA which is borderline for a 60 amp charger doing 60 amps at 14.4v. A "2200w" does 1700VA most of them or 1800VA if a Honda. My 1700VA gen is maxed out with my 75 amp converter, but it runs it--just barely until amps taper and it gets easier on the gen.

You are right IMO to try it all out first and then see what needs doing. by the time you get it, the sun might even come out and not be raining so much, which should help. " If you can't see the mountains it is because it is raining; if you can see the mountains, it is going to rain"
---------------

Not suggesting SiO2 --I just happen to have them. LFP inside where it is warm is the answer here. My other big point is you don't have to do anything to the existing wiring and converter with the nice new rig and the size and location of the OEM battery box doesn't matter either.

Just meant as an idea that might work for some situations that have come up for TCs or small TTs.

* This post was edited 11/10/21 09:40am by BFL13 *


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srschang

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Posted: 11/10/21 11:28am Link  |  Quote  |  Print  |  Notify Moderator

Before I bought my 2 Battleborns a few years ago, I did a ton of research trying to convince myself they are worth the money. I seem to remember that the 100ah Battleborns are actually like 110 or 120ah. They set the bms to limit charge and discharge so the battery can only use 100ah. That way the battery never charges fully and never discharges fully, but you still get 100 useable ah. The battery does the 10-90 for you automatically.


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Reisender

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Posted: 11/10/21 02:42pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

No clue about EVs. Can you use a DC-DC charger instead of the 7-pin like you can with a gasser? The limit with those is the alternator amps vs the DC-DC input so not to over-task the alternator. What happens with an EV?



Well, I'm definitely not an expert in this kind of thing, but I can tell you the way I understand it.

So, EV's still have a 12 volt battery for providing power to things like lights, fans, heat pumps etc etc and of course the charge line on the 7 pin connector. The 12 volt battery gets its power from the 82 kwh 400 volt motive pack via a DC to DC converter. But, at least in a Tesla, you can't just connect a load to the 12 volt battery and this is why. All outputs from the 12 volt battery are monitored. If you hook up a separate DC to DC converter to just charge a separate battery external to the car, (like the trailer battery) it will detect that more current is going out of the battery than coming in and it will throw a code. I'm not sure of the consequences of that.

So the only other choice is to use the accessory 12 volt plug in the dash or the one in the hatch area. These will provide 12 amp continuous or 16 amp peak power so one can power an inverter and in turn power a small battery charger. I'm sure there are DC to DC converters out there that would work but I couldn't find any.

However, there is a catch. The car needs to be in "camp mode" for those to work. Camp mode is a tesla feature that allows you to car camp. Keeps the display on for watching movies, keeps the HVAC on for staying warm or cool and allows access to all the USB and accessory ports for phones, coolers etc. However, this typically drags the main pack down about 18 percent per day depending on the weather. This is why I think it is a super inefficient way of keeping a trailer battery charged.

A little story. We have a 2 KWH UPS in the house for critical loads like the fridge or entertainment centre. (We need to be able to watch zombie movies during power outages). Good for about a day of power outage. Works well. But last year we thought about in an emergency extending that using the Tesla. So we actually went thru the motions of getting a little inverter and 7 amp battery charger, putting the car in camp mode and hooking it up to the batteries of the house UPS. Worked great, Kept up but got pretty warm. We ran it for a day to prove it would work and then called it quits. And yep, sucked the car battery down 18 percent, almost all of which was wasted running the various systems of the car. So yah, definitely NOT the way to go when camping. A 700 dollar super quite propane inverter generator is a much better way to go.

Here is a pic of what we used. Like I say, once we get the trailer we'll figure it out pretty quick. Our first long trip is from the interior, up the island, ferry up the inside passage to Prince Rupert and then a great circle back to the Okanagan. Figure 6 or 8 weeks should do it. Lots of hiking coming up. [emoticon]

[image]

* This post was edited 11/10/21 02:52pm by Reisender *

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Posted: 11/10/21 02:47pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Reisender wrote:

You are from BC so you know we are kinda blessed with charge infrastructure here and it’s growing super fast as well.


three years ago there were 37 charge points in Regina. Over 1/2 were free to use.


Good to hear Don. I haven't looked at a map of that area on plugshare lately. Sounds like infrastructure is growing.

Cheers.

BFL13

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Posted: 11/10/21 03:52pm Link  |  Quote  |  Print  |  Notify Moderator

Interesting about the Tesla, thanks. What about voltage to the 7-pin and the camping 12v sockets? You can run things at 12v, but actual battery charging requires more like 14v or so.

With a gasser, you use the DC-DC to boost the engine battery voltage from 13.8ish to 14.6ish. Charging at 13.8 is lame. The Tesla might only be giving you 12.6ish or whatever to run your camping things and the 7-pin for trailer signal lights?

Sounds like the portable gen is going to get a lot of work!

Reisender

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Posted: 11/10/21 05:15pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

Interesting about the Tesla, thanks. What about voltage to the 7-pin and the camping 12v sockets? You can run things at 12v, but actual battery charging requires more like 14v or so.

With a gasser, you use the DC-DC to boost the engine battery voltage from 13.8ish to 14.6ish. Charging at 13.8 is lame. The Tesla might only be giving you 12.6ish or whatever to run your camping things and the 7-pin for trailer signal lights?

Sounds like the portable gen is going to get a lot of work!


Our present tesla (Model 3) doesn’t have a 7 pin so no way to check what’s on the charge line. Our model Y delivery date is tentatively February so have to wait till then to check.

We don’t dry camp a lot but when we do it’s usually for a week....and under trees. I suspect I would have to run the genny at least once a day for 45 minutes. Maybe twice a day depending how cold it is as the hydronic heating system has a pump that draws a couple or so amps when called on. Then again. A fantastic fan does as well. We’ll have to wait and see.

I’m looking at a victron dc to dc 9 amp converter so I don’t have a double conversion. I received a tip on how to run camp mode in a lower current draw mode. I’m running a test on it right now. Gotta do something until we can go camping. [emoticon].

BFL13

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Posted: 11/10/21 05:26pm Link  |  Quote  |  Print  |  Notify Moderator

Having an EV for a TV is a whole new thing! Very interesting.

When you wheel up to the EV charging station with the trailer (with its LFPs) hooked on, you should be able to do both the EV and the trailer! [emoticon]

* This post was edited 11/10/21 05:35pm by BFL13 *

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