Lithium batteries - true longitudinal capacity profiles?

[InterBlog]

As for the cassette-style lithium, I would dearly love to scrap everything I’ve got and just roll the EcoFlow DeltaPro in there and run the whole danged van off that.

Unfortunately, that particular product simply cannot be retrofitted. I need 27 inches of clearance for it and I’ve only got 24 in the available space. The central aisle of the Class B is already so narrow that there’s no way I can restrict it by 3 more inches.

Just my dumb luck that EcoFlow decided to configure their product to be long and skinny. Another self-contained product with a different aspect ratio is something I am going to research - they are coming onto the market at breakneck speed now.

My husband warns that we CAN develop a DIY removable battery, but it’s going to be “expensive”. Well, we don’t know what “expensive” means yet, and how that cost might compare to some of these newer solutions.

Two things are certain in my current situation:

(1) I’m not persevering with a half-dead lithium battery. Between purchase and repairs and upfit costs, we have put about a hundred grand into this rig. There is no way I am accepting it as essentially an ON-grid van after everything we put into it to convert it to an OFF-grid van. That would effectively be a penny-wise-pound-foolish decision.

(2) I’m not watching our next lithium battery get similarly cooked in our southeast Texas climate. There HAS to be a better way.

So I will report back on how that research shakes out over the next several months.

[Davydd]

I'm still wondering how a battery cassette system would work. It seems like a good idea. Most Class Bs have a way to disconnect the batteries and that should get you through a storage period but it doesn't answer heat or cold situations. Though my batteries would be easier to remove than my previous van I still don't want to bother to do so. Unless it is as simple as pulling out a toilet cassette. Fortunately in my situation I don't have to or want to. So, just curious.

BTW, I use my van full-time in my condo storage garage since it is also my wood shop and man cave. Mainly, I have lights, power, water, toilet, refrigerator and coffee maker at my disposal. It's kind of a living pod.

[booster]

Originally Posted by Davydd

I'm still wondering how a battery cassette system would work. It seems like a good idea. Most Class Bs have a way to disconnect the batteries and that should get you through a storage period but it doesn't answer heat or cold situations. Though my batteries would be easier to remove than my previous van I still don't want to bother to do so. Unless it is as simple as pulling out a toilet cassette. Fortunately in my situation I don't have to or want to. So, just curious.

BTW, I use my van full-time in my condo storage garage since it is also my wood shop and man cave. Mainly, I have lights, power, water, toilet, refrigerator and coffee maker at my disposal. It's kind of a living pod.

Electric race cars have had quick change battery packs for quite a while now. You may want to look at how they do it. The changes are done very quickly.

[Davydd]

Originally Posted by booster

Electric race cars have had quick change battery packs for quite a while now. You may want to look at how they do it. The changes are done very quickly.

Like loading batteries in your TV remote? The batteries and the connector would have to be designed to work together for that race car?

In further thought I could remove and reinstall my four drop in lithium batteries by 8 connections as is. They have their canvas strap lift handles still installed. My bed can be remade as a lifting lid on a hinge. Right now I have to pull my mattress out and then the plywood platform. Maybe twice a year that would not be a major task and I wouldn't have to bother to do that. I did it just to take a photo of my batteries. Twice a year would not be an onerous task but I don't have to do it in a controlled garage space. I can disconnect the batteries in place with one toggle switch. I guess I am already there for all practical purposes.

My previous van with an estimated 500 lb. lithium package underneath would be a different story. I did manage it in Minnesota's winters outside for 3 of the 6 years with shore power. I needed the self-heat so couldn't disconnect. That set up could not be achieved outside in Phoenix in the summer.

[avanti]

I think a "cassette" battery is a fine idea and is totally doable. However, its usefulness is going to be dependent on how the van is used. If you put it to sleep in October and wake it up in March (or vice-versa in Arizona), it could be very nice. But this is very far from our usage pattern. Our van (like our previous one) is aggressively designed as a 4-season rig, and we use it as such. We go out year around--often on short notice. We would be lugging that cassette around a LOT. Although our two 5KwH batteries are easily accessible through a floor hatch, indoor battery storage isn't really a practical solution for us.

Consequently, instead of moving the batteries to a benign environment, we have focussed on empowering the van to maintain an acceptable environment for the batteries semi-autonomously. The battery box is a small, insulated space so the energy requirements to keep it within an acceptable temperature range should be quite tractable. The box is both electrically heated and two-way vented (either inside or outside air can be forced through it). Most importantly, the whole system is both capable of autonomous operation, and also remotely monitored and controlled for redundancy. We'll see how it works out, but I am pretty confident that the battery itself will be adequate as the power source for 95% of the situations we are likely to face, with remote engine starting as a last-resort backup. Of course, we will use shore power when it is available, but the van will not be dependent on it.

[InterBlog]

There are effectively two different scenarios under consideration here, so let’s articulate them:

(1) I don’t know what our onboard fixed 300 Ah battery weighs by itself, but the DeltaPro’s capacity is about the same, and that entire package weighs just 100 pounds. It’s on wheels with fore and aft handles plus a retractable pull like a piece of airline baggage, and could easily be carted in and out of a van if only there were a place to dock its unusually long body.

(2) Five hundred pounds of lithium is a different thing entirely. It’s not clear to me that an ergonomic solution could ever be developed for that.

300 Ah of lithium (240 useable) plus a means to charge it should keep the average off-gridder pretty danged happy. When my battery capacity was good, I could keep my 12 volt fridge running, my Fantastic spinning, and my lithium power tools (weed eater, chain saw, etc) charged, and all the smaller peripherals including cellular booster and computers going with no issues - 300 watts of solar handily took care of it all. That is the scenario that is ripe for battery management improvements.

[avanti]

Originally Posted by InterBlog

Five hundred pounds of lithium is a different thing entirely. It’s not clear to me that an ergonomic solution could ever be developed for that.

Well, my two 5120Wh Victron batteries weigh 86lb each, so...

[booster]

618ah of SOK lithium (3X206ah) is about 144 pounds.

[Urlauber]

My 100Ah power station weights in at about 28lbs. Very easy to carry in and out of the camper. For the Delta Pro, you'd need two people or some sort of ramp, I imagine.

I think I can do fine with 100Ah (plus a small AGM) 90% of the time with either solar or driving keeping the charge up.
No power tools here.

Only issue would be to stay in a shaded area for more than two days. Most likely there will be some driving to get to trailheads etc.

[Davydd]

My 4 group 27 cased batteries are 42.3 lbs each for a total of 169.2 lbs. But they are drop ins each weighing about the same as a bag of salt for a water softener. That is manageable. I didn't imply carrying them inside the van while traveling other than in place where they belong and are used. So, I've already dismissed the race car solution of plug ins.

You have to have the batteries somewhere and as I mentioned you have to have shore power for long term storage with battery heat in the van in freezing temperatures or a controlled environment in the summer in Phoenix. If you have a controlled environment with your van you can have the batteries in place with a total disconnect switch or shore power as an option. If you don't have any of those situations then pulling the batteries and putting them elsewhere in a controlled environment is the solution.

The outside batteries I mentioned include the protective steel angle cage, fiberglass enclosure and protective skid plate underneath. ARV abandoned all that a long time ago. They now put them generally in a below floor box and get to them by a hinged cover from the inside of the van next to the back doors to easily pull them out. They don't require inside space nor are they outside like I once had. In my current van I thought the unused space under the bunk bed was more logical. I already designed more storage space in my short van than I had in my extended van.

My under bed batteries are in a vented space the same as the general temperature of inside of the van. We travel all seasons but mostly in the above freezing south but have camped in below zero temperatures in northern Minnesota and the Upper Peninsula of Michigan. If we can tolerate the inside temperatures the batteries are safe.

I have experienced almost all cases for 9 years except the Technomadia problem in storing in high temperatures in Phoenix. Lithium batteries take more thought in how you use them climate wise vs. AGMs. Cold weather is more of a problem than heat.

[avanti]

I realize that this message is both off-topic and quixotic, but:

This thread has convinced me that it is time for us to consider finally dropping the bad habit of using the unit "amps" when talking about power. The ampere is a measure of current, the correct unit for power is the watt. It didn't make much difference back when it was a safe assumption that everybody was talking about 12VDC systems. But as this thread illustrates, that is hardly a good assumption these days. I became confused at least three times in the above messages alone.

For anybody who needs a reminder:
watts = amps x volts
The math is not hard. Unlike amps, watts are voltage independent, making discussions like this one much easier to follow.

If you are talking about wire or fuze size, then you probably mean "amps". But if you are talking about battery capacity, you very likely mean "watts". I am not trying to be pedantic, just trying to improve communications.

N.B.: I am NOT writing as a moderator. This is just the personal opinion of one member.

[booster]

Originally Posted by avanti

I realize that this message is both off-topic and quixotic, but:

This thread has convinced me that it is time for us to consider finally dropping the bad habit of using the unit "amps" when talking about power. The ampere is a measure of current, the correct unit for power is the watt. It didn't make much difference back when it was a safe assumption that everybody was talking about 12VDC systems. But as this thread illustrates, that is hardly a good assumption these days. I became confused at least three times in the above messages alone.

For anybody who needs a reminder:
watts = amps x volts
The math is not hard. Unlike amps, watts are voltage independent, making discussions like this one much easier to follow.

If you are talking about wire or fuze size, then you probably mean "amps". But if you are talking about battery capacity, you very likely mean "watts". I am not trying to be pedantic, just trying to improve communications.

N.B.: I am NOT writing as a moderator. This is just the personal opinion of one member.

The amps instead of amp-hours has been a pet peeve of mine for a long time and must be very confusing for new members. As Avanti said watts is probably a better unit when talking about power like how much an appliance takes while running, wire size, or how much charging you send to the batteries from a charging source.


Power is an instantaneous thing in watts, energy is or used is how much power is used or stored over a period of time, typically watt-hours or kilowatt- hours.



I think Avanti probably meant to say battery capacity should be in watt-hours, though.

[avanti]

Originally Posted by booster

watts is probably a better unit when talking about power like how much an appliance takes while running, wire size

Actually, for wire size, "amps" is correct. It is current that determines how big a wire you need. You can squeeze more power through a given sized wire by raising the voltage.

I think Avanti probably meant to say battery capacity should be in watt-hours, though.

Nah... "watt-hours" vs "amp-hours" -- the "hours" cancel out.
[OK, so now I am being pedantic.]

[Urlauber]

Good luck convincing all battery manufacturers.

[MsNomer]

Now that LiFePO4 is in the mix, it's 13+V instead of 12+V.

[booster]

Originally Posted by Urlauber

Good luck convincing all battery manufacturers.

The good ones use amp hours and watt hours for capacity specs. If they don't know to do that, how do they manage to design a battery. It's the sales literature marketing department the fudges and exaggerates everything. That is where it all started, with bogus capacity claims in Roadtrek literature that started with one model when all the others were still correct. I think it was with one of the new Promaster models.



The dealers on the other hand are often not all that bright.

[GeorgeRa]

To continue in the pedantic mode, amphours is not equal to watthour, in fact amphours is meaningless without a stated voltage. Battery maximum power should be stated in Watts but its energy capacity in Watthour.

A direct comparison of units of energy should be ampvolthour which takes into consideration often presumed 12V battery or correct and unambiguous watthours. You will find watthours or kWHr on you house bill, not watts, nor amps, nor amphours, nor pints, nor horses.

I think Amps unit of power, used as unit of energy comes from automotive batteries maximum cranking current which is listed in amps.

[Davydd]

The manufacturer of my batteries list the batteries in amp hours and not watts anywhere in the literature as do just about every 12v battery manufacturer. I think the vast majority in this forum have 12v batteries so it is very reasonable. Volta 48v (actually 56v) system lists in wattage. ARV's in house 48v system also lists in wattage. Who else? It may get to that in time. But for the time being, maybe wattage reporters ought to explain how that compares to the common 12v amp hours for the time being so us electrical dyslexics can relate.

If my "above message" confused you three times I am bewildered because I never said amp hours or ah once.

I was speaking of the gross weight of batteries. I found in checking some other lithium batteries with Booster's general assessment of lithium battery weight, I got curious and found the casings make a big difference in the total weight. So now I am wondering if that rule of thumb that lithium batteries weigh 40% of AGM batteries is totally true.

[avanti]

Originally Posted by Davydd

If my "above message" confused you three times I am bewildered because I never said amp hours or ah once.

Your message only confused me once. The others were different posters.

However:

Originally Posted by Davydd

I have 576ah of lithium in my currant 144 2500 Sprinter van.

[Davydd]

You said "above message" not "messages". You asked previously and I answered:

Four Lithion U27-12XP 12.8 V | 144 AH | 19.2 KG | PN# 1008773 batteries

https://www.lithionbattery.com/produ...s/u-charge-xp/

4 x 144 AH is 576 AH. As I said, most 12v battery RV owners can relate to that. I've never seen anyone referring to a 12v battery system in watts before and it has come into practice with other voltage batteries now. For instance, that same referenced Lithion page for a 24v battery in the same group profile is:

U27-24XP 25.6 V | 72 AH | 19.2 KG | PN# 1008685

So if I said, 4 x 72 AH = 288 AH it would be meaningless or misleading to most without knowing I was referring to 24v batteries. If you just said watts then one would have to do the arithmetic since as I mentioned my battery manufacture doesn't mention watts nor do most other 12v battery manufacturers and most of us don't refer to our battery systems in watts because of it. Most converters don't either.

All my Silverleaf screens (6 of them in great detail) for my battery system only refer to volts and amps. My refrigerator, microwave and Keurig coffee maker are indeed in watts but I am only concerned about what the battery drainage is in percent which I can easily do the calculation (% x AH) of how many amp hours knowing the batteries are listed in amp hours. I work with what I have. Until or unless I have a 48v battery system I won't be interested in watts nor do I want to do the extra steps in math to relate.

I suggest anyone referring to watts should do the extra step and list the voltage of their battery system too.