Storing Lithium with/without Shore Power

[avanti]

As several people have stated repeatedly, you do NOT need shore power to make lithium practical. Nor is this a practical option for a great many people.

What you do need is a plan for protecting your battery under frigid conditions. How difficult this is obviously depends on where you live, but it is an exaggeration to say that it can only be done "in the South". There is no doubt that Minnesota presents a unique challenge, but in the vast majority of the country, extended periods of sub-zero (F) weather are very rare. I say "extended periods" because if the periods are short, then a fully-charged battery will often be enough to get you through (remember: you don't have to heat the battery to charging temperature, you just need to keep it at or above the minimum discharge temperature).

There are several ways to meet this requirement. Shore power is indeed one of them. But so is (for example) committing to carrying the batteries indoors during such an event (remembering that we are talking about rare events in most of the country). In my case, the van will have full-remote monitoring and enough automation to largely take care of itself. In the very rare case of an extended frigid period, occasional brief periods of remotely-initiated engine idling (which is just fine in a gasoline engine) will win the day. And, no, it is not unacceptable to run the engine unattended, at least not in my storage situations.

 

[Davydd]

As several people have stated repeatedly, you do NOT need shore power to make lithium practical. Nor is this a practical option for a great many people.

What you do need is a plan for protecting your battery under frigid conditions. How difficult this is obviously depends on where you live, but it is an exaggeration to say that it can only be done "in the South". There is no doubt that Minnesota presents a unique challenge, but in the vast majority of the country, extended periods of sub-zero (F) weather are very rare. I say "extended periods" because if the periods are short, then a fully-charged battery will often be enough to get you through (remember: you don't have to heat the battery to charging temperature, you just need to keep it at or above the minimum discharge temperature).

There are several ways to meet this requirement. Shore power is indeed one of them. But so is (for example) committing to carrying the batteries indoors during such an event (remembering that we are talking about rare events in most of the country). In my case, the van will have full-remote monitoring and enough automation to largely take care of itself. In the very rare case of an extended frigid period, occasional brief periods of remotely-initiated engine idling (which is just fine in a gasoline engine) will win the day. And, no, it is not unacceptable to run the engine unattended, at least not in my storage situations.

Well in this thread the topic involves Minnesota which JonMN, Booster and I reside. I was in Louisville, KY with our van when it got down to -5F. Much of the nation is susceptible for below freezing temperatures and below 0 temperatures above the Mason-Dixon line that you have to pay attention to your lithium batteries.

Sounds like you are straddled with monitoring your van all winter. Do you really think you could take time away from your home in the winter and allow your van to self idle? Largely take care of itself? Things can go wrong. No one is immune to that. Idling an engine would have to be in an outside situation. You can't shut down your power system because that means idling an engine will not charge in any weather and you will be surprised how much your batteries will discharge if you leave them powered on.

Fully charged batteries don't get you through cold spells. They do discharge but can't be re-charged in freezing temperatures so running an engine is useless. But discharging means you can't employ heating pads. If you have any chance of temperatures going below -4F you will need heated space independent of your van or heating pads for batteries which thus need shore power. With shore power you will have no need of idling an engine.

 

[avanti]

Sounds like you are straddled with monitoring your van all winter. Do you really think you could take time away from your home in the winter and allow your van to self idle? Largely take care of itself? Things can go wrong. No one is immune to that.

Not at all. As I said, the van will be perfectly capable of monitoring itself and asking for help only if it needs it. Please do not underestimate what a game-changer actual automation is.

I COULD arrange for the van to start itself if needed, but I probably will choose to do that manually in the extremely rare case in which that may be necessary.

You can't shut down your power system because that means idling an engine will not charge in any weather and you will be surprised how much your batteries will discharge if you leave them powered on.

This is incorrect. Only a small part of the automation system will have to be on all the time. It is capable of monitoring conditions, and only turning on what is necessary, and only as long as is necessary. I have already documented (in my "Van Automation" thread) that the tiny processors involved draw a current level that is almost too low to measure. You may be picturing all of this being powered by a fully-powered-up van, but that is not how it will work.

Fully charged batteries don't get you through cold spells. They do discharge but can't be re-charged in freezing temperatures so running an engine is useless. But discharging means you can't employ heating pads. If you have any chance of temperatures going below -4F you will need heated space independent of your van or heating pads for batteries which thus need shore power.

I cannot follow what you are saying here.
Fully charged batteries can very easily get you through cold spells. Let's do some math:
My battery is 400Ah @ 24VDC. That is 9,600Wh. Let's round down to 9,000, just to be conservative. Let's say the battery's heating pad consumes 50 watts (heat equivalent to a medium-sized incandescent light bulb). In an insulated battery compartment, that is a lot of heat. 9000 / 50 = 180. 180 hours is 7.5 days. If the heater runs on a 50% duty cycle (which is probably conservative in a small, well-insulated box), that is more than two weeks of continuous heating. Where I live, I have NEVER seen anything close to two weeks below zero. I used to live in Wisconsin. There, I saw such a spell exactly once. I will grant you that Minnesota is a challenge, which I acknowledged up front. Note that (a) I rounded down everywhere; (b) I have completely ignored the above-mentioned second chassis battery, which provides additional amps; (c) since the battery is being used to power the heating pads, there will be some self-heating (also ignored) and (d) since we are talking about a resistive load, the efficiency is 100%. So, these are very realistic numbers.

How will this work in practice? Like this:
1) System "sleeps" with most systems shut down (inverter, 12V buck converter, etc), excepting the tiny monitoring processor.
2) Nothing happens until the battery temperature approaches damaging cold, at which point the heating pad is activated to prevent damage, powered by the main batteries. We can stay in the state for up to two weeks (with the above-stated assumptions) if necessary.
3) If frigid temperatures continue and battery is getting low, the system will raise the heat pad temperature in order to bring the battery up to "ok to charge" temperatures. Van sends a text to my phone asking permission to start engine. I reply "OK" and the charger is turned on and the engine runs long enough to get to a safe charge level.
4) Repeat until weather gets warmer. Note the none of this happens unless and until the weather gets very cold.

Not only is all of this possible, it is quite easy if the van is designed properly, as mine is. One can be as skeptical as may be, but this is all for real.

I will use shore power when it is available. But I will not be a slave to it.

 

[GeorgeRad]

................ Let's say the battery's heating pad consumes 50 watts (heat equivalent to a medium-sized incandescent light bulb). In an insulated battery compartment, that is a lot of heat. 9000 / 50 = 180. 180 hours is 7.5 days. If the heater runs on a 50% duty cycle (which is probably conservative in a small, well-insulated box), that is more than two weeks of continuous heating. Where I live, I have NEVER seen anything close to two weeks below zero. I used to live in Wisconsin. There, I saw such a spell exactly once. I will grant you that Minnesota is a challenge, which I acknowledged up front. Note that (a) I rounded down everywhere; (b) I have completely ignored the above-mentioned second chassis battery, which provides additional amps; (c) since the battery is being used to power the heating pads, there will be some self-heating (also ignored) and (d) since we are talking about a resistive load, the efficiency is 100%. So, these are very realistic numbers.

How will this work in practice? Like this:
1) System "sleeps" with most system shut down (inverter, 12V buck converter, etc), excepting the tiny monitoring processor.
2) Nothing happens until the battery temperature approaches damaging cold, at which point the heating pad is activated to prevent damage, powered by the main batteries. We can stay in the state for up to two weeks if necessary.
3) If frigid temperatures continue and battery is getting low, the system will raise the heat pad temperature in order to bring the battery up to "ok to charge" temperatures. Van sends a text to my phone asking permission to start engine. I reply "OK" and the charger is turned on and the engine runs long enough to get to a safe charge level.
4) Repeat until weather gets warmer. Note the none of this happens unless and until the weather gets very cold.

Not only is all of this possible, it is quite easy if the van is designed properly, as mine is. One can be as skeptical as may be, but this is all for real.

I will use shore power when it is available. But I will not be a slave to it.

With a 100W solar panel you could keep batteries warm (prewarming) at higher temperature to extend time before firing the engine at frigid conditions. Certainly, snow would be an issue. Looking forward to see your write-up.

 

[Davydd]

Below freezing is the achilles heel for lithium batteries not below 0 degrees unless you are talking celsius. In fact the the battery companies recommend keeping your batteries above about 40F because below they loose permanent power accumulatively. I don't know about your batteries but mine can discharge below freezing but cannot accept a charge. That means idling alternator current OR external shore power OR a generator doesn't charge your batteries. Aren't your batteries either on line or fully shut down? Do you have a secret for another scenario? If you have heat, then they are on. If you system is "sleeping" power has to wake them up. If you are receiving information on a cell phone doesn't that mean your cellular network is on and active? BTW, I too have an app that monitors and controls my Silverleaf screens by Wifi at present 9 miles away. Does that take power? Do you have an inverter/converter? Where does it gets its power? Mine has a cooling fan. What about alarms? Do you have recommended practice of keeping you batteries on 60% charged and the ability to maintain that? There is also just natural loss in your batteries. What I am saying is if you have a lot of electrical dependent stuff and you are losing battery amp hours more than you think if your batteries are on line. That's why in winterizing you are best to hard shut down your batteries so you can get through a typical winter but you can't with lithium with cold weather in the equation. That's why some take them out and put them in their house--a warm environment. That's easier than automation.

But given all that, as in my oil heater shoved under the van calamity, what does your system do if your heat mechanically fails like in the light bulb burns out, in your equivalency comparison? ...and that was with shore power. All the power available including fully charged batteries were useless. Insulation is only good until you reach equilibrium unless you have power. Don't take a two week Caribbean cruise next winter if you don't have any redundancy fall back on as Booster recommends.

My redundancy learned from 8 years with lithium battery experience with two entirely different systems ans a company with 10 years experience that built the Class B van and getting active feedback from customers in all climates:

Siverleaf controls and monitoring: Set to fully shutting down batteries arbitrarily with what you set. I set it at 40F. and 40% charge where Autogen starts the engine. I don't need it in storage because I have:

Shore Power: To keep the batteries charged. The Silverleaf controls the charging and charging shuts down at 99% and doesn't come back on until the batteries drop to a set percent. So I have full use of my van and don't worry about power loss stored in a:

Heated Garage: Where I don't need to winterize, I can keep my beer cold, turn on the van lights, run the water, and use the bathroom and kitchen galley. It's a man cave adjunct. Of course, I don't have to now worry about mechanical failure of a heating system in the van because it doesn't come on. And If I want to:

WiFi or cellular app on my iPhone: To monitor and change the controls because Sliverleaf is a touch screen and the app mimics it. I don't bother to use it but I could if I worried about the garage electricity going off. With 269 other garages I'm confident it would be taken care of promptly. If only my garage, I've experimented and found that the other surrounding garages will keep my heat above freezing.

 

[avanti]

Most of the message to which I am responding raises issues which I have already addressed. I will not repeat these. I will make a few clarifications:

Below freezing is the achilles heel for lithium batteries not below 0 degrees unless you are talking celsius.

There are three thresholds:
1) Minimum charging temperature (typically around 32 degrees F).
2) Minimum discharge temperature (typically around 0 degrees F).
3) Minimum storage temperature (varies, but typically well below 0 degrees F).

I don't know about your batteries but mine can discharge below freezing but cannot accept a charge. That means idling alternator current OR external shore power OR a generator doesn't charge your batteries.

This makes no sense. You first use your power to heat the battery and THEN use it to charge.

Aren't your batteries either on line or fully shut down?

No. Neither are yours. ALL batteries are always fully "on". It is inverter/chargers (and perhaps BMS) that can be "on" or "off". There is always power available if the batteries are not fully discharged. Moreover, as I explained, I also have the Transit's aux AGM battery available. So, there are redundant ways to power an automation system (which itself can spend most of its time in a deep sleep, waking up only periodically)

Do you have a secret for another scenario?

No secret. I described it in detail above. If there is an error in my logic, please point it out in detail.

If you are receiving information on a cell phone doesn't that mean your cellular network is on and active?

It is obviously "on" while it is sending, but like everything else in the van, the automation system can turn it on and off as needed, so it is rarely on.

Do you have recommended practice of keeping you batteries on 60% charged and the ability to maintain that?

Actually, yes. There is a switch on the dash that will be labelled something like "Prepare for Storage". If it is "off", the automation system will charge to 100%. If it is "on", it will charge to 60% (or whatever).

in winterizing you are best to hard shut down your batteries so you can get through a typical winter but you can't with lithium with cold weather in the equation.

But I can, as I have explained.

That's why some take them out and put them in their house--a warm environment. That's easier than automation.

If you say so.

what does your system do if your heat mechanically fails like in the light bulb burns out, in your equivalency comparison? ...and that was with shore power.

First of all, although anything can fail, heating pads would be very low on my list. Secondly, I DO have a backup heat source, which I will explain in my post-delivery description.

Insulation is only good until you reach equilibrium unless you have power.

Obviously. Why did you mention this?

Don't take a two week Caribbean cruise next winter if you don't have any redundancy fall back on as Booster recommends.

The only reason I am participating here is to describe the layers of redundancy that I have available.

Siverleaf controls and monitoring: Set to fully shutting down batteries arbitrarily with what you set. I set it at 40F. and 40% charge where Autogen starts the engine.

Sounds good. So, why are you arguing that it is impossible?

 

[Davydd]

I'm ending this discussion for me. Get a year's experience in the winter and get back to us and don't be a slave to shore power.

 

[JonMN]

On a related note--it was winter when I went shopping for my RV here in MN. I was surprised how many were sitting out in the cold with completely dead coach batteries! You would think dealers would be more cognizant of the batteries. On the other hand, running cords to a lot full of RVs would be a huge project.

 

[booster]

On a related note--it was winter when I went shopping for my RV here in MN. I was surprised how many were sitting out in the cold with completely dead coach batteries! You would think dealers would be more cognizant of the batteries. On the other hand, running cords to a lot full of RVs would be a huge project.

Unfortunately, that is the way it appears to be, and lots of bad batteries sent out because of it, I think. Our 07 was new but on the lot 15 months when we got it in Oct of 08 at a very good price. The apparently just charged up the two gp27 Exide wet cells just before we picked it up as we found when we went out for a quick overnight they didn't even hold up through that one night. Roadtrek said it was an Exide warranty item, and Exide said that the warranty year started when the batteries were installed by Roadtrek and both bailed on us, as did the dealer that sold us the van.