More interesting Tesla battery news

[Jostalli]

Originally Posted by Davydd

I don't think it is as simple as keep your your cells inside a van. A van is not a conditioned space 24/7 like a house. I have experience with this issue. Try living in Minnesota and head out for a trip on February 2. I'd also like to re-emphasize this. Space inside a B is precious. An 800ah battery pack as I have would essentially kill all the under bed storage I have. That is not acceptable especially when a simple heating system works.

Everything I have read is the jury is still out about where you keep your batteries charged, but at 50-60% you are handicapping yourself for no benefit. There has been enough testing to predict 5,000 cycles if properly cared for at full charge. That's over 13 years. Even if you lose charge like Technomadia claimed they still have battery power greater than 50-60% available. Besides, how does one keep a battery charge at 50-60%?

I was simply providing an example of a bare minimum setup to use a LiFePO4 battery. Not the ideal setup for everyone.

LiFePO4 batteries like to be stored at 50-60%. Not 100%. So when you are not using your van don't leave it on a trickle charge like other batteries. Leave them disconnected. They are fine.
I'm not advocating to always try to keep the battery charge to 50-60%.

[Davydd]

Do you have an authoritative link or source on that 50-60%.

[Jostalli]

Originally Posted by Davydd

Do you have an authoritative link or source on that 50-60%.

Best layman's guide to LiFePO4 batteries available: http://www.pbase.com/mainecruising/l...n_boats&page=1

[gerrym51]

don't the 12 volt heaters draw power from the batteries?

[booster]

Originally Posted by gerrym51

don't the 12 volt heaters draw power from the batteries?

That is the catch 22 on lithium battery heaters, they use power from the batteries to heat themselves, through the inverter if they are 110v, if there is no other source of power available.

[Davydd]

Originally Posted by Jostalli

Best layman's guide to LiFePO4 batteries available: http://www.pbase.com/mainecruising/l...n_boats&page=1

That is one guy's opinion and this is what he says?

Floating LFP is a complex subject and I will touch on this later. Bottom line is to avoid floating LFP banks if you can. Some have argued that a float voltage of 3.35VPC or lower (13.4V for a 12V bank) is not badly damaging. Remember this type of charging keeps you in the upper SOC range for long periods of time and these batteries prefer to sit at 50-60% SOC when not being used not 90%+ SOC.. Can you float at 3.35VPC or lower? Sure you can do what ever you want to, but we don't really know the long term affects other than to say it is likely going to shorten the life. Of the 80 or so white papers I have on LFP batteries not a single one of them has dealt with fractional "C" use and floating at 3.35V or lower, not one.

What does Tesla say on the subject when they give 10 year battery warranties? Apple claims charging to 100% does not affect longevity, but of course that is computer batteries and not RVs. And as I mentioned earlier, what is the long term goal if charging 100% still gives you 10 years or more on batteries and full use of all power available that will most likely still be higher than 60% most of the life of the batteries?

[Davydd]

Originally Posted by booster

That is the catch 22 on lithium battery heaters, they use power from the batteries to heat themselves, through the inverter if they are 110v, if there is no other source of power available.

Not really much of a catch 22 when you have enough battery power to heat what is practically indefinitely. The power draw is minimal. Also, when batteries are in use they heat up. For long term in extremely cold weather you have these options.

1) Disconnect batteries. Lithium ion will easily last through a winter and keep charge.

2) Plug into shore power to keep heat on.

3) If not plugged into shore power with autogen it is a recycling cycle. Batteries drops charge and provides no heat to pads. Engine auto starts and recharges batteries for a set period of time. If batteries drop again. Then engine starts again and recharges again and on and on. Obviously, only a complete idiot would allow that to happen and most likely wouldn't anyway unless the B was totally neglected when option 1 would do.

4) I have automatic battery shut down if the batteries do go below freezing. They disconnect and don't charge or accept charge. That would then mean moving the B to a heat source or a reminder to get the hell out of Minnesota.

[Jostalli]

Originally Posted by Davydd

That is one guy's opinion and this is what he says?



What does Tesla say on the subject when they give 10 year battery warranties? Apple claims charging to 100% does not affect longevity, but of course that is computer batteries and not RVs. And as I mentioned earlier, what is the long term goal if charging 100% still gives you 10 years or more on batteries and full use of all power available that will most likely still be higher than 60% most of the life of the batteries?

Instead of being critical please read the paper I posted so you can learn something.

Tesla and Apple use different batteries than what the paper is discussing (and what we are all using).

[booster]

I wonder about the "minimal" amount of power use, as you have to have the inverter on to run the heaters off the batteries, and you have stated you use near 10 amps just sitting, plus whatever the heaters are using. I would think in cold weather you could be to cutoff in a couple of days if you forget the batteries on, or can't get some charging source.

[Boxster1971]

Originally Posted by Jostalli

Best layman's guide to LiFePO4 batteries available: http://www.pbase.com/mainecruising/l...n_boats&page=1

+1 on that guide and the cruisers forum.

[Davydd]

Originally Posted by booster

I wonder about the "minimal" amount of power use, as you have to have the inverter on to run the heaters off the batteries, and you have stated you use near 10 amps just sitting, plus whatever the heaters are using. I would think in cold weather you could be to cutoff in a couple of days if you forget the batteries on, or can't get some charging source.

I just gave you the four options I am aware of. Option 3 covers your question.

My first four days of my Advanced RV ownership I was on the road in -5F to a high of 27F, never over freezing to bring it home from Cleveland to Minnesota. Not once was I plugged into shore power on the trip. I did the same in traveling from Minnesota to Oklahoma City in two days to get out of freezing weather. I have no doubt the batteries will stay above freezing in any traveling I would ever attempt.

I have a high electrical use. However, it actually sits unused as much as I can tell with refrigerator turned to on and inverter on about 6.5-8 amps average. But I also stated I desire a B that is transparent in use without needing to constantly track electrical usage (conservation) when boondocking same as being on shore power. If I desired I could shut down my use to the same as most everyone else with the singular exception of the Silverleaf control monitor which I can also dim to off if I choose to. The difference is I don't have to. This all was an achieved goal and until you experience it you may not understand what sense of freedom it gives you.

[booster]

Yeah, if you drive a lot, no issue. If you, or some else, forget the batteries on when parked and cold, it will be dead quickly--is what I said. It would not be hard to have the engine supply power to run the heaters if the batteries were cut out-I don't know why they wouldn't do it that way.

[Davydd]

Originally Posted by booster

Yeah, if you drive a lot, no issue. If you, or some else, forget the batteries on when parked and cold, it will be dead quickly--is what I said. It would not be hard to have the engine supply power to run the heaters if the batteries were cut out-I don't know why they wouldn't do it that way.

Go back and read option 3 I posted. The engine does keep the batteries warm and in an automatic way. That is just not going to happen, at least with me, as I said, but could.

Besides, I or someone else, could sit for 75 hours before the batteries deplete. That is never going to happen either in cold weather if one has any sense. The point I have tried to make is batteries fail-safes below freezing temperatures are covered. You can still drive the B. My batteries should never go dead with all the fail-safes built in unless abandoned over a long period of time.

[booster]

With autogen that you said you wouldn't want to use. What do you do if the batteries a low temp shut off? You have said over and over that you have to plug in or go somewhere warm. It needn't be that hard if the engine could provide the power to warm them, once they have kicked out.

[wincrasher]

I have alot of LiPo batteries I use in my drones and RC planes and boats. All of them come with instructions to discharge the batteries to 50% for long term storage.

On my drones, the batteries would tend to bulge out if left at full charge for a few weeks. So the drone manufacturer put in software to automatically discharge the batteries after a set amount of time.

Most of the hobbists say to discharge the batteries to 50% if you aren't going to use them for 3 days. The fancy chargers I have have a pre-programmed mode to do it.