LiFeMgPo4 Battery

[hbn7hj]

Bottom line is if you have external batteries with a heat pad you are good to go. One would need the BMS tied to a display with temp readout. I bet the whole thing is terribly expensive but available. If the -40F storage spec is correct then all is well.

[Davydd]

In the Lithiumwerks web site you have to give up your name and other information to get access to the data sheets. There you will find:

Storage temperature -40°C to 50°C

-40°C is identical to -40°F Advanced RV corroborated this to me.

I won't comment to the expensive comment just to say every Advanced RV customer hasn't had a problem with it, nor I.

I've alway had a 12v 10 amps total electric resistant heating pads in my external battery case controlled to keep the batteries above 41 deg. F. at all times. It draws directly off the batteries and if you are plugged into shore power it is an infinite draw. Boondocking with an 800ah battery pack it is just another minor load because at those temperatures you mostly likely will be driving frequently while on the road and can certainly last a weekend stationary in any temperature you can endure. In storage you can either be plugged into as low as 15a shore power or just disconnect the batteries as the batteries most likely will never drop to -40 at least in the lower 48 unless you live in International Falls, MN where they often test cold temperature situations for publicity purposes.

So far ARV is placing the batteries inside the 144 Sprinters they are building. I don't know what they are doing with the 170 WB Sprinters. Whether they do the Winnebago Revel thing of needing to heat the cabin first before charging batteries or will be providing external heat to maintain 41 deg. F. all the time, I haven't discussed it with them. I would prefer external heat like the heating pads even though I have a heated garage now. On the road I would like the freedom of leaving the van while on the road for a period of time and not worrying about the battery temperature.

[avanti]

A while ago over at Sprinter Source, Davydd posted a link to an Advanced RV white paper on battery technologies that I do not believe has appeared here:

https://advanced-rv.com/wp-content/u...hite-Paper.pdf

It is a very informative document, and contains useful tables that compares the three ARV battery technology choices (plus several others) along a number of important dimensions. It confirms the Valence's -40 degree storage temperature (as does the Lithiumwerks spec sheet which you can indeed download upon registration).

I think that this is kind of a big deal. As I said, it appears to remove the last potentially-fatal argument against moving from AGM to lithium. The Valence batteries do have a somewhat higher minimum usage temperature than other chemistries (+14 degrees F, vs -4), but I put this in the same category as the 32 degree charge temperature: Potentially inconvenient, but not fatal. It does complicate a cold startup, but as long as there is some way to bootstrap from the vehicle alternator or some other external source, I consider it acceptable. On ARV's "Good-Better-Best" scale, I think I would put the Valence system ahead of Volta.

I am a little surprised that LiFeMgPO4 hasn't gotten more attention. I guess the problem being addressed is not yet well understood in the market.

(Un)fortunately, my 4-year old AGMs are doing fine and more than meet all my needs. But, for the first time, I could imagine making a decision to move to lithium when replacement time comes around.

[Davydd]

That document was a hand out at Advanced Fest and is a year old. Who knows what ARV knows today. As for their good, better, best rating it was based on price and capability of capacity in a B. The Volta system, I think, gives more amp hours at a smaller footprint and lighter weight with faster charge rate and probably is a physical decision to achieve the greater amp hours. In my Valence design 828ah is the maximum I can get in and is more than enough. Other factors could include quality and capability of the BMS and how easy it is to relate to their Silverleaf system. I decided on the Valence system, not for cost, but many other factors and considered the Volta system was overkill for my needs. So good, better, best is somewhat subjective to the individual customer. I don't know if the Elite Power Solutions batteries are pushed much by ARV.

As for the 14 deg. F. discharge temperature of the Valence batteries I think the key statement is, "From personal experience, I know that people who live in those places will be prepared for the cold." The paper was prepared by Fred Ahlgren, a northern Minnesota native. Plus, ARV makes provisions and capability to keep the batteries above the optimum 41 deg. F. at all times for all their systems. So, it is really not inconvenient if you design for it.

Those maps tell you cold consideration is a concern in most all the United States and if you use lithium batteries you should prepare for it as you are not going to avoid it. I can vouch for that. I've camped overnight in 0 deg. F. in the Southwest in Gallup, NM Cracker Barrel. This last trip it got into the teens and snowed near Las Cruses, NM in March! and got below freezing in Big Bend National Park. Those were all no shore power situations.

[hbn7hj]

ARV has the upper temperature for LiFePo4 batteries at 100F. Battleborn has it at 130F. Hope the higher limit is correct because there is no way I can stay below 100F in Phoenix. I guess I'll find out 'cause I'm not gonna remove them for indoor storage. With two RVs, one of them is gonna fry!

[Davydd]

Maximum cell temperature of the Valence batteries under discussion in this thread is 140 deg. F. with maximum storage of 122 deg. F. I've considered this in that I would never tour in a van in Phoenix in the summer and have broke 100 deg. just a couple of times in all my travels over a dozen or so years.

My condo garage where I store my B, in checking never got over 80 deg. in all the times I checked it and typically maintained 70 deg. when it was 90 deg. ambient. It is well insulated with the insulated garage door only facing an outside wall and the other three sides are sheltered by adjacent garages. I think I am good to go on the high side.

On the low side I maintain 45 deg. and seldom is my heater on because of the same adjacencies maybe maintaining a higher temperature. A lot of people work out of their garages.

[avanti]

Originally Posted by Davydd

As for the 14 deg. F. discharge temperature of the Valence batteries I think the key statement is, "From personal experience, I know that people who live in those places will be prepared for the cold." The paper was prepared by Fred Ahlgren, a northern Minnesota native. Plus, ARV makes provisions and capability to keep the batteries above the optimum 41 deg. F. at all times for all their systems. So, it is really not inconvenient if you design for it.

Actually, I think the key statement is you can't use your batteries if they are below 14 deg F. That counts as an inconvenience. I agree that it is a tolerable inconvenience.

It doesn't matter how prepared Mr Ahlgren is for the cold. The fact is that if a van has been in long term cold storage without shore power, it is not possible to "keep the batteries above the optimum 41 deg. F." The ARV white paper says as much. Starting up under these conditions would entail an inconvenience. An acceptable (for me) inconvenience, but an inconvenience none the less. I do not store my van with continuous access to shore power, and I do not desire to. It would not be convenient.

As I said, this chemistry would require extra provisions for heating the battery from either shore power, a lead-acid battery, the engine, or a genset, and it would have to work without either using or charging the Li batteries. This can certainly be done, but it is most certainly an inconvenience.

Personally, I think it is both possible and useful to admit that a system can be good without insisting that it is perfect.

[Davydd]

You don't have to keep batteries above freezing or 41 deg. That is the optimum when batteries are in use. In long term storage you can disconnect the LiFeMgPo4 batteries and they will still withstand the cold equal to AGMs at -40 and a lot longer time with less parasitic loss. So your inconvenience is going on a trip most likely waiting when it is warmer out and the batteries could immediately be charged or maybe the inconvenience of heating the cabin up a couple of hours running the engine like the Winnebago Revel mentions if you want to go skiing in the winter. So you don't need shore power, lead-acid battery or a genset. You just need warmer weather or your Class B engine. It is just common sense and you don't to do anything to prepare for the cold after all. It is not all that difficult.

BTW, Fred Ahlgren built the most sophisticated DIY T1N Sprinter Class Bs several years ago that I've ever seen and also designed and had Advanced RV build Gustav, one of the most custom Class Bs Advanced RVs built so far in equipment, cabinetry and floor plan. He's retired, but in his spare time develops battery systems and investigates stuff like the Houghton air conditioner. He is not technically an employee. He consults.

[chris_g19]

Stick with the popular and standard lifepo4, unless you have full warranty support. Lifepo4 is your only logical option if you want DIY options. It's also safest and most stable.

Sure you can get better energy density chemistries, but that's not always the most important thing to make a decision. Safety, reliability, cycle life, etc.

Over the lifetime lifepo4 is the cheapest per kWh consumed...... So definitely if you are a full-time stick with it.

[avanti]

Originally Posted by chris_g19

Stick with the popular and standard lifepo4, unless you have full warranty support. Lifepo4 is your only logical option if you want DIY options. It's also safest and most stable.

Sure you can get better energy density chemistries, but that's not always the most important thing to make a decision. Safety, reliability, cycle life, etc.

Over the lifetime lifepo4 is the cheapest per kWh consumed...... So definitely if you are a full-time stick with it.

That's fine if you are willing to ignore the very real low-temperature storage issue. But almost nobody who needs to store their rig outdoors without access to shore power can afford to do so.

Also, what evidence do you have that LiFeMgPo4 is less safe than other alternatives?