Home Forums Truck Camper Adventure Forum Lithium Batteries

Viewing 7 reply threads
  • Author
    Posts
    • #68345
      John Vansant
      Participant

      This is a question for Mike, – or anyone else that feels qualified to answer.

      I’ve traveled, and plan to continue to travel, all over the United States. I specifically purchased a 4 season truck camper, as I am often in areas where the temperatures are well below freezing. Additionally, when not traveling, I make my home in Kansas. My truck camper is stored on the truck, outside, under an open carport.

      My question involves coach batteries. My camper currently has 2 AGM batteries, which are stored in an exterior battery compartment. My charging system consists of one 180watt photovoltaic panel and a 2500 watt propane fired, on board generator and of course, shore power. I do not have a DC to DC charger or any tow vehicle charging capability other than the standard 7 way trailer plug.

      My questions involve converting lithium batteries;

      * By storing lithium batteries in an un heated exterior compartment, while using and storing the camper in below freezing temperatures, wouldn’t any strategies needed to protect lithium batteries in below freezing temperatures battery, negate the positive aspects of changing to lithium batteries ?

      * In converting from AGM to lithium, would it be necessary to replace the existing battery charging apparatus if it was originally designed only for lead acid/AGM charging.

      * Also, this camper is mounted on a SRW truck, and although under GVW, weight reduction offers some value. What type of weight savings can lithium batteries offer?

      Any commenters, thanks in advance !

      Johnny V.

    • #68347
      Joel Gambino
      Participant

      Some of the new Lithium batteries are “self-heating”, so that should take care of the first concern. That is assuming that you have some way to charge during storage. As far as negating the benefits of Lithium, that depends on what is important to you. To me the benefits are: 1) higher operating voltage and very little voltage droop under load, 2) more capacity per weight and volume. The downside is cost, but the prices have come down considerably over the last couple years.

      As far as needing a new charger, it depends. If you have a charger with programmable parameters, chances are you can set it up to do a good job charging Lithium. From what I’ve seen, charging Lithium is more simple than charging lead acid. Pretty much constant voltage, no float and definitely no equalization. I have a Bogart charge controller and have found settings to use for Lithium. My on board converter (for shore power) is not programmable as far as I know so I will most likely have to change that. (I have 2 100 amp-hour lithium batteries, but haven’t installed them yet).

      I would guess Lithium batteries are about 1/2 the weight of a comparable lead acid battery. But you get more usable amp-hours from Lithium, so the effective weight saving is even more.

      I’ll be interested to see what others have to say.

      Joel

    • #68356
      John Vansant
      Participant

      Thanks for your input Joel!

      Yes, I think a lithium battery with a self heating provision would be necessary in the climate that I use and store my camper in.

      One major concern concerning this type of battery would be the amp draw of the batteries self protective heating circuit.

      I don’t see storage as being a problem, but it would not be out of the ordinary for me to spend days camped in sub freezing temps without shore power, all this time running the furnace, coach lights, water pump etc.

      In reality I guess this is where a DC/DC charger and OBG come into play.

      I guess the question revolves around the fact that if in cold climates, you need to run your truck or generator for several hours each day to keep your “self heating” lithium batteries charged, is there really any great advantage in switching from AGM?

    • #68391
      Phil Patterson
      Participant

      Much of this depends of what you mean by sub freezing temps…Why??

      Typically, even a non-heated lithium battery can be safely discharged as low a -4 dF, so the main constraint has to do more with ‘charging’ which should occur at 32df and above…

      I have three 200a/hr LFP’s (in parallel, with two paralleled solar systems), but able to mount all three beneath the dinette…So I don’t really have any experience with internally heating LFP’s – I’d be curious to know if the heater only comes on when charging, or say, whenever the batt drops to below 32 degrees (the latter seems somewhat impractical to me)…Another alternative might be to use an externally heated battery warmer blanket (Amazon) which enables you to control it’s operation…Some LFP’s have a provision that prevents charging at less than 32df…

      As far as charging goes, a conventional charger will usually do the trick so long as the voltage doesn’t exceed 14.6v (14.0-14.4v will do just fine, but at a slightly reduced rate), and constant voltage-constant current (CV/CC) is best, with no equalization cycle, and there’s no necessity to float – but if you must float, 13.5v or less (as measured at the battery) is advisable (for longevity)…

      For long-term storage, it’s best to isolate battery (I use a dedicated disconnect switch) and reduce the SOC (state of charge) to about 50-55% or so…Parasitic drain for LFP’s is uber low – It’s been reported that Shelf-life SOC often remains within an acceptable level for up to 6 mos or even more…

      (Continued)

    • #68392
      Phil Patterson
      Participant

      Also,

      For long-term storage, it’s best to isolate battery (I use a dedicated disconnect switch) and reduce the SOC (state of charge) to about 50-55% or so…Parasitic drain for LFP’s is uber low – It’s been reported that Shelf-life SOC often remains within an acceptable level for up to 6 mos or even more…

      (Continued)

    • #68393
      Phil Patterson
      Participant

      (Note, Having to break post up)

      Determining accurate SOC with a LFP can be somewhat problematic (unlike conventional batteries) due to it’s relatively flat voltage plateau, and my experience with the typical mfg’s built-in Blue-Tooth feature (some offer) has not been all that accurate…

    • #68402
      John Vansant
      Participant

      Thanks for your input Phil, this is useful information!

      Again, without access to shore power, it doesn’t seem practical to use the lithium batteries own stored energy to protect itself, and or to bring it up to temperature in order to allow for safe charging. And, with your batteries being stowed under the dinette, in reality you’re using the fantastically cheap and concentrated energy stored in propane, to keep your batteries warm.

      Also, from my perspective, although the word is that lithium batteries are lighter, in my opinion, there is HUGE convenience factor associated with having coach batteries located in an easily accessible exterior compartment

      I mean, maybe I’m off base here, but with all of these factors at play, it doesn’t seem as if with currently available lithium battery technology, it’s a practical proposition for lithium batteries to be used for coach batteries, off grid, for extended periods in cold weather – primarily because of the additional energy needed to keep them warm

    • #68448
      Steven
      Participant

      My questions involve converting lithium batteries;

      * By storing lithium batteries in an un heated exterior compartment, while using and storing the camper in below freezing temperatures, wouldn’t any strategies needed to protect lithium batteries in below freezing temperatures battery, negate the positive aspects of changing to lithium batteries ?

      * In converting from AGM to lithium, would it be necessary to replace the existing battery charging apparatus if it was originally designed only for lead acid/AGM charging.

      * Also, this camper is mounted on a SRW truck, and although under GVW, weight reduction offers some value. What type of weight savings can lithium batteries offer?

      Any commenters, thanks in advance !

      Johnny V.

      for storage if the temp is below freezing and your storing for a long period of time it is best to bring LiFePO4 batteries inside the house or heated garage. short period they are good to -35C as a minimum you want to have a total disconnect installed so you can isolate them from every power source or draw. if you bring them in fortunalty they are a lot lighter than regular batteries, I have a 300AH battery and it is 50lbs.

      it is not necessary to convert but it is beneficial if you want to use the full capacity. for your house you just need to change the converter section of your power panel to one thats Li compatible. I wouldn’t worry about a dc to dc charger unless you feel you need one. (you have the solar charging while you are driving and the genny for emergency)just unplug the fuse that feeds power through your wiring harness as it really isn’t doing you any good anyways unless you have upgraded the wire size

      weight savings like I mentions my 300AH battery is 50lbs and it replaced two GC2 batteries that gave me 100 usable AH that weighed close to 150lbs so in my case I nocked 100lbs off my weight and got 3x the capacity

Viewing 7 reply threads
  • You must be logged in to reply to this topic.