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Yet Another Battery Upgrade

AnOldURAnOldUR Member Posts: 1,616
edited September 13 in Battery/Electrical & Solar
We store our T@B in a heated garage and don't camp in extreme cold, so the added indoor storage makes keeping our lithium batteries in the front outside storage box our preference. There are a few loose ends to finish up, but this upgrade to two 300Ah LiFePO4's is almost complete. I dragged it out of the garage between rain storms to do some testing. So far, so good. 

Last winter I replaced the small factory rooftop solar panel with a 310W Sunflare panel that comes on 400 T@B's. I upgraded from the 75/10 Victron controller to a 100/30 to take advantage of the additional wattage. It worked considerably better, but the factory 10awg wire running from under the bench seat to the front box was resulting in too much voltage drop. My first thought was that I'd have to find a way to run heavier wire, but recently thought that I could simply move the controller closer to the battery. I'll need better sun for a good test, but the app voltage reading has me believing that it was a good move. Now I'm not seeing the different battery voltages from the two controllers.

For good or bad, I reuse the post type distribution blocks from my old setup instead of dedicated bus bars. While at it I switched from the SAE solar suitcase port on the side of our box to a 45 Amp PP15 Anderson connection. ..... Yes, there will be a cover over the batteries. 
 
Before installing, I fully charge each battery independently. I'm currently running the air conditioner to completely drain them. Looks like that will take about eight hours. Next up will be recharging to see if the shunt confirms the 600Ah capacity.

So, any comments or critiques on this amateur electric work?


edit to mention that the battery boxes that the old 100Ah batteries were in were barely too small for the 300AH. At the base it was a good snug fit, but the taper and handles would keep the 300Ah from sliding all the way in. I ended up cutting the boxes about an inch up from the base and screwing that to the bottom of the truck box as a way to secure the battery from sliding. (see second picture)
Stockton, New Jersey
2020 nuCamp T@B 320S * Jeep Wrangler
(47,171 towing miles through the end of 2024)
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Comments

  • Grumpy_GGrumpy_G Member Posts: 641
    Well, I've seen worse .... :) Just kidding, looks good and clean. Moving the charge controllers close to the batteries avoids the potential issue with the controller having the wrong idea of the battery state of charge due to voltage drop. Also, the controllers being the MPPT type they can optimize voltage vs current even if the panel wiring is a bit longer.
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  • qhumberdqhumberd Administrator, Moderator Posts: 665
    Grumpy_G said:
    Well, I've seen worse .... :) Just kidding, looks good and clean. Moving the charge controllers close to the batteries avoids the potential issue with the controller having the wrong idea of the battery state of charge due to voltage drop. Also, the controllers being the MPPT type they can optimize voltage vs current even if the panel wiring is a bit longer.
    I wondered where the name @Grumpy_G came from. Now I know.

    I think this install looks pretty good, but was wondering if the components are weather resistant. How much moisture gets in the tub when driving in a hard rain?

    2019  T@B400 Boondock Lite "Todd"

    2016 Toyota Tundra 5.7 Crew Cab
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  • AnOldURAnOldUR Member Posts: 1,616
    @qhumberd, we've had the Tractor Supply box on for nearly five years and over 50K of towing miles. Even with the venting for propane, there has never been any significant moisture getting into the box. The lid seals very well. 

    I'm not thinking that @Grumpy_G was being grumpy. There are certainly things about my mod that have room for improvement. I was hoping for constructive criticism and opinions on what might be seriously unsafe.
    Stockton, New Jersey
    2020 nuCamp T@B 320S * Jeep Wrangler
    (47,171 towing miles through the end of 2024)
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  • AnOldURAnOldUR Member Posts: 1,616
    edited September 13
    The discharge cut-off on my LiFePO4's is 9.2V. My plan was to run the air conditioner until it reached the cut-off, but the manual say repeated dropping below 10% SOC (11.8V) reduces battery life. A Will Prowse video made me think there was no damage done by doing this. To be on the safe side, I stopped the test when the shunt got to 600Ah consumed. The battery voltage had hit 11.4V. The AC was still running strong, but as the battery voltage dropped, the amperage being drawn went from about 70 to almost 90. 

    Overall I was happy to get the rated 600Ah, but was left wondering how much capacity it would shown if I had let the test continue. (Just not enough to risk future battery life.)

    I'm now in the process of recharging the bank. Curious to see if the shunt will show the same 600Ah returned. Using a 30 amp charger, it will be a while before I know.  ;) 

    edit to add:
    Left the 30amp Victron charger on for a couple of days in an attempt to balance the cells. At the end of this time the app showed about 610Ah had been sent to the batteries. 

    Stockton, New Jersey
    2020 nuCamp T@B 320S * Jeep Wrangler
    (47,171 towing miles through the end of 2024)
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  • Grumpy_GGrumpy_G Member Posts: 641
    The charge controllers are IP 43 (spraying water) but the charger is only 22 (dripping water) so you might want to check it after driving in the rain. 
    Full discharge indeed reduces the lifetime of LiFePo batteries to less than half the number of cycles vs 80% discharge. However that is still 1000+ cycles doing 100% discharge, draining the battery to empty a few times does not significantly affect longevity. 
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  • glesieutreglesieutre Member Posts: 26
    I might try an upgrade like this next spring -- but less ambitious -- so I'm curious. I'm guessing that's almost 120 lbs of batteries in the storage box -- is that right? That might be an issue for tongue weight with my tow vehicle. 
    2015 T@B S-Max towed by 2016 Subaru Outback 3.6R -- central Pennsylvania
    "Travel is fatal to prejudice, bigotry and narrow-mindedness." Mark Twain, The Innocents Abroad, 1869
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  • Grumpy_GGrumpy_G Member Posts: 641
    That is a valid concern with a crossover tow vehicle, but a regular tongue box can't fit those batteries to begin with (the OP has a truck toolbox I think). A typical lead-acid deep cycle battery is 45+ lbs which is about the weight of a 200 Ah LiFePo battery. While not the OP's 600 Ah total a 200 Ah battery would still be a significant upgrade. 
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  • AnOldURAnOldUR Member Posts: 1,616
    My tongue weight is sitting at a little over 300 pounds with the new batteries. Well within the 10-15% safe limits. Over the five seasons that we’ve had our T@B, I’ve made a few battery changes. It came with a 80Ah that was about 50 lbs. Then came two 125Ah AGM’s at 75 lbs each! After that, two LiFePO4’s at 25 lbs each. These 300Ah batteries are a little over 50 lbs each. We haven’t towed with the new setup yet, but I’m not worried.
    Stockton, New Jersey
    2020 nuCamp T@B 320S * Jeep Wrangler
    (47,171 towing miles through the end of 2024)
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