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Tuesday, November 1, 2016

Installation Of LiFePo4 Prius House Battery

From my bench test of my new LiFePo4 30 ah battery and 10 amp LiFePo4 charger (above) to installation, was my job for the day.

I first needed to remove the multi chemistry sealed lead acid battery charger and 3 12 volt 8 amp hour batteries below.

I prepared the LiFePo4 battery with 2 conductor quick connect that is fused.  I used these quick connects in my previous house battery versions for ease of assembly and upgrades.

I wanted to protect the terminals on my LiFePo4 battery so I used PVC wood, that I use in many of my projects.  I used 1/2" PVC for two layers.  I drilled out the first layer to accommodate the battery terminals and wires so it would lay flat.  I then added a smaller piece to cover the top of the terminals that were flush to the top after drilling and laying on top.  I glued the top piece on with PVC glue.

The picture above shows the drilled shoulder holes with routings for wires.

I attached the PVC protection with 2 Velcro buttons.

I cut the plastic to size and put a radius on the corners to match the size of the battery.

The rear storage hole in the rear driver's side of the Prius is not flat and as it turns out the 1" of PVC I added was just right to fill the void allowing the battery to lay flat with terminals down. 

Next I needed to hold down the new LiFePo4 10 amp charger in place of the other charger, behind my dropdown panel.  I chose to use aluminum vinyl siding starter as this is what was available in my garage.  I bent it and made flanges that screw down to my plywood base.

Final step was to plug in new battery and new charger into my circuit and my upgrade to LiFePo4 is complete.



  1. What do you think the cost will be for your house battery and charging setup plus wires/fuses/etc. when all is said and done?

    1. Bryce,

      The LiFePo4 battery and specific 10 amp charger with shipping was about $350. I had the rest of the connection parts but they were about $25. If you take what I already had for switches and blue seas USB and cig outlets fuses add another $30

      This does not include the 120v 400 watt PSW inverter to supply the power to the charger.


  2. Brilliant
    On my list to check it out in person, in January.
    What is the weight of the new battery?
    What was the weight of the 3 lead acid 8 amps now replaced.

    1. David,

      Good question.

      New LiFePo4 30 ah battery is 8 lbs and 245 cu in or .032 lbs/cu in
      Old 3-12v 8ah batteries are 15 lbs and 174.4 cu in or .086 lbs/ cu in

      So the LiFePo4 weighs less than half per cu inch

      Yes, see you in Jan.


  3. Do you have any worry about the balancing and protection electronics not being able to cool with the battery upside down?

    1. Tim,

      I'm not totally sure of you question so if I don't fully answer it let me know.

      Lithium battery technology does not care about its orientation to gravity unlike lead-acid batteries.

      There are multiple built-in protections for the 30 ah LiFePo4 battery. One is temperature. It will shut down if it overheats. It will also shit down for over current in and out. This is in addition to over/under voltage conditions. These are controlled internal to the PCM circuitry in the battery pack.

      The 10 amp LiFePo4 charger that I charge the battery with also has protections provided in the internal circuit too. The charger has a fan that runs as long as it is charging and why the charger is in the compartment where I can open the door to allow more air for cooling while it is charging.

      Not described elsewhere is my method of charging my battery. I do not like charging my battery in high ambient temperatures. As soon as I get up and "on the road" I start charging my batteries while it is cool to take advantage of the lower ambient temperatures so I don't have to worry about the charger heating and shutting off and not getting a full charge.

      If you have a follow up to my answer let me know.


    2. Most of the lifePo4 I have looked at said little about thermal protection. As you know most electronic generate heat, I was unsure if it would be bad to have them upside down do to heat generated buy them. With thermal protection it should be moot. Thank you. Tim

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  4. Tim,

    I found the specs on LiFePo4 vendors lacking and I needed to ask many questions after reviewing spec sheets. I believe that most Lion batteries that are drop-in replacements for lead-acid are not LiFePo4 and don't have PCM or BMS.

    As stated the lithium battery doesn't care about orientation.

    The PCM protects from overcharge, overdischarge, overcurrent, and temperature.

    The BMS does the balancing