Thursday, May 7, 2020

Fixes and Fails - LiFePO4 Lithium upgrade part 2

We were staying at Dellanera RV park on the beach in Galveston and since we have a son in the Houston area, who is an Electrical Engineer by training, I invited him to help me.  Actually, I think I begged!

In Part 1 Click here to view Part 1, I discussed how I researched and determined what I would need to upgrade the lead acid batteries to Lithium.  Here I am going to share the installation process and some things I learned.

First thing was to unpack all the Battleborn batteries and verify they all had similar voltage.  Since these things were delivered on a pallet, we actually had them delivered to my son's house where we de-palletized them and transferred to our car for the drive back to Galveston.
4 - 100 ah LiFePO4 (Lithium Iron Phosphate) batteries
They all had almost exactly 13.2 volts, so, we shutdown all electrical systems, which is harder than you would think.  We unplugged the 50 amp AC and tripped the 2 - 100 amp breakers near the batteries, but the inverter was still powered up and reporting to the panel, so we pressed the Salesman switch by the door, which we never use.  That shut it down, but that is just a signal to the inverter, not an actual breaker.  OK, whatever, we removed the negative battery cable, don't see how there could be power after that.

There is a little 6" x 6" door on the outside behind the fridge that is where you can shut-off the ice maker.  Turns out it is also where the fridge is plugged in, so we got in there and connected an extension cord to the RV power pedestal's 20 amp outlet.  OK, at least the wine will stay cold!


We removed the original batteries, which were heavy.  Glad my son was there to help.  After getting them out, we noticed that, since there were vent holes and water can enter when driving in the rain, there was a fair amount of rust on the bottom of the battery compartment.  I have to assume that battery gasses contributed also.  We cleaned it all up, sanded it down, applied some navel jelly, and a couple coats of paint before gluing a piece of Plexiglas over the holes on the bottom.  There are still vents at the top, but with all the cables through them it would be very hard to plug those.
Chassis batteries are mounted above
There was a temperature sensor connected to the batteries which is used by the Inverter to ensure it doesn't overcharge when the batteries are hot.  This is not needed for the Battleborn batteries, so we disconnected it on both ends.

We put the new batteries in place and determined that we could re-use some of the existing battery cables, but we needed to make a few.  We cut them to length with a hack-saw, but since we didn't have a tool for crimping 4-0 cable, we laid it in the groove on the side of a pipe wrench with a flat bar across it and then hit the bar with a hammer.


Seemed to work pretty good.  Put shrink-wrap on all the new stuff and bolted them to the batteries, connecting all the positive terminals and all the negative terminals to their corresponding terminals .

4th battery is back behind on the left

Replaced the BIM with the Li-BIM.  Appeared pretty straight forward.



Since we were installing the BMV-712, it needed a Shunt on the negative connection to ground, but that was way in the back, so we made a cable to extend out to the front and mounted it there. There is also a connection from the shunt to monitor the voltage on the Chassis batteries, which we connected at the BIM and also a connection to the positive side of the house batteries. Connected the positive side first and then finished with the negative to the shunt. The BMV-712 has a remote, but since I was controlling through Bluetooth and wasn't ready to pull a cable to the wall inside, we just mounted it in the Inverter compartment.
BMV-712 Shunt

Victron BMV-712 Battery Management System
Powered everything up, setup the BMV-712, and programmed the Battleborn specific setting using the RC-50 remote.  One thing that was not clear was what to set for absorption time. After a call to Battleborn I set it to 30 minutes per battery or 2 hours for our 4 batteries.  Completed similar setup on the Victron Solar charge controller.

Noticed that the BIM was staying connected, when it shouldn't, so after a call to Battleborn, determined that while the original BIM just had connections for battery A and battery B, the new one was specific about which battery went where and in the configuration that matched the old one, it was backwards.  So, I flipped it over and that fixed it.


To test everything out, we shut-off the breaker at the pedestal for a couple of days and ran on batteries (plus solar) only for a few days.  Everything worked great, except when we got down to about 50% battery and plugged back into power, I noticed that it was only charging at a maximum of like 15 amps.  Some quick math told me it would take days to get back to full charge.  Maybe this is why running the generator when we were stranded didn't make a great impact on the batteries?

So, I plugged in the RC-50 remote to see if I could find the cause.  The Inverter only has one connection for a remote, so I unplugged the Firefly connection and plugged in the RC-50 remote.  Almost immediately the charging amps jumped up to 100 amps and then settled down around 95.  So something in the Firefly was restricting the charging.  We asked Firefly about this and they are investigating, but I don't consider it a serious problem, since we are charging primarily with Solar and I have the RC-50 as backup if needed.
Magnum RC-50 remote
I made the following changes on the Magnum MS2012 to work with the Battleborn batteries:

02 LowBattCutOut  = 11.5
03 Absorb Time  = 2.0 Hours (Battleborn said 30 minutes per battery, I have 4)
Battery Type = Custom
  Absorb = 14.4
  Float = 13.6
  Equalize = 14.4 (Should never use, but it needs to be set to something that won't harm)
05 Charge Rate = 90%
09 Final Charge = Silent
  ReBulk = 13.3

I suspect it is the default Final charge setting causing the Firefly to never kick in to Bulk charging

On the Victron MPPT 150/85, I set the following:

Absorption Voltage = 14.4
Float Voltage = 13.6
Equalize Voltage = 14.4
ReBulk Offset = .10V
Absorption duration = Fixed
Absorption Time = 2h 0m
Tail current = 2.0A
Automatic equalization = Disabled
Temperature compensation = Disabled
Low temperature cut-off  = Disabled

As of now, I have shut off the breaker that powers the MS2012 charger and only turn it on if we need to cook something in the Convection oven as that pulls over 1800 watts.  So, these batteries (charged by solar) are powering all lights, cellphone chargers, roof vent fans, furnace fan, Microwave, Fridge, and all 110 volt outlets (TVs, Picture Frame, PC, Sewing machine).  Depending on how much the furnace runs, we are seeing the batteries drop by about 33% overnight, so unless we get 3 continuous days of rain, we should be OK.

Comment, if you have any questions.

Pat

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