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07-18-2022, 05:07 PM
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#1
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Senior Member
Join Date: Sep 2017
Location: Sequim, Washington
Trailer: 2018 5.0TA towed with a 2017 GMC Canyon V6
Posts: 143
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My Lithium Battery Installation
Spoiler alert: This is just how I mounted the battery.
I'm in the process of converting to lithium in my 2018 5.0TA. From the factory, it came w/ dual 6V batteries, a single 160 watt solar panel and inverter. Yesterday I changed the controller from the factory WFCO 8955 to a Progressive Dynamics PD4655TV I got from Best Controller (Randy is great), which is the latest iteration of this replacement controller, which is configured for lithium
The battery I selected is the Power Queen 12.8V 200Ah LiFePO4 Battery. It has an internal 100 amp BMS.
Today I removed the factory dual 6V batteries and box (under the passenger seat dinette) and made a new hold down to mount the new lithium in the same spot. I mounted the battery on a 3/4" piece of plywood with a hole cut out to accommodate the frame bolt that protrudes from the floor as seen in the first picture. The philips screwdriver points to how I attached it to the seat box in the front and the flat screwdriver points to the two bolts that go through the floor. The second picture shows the bolts from the bottom. Note the cleats on the side and the front to keep the battery in place. There is also a small plate attached to the back as well. The metal brackets in the middle are anchor points for the battery hold down. The third picture shows the installed battery with the top cross bar. Note the steps in the cross bar so it only bears on the edges of the battery. I cut those steps because I noticed the top of my battery was raised up slightly in the middle and didn't want to compress it there in case the the BMS or something sensitive was under it. The last picture shows the completed installation.
Next is upgrading the stock 200 amp fuse.
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07-18-2022, 07:09 PM
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#2
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Site Team
Join Date: Dec 2017
Location: Mid Left Coast, California
Trailer: 2014 Escape 21
Posts: 5,119
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If that battery has a 100A BMS, I don't think you want to use a 200A fuse
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07-18-2022, 07:46 PM
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#3
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Senior Member
Join Date: Sep 2017
Location: Sequim, Washington
Trailer: 2018 5.0TA towed with a 2017 GMC Canyon V6
Posts: 143
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Well, actually I am a bit unsure about the fuse size. The original fuse w/ the dual 6V batteries was 200 amp. Yes, the BMS is limited to 100A, but will allow up to 280 amps for 5 seconds. Also, the wire size coming off the battery to the solar controller /inverter is 2 AWG, which I believe will handle 200 amps. But then again, the inverter is 1500 watts.
If I use this fuse calculator, https://www.explorist.life/what-size...ctrical-setup/, I should have a recommended 120 amp fuse, but the maximum size is 315 amps.
But my inverter is a Go Power GP-HS1500 1500W. The manual states "Please use 10 ft or less of #2 Cable with a 200 Amp fuse." So that's what I settled on.
Quote:
Originally Posted by John in Santa Cruz
If that battery has a 100A BMS, I don't think you want to use a 200A fuse
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07-18-2022, 08:28 PM
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#4
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Site Team
Join Date: Dec 2017
Location: Mid Left Coast, California
Trailer: 2014 Escape 21
Posts: 5,119
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running a hair dryer off the 2000W inverter I installed drew a steady 166 amps from my dual LFP's according to the SmartShunt. I initially fused each LFP at 150A but I'm planning on rewiring it with a single 225A fuse and heavier gauge wire (single 1/0 instead of separate AWG 4 for each batt)
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07-19-2022, 01:13 AM
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#5
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Senior Member
Join Date: Oct 2020
Location: San Jose, California
Trailer: 2022 5.0 TA
Posts: 669
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I am in the middle of my lithium upgrade, actually using some of the lithium thread that John in Santa Cruz did for some of my installation. One thing I will probably do differently that you may consider, is just leaving the fuse out. The fuses that are provided for the inverter when connected to a FLA battery aren’t the right type for a lithium battery — and actually not really needed at all for a lithium battery that has a BMS. The BMS will catch faults and disconnect.
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07-19-2022, 03:43 AM
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#6
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Site Team
Join Date: Dec 2017
Location: Mid Left Coast, California
Trailer: 2014 Escape 21
Posts: 5,119
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Fuses are to prevent catastrophe... If the BMS fails during a short circuit event such as a crash, there will be fire if there is no fuses in the circuit.
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07-19-2022, 02:16 PM
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#7
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Senior Member
Join Date: Apr 2014
Location: Arvada, Colorado
Trailer: 2015 E'21 - 'Velocity'. Tow: Toyota Tacoma V6, 4X4, manual.
Posts: 1,682
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Another opinion:
The state of the BMS can not be determined by eyeball like a fuse.
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07-19-2022, 03:28 PM
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#8
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Senior Member
Join Date: Oct 2020
Location: San Jose, California
Trailer: 2022 5.0 TA
Posts: 669
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If the BMS shorted, the fuse wouldn’t help, it’s in the wrong place in the circuit.
To me, it seems more likely that the fuse will be a liability than an asset. But that’s just me.
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07-19-2022, 04:00 PM
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#9
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Site Team
Join Date: Dec 2017
Location: Mid Left Coast, California
Trailer: 2014 Escape 21
Posts: 5,119
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Quote:
Originally Posted by splitting_lanes
If the BMS shorted, the fuse wouldn’t help, it’s in the wrong place in the circuit.
To me, it seems more likely that the fuse will be a liability than an asset. But that’s just me.
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the power part of the BMS is between the internal battery plus and the external positive terminal. its not going to short to ground, if it shorts, then its no longer a BMS and can't limit the output current.
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07-20-2022, 12:09 AM
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#10
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Senior Member
Join Date: Oct 2020
Location: San Jose, California
Trailer: 2022 5.0 TA
Posts: 669
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Quote:
Originally Posted by John in Santa Cruz
the power part of the BMS is between the internal battery plus and the external positive terminal. its not going to short to ground, if it shorts, then its no longer a BMS and can't limit the output current.
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Yep, you’re right. I read that power MOSFETs most common failure mode is a short circuit resulting in current pass-through. I ordered a gopower class T block and fuse.
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07-20-2022, 11:29 PM
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#11
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Site Team
Join Date: Dec 2017
Location: Mid Left Coast, California
Trailer: 2014 Escape 21
Posts: 5,119
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Quote:
Originally Posted by splitting_lanes
Yep, you’re right. I read that power MOSFETs most common failure mode is a short circuit resulting in current pass-through. I ordered a gopower class T block and fuse.
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45 years of doing electronics as an adjunct to a computer systems software career....
happily retired and restricted to enjoying life and not spending 80 hour weeks debugging other peoples $#@$@#.
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