I have been considering a second battery for aux loads since I bought the truck about a year ago. I went through a few iterations before ending up where I am now.
Goals were to power aux loads like the fridge, lighting, radio gear, charge devices, etc for several days while camping, jump start the truck if needed (I also carry a lithium jump pack), light weight, low maintenance and safe.
First I was trying to shoehorn a group 24 or 27 AGM battery in the engine bay and using a Redarc BCDC to charge. I wasn't able to find a way to fit anything larger than a group 35 cleanly without more effort than I was interested in. Another downside of the lead acid battery is the low capacity even with the largest group 27.
Second I considered installing an AGM battery in the cargo area, but quickly abandoned that as I did not want a lead acid battery in the passenger area due to potential gas release. And again, low capacity.
Third I looked at off the shelf LiFePO4 batteries like the Battle Born Lion Energy, ReLion, etc. I was attracted to the high energy density, deep discharge capability, low weight, high cycle count and safe operation (compared to other lithium chemistries). Problem with these "drop-in replacement" lithium batteries was the size. They were a bit too large for the space I wanted to use. I wanted to install in under the driver side ARB drawer wing. I have seen a few installs in this area, but it was a tight fit scratching up the plastic panels and blocking the AC vent.
I also considered the lithium power stations like Goal Zero, but felt the price point was too high.
At this point I was committed to LiFePO4 so I started looking at building a battery from raw cells. I looked at various manufacturers, shapes and sizes. I found some 105Ah prismatic cells, took some measurements and determined I could stack 8 of them and still barely fit the space.
I ended up with 8x of the EVE 105Ah cells in a 2P4S configuration. I added a Overkill Solar BMS (rated 120A), BlueSea manual disconnect switch, BlueSea class T fuse (150A) and Victron SmartShunt to complete the "battery". Charging will be done with a Victron Orion Smart DC-DC charger and Victron MPPT Smart solar charge controller. The Victron "smart" devices are bluetooth enabled and can all be configured and monitored by app.
This battery has 210Ah of capacity (>200Ah usable). It is capable of 3C discharge rate or >600A in the current configuration. The BMS is rated for 120A but being a Chinese made and FET based I wouldn't feel comfortable pushing much more than half that. If I needed to use the battery to jump start the truck I would remove the cover and attach jumper cables directly to the bus bar.
Here are some pics:
Initial assembly with all cells in parallel using 3/4 birch ply in a compression fixture and performing the initial top balance to 3.65V.
The prismatic cells need to be compressed to maximize longevity. I am using all-thread top and bottom.
Goals were to power aux loads like the fridge, lighting, radio gear, charge devices, etc for several days while camping, jump start the truck if needed (I also carry a lithium jump pack), light weight, low maintenance and safe.
First I was trying to shoehorn a group 24 or 27 AGM battery in the engine bay and using a Redarc BCDC to charge. I wasn't able to find a way to fit anything larger than a group 35 cleanly without more effort than I was interested in. Another downside of the lead acid battery is the low capacity even with the largest group 27.
Second I considered installing an AGM battery in the cargo area, but quickly abandoned that as I did not want a lead acid battery in the passenger area due to potential gas release. And again, low capacity.
Third I looked at off the shelf LiFePO4 batteries like the Battle Born Lion Energy, ReLion, etc. I was attracted to the high energy density, deep discharge capability, low weight, high cycle count and safe operation (compared to other lithium chemistries). Problem with these "drop-in replacement" lithium batteries was the size. They were a bit too large for the space I wanted to use. I wanted to install in under the driver side ARB drawer wing. I have seen a few installs in this area, but it was a tight fit scratching up the plastic panels and blocking the AC vent.
I also considered the lithium power stations like Goal Zero, but felt the price point was too high.
At this point I was committed to LiFePO4 so I started looking at building a battery from raw cells. I looked at various manufacturers, shapes and sizes. I found some 105Ah prismatic cells, took some measurements and determined I could stack 8 of them and still barely fit the space.
I ended up with 8x of the EVE 105Ah cells in a 2P4S configuration. I added a Overkill Solar BMS (rated 120A), BlueSea manual disconnect switch, BlueSea class T fuse (150A) and Victron SmartShunt to complete the "battery". Charging will be done with a Victron Orion Smart DC-DC charger and Victron MPPT Smart solar charge controller. The Victron "smart" devices are bluetooth enabled and can all be configured and monitored by app.
This battery has 210Ah of capacity (>200Ah usable). It is capable of 3C discharge rate or >600A in the current configuration. The BMS is rated for 120A but being a Chinese made and FET based I wouldn't feel comfortable pushing much more than half that. If I needed to use the battery to jump start the truck I would remove the cover and attach jumper cables directly to the bus bar.
Here are some pics:
Initial assembly with all cells in parallel using 3/4 birch ply in a compression fixture and performing the initial top balance to 3.65V.
The prismatic cells need to be compressed to maximize longevity. I am using all-thread top and bottom.
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