So I'm adding some high performance bits to my truck and have been looking at various charging options.
I've got some... off the wall ideas that I'm sort of considering. I know the mad scientists here may have some useful ideas!
1) Main charging source is the 12-14v car battery system.
2) I've built a pair of 12v Headway LifePO4 packs using the 8Ah HP cells (200A discharge each in 4p4s packs, so 800A max. :O )
Figure on 1.3Kwh to work with at 80 percent DoD.
3) I have a couple basic BMS that I picked up when planning on pure 12v, no big deal they were cheap.
Problems to solve:
1) My winch will be 24v. This thing can pull say 250A at high load (worst case). (7hp 24 RED Winches OX Motor) - That load won't go through the BMS, but I will add LV cutoff to the control circuit. A given winch pull would likely be 1-4 minutes if that.
2) Also adding in a 24v air compressor - it was like half the price of the 12v and it got me on the whole 24v idea.
3) I'm gonna need some significant charging for winch sessions. I can always wait 5-10 mins to recharge. That said I don't usually need to winch a ton, but once in a while it's like 4 pulls in a row in the snow.
Ideas I'm considering:
1) 12 to 24v DC-DC charging. This is the easiest, but provides the least charging output. The simplest example of this would be a Victron 12/24 DC-DC charger, takes in 12v, outputs 24v (tunable for lifepo4) maxes out at 15A. this thing is around $270ish with bluetooth. Most loads would go through an 8s BMS with additional temperature cutoffs from a custom battery monitor.
2) A pair of Isolated DC-DC chargers that are built for 12v. This feels a little weird but would maximize efficiency and optimize available charging. For example, a pair of the 12/12-30A from above. edit: there are many cheaper 12/12 options. If I were buying a pair of the orion-tr's I'd just buy a pair of the 24v. Use each to drive one 12V pack. In theory, since these are isolated chargers, I should be able to stack them. This doubles my charge rate to a total of 30A at 24v.
I figure I'd want a 4s BMS on each pack and the chargers would each feed into a BMS.
I may combine this with an 8s BMS to drive 24v loads through. This could also be used to over-ride the winch load, which would be directly connected (aside from solenoid switching for on/off). Again, I'd have a custom battery monitor to monitor battery temp and provide extra cutoffs.
3) All options will end up with a solar controller, charging the pack at 24v. It's one more source, but probably a factor for my winch discharge/recharge events.
In the end, I may just be overthinking this. For example, I can parallel the 12/24 chargers and easily double the charging and have a simple 24v system to work with.
I've got some... off the wall ideas that I'm sort of considering. I know the mad scientists here may have some useful ideas!
1) Main charging source is the 12-14v car battery system.
2) I've built a pair of 12v Headway LifePO4 packs using the 8Ah HP cells (200A discharge each in 4p4s packs, so 800A max. :O )
Figure on 1.3Kwh to work with at 80 percent DoD.
3) I have a couple basic BMS that I picked up when planning on pure 12v, no big deal they were cheap.
Problems to solve:
1) My winch will be 24v. This thing can pull say 250A at high load (worst case). (7hp 24 RED Winches OX Motor) - That load won't go through the BMS, but I will add LV cutoff to the control circuit. A given winch pull would likely be 1-4 minutes if that.
2) Also adding in a 24v air compressor - it was like half the price of the 12v and it got me on the whole 24v idea.
3) I'm gonna need some significant charging for winch sessions. I can always wait 5-10 mins to recharge. That said I don't usually need to winch a ton, but once in a while it's like 4 pulls in a row in the snow.
Ideas I'm considering:
1) 12 to 24v DC-DC charging. This is the easiest, but provides the least charging output. The simplest example of this would be a Victron 12/24 DC-DC charger, takes in 12v, outputs 24v (tunable for lifepo4) maxes out at 15A. this thing is around $270ish with bluetooth. Most loads would go through an 8s BMS with additional temperature cutoffs from a custom battery monitor.
2) A pair of Isolated DC-DC chargers that are built for 12v. This feels a little weird but would maximize efficiency and optimize available charging. For example, a pair of the 12/12-30A from above. edit: there are many cheaper 12/12 options. If I were buying a pair of the orion-tr's I'd just buy a pair of the 24v. Use each to drive one 12V pack. In theory, since these are isolated chargers, I should be able to stack them. This doubles my charge rate to a total of 30A at 24v.
I figure I'd want a 4s BMS on each pack and the chargers would each feed into a BMS.
I may combine this with an 8s BMS to drive 24v loads through. This could also be used to over-ride the winch load, which would be directly connected (aside from solenoid switching for on/off). Again, I'd have a custom battery monitor to monitor battery temp and provide extra cutoffs.
3) All options will end up with a solar controller, charging the pack at 24v. It's one more source, but probably a factor for my winch discharge/recharge events.
In the end, I may just be overthinking this. For example, I can parallel the 12/24 chargers and easily double the charging and have a simple 24v system to work with.