hour
Observer
If you have a rather predictable load (solar keeping battery system floating all day, fridge the only draw in the evening) could one just buy an ammeter battery monitor for 1/10th the price? I figure the worst my setup will see is an uncharacteristically warm evening @ 10,000 ft, and a lot of drinking after sundown. If I get through one of those nights and find my capacity is fine the next morning before solar starts producing, I wouldn't really care to monitor the state of things too often. Certainly not enough to warrant a $150-200+ battery monitor.
Second, I just committed to a lifepo4 setup to run my fridge and charge USB devices during the day. Here's what I have so far...
- Victron 75/15 charge controller (connected to the soon-to-be-replaced 110ah failed deep cycle)
Just bought:
Following this seemingly smart kid's guide, here's what I plan to do when I receive the above.
I have no BMS, and the guy in the video seems to think that's okay because the cells shouldn't be coming out of balance in a "low C solar application". Does that sound right? If not, I can get a 4S lifepo4 BMS of suitable amperage. If YES to BMS, since the connector will be the same (5 pin) to the BMS and the charger/discharger/balancer, is it appropriate to swap the harness from the BMS to the charger, or should there be a dedicated harness and keep the BMS hooked up permanently?
I'll be running this system in my living room for a week or two to get comfortable with things and observe individual cell voltage as the pack charges and discharges. I intend to hook up the Victron BatteryProtect with a rather high cutoff during this time to play it safe.
Does this sound like an appropriate plan?
Also, the ISDT 300w/14A charger/discharger/balancer accepts DC input of 7-32v, 15A max. If I return home from camping and my solar setup has blown off on the highway, I suppose that means I could connect a dumb DC power supply to it and top things off. But that also has me wondering about powering from the car, skipping the Redarc dc to dc smart charger or any isolator setup (do not own, would prefer not buy).
The only time I've ever needed charge from my alternator for my existing setup is when heading to camp. panels shadowed by stuff on the roof rack, and fridge chugging away. Since everything is floating and full up until I shadow a panel, that means I have a few hours of drive time where the fridge is cycling and I'm consuming a bit more than I'm putting back in. Charging at even 30w would basically make this all a null issue. So how about an ignition triggered relay and 10 gauge wiring to the truck bed with an XT60 connector that I can plug directly in to charger/discharger/balancer, and set the max charge current to 5 amps. More than enough to cover what's being used for the fridge and easy on the wiring. While I understand this isn't a plan with growth in mind, is it a sound plan?
If anyone made it to the bottom of this, thank you. It's 6:30am, not a wink of sleep, work in 2 hours, but tonight I succumbed to the lifepo4 itch.
Second, I just committed to a lifepo4 setup to run my fridge and charge USB devices during the day. Here's what I have so far...
- Victron 75/15 charge controller (connected to the soon-to-be-replaced 110ah failed deep cycle)
Just bought:
- 4 x 3.2v K2 Energy 90AH Lifepo4 cells
- Victron BatteryProtect Smart-65 amp (with the new bluetooth ability, and 65a because I know I'll never exceed that...)
- ISDT 300w/14A smart battery charger/discharger/balancer
- A harness to make balancing leads that plug in to the ISDT unit
Following this seemingly smart kid's guide, here's what I plan to do when I receive the above.
- Test voltage of each cell.
- Hopefully discover in step 1 that they're close enough to be paralleled to one another and left to equalize that way
- Once equalized, wire them up in series
- Connect balancing leads to cells and then hook up battery charger/discharger/balancer
- Run inverter or some significant load to drain the battery down to resting voltage of around ~3v per cell, monitoring each cell during
- Bottom balance the cells
- Charge them up to full
I have no BMS, and the guy in the video seems to think that's okay because the cells shouldn't be coming out of balance in a "low C solar application". Does that sound right? If not, I can get a 4S lifepo4 BMS of suitable amperage. If YES to BMS, since the connector will be the same (5 pin) to the BMS and the charger/discharger/balancer, is it appropriate to swap the harness from the BMS to the charger, or should there be a dedicated harness and keep the BMS hooked up permanently?
I'll be running this system in my living room for a week or two to get comfortable with things and observe individual cell voltage as the pack charges and discharges. I intend to hook up the Victron BatteryProtect with a rather high cutoff during this time to play it safe.
Does this sound like an appropriate plan?
Also, the ISDT 300w/14A charger/discharger/balancer accepts DC input of 7-32v, 15A max. If I return home from camping and my solar setup has blown off on the highway, I suppose that means I could connect a dumb DC power supply to it and top things off. But that also has me wondering about powering from the car, skipping the Redarc dc to dc smart charger or any isolator setup (do not own, would prefer not buy).
The only time I've ever needed charge from my alternator for my existing setup is when heading to camp. panels shadowed by stuff on the roof rack, and fridge chugging away. Since everything is floating and full up until I shadow a panel, that means I have a few hours of drive time where the fridge is cycling and I'm consuming a bit more than I'm putting back in. Charging at even 30w would basically make this all a null issue. So how about an ignition triggered relay and 10 gauge wiring to the truck bed with an XT60 connector that I can plug directly in to charger/discharger/balancer, and set the max charge current to 5 amps. More than enough to cover what's being used for the fridge and easy on the wiring. While I understand this isn't a plan with growth in mind, is it a sound plan?
If anyone made it to the bottom of this, thank you. It's 6:30am, not a wink of sleep, work in 2 hours, but tonight I succumbed to the lifepo4 itch.