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  1. fratermus

    re-charging a big power station while driving

    starter battery -> inverter -> wall adapter -> power station like you describe is a fairly common workaround for the issue. As Dave points out having a 1500w wall charger does not guarantee your alternator will be happy to provide another 1500w (plus inverter losses). 180w of solar lying...
  2. fratermus

    Never Renogy - App Terrible

    There are at least two Renogy apps. IIRC the old one (Renogy BT app) does not have that requirement.
  3. fratermus

    Two solar charge controlers on the same battery

    Let's say you need to see 0.02C at Abs voltage to terminate, so 4A for a 200Ah lead bank. You set the controller to watch for 4A trailing amps to trigger the end of Absorption and the beginning of Float. At 6A it's still Absorping because 6A > the 4A setpoint. Things are going according to...
  4. fratermus

    How to make a cheap isolated dual-battery setup for $50

    It is a VSR, which the original post mentioned: "Note #3: The big difference between this and the fancy setups (other than the cool battery gauge things) is those will usually use a voltage-sensing time-delayed-opening solenoid-type dohickey". Prices have come down since 2012. There are...
  5. fratermus

    Best deals on 100ah LiFeP04 batteries?

    IMO the reach and maintain approaches require different levels of heat reach is seen with self-heating batteries that wait for charging to do their work. The batts are allowed to freeze (overnight, typically) then are heated when charging power becomes available. If we want to start actual...
  6. fratermus

    Adding a second DC/DC charger on 400ah Battle Born battery bank, does it makes sense? Victron, Supertramp Camper

    Agreed, if the controller is maxxed at 15A for a nontrivial amount of the time. If they aren't hitting 15A regularly then >15A is makes no difference. The website for the camper shows shrouded fans on both ends of the solar array. My guess is the mfg predicts the raised shrouds will shade...
  7. fratermus

    Adding a second DC/DC charger on 400ah Battle Born battery bank, does it makes sense? Victron, Supertramp Camper

    Since there will already be one Orion provided it's not a crazy idea to parallel another one. If we were starting from a blank sheet the discussion might go off in different directions. 30A into 400Ah is a 0.075C charge rate, quite mild. The max recommended charge rate for 400Ah of BB would...
  8. fratermus

    Solar to starting or house battery?

    That would be highly unusual. Providing power to the starter side causes weird behavior unless charging power is greater than the DC-DC's rated output: solar charges starter batt at 10A starter batt voltage rises to DC-DC cut-in DC-DC starts charging house bank at 30A starter battery voltage...
  9. fratermus

    Two solar charge controlers on the same battery

    Yes. with a couple edge-case caveats: * if the controllers don't talk to each other AND you are relying on trailing amps to terminate Absorption you could get premature termination * with monster installs it could be possible to end up with more Bulk charging current than one intends. On the...
  10. fratermus

    How to trickle charge starter battery from house battery set up?

    AFAIK the Kisae doesn't do the "trickle charge starter battery from house battery" thing. It also doesn't do low temp charge cutoff natively, but can be tricked into it. The manual says the DCC50S maintains "the starter battery via solar panels if the service battery is fully charged". It's...
  11. fratermus

    Solar panel question

    The Isc number (current, short circuit) in the specs is the max amp output. Imp is current at max power. Because of cell temp derating and other factors, the observed current from the panels will likely be lower than Imp. Extracting maximal power power from the array is one of MPPT's defining...
  12. fratermus

    DC to DC Charger Needed?

    They do the same thing but {operate and are installed differentl}, affecting how we direct-charge lithium. IMO the solenoid is easier to work with here since it can be manually disabled by disrupting the control circuit (IGN, D+, whatever) and does not have to be removed if you install DC-DC...
  13. fratermus

    DC to DC Charger Needed?

    Motor yachts have traditionally used dead-simple alternators with external regulation. Balmar, etc.
  14. fratermus

    DC to DC Charger Needed?

    The lead batts probably needed DC-DC staged charging more than the lithium does. Lithium does fine with "charge and stop". The stop part is problematic with actual isolators (diode or FET-based); due to how they are wired in there is no easy way to stop them. If the isolator is a...
  15. fratermus

    Best Style Battery Inside the Cabin?

    How will it be charged? If by alternator I'd probably go AGM and if solar maybe gel, due to their current/voltage requirements. I don't know of any sealed (maintenance-free) flooded that are actually deep cycle. A self-heated 50Ah lithium might be cheaper Wh/$ in the long run under those...
  16. fratermus

    Dumb question about a Goal Zero Lithium 500X and National Luna 50L Legacy Fridge/Freezer

    Sounds like a question for the manufacturer. The manual doesn't specify power consumption, but does refer to a power placard affixed to the fridge. The manual also has a section describing maintenance to remove dust and crud that may affect performance. The manual does specify a 15A fuse for...
  17. fratermus

    Dumb question about a Goal Zero Lithium 500X and National Luna 50L Legacy Fridge/Freezer

    It's a power consumed > power harvested problem, as the "Input 45w Output 113W" display suggests. @NatersXJ6 has done the math for you. Normally I'd say "add panel", but the input limitations on the Yeti are rather restrictive: Charging Port... 13-22V, up to 10A (120W max) Options at this...
  18. fratermus

    Blue Sea 7650 Dual Battery Install Question

    I am a big fan of working with what one already has. The main challenge in this situation is lead wants to be 100% state of charge all the time.* In practice we limit damage by keeping it 100% SoC as much as possible. Adding solar is the usual approach but I understand that's not happening...
  19. fratermus

    Blue Sea 7650 Dual Battery Install Question

    I value your input on this thread. If the recommendation against ACR/VSR is particular to OP's stated use case then I agree. If it is a deprecation of relays in general then I will push back. In situations where solar is present the solar charge controller will be providing the proper...
  20. fratermus

    System Design Help

    Just so we're clear about what's being discussed in the thread:
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