BVasily
Member
Can anyone advise how to separate house loads from Port starting battery on Sea Ray Sundancer 42? I want to install Lithium for house and solar but these are not ideally suited for starting diesels .
Separating House Loads from Port starting batteries for LiFePO4
- Thread starter BVasily
- Start date
-
- Tags
- lithium battery
Not easy is the answer. The port and starboard starting systems are intertwined as port and starboard house supply power. Do you plan to move the navigational equipment to the LI and move the emergency systems like bilge pumps? Also, your engine controls are from a breaker that is integrated with the house power from a buss standpoint. It gets complicated pretty fast and from my knowledge you will end up pretty much tearing a lot of wiring out to replace for a separate power source.
Solar aside, I'm moving the entire boat over to Lithium batteries including starting; except for the generator and thrusters which will remain on a lead acid batteries. I would be into that mod now but the boat was involved in a lightning strike and we just finished fixing the boat November. The below sketches are where we are going with the LI conversion; they are in a FMEA and AYBC review -
Solar aside, I'm moving the entire boat over to Lithium batteries including starting; except for the generator and thrusters which will remain on a lead acid batteries. I would be into that mod now but the boat was involved in a lightning strike and we just finished fixing the boat November. The below sketches are where we are going with the LI conversion; they are in a FMEA and AYBC review -
Last edited:
BVasily
Member
Helpful answer.
Are you installing 10X 100ah LiFePO4 ? The momentary discharge charge rate is 200aH for single battery. What do you believe would be required for just a single port diesel engine?
The idea of simply replacing the port with a 200ah or 300ah lithium would meet my requirements if the battery will function well enough to also start the diesels. The goal is more efficient charging of the house batteries from solar when on hook for an extended period.
Are you installing 10X 100ah LiFePO4 ? The momentary discharge charge rate is 200aH for single battery. What do you believe would be required for just a single port diesel engine?
The idea of simply replacing the port with a 200ah or 300ah lithium would meet my requirements if the battery will function well enough to also start the diesels. The goal is more efficient charging of the house batteries from solar when on hook for an extended period.
The baseline for the battery bank sizing to support the two forward HVAC systems on the boat for up to 8 hours (over night without the generator running). Starting current for Cummins QSM11 is 345 amps. Average start cycle is less than 5 seconds which is around 28 ah.
The batteries we are planning to use can support up to 200 amps current for 20 seconds but one wouldn't want to even be close to that limit. I will have a capability of 2000 amps for 20 seconds so a 5 second 345 amp demand is incidental. To maintain assurance of engine start anytime a maximum DOD will be 80% at which point the generator starts and begins a recharge cycle. At 80% DOD any worst case engine start scenario can be supported yet keeps the batteries within their maximum life expectancy. There is no room for PV's on the boat but I'd love to have them.....
The down side of SR boats is they are power hungry from lighting to entertainment. So a 200ah Li battery is suitable up to 180ah useable. Don't know what demand you plan for the combined system....
The batteries we are planning to use can support up to 200 amps current for 20 seconds but one wouldn't want to even be close to that limit. I will have a capability of 2000 amps for 20 seconds so a 5 second 345 amp demand is incidental. To maintain assurance of engine start anytime a maximum DOD will be 80% at which point the generator starts and begins a recharge cycle. At 80% DOD any worst case engine start scenario can be supported yet keeps the batteries within their maximum life expectancy. There is no room for PV's on the boat but I'd love to have them.....
The down side of SR boats is they are power hungry from lighting to entertainment. So a 200ah Li battery is suitable up to 180ah useable. Don't know what demand you plan for the combined system....
