I installed a lithium/solar power system in my travel trailer 2 years ago but now want to upgrade the battery to a DIY lithium so as to give myself a little more breathing room on battery capacity. I am new to DIY lithium battery builds and spent a lot of time reading the various threads on this forum but I have a couple of lingering questions I would like to get your expert opinion on. Sorry in advance for length of post but it seems its helpful to have as much information as possible for you to evaluate.
Current system:
170ah renogy lipo- 2 yrs old and works fine in present system....just want a little more capacity so I don't have to watch the battery so closely. Max d/c rate for this battery is rated at 100amps but I have been able to run the microwave for short periods of time with BMV showing 125 amps out.
Victron 2000 watt inverter multiplus 80 Amp charger-has been handling our modest AC needs but we don't need much as we don't any high power appliances such air conditioner, hair dryers etc. Microwave is the only one above 600 watts and we rarely use it.
Victron 75/15 mppt to support 220 watts of sunpower portable panels (these work great!)
Victron 100/50 mppt to support 400 watts of panels on roof
Victron Bmv 712
2/0 wire from battery to bus bar and to multiplus with 300 amp fuse between battery and system bus bar and 300 amp fuse for multiplus
Current settings for charge controllers:
absorption=14.4v
float= 13.6v
Current settings for inverter/charger:
absorption=14.2v
float=13.5v
Planned upgrade:
4 CATL 310ah cells to replace 170 ah Renogy. Daly smart BMS 4S 150a. Battery bus bars that came with the cells are 16mm x 2mm x 95mm.
I just finished top balancing the cells to 3.6v (they have drifted down to 3.54v but are all the same). As there were only 4 bus bars that came with the cells, for top balancing the cells I made six bus bars out of 5/8” copper pipe which when smashed flat are about 1” wide x 2mm thick .
I want to move on to put the battery together and put on the BMS but have a couple of lingering questions:
1. Are the supplied bus bars adequate to handle the 150 amp discharge current that the BMS can put out?
From looking at some of the ampacity tables it looks like they are right on the edge. I don't think I will ever use more than 125 amps (from 1500w microwave) and that would only be for a couple of minutes but given 150amp rating of BMS its at least possible that I could pull up to 150amps. The copper pipe bus bars I made handle a little more as they are 1" wide (as opposed to the 5/8" provided bus bars) but aren't tinned. I also have some 1/4" x 1" aluminum bar in the garage that I could use to make some bus bars but not sure what else I need to do to use aluminum.
2. What sort of compression/padding should I plan for when I put the cells into series?
I planned on compressing them with wood but then wondered if I should introduce any padding between cells (or VHB tape), around the edges of battery or underneath as these will be in a travel trailer and we sometimes take the trailer on washboard roads.
3. Once I have made the battery and attached BMS, what settings should I program into the BMS (other than battery capacity of 310ah)?
4. When the battery is assembled and BMS settings entered can I just replace the old battery with the new one?
I am assuming the 2/0 cable and 300 amp fuses will be sufficient for the potential 150a max output
5. Once the battery is attached to existing system should I change the multiplus and/or charge controller settings from what I have above?
I am not sure if change from Renogy to the CATL cells means I need different settings.
6. Any thing I am doing wrong here? I don't need to squeeze every little last amp out of the system and my emphasis is always on safety.
Thanks so much for taking the time to review this and thank you in advance for any input/help you can give me.
Lori
Current system:
170ah renogy lipo- 2 yrs old and works fine in present system....just want a little more capacity so I don't have to watch the battery so closely. Max d/c rate for this battery is rated at 100amps but I have been able to run the microwave for short periods of time with BMV showing 125 amps out.
Victron 2000 watt inverter multiplus 80 Amp charger-has been handling our modest AC needs but we don't need much as we don't any high power appliances such air conditioner, hair dryers etc. Microwave is the only one above 600 watts and we rarely use it.
Victron 75/15 mppt to support 220 watts of sunpower portable panels (these work great!)
Victron 100/50 mppt to support 400 watts of panels on roof
Victron Bmv 712
2/0 wire from battery to bus bar and to multiplus with 300 amp fuse between battery and system bus bar and 300 amp fuse for multiplus
Current settings for charge controllers:
absorption=14.4v
float= 13.6v
Current settings for inverter/charger:
absorption=14.2v
float=13.5v
Planned upgrade:
4 CATL 310ah cells to replace 170 ah Renogy. Daly smart BMS 4S 150a. Battery bus bars that came with the cells are 16mm x 2mm x 95mm.
I just finished top balancing the cells to 3.6v (they have drifted down to 3.54v but are all the same). As there were only 4 bus bars that came with the cells, for top balancing the cells I made six bus bars out of 5/8” copper pipe which when smashed flat are about 1” wide x 2mm thick .
I want to move on to put the battery together and put on the BMS but have a couple of lingering questions:
1. Are the supplied bus bars adequate to handle the 150 amp discharge current that the BMS can put out?
From looking at some of the ampacity tables it looks like they are right on the edge. I don't think I will ever use more than 125 amps (from 1500w microwave) and that would only be for a couple of minutes but given 150amp rating of BMS its at least possible that I could pull up to 150amps. The copper pipe bus bars I made handle a little more as they are 1" wide (as opposed to the 5/8" provided bus bars) but aren't tinned. I also have some 1/4" x 1" aluminum bar in the garage that I could use to make some bus bars but not sure what else I need to do to use aluminum.
2. What sort of compression/padding should I plan for when I put the cells into series?
I planned on compressing them with wood but then wondered if I should introduce any padding between cells (or VHB tape), around the edges of battery or underneath as these will be in a travel trailer and we sometimes take the trailer on washboard roads.
3. Once I have made the battery and attached BMS, what settings should I program into the BMS (other than battery capacity of 310ah)?
4. When the battery is assembled and BMS settings entered can I just replace the old battery with the new one?
I am assuming the 2/0 cable and 300 amp fuses will be sufficient for the potential 150a max output
5. Once the battery is attached to existing system should I change the multiplus and/or charge controller settings from what I have above?
I am not sure if change from Renogy to the CATL cells means I need different settings.
6. Any thing I am doing wrong here? I don't need to squeeze every little last amp out of the system and my emphasis is always on safety.
Thanks so much for taking the time to review this and thank you in advance for any input/help you can give me.
Lori