SupraSPL
Solar Enthusiast
- Joined
- Aug 28, 2022
- Messages
- 222
I have to run 4 Cambro food warming/cooling units (1450W actual draw, 1750W on label) in a box truck, sometimes all at once, sometimes for 2 hours. They are 120V, resistive loads. Rarely, all 4 will kick on at once so total load could be as high as 5800 Watts intermittently (225 amps at 26V).
I also need to be able to charge the batteries from standard 120V 15A shore power outlets, sometimes during freezing winter temps.
So I installed a pair of Sungoldpower 24V 4000W 120V low frequency inverter chargers and 4 300ah LPFMax 12.8V lifepo4 batteries, wired in 2S2P for 24V 600ah total, 15.36kwh.
That is way more capacity than I need but I need enough BMS to run that 225amp load. These batteries have 200amp BMS with bluetooth and heating, since there are 2 banks in parallel that is good for about 400 amps and easily handle a 225 amp load. The BMS shows up the My-BMS and also the Xiaoxiang ap. I tested each inverter with a 3300W load and there was almost no voltage drop on the AC or DC side (119V and 13.2V). I told the ap they are in parallel just so I could monitor all 4 at once but they are actually in 2S2P. You can see that one set has a lower resistance than the other, because they came from 2 different batches but it's close enough and they all top balance very well.
On the DC side I used a 300amp class T fuse and 2 awg welding cable. I used a hydraulic crimper with thick copper lugs, flattened the lugs and the battery terminals with a file. The maximum current in any cable will be 112 amps intermittently and the longest run is 2 feet.
On the AC side I used marine grade cable for the charger port wire and white 120V Journeyman power inlet. On the inside I used 2 runs of 12 gauge thwn in a pair of 1/2" conduit, one set of 12 gauge for each outlet. The outlets are commerical grade, mounted in heavy duty 4" steel boxes.
I mounted the control panels in the cab. Made some custom length flat ethernet cables to run into the inverters.
I set the inverter dip switches for AC priority and 3 second power sense for power saver function. I set one inverter for the lifepo4 charging profile (28V 1225W) and turned off the charger on the other unit. It pulls 1500W 14A from the outlet when charging at maximum (.89pf). The batteries report they are taking in 1250W but when I clamped the DC side of the inverter I measure 1200-1225W. So charging efficiency is about 81% if you don't penalize for power factor.
I attached the battery temp sensor to the inverter so it won't charge if the truck is cooking in the sun with the door closed. They act like greenhouses because the roof is just a sheet of white fiberglass and iR can radiate through.
I also need to be able to charge the batteries from standard 120V 15A shore power outlets, sometimes during freezing winter temps.
So I installed a pair of Sungoldpower 24V 4000W 120V low frequency inverter chargers and 4 300ah LPFMax 12.8V lifepo4 batteries, wired in 2S2P for 24V 600ah total, 15.36kwh.
That is way more capacity than I need but I need enough BMS to run that 225amp load. These batteries have 200amp BMS with bluetooth and heating, since there are 2 banks in parallel that is good for about 400 amps and easily handle a 225 amp load. The BMS shows up the My-BMS and also the Xiaoxiang ap. I tested each inverter with a 3300W load and there was almost no voltage drop on the AC or DC side (119V and 13.2V). I told the ap they are in parallel just so I could monitor all 4 at once but they are actually in 2S2P. You can see that one set has a lower resistance than the other, because they came from 2 different batches but it's close enough and they all top balance very well.
On the DC side I used a 300amp class T fuse and 2 awg welding cable. I used a hydraulic crimper with thick copper lugs, flattened the lugs and the battery terminals with a file. The maximum current in any cable will be 112 amps intermittently and the longest run is 2 feet.
On the AC side I used marine grade cable for the charger port wire and white 120V Journeyman power inlet. On the inside I used 2 runs of 12 gauge thwn in a pair of 1/2" conduit, one set of 12 gauge for each outlet. The outlets are commerical grade, mounted in heavy duty 4" steel boxes.
I mounted the control panels in the cab. Made some custom length flat ethernet cables to run into the inverters.
I set the inverter dip switches for AC priority and 3 second power sense for power saver function. I set one inverter for the lifepo4 charging profile (28V 1225W) and turned off the charger on the other unit. It pulls 1500W 14A from the outlet when charging at maximum (.89pf). The batteries report they are taking in 1250W but when I clamped the DC side of the inverter I measure 1200-1225W. So charging efficiency is about 81% if you don't penalize for power factor.
I attached the battery temp sensor to the inverter so it won't charge if the truck is cooking in the sun with the door closed. They act like greenhouses because the roof is just a sheet of white fiberglass and iR can radiate through.
