I have the need to put some power into a 36v golf cart battery at a remote location but not tie the cart to a solar charger during the daylight hours. I already have an investment in some 24v portable battery packs and emergency power boxes. I purchased a boost converter with CC/CV output. I did the first test last night and results were good.
I had a shut meter in line on the 24v side and recorded 968 watt-hours out of my 24v LiFePo4 pack (64, 32700 cells). 24 amp hours went into the 10s Li-ion golf cart with the battery voltage about 37v, showing a conversion of about 92%, just looking at (power in 36v/power out 24v). The 24v pack I was testing with has a 30 amp BMS, so I limited the load, pulling about 20 amps from the 24v to deliver about 12 amps to the 36v battery. The boost converter has an adjustable low voltage cut off, to save the source battery from going into BMS cut off. I set it to drain down to about 3.05v per cell for my LiFePo4 pack. The low voltage cut out causes the current to approach zero as the battery voltage approaches the set point, so is not like a digital "off" set point. It slowly turns off and is a bit confusing to adjust. The adjustment point, indicated by a red LED coming on, under no load is not the same as under load, or so it seems. Adjusting by test cycling right above the desired cut out works fine.
The need to do this type of charging is for a multi-day deer camp trip where we have no AC and don't want to be running a generator. The camp location is on our land and we have a permanent camp there, but this camp is hours from home. So no running back to the house at night for AC power. I have a couple of used 60 cell solar panels that I can get about 400 watts from (total watts in full sun) that will be mounted and left at the camp. I can show up with my battery box (built in solar charger) and charge my 24v battery during the day. At lunch time or at the end of the day, we can dump the 24v battery to the golf cart to keep it with a good charge. The golf cart is new to this use for us. The area is pretty hilly and the cart battery is not large. It has a solid, usable, 80 amp hours but on these hills with a load, the amps can go up in a hurry. When the battery is low, a high amp challenge can make it take a nose dive to a cell low voltage cut off, so I want to keep it in the solid voltage range while we have it at the camp. Adding 24 amp hours to a 80 amp hour battery is a reasonable boost. I think the cart battery would last us 3 or 4 days without the boost but with the boost, we should be in great shape. So, good test. I need to get the boost converter mounted in a box next.
I had a shut meter in line on the 24v side and recorded 968 watt-hours out of my 24v LiFePo4 pack (64, 32700 cells). 24 amp hours went into the 10s Li-ion golf cart with the battery voltage about 37v, showing a conversion of about 92%, just looking at (power in 36v/power out 24v). The 24v pack I was testing with has a 30 amp BMS, so I limited the load, pulling about 20 amps from the 24v to deliver about 12 amps to the 36v battery. The boost converter has an adjustable low voltage cut off, to save the source battery from going into BMS cut off. I set it to drain down to about 3.05v per cell for my LiFePo4 pack. The low voltage cut out causes the current to approach zero as the battery voltage approaches the set point, so is not like a digital "off" set point. It slowly turns off and is a bit confusing to adjust. The adjustment point, indicated by a red LED coming on, under no load is not the same as under load, or so it seems. Adjusting by test cycling right above the desired cut out works fine.
The need to do this type of charging is for a multi-day deer camp trip where we have no AC and don't want to be running a generator. The camp location is on our land and we have a permanent camp there, but this camp is hours from home. So no running back to the house at night for AC power. I have a couple of used 60 cell solar panels that I can get about 400 watts from (total watts in full sun) that will be mounted and left at the camp. I can show up with my battery box (built in solar charger) and charge my 24v battery during the day. At lunch time or at the end of the day, we can dump the 24v battery to the golf cart to keep it with a good charge. The golf cart is new to this use for us. The area is pretty hilly and the cart battery is not large. It has a solid, usable, 80 amp hours but on these hills with a load, the amps can go up in a hurry. When the battery is low, a high amp challenge can make it take a nose dive to a cell low voltage cut off, so I want to keep it in the solid voltage range while we have it at the camp. Adding 24 amp hours to a 80 amp hour battery is a reasonable boost. I think the cart battery would last us 3 or 4 days without the boost but with the boost, we should be in great shape. So, good test. I need to get the boost converter mounted in a box next.