12V & 24V SYSTEM VS 48V BATTERY SYSTEM:
At Enerdrive we have seen a lot of talk & been asked about using 48v battery banks in caravans, motorhomes and sometimes even utes for the house battery setup due to the slightly better efficiency of components and ability to run smaller sized cables due to the reduced amp draw (Watt/Volts = Amp).
This is all well and good when it is a standalone application, like a communication site, house or cabin where you can control the environmental surroundings for your solar array or only charger of AC from Mains or a generator. But when it comes to a mobile application there are a few other factors to look at.
CHARGING FROM SOLAR:
With a 12v or 24v battery bank we recommend running the panels on the roof of the van in a parallel configuration (12v modules-approx. 20voc for 12v system & 24v modules-approx. 40voc for a 24v system) this way the arrays are less likely to be affected if 1 or 2 panels are shaded as only the shaded panels will be affected.
With a 48v battery bank, you are required to string up multiple panels in series to raise the voltage high enough to be able to charge the 48v battery bank. This will normally be around 80VOC. If any panel in the string is shaded, this will drop the overall string voltage to a level that is no longer able to supply charge to the battery bank. So, unless you can guarantee you will not have any shading from trees, roof top air conditioner or satellite dish then a 48V array is not the best option.
The other concern is anyone working on the system needs to be aware of the >80VDC when working on or around the cables between the solar panels and the Solar Controller.
Why? Because it is VERY dangerous – make a mistake with voltage this high & serious injury will likely result.
CHARGING FROM A VEHICLE (12V/24V & 48V):
Most Alternators in Tow vehicles and motorhomes are 12v or 24v which are a great means to recharge your house battery. For this we would recommend a DC2DC charger between the start and house battery. Good quality DC2DC Chargers like the EN3DC40+ & the EN3DC30-24V can take 12v/24v on the input to charger their respected battery bank.
Unfortunately, with a 48V battery bank, there are not many viable options to charging from 12v to 48v, which then limits you from what is a great resource to recharge from.
48V BATTERY SYSTEM LEGACY THINKING:
In the past, before lithium, not many people ran large loads from their lead acid battery banks due to the large amp draw and affects this had on the life of the batteries. This is where 48v system were great as by raising the voltage from multiple batteries in series would allow lower amp draw I higher loads to prolong the life of the batteries.
Today, we are fortunate to have access to lithium batteries which are not adversely affected by the high discharge currents like lead acid was. This now allows us to run high amp loads like air conditioners, coffee machines and other demanding loads from an appropriately sized 12v battery without killing it.