I am leaning to buying the BCDC 1240-LV battery charger and would like to clarify the earthing arrangement. The Redarc manual seems to explicitly indicate that all earthing should be to the vehicle chassis (a caravan chassis in my planned installation). I have always favoured the idea of earthing connections being made to the negative terminal of the supply battery (or a dedicated busbar which in turn is connected to the battery). This is to minimise the possibility of failure of earthing points which can occur on chassis connections.
Is it absolutely mandatory that I connect the negative lead of the Redarc to a chassis point or can I connect it to the supply battery terminal without creating problems for the unit operation?
Hi Kel, The BCDC1240-LV is designed to give the same optimal charge level in your auxiliary battery as the BCDC1240 when running from a vehicle with a variable voltage alternator. One specific difference between standard alternators and variable voltage alternators is that variable voltage alternators feature a current sensing device between the battery negative terminal and chassis earth. This current sensing device influences the output of the alternator. If a device is connected straight to the battery terminal it will bypass the current sensing device and the alternator will not react to changes in load as accurately. For this reason, BCDC-LV models must be earthed to the chassis and not the negative battery post of the vehicle start battery. I would suggest following the chassis earth lead from the negative battery terminal to its earth point on either the body or the chassis. If you connect your earth points to this point you should minimise the possibility of failure of multiple earthing points. Having said all this, you have not mentioned specifically where your supply battery is located and i am assuming it is the vehicle start battery. The BCDC1240-LV manual also assumes this. Finally, if you are referring to the start battery as supply, for a caravan installation you are not required to wire the BCDC1240-LV earth to the chassis of the caravan. This connection would go to some sort of trailer plug. On the vehicle side of the trailer plug however the earth must be connected to the chassis.
Thank-you for your reply Dylan@Redarc. Your assumption is correct, the vehicle starting battery is the supply battery to the charger which I intend mounting in the caravan. I note your comment regarding the earthing to the vehicle chassis via a trailer plug in my proposed installation. I wanted to go with the BCDC1240-LV because of the possibility in the future that I might purchase a vehicle with a variable voltage alternator. I presently have a Prado 120 series 4, cylinder diesel (mid-2003 build) and I don't think the LV is necessary. Could you confirm this is the case please and if it is, whether installing the LV to my present vehicle would create any issues or alternative connection of the LV version of the BCDC1240?
Hi Kel, Your Prado does not require an LV unit and will work fine with the standard BCDC1240 or with the LV version. If you plan on buying a vehicle with a variable voltage alternator in the future the LV would be a wise purchase.