Trail Talk
Well-known member
We recently switched our house AGMs for lithium and doubled our capacity with half the weight, but did lose a bit of functionality compared with our previous set-up.
Our upfitter installed the necessary DC to DC charger (Victron Orion) to charge the house batteries from the truck's smart alternator. Our old Samlex ACR-160 dual-sensing voltage relay in the engine compartment was disconnected, which means it can no longer charge our truck batteries while on shore power.
I am concerned about extreme cold temperatures during winter outings, on starting and overall battery health, so am hunting for a solution. Many years ago we would use a electric battery blanket in combination with the block heater if parked outside during the coldest nights. But, if you can't have both, it seems from what I've read on the 'net that a fully charged battery is preferable to the battery warmer. Planning for only 15A of available shore power so, indeed, I can't have both.
Option 1: first considered simply mounting a 120V maintenance charger in the engine compartment and plugging in when shore power is available, but something inside me resists such an inelegant solution with two cords laying about. A very expensive Option 2 would be to upgrade to an inverter/charger with two 120V outputs and run the second output to the charger ...maybe later but won't happen this winter.
Option 3: use the 12V available from the lithium house bank. Researching this brought up a device I hadn't heard of before: TecMate OptiMate DC-DUO.
Anyone have experience with this device or any other 12V to 12V battery charger for the same purpose? The ACR and its cables are still in situ so we have an easy connection. Could we add another DC to DC to function in reverse, from house to starter battery? It seems intuitively "yes" but I can't find any mention of one being used other than alternator to house battery.
A related question; is 2A charging of the OptiMate enough for our dual truck batteries totalling 156 Ah? With Option 1, I was considering the 5A Noco Onboard as a minimum.
Our upfitter installed the necessary DC to DC charger (Victron Orion) to charge the house batteries from the truck's smart alternator. Our old Samlex ACR-160 dual-sensing voltage relay in the engine compartment was disconnected, which means it can no longer charge our truck batteries while on shore power.
I am concerned about extreme cold temperatures during winter outings, on starting and overall battery health, so am hunting for a solution. Many years ago we would use a electric battery blanket in combination with the block heater if parked outside during the coldest nights. But, if you can't have both, it seems from what I've read on the 'net that a fully charged battery is preferable to the battery warmer. Planning for only 15A of available shore power so, indeed, I can't have both.
Option 1: first considered simply mounting a 120V maintenance charger in the engine compartment and plugging in when shore power is available, but something inside me resists such an inelegant solution with two cords laying about. A very expensive Option 2 would be to upgrade to an inverter/charger with two 120V outputs and run the second output to the charger ...maybe later but won't happen this winter.
Option 3: use the 12V available from the lithium house bank. Researching this brought up a device I hadn't heard of before: TecMate OptiMate DC-DUO.
Anyone have experience with this device or any other 12V to 12V battery charger for the same purpose? The ACR and its cables are still in situ so we have an easy connection. Could we add another DC to DC to function in reverse, from house to starter battery? It seems intuitively "yes" but I can't find any mention of one being used other than alternator to house battery.
A related question; is 2A charging of the OptiMate enough for our dual truck batteries totalling 156 Ah? With Option 1, I was considering the 5A Noco Onboard as a minimum.
Attempting to answer my own question re another DC to DC, it looks like Victron's Orion-Tr 12/12-9 should work if it can be configured to charge only when on shore power. The literature mentions a remote on/off triggered by a switch or engine start, as suits a more conventional application.