Dashcam drain
I had a Blackvue DR650S 2ch front and rear camera system professionally installed in my 2010 Lexus RX450H. I also fitted a Power Magic Pro, which is set to power the cameras until battery voltage reaches 12V, after which they close down. This morning, the cameras closed down and I checked the battery voltage with a multimeter, which read 11.75V. The car initialised the hybrid battery and started OK. If the alarm is also drawing current, how long can I leave the car before it flattens the 12V battery?
I tested the battery using my Sealey digital battery tester, which claimed the battery was at 47% capacity and just needed a charge. I think the battery state is caused by me only making short journeys. If I change the battery, what would you recommend? I believe that the battery CCA is unimportant as it is the hybrid battery that starts the engine. The original battery was made by Panasonic, but I have not been able to find one of these outside of Lexus/toyota main dealers. The battery currently fitted is a
Lion 068 12V 70Ah, which was new when I got the vehicle 21 months ago.
I’m considering charging the battery every month. My only concern is when I go on holiday, although I do have a Halfords power pack and a Ring lithium jumpstarter that I could leave in the boot.
Dave Brown
The Power Magic Pro is adjustable and I would advise setting the power cut-off point to 12.5V.
This will give a margin of error and allow the battery to continue to maintain the required current for the vehicle systems.
The current draw of the Blackvue camera system is listed as ‘Avg. 400 ma (4.8W at 12V, when GPS and Wi-fi is on)’. The formula to establish the runtime of the appliance is 10 times the battery capacity (in Ah) divided by the load in watts; this will equal the runtime
in hours. So, your 70Ah battery x 10 = 700 – dividing this by the camera drain at 4.8W should give a runtime of 145 hours. Of course, the battery should never be drained by more than 50% of its capacity, so this figure should be halved to 72.5 hours.
I cannot find a definitive figure on the drain of the alarm, but I would expect this to be relatively low, allowing the vehicle to stand for three weeks with a good battery. It would be better to preserve the battery by turning off the camera when parked for long periods.
Although the hybrid battery will start the engine, it should not be relied on. I have worked on a Lexus hybrid with a flat battery that wouldn’t start under its own hybrid battery power. If the hybrid battery is not charged sufficiently, the vehicle battery will be needed. It will certainly not hurt to charge your battery regularly using a charger, and keeping the jump-starter in the boot would also be a good option.
When purchasing a batWith a drain container tensitioned untineath the gearbox’s sump, undo the drain plug and leave the oil to drain for several minity and build of the batboxes hold around 10 litres.t some of the 068 batteries available are listed as 75Ah and this higher output would also be beneficial, especially if the vehicle is left for longer periods.