DC to DC Charger

This is part of the Inverter Power project.

Charging while driving. 170A Alternator two batteries in the truck. Why two? Cold start of the Cummins diesel requires, of course, some form of pre heat. Some diesels use glow plugs, Cummins utilized a grid heater which preheats the intake air. It’s a power hog. Hence the second battery. You can watch the volt meter go like a windshield wiper when it’s cycling, which lasts as much as 5 minutes in serious cold conditions. So I decided to tie into the second battery, and install a cutoff switch so I could bring the charger on line after the heater was done.

Charger? Yes. The alternator and the circuitry, which is pretty sophisticated these days, look at the truck’s needs. They have no clue about a large LFP bank. It can mess up its brain, and it certainly won’t provide a proper, let alone efficient, charge profile for the “house bank”. So you use what’s called a DC to DC charger, 12VDC to 12VDC in this case. Other combinations are available as it is basically a transformer which sends voltage from one end to the other of the windings, passing on the current without physical contact. Magic. But, it nicely controls the output to form a proper profile for your (selectable) chemistry.

There’s a lot of them out there. I went with the Sterling, a tried and true performer. And, when you call the US number (they are made in the UK) a person answers the phone who knows his shit and loves yakking about it. My kind of company.

The B2B charger is the only thing that you may want to look at when in the driver’s seat, to see whether it is doing its job. Yes there is a remote, but that’s another thing to figure out where to put. Where it is here I can actually see the LED’s……

After reading the manual for a while I was able to program it for LIP and fired it up. After starting I let the truck run for a little to recover the start battery so as to not overload the alternator. Then I brought it on line and it very nicely went to work. Nothing getting hot or complaining.

So, this appears to be working!

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