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Why a Battery Recorder?

Toward the end of 2019 we found ourselves camping on the South Coast of New South Wales. That’s not unusual for us – we regularly set out in our camper trailer, setup to live comfortably off-grid with 2 x 100Ah batteries and a hefty 240W of solar panels.

At least, it’s usually comfortable. Over that summer, much of the South Coast was engulfed in fire. We were ok, but for days the sky was full of smoke and although we could see the sun, it was a feeble, strangely coloured thing.

Now, like a lot of campers with a 12 volt solar setup, I like to regularly check the battery voltage, to keep an eye on how much charge we have left. I wonder if the solar panels are doing their job, and whether we have enough charge left to keep the fridge running until there’s enough sunshine to charge again.

And on this trip, I was getting worried. Our solar panels were out, pointed toward the sun, but the battery voltage just didn’t seem to be going up! In fact, for a few days it was slowly and steadily getting lower. So I’d continually go and check it, a bit nervous about how it was going. For me, there’s a ritual involved – get up, walk around to the other side of the camper trailer, open the door to the battery compartment, read the voltage, close it, and walk back.

I thought – wouldn’t it be convenient to be able to check the voltage from inside the camper trailer, or from out the front or when sitting around nearby, beer in hand, without having to get up and walk around?

More to the point, I wondered if our solar panels were even working, or was it simply that the smoke was blocking the sun? More likely the latter, but how would I know? Were the solar panels making any difference, at least slowing the voltage decline? Maybe they charged a little in between the times I checked, and maybe sometimes I was checking the voltage right at the point when the fridge is drawing power, temporarily pulling the voltage down. Who knew?

I realized that to know how well our solar panel and battery setup was coping I needed to know, not just what the battery voltage was right now, but what it had been over the past few hours or days. I needed to see the trend. If the voltage was falling faster overnight than during the day, well at least that would show that the solar panels were doing something. But I needed that historical data – a record of the battery voltage over time. And I needed to be able to see it, quickly and easily. And wouldn’t it be nice to be able to see the current readings, as well the latest graphs of battery voltage, from anywhere near the camper trailer, and not have to go for that regular walk to check on it?

Now, at the time I was working as an electronics design engineer at company that makes data loggers for industry. I knew how to design a quality product that would be genuinely useful for keeping track of battery voltages, from the convenience of a mobile phone. And I could include other desirable features such as a temperature sensor (when out camping, I’d often wake up in the morning and wonder whether it was really as cold as it felt last night…) and an input for a second battery, because plenty of people have two batteries to keep track of.

I didn’t find anything in the market that met my requirements, and since I’m a electronics engineer and my partner is a software developer, why not develop a battery monitor and recorder that will be useful for us, and the many people like us with a 12 volt solar battery installation, especially our fellow campers?

The result is the Bushgeek Battery Recorder. We hope you’ll like it!

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