You can see how the daily minimum voltage keeps dropping bit by bit every day so obviously not charging quite enough. It's also why I'm going to study the solar regulator settings a bit more closely as it seems to be cutting off the absorption phase a bit soon. I'm thinking the load is too small for the regulator to pick it up but enough for the battery to "notice". As mentioned before, the current drawn by the raspberry is small (0.14-0.2A), but it still adds up and not worth it over a foggy winter when the solar panel isn't producing much of anything, or the regulator just doesn't think it's worth it. I'm also not too keen on continuing with the logging. What the experiment proved to me is that my wiring is not even close to ideal for efficient charging while on the move, even though it's technically (almost) to EBL manufacturer specification. Fridge and radio were the only loads while driving, except for the portion where I turned radio off to see if there's any change. Especially interesting are the drops when going through the tunnels which clearly indicates how much of the supply comes from the solar panel even when driving and you'd think the alternator takes care of everything. Logging was set at 15 minute intervals except where indicated otherwise (switched to 1 minute) to see variations more clearly. One chart shows the entire period and two are from a day of driving over the Grossglockner Hochalpenstrasse ( ) to Ljubljana on a sunny day. Attached are 3 annotated current/voltage charts for those curious what's going on with the battery in real time. So I'm returning the RPi 3b+ and my experiment is over after a month.
#RV CONTROL PANEL WITH RASPBERRY PI BLUETOOTH#
If the BMV stored the data (within its existing, tiny current usage) and relayed it on demand to the Victron iPad app via Bluetooth for graphical display - that I would pay for. The challenge of getting it working and monitoring the charging and discharging curves would be fun but I wouldn’t be doing it long term. With 180Ah of LFD90 and 120w of solar, I really do not need to be continuously monitoring the batteries in this detail. It did cause me to total up that of the 76 nights we spent away this year, 17 were off-grid with the longest duration being 4 nights.
Putting this information together with the £20 cable cost (not a big issue) and the RPi high power consumption (much bigger issue, thanks for mentioning it) made me conclude that I would not be taking this any further.
#RV CONTROL PANEL WITH RASPBERRY PI SERIAL#
I have the Victron BT module attached to the BMV and believe that this needs to be disconnected to allow the serial cable to be attached to the same port. I did look into the various Rpi versions as you suggested and had formed the opinion that BT did not work on the latest board. None of which we would have been doing is we hadn’t accidentally fell upon motorhoming in 2014 after hiring in NZ as a convenience. We were reflecting only an hour ago while exercising and listening to bands we have found in recent years. It often leads to other interesting discoveries. Curiosity, exercising brain cells by investigating areas of interest. It does raise the question of whether very shallow discharges count as cycles or not? Whether it might actually help with neutralising negative effects of long term charging and so on. I'll evaluate again after about a month and see if it's worth continuing. I'll investigate whether there's a way to lower it further. Not much but possibly significant during dark winter days. Raspberry consumes 0.15-0.2A which equates to about 2Ah during the night. It has to be said there is a downside to all this. Days are getting shorter and I'll be in an alpine valley so solar output might be miserable. I've got a trip coming up soon where I'll be off grid all week and I guess that will be more interesting. I'm attaching a screenshot of this past week when the van was constantly parked at home so not much going on. Venus can do a lot more that that if you've got the necessary/compatible hardware but battery monitoring is what I'm interested in. Data is logged at 15min intervals (can be whatever you want) and sent online whenever it connects to a known wifi signal.
I can now monitor the leisure battery state online on the VRM portal.
3b) so I got to work again and installed Victron's open source Venus OS Recently everything fell into place as I got my hands on a loaned new Raspberry Pi (ver. I've been playing with this idea about a year ago but hardware incompatibility made it more difficult than it had to be so I gave up.
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