lifepo4

Interesting times…

This week just gone, we not only had a state election here in Queensland, with a conservative government (LNP) returned to power… we also witnessed the US hold their federal election, and vote in a conservative party there too.

In both regions, the term supposedly is 4 years. Well, here I expect the 4 year term will be upheld… this has never been an issue before and while I do remember a time when our state parliament sat for a 3 year term, it never has been infinite.

Over in the US, there were rumblings along the lines of “we’ll fix it so you don’t have to vote anymore”. Make of that what you will.

Next year, Australia goes into federal election mode… While our mainstream conservative parties are nowhere near as right-wing as some of the minor parties (looking at you, FFP, ONP and KAP), and state politics is theoretically separate from federal, hearing Queensland LNP front-benchers contradict then opposition leader (and now Queensland Premier) David Crisafulli on issues like abortion really does feel like they’re echoing the right-wing governments overseas.

Of course, it was one of the right-wing minority party leaders, KAP’s Robbie Katter, that happened to toss that grenade into the mix… nearly de-railed the train entirely for the LNP. I think therefore this is just a taste of what we can expect next year: minor parties (especially conservative ones) throwing their smoke bombs into the debate whenever possible on all kinds of issues… and some of them drawing “inspiration” from overseas.

The previous LNP government wound up being a disagreeable mob that argued with everyone, Campbell Newman (who we had as local member here in the seat of Ashgrove) and his government were tossed out at the very next opportunity. I think they may have learned from that and will pull their heads in a bit more… we’ll see.

Their big platform was on youth crime, and their big headline remedy, “adult crime: adult time”, has been criticised as not having solved the problem anywhere else where it was attempted. There’s apparently some early intervention to try and address issues before they boil-over into major societal problems… that should have a positive influence… the efficacy of punishments though will need to be proven.

Federally… we’ve got different challenges now. The US threatening new tariffs will not only push up inflation in the US (a nice foot-gun you’ve got there, Trump), it’ll also spell trouble for Australian exporters, notably our mining operations. The rhetoric during this year seems to spell trouble for both the NATO and AUKUS alliances. If the US pulls out of these, Australia will be very isolated as the UK is on the opposite side of the planet and (thanks to Brexit) a financial basket-case.

A regression in the situation in Ukraine will make things unstable in Europe generally, if that spills over, the fact that we’ve got the UK as an ally may be meaningless as there’s a lot of ocean to cover for their aid to reach us. Closer to us is China and Taiwan, which is quietly simmering away… whilst Israel wages war with both Palestine and Lebanon.

Donald Trump’s rhetoric over the previous term does not endear a world of peace. Some have praised his manner of speaking as being “refreshing”… well it most definitely is different. Diplomacy is a game of subtle nuance. Always has been. I’m not sure shouty-shouty megaphone diplomacy will work. It didn’t work that well for Germany in the 1930s, and many today draw parallels between that time, and today’s US. The last US presidential debate between Trump and Kamala Harris gave us a pretty good peek as what we will probably get. Malcolm Turnbull’s “robust discussion” with Trump back in 2016 suggests as much too. For a few weeks I had this cartoon living rent-free in my head…

“Debating an idiot is like playing CHESS with a PIGEON… He’ll just knock pieces over then claim he won!” — my take on the US Federal Election 2024 posted to Mastodon. Yes, I am terrible at drawing people, but that does not stop me from trying my hand anyway. At least I didn’t use an AI!

Well, world leaders and heads of state alike, will be debating the pigeon for another four years.

Next year, it’ll be our turn in Australia. Federal parties will need to balance the urban and rural needs: this is an area where Queensland’s parties failed. Labor did really well in urban seats, but failed miserably in the regions. A similar pattern was seen in the US election, with most of those in rural areas, preferring the Republican party, whilst in urban areas, Democrats were favoured.

A party should not be solely representing just the regions or just the urban centres. They are being elected to represent both. Cost of living is a big issue right now, something a third world war will not improve. A world war might mean we in Australia are isolated, and unable to import a lot of things, making every day things a lot more expensive. So encouraging local production and level-headed diplomacy will be critical.

Healthcare is a big issue in the regions, especially for specialist services. As it happens, our food and minerals do not come from the CBDs of capital cities — so we really do need to be helping out there to make life more viable. This means hospitals should be aiming to provide what their patients need, not inflicting restrictive guidelines on people who have few viable alternatives.

Climate change will affect us all, urban and rural… we can’t rely on digging up former dinosaurs to fuel everything long-term… we’ve left it a little late to be constructing big nuclear plants. While smaller options exist (small modular reactors are used quite successfully on submarines), a big honking reactor the size of Tarong is a biiiig risk in Australia’s climate.

Yes, Europe has lots of them, but Europe built nearly all those decades ago, when they were not getting massive wildfires and 40°C+ temperatures. A small reactor that we can shut down, crane onto the back of a truck, and shift out of harm’s way might be useful for propping up parts of the grid in times of need. A reactor that is too big to move is a major risk in a flood or bushfire emergency, and we have had a longer and more frequent history of these than any part of the world that currently uses nuclear. Fukushima, despite the low number of people killed as a result of the reactor (most people in that disaster lost lives due to the tsunami), is not a blueprint for how to build a large reactor in a risky area.

Battery technology isn’t ideal right now, not sure I like the idea of dealing with bushfires that are lithium-enhanced… but lithium batteries are not the only option out there for fixed installations. This blog runs on dated but still useful AGMs. There exist other storage technologies which could be viable at scale and should be considered. A former manager of mine was keen on the Zebra battery, which is a form of molten-salt battery. I couldn’t source one for him in 2008, we ended up going with LiFePO₄ cells… but there is probably wisdom in using a battery that is fine with heat.

We’re likely to see a big influx of migration over the next few years, as conflict and hatred makes the planet overall a more dangerous place. We’re hearing the phrase “your body, my choice” a lot now, a phrase no woman deserves to have levelled at them, women are more than just brood stock.

Increasingly some governments have shown transgender attitudes as well, a group that does not choose their condition any more than a baby born without eyes chooses to be blind. Everyone has challenges, and everyone deserves assistance with their challenges whatever those happen to be. We shouldn’t be discriminating against people on the basis of the (sometimes unique) challenges an individual might face.

Neurodivergence also seems to be in the cross-hairs: if that ever gets imported into Australia’s mainstream politics, yours truly will be in the cross-hairs here! I’ve faced discrimination before (looking at you Hilder Road & The Gap State Schools).

Lots of people from these marginal groups will be on the move escaping discrimination. We need to do our best to ensure the same hate movement does not rise here: these are people that have a lot to give if given the opportunity.

Circling back to health for a moment too… COVID-19 still rages on, there was a pleasing-looking trend last month in Queensland hospitalisation statistics showing COVID-19 and Influenza cases well down a month or two back. Not zero, they’re not gone… but not as bad as they once were. Sadly it won’t stay that way. Over in the US, they’re talking of giving the portfolio of health to Robert F. Kennedy Jr, someone who seems keen to continue grinding Andrew Wakefield’s axe, and seems to be very much against current preventative measures for containing contagious disease. With H5N1 (bird flu) rearing its ugly head, the never really dealt-with and worsening COVID-19 situation over there, and diseases we thought we had beat like polio making a come-back… we may see some particularly nasty bugs hit our shores. Get ready for Pandemic 2.0.

So a lot in store for the next 4 years at least… I think Europe is going to play a major role in the medium term. They are already showing a lot of leadership over technical standards (we can thank the EU for universal charges on portable devices for example). Whilst it’s not all good news there (end-to-end encryption being a controversial issue), on balance they seem to be headed in a better direction than the US is right now. Here’s hoping cooler heads prevail and things settle down, but right now I think we need to buckle up for a bumpy ride!

Solar Cluster: Charge controller testing, battery bank dimensioning and other thoughts

So, further progress on the charge controller.

Thinking about the problem … I realised that I really do not want to be testing for VBNVH when entering the CHARGE_CHECK state, as it’ll prematurely terminate the charge when the battery is being bulk-charged.

Better to wait until the charger decides to stop … which we’ll see due to the battery voltage ceasing to increase. We do want to check we’re not critically high however, so we can swap out VH for VCH.

Next, when we find that VBNVBL, meaning the battery is not charging, there we can check for VBNVH and stop charging at that point.

That change, worked pretty well, but it was still flapping between sources. A little state management helped this. If we declare another state variable, charger_warning, we can flip this to 1 upon first detecting that VBNVBL, then wait a little longer. If after a time-out this is still the case, then we can take action. Thus we define a new timer tCWARN, which delays acting on the not-charging case.

A bit of threshold tweaking, and things are behaving themselves. I’m using an el-cheapo 3-way camping fridge as the stand-in for the cluster. This is an Aldi special bought some years ago that draws about 5-6A… and when running on 12V power, features no thermostat.

We’re finding that its cooling capacity is no match for Brisbane’s early autumn weather anyway, so it’s pretty much would be a constant load even if the thermostat worked on 12V.

The battery we’re using is an old 105Ah AGM battery… which is one of two batteries from the caravan we have here. They were the original batteries, and this battery’s mate had failed when both were replaced. We’ve noted this battery getting warm whilst charging, so we think it might now be on the way out too.

What to replace it with? LiFePO₄ is AU$1000 for 100Ah, so too expensive. AGM is still the better bet. I can get 300Ah AGM batteries, but they weigh nearly as much as I do. I can just manage the 105Ah, so we’ll stick with those. I will need more than one long-term.

That brings the thorny issue of connecting them. I am not keen to hook batteries in parallel for various reasons. At least not permanently.

Now, the charger I’m using for mains is a 3-channel charger. I can make additional charge controllers (with the caveat that I need heatsinks for the MOSFETs…sigh!) and I can look for 3-channel solar chargers, or just get multiple chargers for the extra batteries. This can be done.

The load is the elephant in the room. I’d ideally like to manage it as a single load, although conceivably, I could put the switch and one storage node on one battery, a second storage node and a compute node on a second, and the final storage and compute nodes on the third. If the switch goes however, my cluster is toast.

I can put batteries in parallel, but this really does need to be done with care, using carefully matched batteries. So the better solution is to have a controller that chooses the battery with the highest voltage.

There might be an analogue means of implementing this, but a microcontroller is a single-chip solution. The ATTiny24As have up to 8 ADC/GPIO pins and three non-ADC GPIO pins. It’s what I’m already using for the charge controller, so is an easy choice.

The cluster will not tolerate a break-before-make switch-over. I thought about using a capacitor bank to keep the cluster alive during a brief (~1sec max) switch-over. Back-of-the-envelope calculations suggested I would need a 10F capacitor bank. I can get a 16V 470mF capacitor for AU$70 each… and would need 20 of these. Ouch!

A small battery is another option, maybe a 7Ah, but that has its own maintenance issues, and represents a single point of failure.

I can get Schottky diodes capable of 40A, they still present a 0.6V voltage drop. At 30A, that represents 16W! For comparison, a relay with a 225ohm coil resistance will draw ~60mA when the battery is at the maximum of 15V, representing a load of 1W.

Or I can use more MOSFETs like the ones I’m already using, which draw even less power; poor man’s solid-state relays. Latching relays also exist, but they can be rather expensive, more so than a solid-state relay.

I can probably get away with temporary parallel connections, so a make-before-break would let me switch sources. Or, I could place my switch across a Schottky, meaning I put up with that 16W load for a brief moment while I switch sources.

So more to think about, but we are getting close. I can defer this decision until I get a second battery, but I am getting close to the point where the cluster will be running full-time.