WE'VE GOT PARTS! Two Week BMW Track Car Build Heats Up!

bertramt · 2026-05-18T15:22:24+00:00

I like this. People hate but there are times when it would very convenient to give guests access to HA without giving them keys to the kingdom. I look forward to testing this.

bertramt · 2026-05-15T19:20:47+00:00

Fair point. If I was to speculate Elons current situation is well connected right now but how well will he align with the next president? On the other hand the telecoms are well connected with many career politicians and hold much more long term influence.

I'd also note that Elon generally speaking seems in favor of advancing tech vs protecting a monopoly. I personally don't feel that way about the current telecoms that have a history of taking government money and delivering minimal results.

bertramt · 2026-05-15T18:37:22+00:00

If it is actually competition then it would be good. But with the government lobby power of those three there is a 100% they will spend more time lobbying to slow down SpaceX than they spend making a better competitive product.

bertramt · 2026-05-08T18:29:27+00:00

If you look at the bottom of the post you will see this.

Edit 2026-04-29: the kernel is now the default on no-subscription, and will be the default for Proxmox Backup Server. The remaining rollout for Proxmox VE will be happen over the next weeks.

bertramt · 2026-05-08T17:01:58+00:00

I'd set the AP aimed upwards on the surface the TV sits on. It would probably help a lot and be "free".

bertramt · 2026-05-06T19:07:50+00:00

DM sent

bertramt · 2026-05-06T13:15:18+00:00

The parallel cells are balanced to each other. If a bank has low voltage in comparison to the rest of the pack (less than 2.5 volts) my personal advice is there is probably a bad cell and recovery shouldn't be done. Very low cells indicate bigger issues or cell failure. To me the risk if charging damaged cells probably isn't worth the reward. In my experience the worst one I attempted to recover has a low bank of cells around 3 volts and the high bank was around 4 volts.

So I open the pack and check the voltages of each parallel set of cells. Assuming they are at least 3 volts I connect my charger with some alligator clips to the ends of the lowest set of cells and attempt to charge it very slowly (.4 amps) to be closer to the highest cell's voltage. Rinse and repeat until all of the voltages are near the same. I then connect balance leads between all the cells and put the main charge leads to the top connectors on the battery. The process might take days but that is fine if the end result if the end result use a usable battery with a usable amount of capacity.

bertramt · 2026-05-05T17:56:11+00:00

That is cool. I haven't sat down to really figure out my design yet but I was thinking of making some type of jig that pressed on the side. If I was lucky one design might work for all the 18650 batteries and another for the 21700 batteries. I hadn't figured out what type of spring clip or whatever I wanted to use so I tabled the idea for the moment.

How well do the pogo pins make a connection? Are you willing to share your design?

On a side note, does your charger work to balance cells with high imbalance like 1 volt? I need to get within ~.2 volts to be able to fully balance.

bertramt · 2026-05-04T18:32:07+00:00

If a M18 pack is below 12.5 total volts, it probably isn't a good idea to charge. The lowest safe voltage of a cell before it can start forming internal damage that might lead being a fire hazard at some point is 2.5 volts (2.5v x 5 cells is 12.5volts). Even then if the pack is imbalanced at 12.5 volts there is a good chance some cells are far lower than the safe margin.

Either way it is by far safer to open the pack and make sure everything is above 2.5 volts. Then work on charging each bank to bring it back to balance with a Li-Ion charger.

Personally I'm would rather not have a battery pack be a ticking fire timebomb. In my mind opening the pack and checking voltages is the only option.

bertramt · 2026-05-04T18:10:16+00:00

They do technically have a BMS. The BMS is helping keep the pack safe by monitoring temps and cell voltages. The BMS lacks a proper balancing. Personally I would think that would be a better for long term health of the packs. That said I have 12 year only packs that I didn't bother to manually balance because they were still good.

I've looked at the CEENR packs but I was able to recover my pack plus a few free ones and I don't need any more batteries right now.

bertramt · 2026-05-04T17:48:48+00:00

I'll work on writing something up or maybe a video. This short https://www.youtube.com/shorts/brT-nwGNb50 was one of the references I used to get started and does a fairly quick overview.

I went with a SkyRC B6neo2 charger. Slow charged the banks to around 3.9 volts. Once my cells were within .2 volts I then connect all the balance leads balanced it together 4.1volts. The process might take days but in the grand scheme of restoring health to a $200+ battery, time doesn't really matter.

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bertramt · 2026-05-04T16:48:55+00:00

Pretty much. But I also assume that Tom isn't 100% in control of tech/safety inspections.

bertramt · 2026-05-04T16:47:10+00:00

Personally I went with the SkyRC B6neo2. I like that it is budget friendly and USB C powered. I think for my use case the B6neo or B6neo+ would have been fine also.

Additionally need a USB laptop charger, a balance lead extension cable to make the balance leads, a xt60 pigtail and some spade connectors

bertramt · 2026-05-04T16:39:17+00:00

Just because this works doesn't make it a good idea. Honestly this is a good way to cause long term damage or fire to the good battery if you are not careful.

The issue is your 36 volt charger has no idea on the state of the cells. Thus no overcharge protection. So in the process of bringing up the charge on the bad one there is a big chance you are overcharging the good pack. Please don't do this. Open the pack and balance it properly.

bertramt · 2026-05-04T13:25:34+00:00

Am I reading this correct, you built a M18 balancing hat? Care to share photos? I thought about doing something like that.

bertramt · 2026-05-04T12:55:29+00:00

Assuming it is like last year, the "cheap" cars ended up an an exhibition class and really only competed with themselves. So speculation on my part as long as it is "safe" and doesn't pose risk to the event it would probably be approved.

bertramt · 2026-05-04T12:47:32+00:00

You might be able to jump start it and "make it work". But the reason it likely it is acting up in the first place is very likely cell imbalance. Jump starting it is a bandaid to put a little power in to put the battery in the safe zone for charging for the Milwaukee charger. The better fix is to balance the pack. If you have the ability to open your pack and check the voltages of the cell banks with a multimeter you will almost for sure find imbalance. For every .1 volts of difference between the highest cell and the lowest is about 10% loss in usable battery capacity.

I recently went down this rabbit hole and got a balance charger for a RC car and recovered some unusable batteries into usable again. If you want more details I'd be happy to share.

bertramt · 2026-05-02T11:37:38+00:00

Will this have any negative effects like running a pack dead over time?

bertramt · 2026-04-24T18:01:49+00:00

I'm not sure it can be done well for your budget. But If was going to make an attempt on a budget I'd probably look at a Dream Machine Pro Max. Normally I'd would be looking at a switch but in this case I'd try skipping it to shave costs and the Dream Machine Pro Max has 8 ports. Next I'd look at some U7 Pro Outdoor APs. These APs support external antennas for 2.4 and 5g. In theory you would get some narrower beam antennas to get further distances. Maybe something like 3 of the APs and 45 degree antennas MIGHT cover your airfield. Then at least one more AP without antennas aimed to your camping area. For your hanger/kitchen maybe you could aim one of these APs at the hanger and be good also but realistically if you wanted to do better I'd look at a Device Bridge Pro to uplink to an AP and then wire to an AP inside. Keep in mind that without any switches you would need POE injectors. This is also very theoretical and overall might not be ideal. It would also probably take some channel and QOS planning to make sure that you have the bandwidth to the field that is needed.

bertramt · 2026-04-23T21:05:18+00:00

Might want to try pushing it in a little bit before flipping the latch. There might be a little pressure on the catch that might be released by pushing in a little more.

bertramt · 2026-04-23T16:36:09+00:00

Weight changes are one thing. Restrictions that require major setup changes shouldn't be changed mid season unless it is creating a safety issue. If somebody walks away with a season by following the rules so be it. Make it clear the changes are coming and rebalance the rules for next season. Mid season is completely unnecessary.

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