Great job on all this stuff. I've been told though that the charge under temp should be somewhere between 3Ç and 5C. The reason I was told was that a portion of the battery away from the temperature sensor might be below freezing. Additionally the cells themselves can't take the rated C rate for charging near freezing temps. Low C rates I hear can be charged below freezing, but why take the chance. My JK BMS has an integrated heater port where I have silicon mats inside the wooden case. On my older batter sets I used a device to trigger the pads.

Great job, Herby! Thanks. 👍👍👍

This is brilliant

I still have to make my battery, but one important detail that I have read/seen somewhere else is that is very important that the cables are exactly the the same length (positive to positive and negative to negative respectively, because the cable itself has a resistance) and to not make loops with them (to prevent it heating anything metalic inside le loop, like in a induction forge).

@RiggingDoctor

9 ай бұрын

That’s a good point. The amperage flowing through them will generate quite the magnetic field!

@ericblackburn9829

8 ай бұрын

Do yourself a favor and search for “off grid garage”. You’ll get much better information from that channel about lifepo4.

Seems a whole lot better than the dahlgren BMS I used a couple years ago when i built the cells on our bus.

I would always suggest to work with isolated tools and to cover the metal connectors (Sorry, i´m not a native speaker/writer)

Your to good at this! Ya know what i mean!❤ Are y'all going to the boat show and bring Jr.?

Again with the fire threats. Cya

@RiggingDoctor

9 ай бұрын

Filmed them all at once, there’s one more after this 🫠

@RiggingDoctor

9 ай бұрын

Fire: kzread.info/dash/bejne/Ymt2tZiKiZbdeZs.htmlsi=iCobW7jdAmJFPmmv

Nicely done video. I'm not quite following what determines Most, and Least negative/positive. I follow how the series connections step up the voltage, but the most vs least is confusing. Also, would conductive loctite make sense on the internal blot threads, seems like heating and cooling might cause the to loosen. Really informative series.

@RiggingDoctor

9 ай бұрын

When you follow the series from start to finish, the negative and positive ends of the series is the most positive and negative. -/+.-/+.-/+.-/+ ↑most neg ↑most positive Good point about the heat cycles and the threads. I haven’t seen or heard of an issue, but I’m sure it wouldn’t hurt to do on future builds!

@johnlove4183

9 ай бұрын

Ok so it’s the only negative terminal not connected and the only positive terminal not connected to another battery. Makes perfect sense.

Nice descriptor of these type of serial (internal) BMS-“just an interruptor switch.” This is one reason these are not well suited for alternator charging: when they are full, or detect a fault-they stop charging without warning and the alternator fries. (Wanted to say “explodes” but it really is just releasing the magic smoke😂) How do you feel about some of your busbars not being flush onto the posts/pads? You could easily solve this by putting the “serial” busbars on top of the “parallel” busbars. You might try a thermal heat camera to monitor the heat distribution around the posts under heavy load. You don’t mention, but what is the number of paralleled 12v batteries with this BMS? How about number of serial connected batteries? (Number of batteries with BMSs, not cells)

Thanks for the useful info. What’s your opinion on putting an AGM battery for engine starter with a DC-to-DC charger for house lithium battery? As opposed to going all lithium.

@RiggingDoctor

9 ай бұрын

That is an option since starting can chug the amps. The dc-dc converter will keep the starter battery charged up. I would suggest turning the converter in selectively so that the AGM doesn’t drain the lithiums down as it discharges naturally. The AGM will be full charge at a lower voltage than the lithium so make sure the dc-dc converter is set to the right voltages to keep both happy. Basically, the AGM is a capacitor to start the motor and the boat runs on lithium. To be fully lithium, you will need a massive bank so that it can supply the huge load to start the motor. AGM / lithium is a much easier setup to start with.

@airgapmachine

9 ай бұрын

@@RiggingDoctor Actually the dc-to-dc charger is for charging the house lithium from starter AGM. It turns on only when alternator is running. Apparently this is needed so lithium doesn’t kill the alternator by demanding too much current. Then, like you said, the AGM is needed to handle the demand by engine starting, which protects the lithium bank. However, sailboats typically have a relatively small inboard which needs ~400 CCA. You can even buy little hand held starter lithium batteries for starting engines. I thought a sizable bank ~200Ah could handle starts, and protecting alternator without AGM is another question.

@ericblackburn9829

8 ай бұрын

I have 912AH 12v of lifepo4. I also have an AGM starter battery. My externally regulated alternator (100 amp) charges my Lifepo4 bank and a dc to dc Victron charger that charges the starter battery from the lifepo4 bank. I also added a switch at the helm so I can turn on and off the alternator if I need it or not.

@airgapmachine

8 ай бұрын

@@ericblackburn9829 my understanding is your setup has a risk that if the lifepo4 battery mostly discharged and engine is running at low rpms (under powering alternator) this puts a strain on alternator that can burn it out. Maybe you never put it under this strain or maybe your bms or alternator has built in protection. Something to consider.

@ericblackburn9829

8 ай бұрын

@@airgapmachinethat’s why my alternator has an external regulator. It’s a balmar mc-614. It throttles down the alternator before it overheats. No problem. With this setup you get the most out of your alternator. With a dc to dc you’re limited to the dc to dc output. I have a 100 amp alternator. If I use a 30 amp dc to dc charger I’ll only get 30 amps in to my giant Lifepo4 bank. With my setup I get around 60-80 amps depending on ambient temperature. I’m thinking about adding a blower to pull the hot air away from the alternator to see if I can get a bit more.

What was the purpose of the switch you chose not to use or install?

@RiggingDoctor

8 ай бұрын

I do not really know, which is part of why I don’t mess with it. It is the “remote switch” which I believe let’s you turn the BMS on or off, but you are able to perform that task via the app, hence why I don’t bother with it.

Hi Rigging Doctor(s), I live on a small (25ft) boat and am going to be moving to Maryland next year. I need a cheap residential address, so I'm looking for the cheapest possible mooring rental (no marina amenities, just the mooring ball and address). Do you all have any advice about where/how I should look for that in MD, and do you know what the usual rental requirements are (e.g., is liability insurance usually required)? Thanks

@RiggingDoctor

8 ай бұрын

I always lived aboard in marinas so I’m not familiar with where you can live and get an address with a ball, but I have seen a good sized mooring field near Hartge Marina (spelling?) in the West River. The marina has liveaboards so if the balls belong to them, that would be a good option. Alternatively, you are allowed to have up to 3 mooring balls in Maryland for free. I don’t know if this would satisfy the address requirement though. Would a PO Box suffice?

@jonathanm8197

8 ай бұрын

@@RiggingDoctor Thanks for the recommendation. Unfortunately, due to the federal Patriot Act and Know Your Customer (KYC) laws, investment banks, the MVA, and similar places don't allow one to use PO Boxes or commercial PMBs (e.g., at the UPS Store or Anytime Mailbox) as one's residential address, because one can't live in a mailbox. There are a few boating and RV-friendly states (FL, SD, and TX) that have campground mail forwarding companies (e.g., Escapees) that do qualify as residential addresses, but I'm poor and can't afford health insurance in those states (because they're conservative-majority states that haven't expanded Medicaid to the general population). No liberal-majority states in the US, as far as I know, have campground mailbox companies -- hence, my search for a cheap mooring with an address. I've seen people in California do this (e.g., see the Sailing Emerald Steel channel on KZread), but I need to stay on the East Coast for family reasons. Marinas often don't have very informative websites, so I guess I'll have to call around.

You have it on 3.55v and 28.4v? Thats correct? I want to fix and my bms

@RiggingDoctor

5 ай бұрын

That is correct

Temperature sensor should be in the middle of the pack, because thermal runaway starts here.

@RiggingDoctor

9 ай бұрын

Very good point!

😀👍👍👍❤

how much can we save by building a 200 aH LiFePO4 battery by ourselves?

@RiggingDoctor

9 ай бұрын

About $800 for 200ah.

@RiggingDoctor

9 ай бұрын

They cost about $1000 for 100ah, so $2000 for store bought. The materials cost $2400 for 2x200ah, so $1200 for each 200ah battery.

@pmnfernando

9 ай бұрын

@@RiggingDoctor thanks!

Umm, I think the battery is 200AH but when you were setting the maximum discharge rate I got that you said you were setting it to 1C at 100A. I am thinking that 200A would be wrong as well because you derated the battery slightly less than 200AH further up. (Its hard to keep all these numbers straight in my head so maybe I misheard) However, you had switched to battery1 so maybe it is only 100AH? (that doesn't make sense if they are a pair) Or you had purposely set battery1 to discharge only to 0.5C and said 1C by mistake. That would of course mean that max charge was 0.35C or so.... 0.5C discharge would be perfectly valid for most house systems (200amps from two batteries of 400AH total). Maybe perfectly valid for motor use too as I can't think of many people who want to motor no more than 2 hours max. Anyway, it was still quite well laid out and I found it helpful. We are currently running LA but will be switching lifepo4 when these wear out.

@RiggingDoctor

9 ай бұрын

I misspoke, good catch. The battery is 200ah and discharging at 100amps is only 0.5C, with both in parallel they will be working at 0.25C so these batteries will have a cakewalk of a life :)

Overkill solar is far from the best bms. Why don’t you talk about balancing current? In my opinion the muller bms with 5amp active balancing from muller energy is the best bms. It’s good when the cells are new and fairly balanced and great when the cells get a little older and begin to drift during heavy deep discharge. Most any bms looks great in the beginning when the cells’ internal resistance is similar. But over time, the typical 1 mA passive balancing is just not enough. Ask me how I know after years of owning Daly, JBD, and yes overkill solar bms’s.

@RiggingDoctor

8 ай бұрын

I like how their safety features really work. To me that is the most important part! Setting up the battery pack properly then circumvents any downsides that it may have in the balancing department.

@ericblackburn9829

8 ай бұрын

You’ll see in a few years as your cells degrade. Your balancer will not overcome the imbalance caused by uneven cell degradation and you will inevitably enter the world of active balancers. When that day comes, reach out and I’ll help you.

@svsalserenity4375

6 ай бұрын

@@ericblackburn9829 I have had my Lifepo4 bank on my boat for almost ten years with no active balancing. they are still within .06 volts of each other