Hello from Central Massachusetts

Hi everyone,

I’m a new contributor to forum, drawn in by my first battery build. Retired and in the process or upgrading a new RV for boondocking(primitive camping with privileges).

I’m in the process to converting to sustainable living with respect to food production and energy use except when traveling great distances by land or air.

Like you, I embrace DIY projects that would be beyond the reach most people. Some pertinent projects to date include upgrading 200A service to 300A, 3 phase power converter to support large wood wooding tools and I designed and implemented a 10kW roof mount PV system(net metered, no batteries yet).

I’m retired from a well know semiconductor company, where I designed test hardware and equipment to characterize high speed IOs and power delivery systems for their flagship CPUs. Some of the challenges were counting nH and nF and de-embedding test equipment parasitics from measured results, at single digit Ghz speeds on hundreds of IO data pins. And delivering power from test equipment to silicon with typical worst case conditions of 50A di/dt imposed of an 800mV power rail over temps of 0-100C Tpackage.

Some of the issues I’m still wrestling with for this current RV battery project are the impact of vibrations due to long distance road travel, lack of experience with current state of art BMS features, make dozens of holes in a new RV roof and reducing GenSet noises.

I look forward to learning from the collective experiences of all you and to contribute to the learning of others where I can.

Favorite quote: Steve Jobs said “You can never guarantee that you will always succeed, but when you never bet on yourself and try something new, you can definitely guarantee that you will never succeed."

regards,

Jim St Laurent

Welcome to the forum Jim! Hope you learn lots here on your endeavor. BTW, nice Steve Jobs quote... And thank you for your contribution to our semiconductor development for all those years!

A quick note on LiFePO4 battery installs on mobile applications (where shock and vibration are a concern). In my opinion, all mobile applications should have the cells clamped together tight, heat pads installed on an aluminum base (in cold climate areas), and use flexible bus bars (non-solid)... You can see my pictures thread here which gets into my 12v RV battery build: https://diysolarforum.com/threads/pictures-battery-bank-clamp-assembly.22280/ (mine does have flexible bus bars installed)

And your note on GenSet noises, not sure what kind you own (I have a Safari Serengeti with an Onan 6.5 GenSet), but some models like the Onans run at 1800 RPM vs the standard 3600 RPM, so if yours is 3600 RPM, one way to quiet down is to get a 1800 RPM (4-pole) generator, they are a lot quieter as they run slower.

Also make sure it is mounted on rubber insulators and has a good muffler... I suppose some dynamat lined in the generator compartment could help to reduce noise, but a lot of the noise coming in is noise transferred from the engine mounts... I have seen some people put long tailpipes on too that go up to the roof to make the exhaust noise quieter.

Samsonite801 said:

Welcome to the forum Jim! Hope you learn lots here on your endeavor. BTW, nice Steve Jobs quote... And thank you for your contribution to our semiconductor development for all those years!

A quick note on LiFePO4 battery installs on mobile applications (where shock and vibration are a concern). In my opinion, all mobile applications should have the cells clamped together tight, heat pads installed on an aluminum base (in cold climate areas), and use flexible bus bars (non-solid)... You can see my pictures thread here which gets into my 12v RV battery build: https://diysolarforum.com/threads/pictures-battery-bank-clamp-assembly.22280/ (mine does have flexible bus bars installed)

And your note on GenSet noises, not sure what kind you own (I have a Safari Serengeti with an Onan 6.5 GenSet), but some models like the Onans run at 1800 RPM vs the standard 3600 RPM, so if yours is 3600 RPM, one way to quiet down is to get a 1800 RPM (4-pole) generator, they are a lot quieter as they run slower.

Also make sure it is mounted on rubber insulators and has a good muffler... I suppose some dynamat lined in the generator compartment could help to reduce noise, but a lot of the noise coming in is noise transferred from the engine mounts... I have seen some people put long tailpipes on too that go up to the roof to make the exhaust noise quieter.

Click to expand...

Samsonite801, Thanks for warm welcome! And you have some sweet looking battery packs! Can I ask where you sourced those flexible bus bar from?

I plan to spring load compress the 4S 280Ah cells. A heating soultion will follow after I play with the first cell pack, want to fully understand my use model needs first.

The GenSet is a new Onan enclosed 4Kw 3600 RPM model. Came with the RV, so it'll be around for a while. After the battery power system is completed I make some measurements and see what can be done to lower the noise levels.

regards,

Jim

JimStLaurent said:

Samsonite801, Thanks for warm welcome! And you have some sweet looking battery packs! Can I ask where you sourced those flexible bus bar from?

I plan to spring load compress the 4S 280Ah cells. A heating soultion will follow after I play with the first cell pack, want to fully understand my use model needs first.

The GenSet is a new Onan enclosed 4Kw 3600 RPM model. Came with the RV, so it'll be around for a while. After the battery power system is completed I make some measurements and see what can be done to lower the noise levels.

regards,

Jim

Click to expand...

Any good LiFePO4 cell purchase should include quality bus bars, and both the purchases I made they came with the flexible style bus bars.

Here is the example of the latest purchase I made (8x 280ah cells), I bought from this seller:


They had cost a bit more than some of the other sellers you can find there on AliExpress, but they had good feedback, and turned out to be good enough for me (high quality, excellent packing, etc). There are other threads on this forum, listing sellers who are good to use, that others had good luck with. Or you can find some local sellers here in the US if desired. My first purchased of 32x cells came from a Colorado seller. You can always ask the seller which bus bars they offer before purchase.


As far as the GenSet goes, that is too bad you're stuck with the 3600 RPM, they are literally twice as loud. One option might be to buy a used 1800 RPM on eBay or something, and then swap it with yours, sell the old one to recap much of the money.

Sounds like you may not want to bother as it is more work, but boy, I really appreciate how my RV is so much quieter than standard 3600 RPM ones... Seems like they would last longer too (like perhaps twice as long exactly?)... I know mine is off to the side, right under the rear queen bed in the back, it is about as loud as I could be able to handle it (if I were to try and sleep with it running). I can only hear a hum of it up in the main cabin area though, pretty reasonable.

Anyways, if you don't want to ever change it out, you can look into the other items, like increased rubber foot dampening, Dynamatting the compartment, possibly larger muffler, extended tailpipe, etc, to see if possible to shave off some excess DBs.

Try to figure out what kind of noise is coming from where. Like is it exhaust sound, low bass vibration from motor mounts, higher frequency sounds (from compartment in general), etc, to help decide which type of sound is most prominent, and work on that area... I also discovered sound can even come from intake as well.

I have a full-size vertical-standing air compressor in my shop which I discovered was so loud mainly because of the intake noise, so I hooked a long intake pipe on it and plumbed it through an automotive exhaust muffler and it made it so quiet, I couldn't believe the actual difference it made.

Then the rubber feet I put on the floor got rid of the deep bass coming from it, just leaving the ambient sounds coming of the unit itself (which I never built a compartment around it, as I didn't want too much heat buildup), but it was still very quiet... Granted, that was an air compressor, but many of the concepts still apply.