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Troutboy · 09-17-2017, 03:30 PM

Quote:

Originally Posted by LB_3

We avoided damage in the flood. Only issue was rain entering the water heater vent pipe and knocking out the pilot light.

Good to hear LB3, we have an office of 25 folks in Houston. Two had flood damage, the rest are good. Looking at news and online pics it's amazing that anyone was left dry.

bbandeddie · 10-20-2017, 06:05 AM

Looks like Dacian May have worked out a solution to some of the failure modes you guys have been discussing? He is now shipping diodes with the SBMS120 to connect between batt+ output on SBMS and the battery negative to resolve the inductance in cable issue. (Not that I understand it but it sounds like the conversation back in this thread)
https://plus.google.com/+electrodacus/posts/eC2tYfVGt3g

LB_3 · 10-20-2017, 08:16 AM

Thanks for the heads up on the diodes being added to the latest BMS kits. I haven’t checked his page recently.

I’m not a sparky but the way I read his explanation is that he probably had a large inverter hooked up to his Load+ terminal and when the mosfet closed the electrical equivalent of water hammer smashed through some valves and let out all the magic smoke. I need to look into whether I want to retrofit a diode into our system. Given that we have no large capacitive loads (inverter) on the Load+ terminal gives me some time to consider the issue.

old 10s bum · 10-20-2017, 09:45 AM

I’m mark this thread for the future.

LB_3 · 10-20-2017, 12:49 PM

I wish the mods didn’t have the edit function locked down after 30 minutes. We worked through a number of issues in this thread and I hate seeing incorrect info early in the thread. It’s still a good resource on many topics but it takes a lot of work to read through 500 posts.

wachuko · 10-20-2017, 01:06 PM

Quote:

Originally Posted by LB_3

I wish the mods didn’t have the edit function locked down after 30 minutes. We worked through a number of issues in this thread and I hate seeing incorrect info early in the thread. It’s still a good resource on many topics but it takes a lot of work to read through 500 posts.

+1 ^ Ditto...

amirm · 10-20-2017, 01:29 PM

Quote:

Originally Posted by bbandeddie

Looks like Dacian May have worked out a solution to some of the failure modes you guys have been discussing? He is now shipping diodes with the SBMS120 to connect between batt+ output on SBMS and the battery negative to resolve the inductance in cable issue. (Not that I understand it but it sounds like the conversation back in this thread)
https://plus.google.com/+electrodacus/posts/eC2tYfVGt3g

Thanks for posting that. I had lost touch of his latest developments.

He says this at the end: "Usually this pulse is around 1ms or less so since diodes can handle the mentioned peak current for 8.3ms they will have no problem absorbing this energy. SO you you use a different diode make sure they are rated at least 60V DC and peak current handling capability is at least as good as for this diodes I provide. "

I use a different BMS and the other day it faulted. I hooked up the PC to it and the diagnostic code was: "battery supply exceeded 61 volts!"

So clearly there are massive transients given the huge loads and sources of charge we have.

amirm · 10-20-2017, 01:31 PM

Quote:

Originally Posted by LB_3

Thanks for the heads up on the diodes being added to the latest BMS kits. I haven’t checked his page recently.

I’m not a sparky but the way I read his explanation is that he probably had a large inverter hooked up to his Load+ terminal and when the mosfet closed the electrical equivalent of water hammer smashed through some valves and let out all the magic smoke. I need to look into whether I want to retrofit a diode into our system. Given that we have no large capacitive loads (inverter) on the Load+ terminal gives me some time to consider the issue.

The diodes are just parts he is providing so you can easily purchase and add them to the older system.

There is HUGE danger however in hooking up the diode in reverse as it will likely explode! Must check and double check to make sure the polarity is right as you connect it across the battery terminals as he instructs.

LB_3 · 10-20-2017, 05:02 PM

If I add the diode I’ll color code the wires so I don’t screw up the installation.

Can an in-line fuse be added or does that defeat the purpose of having the diode in the first place?

amirm · 10-20-2017, 07:25 PM

You could put a fuse in there but the problem would be determining the value. The purpose of this diode is to stop sharp but very high current transients. Problem is that we have no data on their duration and hence, can't compute the requirement. If the fuse is too small for that load, it would blow just when you need it. If you make it too big, then the wire would melt and diode would blow up before it does.

One route may be to put in a slo-blow fuse in there.

InterBlog · 10-21-2017, 06:41 AM

Quote:

Originally Posted by LB_3

I wish the mods didn’t have the edit function locked down after 30 minutes. We worked through a number of issues in this thread and I hate seeing incorrect info early in the thread. It’s still a good resource on many topics but it takes a lot of work to read through 500 posts.

Yeah, well, that's where blog posts can be extremely helpful, in boiling things down and presenting the final accurate information. I got as far as getting the correct schematics on this one, but then the effort was OBE and the post series remains as fragments on my hard drive.

FarOutRide, which is one of the very best van sites on the web (an engineering couple who DIY'd their entire rig), recently made a comment which resonated with me - they said that they built the blog mostly for their own recordkeeping purposes, and if it could also help other people, tant mieux (it means "all the better" - they are Francophones). I've lost track of how many times I've been either standing in a store or talking to someone, and suddenly I've said to myself, "Waitaminute - HOW did we do that, now?" I forget the details of my/our own work and need to look it up on my blog. There's too much to recall from memory alone.

FlyFishinRVr · 10-21-2017, 10:07 AM

Quote:

Originally Posted by InterBlog

FarOutRide, which is one of the very best van sites on the web (an engineering couple who DIY'd their entire rig),

Thanks for that link IB. I went through their electrical system design and frankly think your design and amirm's are better engineered SYSTEMS (and I stress the word "systems" because IMO both of your designs take into account how each bit fits as part of the whole vs. what most folks do, including manufacturers, which is selecting an individual component that's sufficient for an individual role). Now if amirm would just publish his final electrical diagram.....

InterBlog · 10-21-2017, 05:41 PM

How much top-notch precedent did they have to follow, though? At this point, every DIYer is applying whatever lessons they can get their hands on, and some of us are doing things that represent unprecedented bleeding edge stuff. What's important is that these people, and a few like them, are publishing honestly (let me make the understatement of the week... there are a lot of showboaters and posers on the internet, and their content can be misleading). Their disclosures allow the community to iterate and make incremental improvements.

We also had the luxury of NOT having to build THE REST of our van, to the point where we could concentrate more fully on a few select systems, with the electrical as top priority, obviously. IRRC, FarOutRide said that it took 1,000 man-hours to complete their build, not counting research on how to do the build in the first place. Out of necessity, they would have had to place limits on how much they were going to invest at each stage of the game, or else they never would have made it onto the road.

LB_3 · 10-21-2017, 10:15 PM

MY ingest dislike of FarOutRide’s system is the inverter on the coach battery used to feed a converter. To their credit, they recognize this wasn’t the right answer and the Sterling battery to battery chargers we used is what they should have done.

But they’ve got a lead acid based system so they don’t have all the complexities we had.

LB_3 · 11-02-2017, 06:10 PM

^My *intense* dislike

I hate leaving egregious typos floating around the ether uncorrected.

InterBlog · 01-28-2018, 04:13 PM

I've begun to consolidate our lithium system description into a series of four blog posts, the first of which is here. There are bits and pieces of this description strewn through this thread and through my blog, and now, after many months of successful road-testing, it's time to summarize and to clarify revisions where they did occur.

Luckily for me, I consider this kind of task to be good for stress management, because it is A LOT of work. It takes my mind off other things. I suppose I could watch soap operas instead, but I doubt that such a choice would protect me from age-related cognitive decline.

Image excerpt from that first post:

Troutboy · 01-28-2018, 08:28 PM

Nice work, read the blog. It’s really hard to document and explain to the masses. I had fun with the travel trailer upgrade and learned a ton. I would love the challenge of a AI! Maybe some day. Thanks for taking the time to do this, looking forward to the next blog(s)!

AI927 · 01-29-2018, 06:34 AM

InterBlog,

Thanks for documenting all of this. Maybe someday I will make the jump to lithium.

wachuko · 02-05-2018, 12:55 PM

Rather than creating a thread for this... thought it would fit the theme of this thread. Hope that is okay with InterBlog.

Interesting read on getting rid of generator and going a 420 Amp Hour battery from Lithionics. Article is from 2016 so maybe it was already discussed...

https://www.thefitrv.com/rv-tips/our...-and-inverter/

amirm · 02-05-2018, 01:26 PM

It was a good read. Personally I find a 12 volt system ill suited for 3KW inverter and the heavy wiring it takes. 48 volt system that Advanced RV uses is a better fit. My electric quad runs that way (and has a 12 volt step-down regulator for 12 volt stuff).

On using the Lithium for AC, it should be noted that the total number of cycles you get out of Lithium cells substantially drops with deep discharge. At 20% discharge you get something like 5,000 cycles. But when you go down to 80%, it can drop below 1000 (these are all from memory). For once in a while usage is fine but if it is routine, that expensive cell will need replacement sooner.