Update. Replacement BMS? What's next?

Hedges

I See Electromagnetic Fields!
Thank you again, very, very much. But . . .

. . . If it is not one thing . . .

This morning, I blew the 175 amp breaker on the main 4/0 cable from the battery to the inverter? That never happened (with my old 450Ah battery array before failure)? I decided to try my small electric coffee pot (easier, faster coffee). It worked fine previously, used daily. So, something has changed, somehow? I know from my previous testing that the coffee pot draws 60 amps +/- for 5.5 minutes to make a small pot.

Therefore, your response about breakers is especially timely. But raises further questions . . .

(1) What might I look for to diagnose what changed and caused the breaker to trip?

(2) Before I invest $100+ on a new breaker, can I safely increase the size to 200 amps to solve this problem?

(3) Is a fuse holder + ANL fuse (200 amp) a suitable replacement for a breaker?https://www.amazon.com/gp/product/B004ZJ0WEQ/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1
Most of my components are Blue Sea because I knew it to be a quality brand from my previous sailing years. I suppose there is a quality difference in ANL fuses, too?

How the heck is a beginner supposed to know all this stuff?

First do the math and figure out how much current was being drawn.
Your system should be designed so fuse/breaker is rated 25% higher than maximum continuous draw.

Next figure out of the breaker is good for its ratings, or is an off-brand that can't be trusted.

How hot does the breaker get with a known load less than its rating?
What voltage drop across it? Voltage drop from its terminal to cable terminal? Terminal to cable strands (puncture insulation if necessary)?
It is possible poor connection contributes to heating.

If you're really tripping a 175A breaker with 60A, something is wrong that needs to be fixed.

ANL fuse ... what kind of battery do you have?
The fuse (or breaker) should be rated to interrupt whatever maximum short circuit current your battery bank can produce.
Car battery, 3000A
100 Ah AGM, 4000A
LiFePO4 battery 20,000A? (I haven't seen ratings or tests, but given 0.17 milliohm IR measurements reported, 3.4V / 0.00017ohm = 20,000A)

I found 2700 AIC somewhere:


This Blue Sea link says 6000 AIC:


To me, those ANL fuses are only good enough for some lead-acid batteries.

For Lithium batteries, class T fuse rated for 20,000 AIC is good. Some breakers like Midnight rated for 50,000 AIC are good.
My inverters have a breaker built in, and I also use class T fuses at my batteries (higher rating, intended to only blow if cable short-circuits.)
 

jesfl

Solar Enthusiast
Thank you again.

I ordered the Eastman Bussman BUSS brand 200 amp breaker from Blue Sea because they had it in stock for arrival to me Thursday (after that I will be boondocking and in the middle of nowhere AZ so I can't receive packages).

I think I also have learned:

(1) ANL fuses are not that great (although 100 amp ANL fuses were previously installed inline from both the AC cable and the genset cable to the batteries/inverter. The 100 amp genset ANL fuse was definitely installed by the Onan generator installer and I am guessing the AC power panel ANL fuse was also installed then because they are exactly the same and are in the same exact location).

I suppose I should replace those ANL fuses, also? 100 amp Class T fuse replacements? These 2 spots seem to me to be a great use of a high-quality fuse. Genset to batteries (through auto-transfer switch and power panel) is 2 AWG cable. The cable from the AC power panel to the batteries seems to be a smaller size AWG, but it is not labeled. It is 30 amp shore power and/or power from the 3600kW generator. My mind is boggled trying to figure out the proper fuse for these incoming-to-my system AC power providers. Your advice will be appreciated.

(2) If I use a Class T fuse, I better have a backup onboard in case the first one blows, since I generally have a hard time receiving packages in the middle of nowhere.

(3) The 175 amp breaker trip this morning because of my coffee pot might have been just an anomaly/random trip caused by the cheap Chinese 175 amp breaker? Regardless, it absolutely needs to be replaced.

I am certainly and unexpectantly learning small bits about fuses.

And, I apologize in advance, but since my mind is filled with fuses at the moment, I have two other questions.

(a) In over 2 years, I have experienced only 1 fuse blowout and that was of the inline 100 amp ANL fuse from the AC power panel in my RV to the batteries/inverter etc. At that time, I just replaced it and paid little attention. I also did not connect the dots until moments ago. But now I think that fuse blew at about the same time that my (old failed) LiFePO4 batteries started misbehaving and would no longer charge.

All of a sudden, to my electrically uneducated mind, I am guessing that fuse blow instant is somehow what caused the BMS units in the batteries to croak causing me 2 months of pain and frustration. Until this moment, I could not attribute the failure of all three batteries simultaneously (to me problematically impossible) to anything specifically? Maybe the mystery is now solved partly? Does that fuse blow conclusion as a possiblity make any sense to you?

Note: Per Will Prowse's videos and other reading, I also have 175 amp ANL fuses at both the pos/neg battery terminals. Those have never blown.

Of course, this also begs the question what caused the 100 amp AC fuse blow incident. It has not happened again. And, could that really have been the cause of the 3 batteries BMS units failing?

(b) What size auto-style 12-volt fuse should I use when I direct connect a cell phone charger cable to my Blue Sea 12-volt busbar? The charger says it is 2.4 amps. I have both 2 amp and 3 amp fuses, and larger. I was about to use a 2 amp fuse, but wondered if that would constantly blow, or just charge slowly? I also wondered if a 3 amp fuse would allow possible damage to the cell phone? I have assumed (which always gets me into trouble) that the actual plugs for the cell phone charger cables have some sort of built-in fuse protection. But, in writing this, I realize it is possible there is some charge current overload protection built into cell phones? This is a no-longer-used 6-year-old cell phone that I thought would be convenient near the batteries for checking the battery status readings via Bluetooth. Not a valuable phone, but I still would hate to burn it up for no good reason other than my lack of fuse knowledge. Any suggestion is welcomed.

Obviously, I am a very long way from truly understanding fuses.

To you and EVERYONE these posts reach on the Forum, may I say:

The volumes I have learned on this Forum are priceless to me. I wish there was an easy way to repay you and all others who have so generously helped me get out of trouble and avoiding trouble. Perhaps someday I will find some small way to make a contribution myself, at least, perhaps gaining enough first-hand knowledge to be able to occasionally explain my specific historical problems and the Forum-member directed solutions.

Again, to EVERYONE who has helped, thank you so much. I am forever appreciative.

Jim
jesfl
 

jesfl

Solar Enthusiast
Your last post and my response passed in cyberspace. FYI, I am now trying to absorb your response from 10:54 am. Thanks, I'll try to think/work it through.
 

GXMnow

Photon Sorcerer
Most ANL fuses work great on 12 volt system. They can be used on many 24 volt systems. The plastic ones are not safe on a 48 volt system. Once you get to a 48 volt system, you should go up to a Class "T" fuse to ensure it can break the circuit from a severe short. Many fuses such as ANL do not open the gap quick enough or large enough and they can strike an arc and just keep burning at very high energy. I did find Bussman brand ANL fuses that are rated to 80 volts DC. The body is made out of fiberglass instead of typical plastic. If you do have ANL fuse holders, this is the fuse type we should be using. Of course, one 200 amp fuse is about $30, not much less than I paid for my Class "T".

My two battery strings are being combined with MRBF fuses that are rated to 58 volts. That is right on the edge as I charge to 57.2 volts. After they combine, I have it go to a Class "T" fuse before the connector where the cables leave the battery bank. In most cases, the MRBF fuse should be able to break the circuit, and they are much cheaper to replace if something does go wrong, but in an extreme case of a very high current surge, there is a chance they won't fully break the current path. They could melt and short out, or even short to the chassis. If something like this does happen, the idea is that the Class "T" fuse will open and shut it all down. After looking at some other builds, I may actually be adding another pair of fuses right at the battery lugs. I do have a few points where a wrench falling into my battery box could short something before the fuses. I never expect anything like this to ever happen, but we should always plan for the worst possible thing, and still make it safe. So I am going to look into how I can add a fuse right on the battery post. Maybe move the MRBF fuses there, and use the 80 volt rated ANL fuses as the combiner before the Class "T" at the output.
 

jesfl

Solar Enthusiast
Bad has gone to worse, it seems.

Bottom line, there is clearly something seriously amuck somewhere in my electrical system, and I do not know how to find it?

Because the whole system crashed again this afternoon when running only the TV (10 amps), ice maker (10 amps), and chargers for phone and laptop (6-8 amps?), all using AC power from the 3000W inverter. So about 30 amps shut it down this time.

I started checking breakers in the solar/battery system, the inside AC/DC power panel. No breakers tripped . . . but I still suspected the (low-quality Chinese) 175 amp breaker that tripped this morning making coffee (60 amps). To test, I took out that 175 amp breaker and put in an extra 175 amp Littelfuse MEGA/AMG fuse (General Mortos auto fuse) as a replacement. I had two others of these installed on each battery post connection (pos/neg), per Wil Prowse's basic solar system design. But, taking out the cheap Chinese breaker did not solve the problem.

Then I checked the two battery connection fuses by taking them out and connecting directly. The fuse to the negative battery connection of my new, only-days-old LiFePO4 battery was bad/had blown. That is very bad, I know.

My beginner assumption is that there must be a short somewhere in the RV's electrical wiring? The solar system wiring worked perfectly for months, and I have not changed anything, so to me that wiring is less suspect than the rest of the wiring in my 18-year-old RV.

I have this sick feeling that a problem somewhere might have been caused by all of the vibrations when towing the RV over the last 10 months on some really bad washboard roads getting to remote boondocking sites?

My problem is, at my level of knowledge, I have no idea where to start looking for a serious short or other problem like that in the internal RV wiring?

Any suggestions of where, what, and how to look will be most appreciated.

For now, I turned it all off and I am going to attempt to get a night's sleep.

I am very, very weary of all this, and I am quite sure some of you are weary of my posts. Yet, I know of no other place to go for information. Clearly, I got into a project that well over my head.

I admire your patience in bearing with me to help me get my system working.

Thank you.

Jim
jesfl
 

Just John

Photon Sorcerer
Bad has gone to worse, it seems.

Bottom line, there is clearly something seriously amuck somewhere in my electrical system, and I do not know how to find it?

Because the whole system crashed again this afternoon when running only the TV (10 amps), ice maker (10 amps), and chargers for phone and laptop (6-8 amps?), all using AC power from the 3000W inverter. So about 30 amps shut it down this time.

I started checking breakers in the solar/battery system, the inside AC/DC power panel. No breakers tripped . . . but I still suspected the (low-quality Chinese) 175 amp breaker that tripped this morning making coffee (60 amps). To test, I took out that 175 amp breaker and put in an extra 175 amp Littelfuse MEGA/AMG fuse (General Mortos auto fuse) as a replacement. I had two others of these installed on each battery post connection (pos/neg), per Wil Prowse's basic solar system design. But, taking out the cheap Chinese breaker did not solve the problem.

Then I checked the two battery connection fuses by taking them out and connecting directly. The fuse to the negative battery connection of my new, only-days-old LiFePO4 battery was bad/had blown. That is very bad, I know.

My beginner assumption is that there must be a short somewhere in the RV's electrical wiring? The solar system wiring worked perfectly for months, and I have not changed anything, so to me that wiring is less suspect than the rest of the wiring in my 18-year-old RV.

I have this sick feeling that a problem somewhere might have been caused by all of the vibrations when towing the RV over the last 10 months on some really bad washboard roads getting to remote boondocking sites?

My problem is, at my level of knowledge, I have no idea where to start looking for a serious short or other problem like that in the internal RV wiring?

Any suggestions of where, what, and how to look will be most appreciated.

For now, I turned it all off and I am going to attempt to get a night's sleep.

I am very, very weary of all this, and I am quite sure some of you are weary of my posts. Yet, I know of no other place to go for information. Clearly, I got into a project that well over my head.

I admire your patience in bearing with me to help me get my system working.

Thank you.

Jim
jesfl
Well, first take a deep breath and tell yourself that you found the blown fuse.

What size is the blown fuse? A 3000 watt inverter is huge for a 12 volt system.
Just the 175 amp breaker is limiting your output to under 2000 watts anyway. So what size is the fuse is important too, as well as the type. A fuse the same size as the breaker is likely to blow first. Other types of fuses can handle a surge, so the type of fuse is important as well.

One thing comes to mind, the short or bad connection is likely on the DC side. Battery connection, inverter connection, and photovoltaic connection. Start by checking those. I assume the battery and inverter are right next to each other?

What type of solar charge controller?

I assume when you say about 30 amps you mean DC, correct?
 

time2roll

Photon Sorcerer
When I was a kid I screwed one of those old fuses into a lamp socket. When I switched it on... 15 amp breaker tripped before 15 amp fuse.
I suppose some breakers and some fuses are a a bit different but that is my experience ;)
 

GXMnow

Photon Sorcerer
A friend had a car that kept blowing a fuse causing all kinds of problems. Put in a new fuse, and it all seemed fine for a day or two, then it would pop again. So of course he brought it to me...

Here is my best advice for finding a short. Pick up a few 12 volt bulbs. Some sockets with wires, or some other way to connect to them. You want goo old incandescent or halogen, and you want the wattage to add up to at least 100 watts. Wire the bulbs (I used a pair of 55 watt fog lights) across the fuse that blew. If the bulbs light up, you have a short, but now the current is limited to about 10 amps. Not enough to fry any wiring, but plenty to show on your clamp on amp meter. Follow the wiring to the power distribution. Find which leg has the current on it. Just keep following until you find the load. Obviously, you can't run a lot of power, and you will likely need to shut off the inverter, but small loads like LED lighting will run if there is no short at this time. If the bulbs only glow, or do not even light, the short is not happening at this moment. This is what I had. It makes it a bit tougher as the short is not solid, it is intermittent. So now, you have someone watch the bulbs, or aim them where you can see the light, and just start shaking and tugging all the wiring around. If you see the bulbs light up bright for even a second, you found the general area where a wire is shorting out. In the car I was working on, a wire to the tail lights got caught under the passenger seat mount, under the carpet. It would only short over a bump while the tail light was on. It took us 3 days to find it. I finally tugged on the harness down the side of the car and saw the light flash. So we traced the harness, and there it was. The more it shorts, the easier it is to find this way.
 

jesfl

Solar Enthusiast
It is all very depressing. And, I still have not gotten past Google searching from several posts early yesterday -- trying to understand abbreviations, what things are, and how to do suggestions, one-by-one. Basic things that are instantly recognized and comprehended to most of you are all new to me. Then I have to correlate all that new stuff. Beginner is an overstatement as a label for me. I have now concluded I am at the sub-beginner, kindergarten level.

But, by the way, I am saving on my computer for offline use every one of these posts and I have a 3-computer-typed-page-and-rapidly-growing list of all the things mentioned that I do not understand as a sort of future study guide.

I tested everything in the solar system connection-by-connection this morning after daylight. There is no point-to-point voltage loss anywhere from PV panels input through the controller to batteries and the inverter . . . and through all breakers, fuses and busbars. Keep in mind, I only know how to use the DC voltage and amps settings on my most simple multimeter.

I suspected yesterday the problem might be with the 18-year old interior wiring in my RV? The comments above imply the same suspicion, I think I understand.

Last fall, when I received the lithium batteries, I also purchased a Progressive Dynamics lithium converter and replaced the 17-year-old converter in the power panel. At that time, I also completely pulled apart the power panel (not really knowing what I was doing) and disconnected/cleaned/added a smidge of dielectric grease and reconnected tightly every single connection on the power panel and in the transfer switch. I will double check the tightness of connections, but I took such care doing that cleaning I am pretty confident that part of the DC power panel connections are OK. No, I did not buy a torque screwdriver.

Yesterday, I checked all of the power panel DC fuses and all are OK. If there is a short in a wire, wouldn't one of those 15 amp fuses blow FIRST before tripping the 175 amp breaker or blowing a 175 amp fuse? What good is are all the 15 amp fuses in the power panel? A tripped 175 amp breaker/blown 175 amp fuse without a blown 15 amp fuse in the power panel just does not make any sense to me? Or does this mean the problem is not really with the internal DC wiring (no blown 15 amp fuses) but somewhere else with a higher current? I am very confused.

Until I can find bulbs and figure out how to use them, is there any other process of elimination I can try to find the vicinity of the problem in the RV? For instance, could I pull all of the DC fuses in the power panel and put them back in one-by-one and then try to recreate the problem of tripping a breaker or blowing a fuse? Or is that just too risky/dangerous?

One last though. With a fresher mind this morning, I vaguely remembered I saw the overhead 12-volt lights in the bathroom flicker (unusually) yesterday afternoon when I flipped on those lights momentarily to reach into a cabinet. So I suspect that circuit might be the problem? Without the lightbulb testing apparatus, is there any other way to test the bathroom light wiring for a short? Then, again, the 15 amp fuse in the power panel for that bathroom light is OK, so I guess it must not be the problem but was just flickering because of a problem elsewhere? Again, very confusing.

Otherwise, for now, I guess I am in a holding pattern until Friday or Saturday when I can get to a city again for lightbulbs, etc. for testing.

Thanks for any thoughts

Jim
jesfl
 

Hedges

I See Electromagnetic Fields!
Might be easier to disconnect existing DC wiring and run a fresh wire from battery to your high-current load.
Could be a good upgrade for higher wattage inverter, anyway.

Use a separate small fuse to patch in each other circuit. If one of those has a short it'll just blow its own fuse.
But to trip a 175A breaker or blow the battery fuse, probably fault is in the heavy wire not the branch circuits. Maybe the run to the fuse box.
 

Just John

Photon Sorcerer
Might be easier to disconnect existing DC wiring and run a fresh wire from battery to your high-current load.
Could be a good upgrade for higher wattage inverter, anyway.

Use a separate small fuse to patch in each other circuit. If one of those has a short it'll just blow its own fuse.
But to trip a 175A breaker or blow the battery fuse, probably fault is in the heavy wire not the branch circuits. Maybe the run to the fuse box.
I'd have to go back and read, but I think he said the solar wiring is the newest and so he doesn't suspect that. I am the opposite, that would be the first thing I would check.

Just a guess on my part that it is the DC side, but usually a short on the AC side gives you smoke and or sparks.I would trust the 18 year old AC wiring as opposed to the newer DC wiring.
 

jesfl

Solar Enthusiast
Thank you again.

So, I am back to checking both the new solar DC wiring and the old RV DC wiring . . . still without really understanding how to do that?

"Might be easier to disconnect existing DC wiring and run a fresh wire from battery to your high-current load."

I don't know what you mean by "high current load?" (Remember, please, I know none of the terminology, abbreviations, etc.) Are you saying a new heavy gauge wire from the batteries/solar/inverter wiring to the interior power panel? If so, that's about 30 feet of wire/cable which gives me more heartburn because of $$$'s. Also, I have no clue about what gauge that might need to be? The 3600 kw genset to battery wire is labeled 2 AWG. The old wire from the power panel to the battery is not labeled, but appears to be smaller (?) than 2 AWG, which confuses me because that is the 120V wire, right? A quick amazon.com search gets me 30' of 2 AWG + lugs for $90. More, of course, if a larger AWG is needed?

"Could be a good upgrade for higher wattage inverter, anyway."

My 3000-watt inverter is not wired into the power panel or system (yet), and may never be? I bought 2 super heavy-duty 25' outdoor/weatherproof extension cords that are plugged into 120V outlets in the back of the inverter. I installed two 20 amp GFCI plugs, one on each side of the main living area for microwave & kitchen appliances on one side of the RV, and for TV, computer, fans/heaters (small) on the other side of the RV. Surprising to me, it is working so well I'm not sure I'll ever bother to figure out connecting the inverter directly to the power panel? If it is connected into the power panel and all of the RV wiring, it will just increase my parasitic amperage draw for wall plugs, etc. I don't ever use?

"Use a separate small fuse to patch in each other circuit. If one of those has a short it'll just blow its own fuse."

Honestly, I have no idea what this means? What type of small fuse, and what's small. What does patch mean? Each other circuit?

If you are referencing the DC fuses in the power panel, then are you saying remove the 15 amp fuses and put in a smaller (5 amp?) fuse and see what happens when I use each circuit? I don't understand, however, what "each other circuit" means.

"But to trip a 175A breaker or blow the battery fuse, probably fault is in the heavy wire not the branch circuits. Maybe the run to the fuse box."

That I do understand and it is what I kinda' guessed and why I asked the question about why the 15 amp DC fuses did not blow? However, the "run to the fuse box" for that cable is inside the flooring of the RV and inaccessible except at the battery compartment and up through the floor at the power panel. So, my only points to check it are the two opposite ends. I am about to go check all the connections looking for loose or damaged wire, that's easy. How do I check to see if that wire/cable is somehow shorting out somewhere in the "run" with no other access to it?

(Note: I read one place that mice can chew on wires in RV's. Over the past 6 months, I've killed two mice in this RV, one about two weeks ago. I guess it is not outside the realm of possibility that one of those mice had some plastic wire covering dinner and started a short problem?)

I am going to go start checking every visible large wire (higher current) connection I can find and look for damage on as much of the wires as I can see.

After that, I'm having a beer. Tomorrow, after a good night's sleep, I'll get back to trying to figure out the rest of the actions and fuses and tests mentioned in the many previous posts.

Thank you, thank you.

Jim
jesfl
 

Hedges

I See Electromagnetic Fields!
I'm thinking that to trip a 175A DC breaker and to blow a battery fuse, there is a short in the wire from battery to inverter (or to charge controller, or or to fuse panel), intermittently connecting that wire to negative/chassis, or otherwise to other side of battery. That would be a wire as fat as your finger or thumb. So that is the wire I'm suggesting replacing.

If by inspection you can find damaged insulation, maybe where it passes through a bulkhead, then all you need is tape. I've observed that where I have Romex pop up into the attic is where rodents prefer to chew.

Because that is such a high current, and any voltage drop in the wire is a large percentage of battery voltage, it is best if battery and inverter are very close together. Maybe 1' to 3' apart, with 2/0 or heavier copper wire for both positive and negative connection - not using chassis as part of the circuit. Could you relocate battery near inverter and save on wire?

"How do I check to see if that wire/cable is somehow shorting out somewhere in the "run" with no other access to it?"
You don't. I might apply a high voltage (similar to ignition system) using a HyPot which I happen to have. I it sparks across the instrument detects it.
For you, the light bulb that was suggested or a buzzer in place of fuse. But only if you manage to disturb the wire and have the short appear will you find it. Permanent faults are much easer to find and fix.
 

Bob B

Photon Sorcerer
I think the most likely place for a short would be where the wire is bent around something metal or going thru a hole in metal.
I had a problem where my boat motor would intermittently blow a fuse .... found that the motor harness at the console was laying against a sharp edge .... couldn't believe they did it that way.
 

Just John

Photon Sorcerer
Thank you again.

So, I am back to checking both the new solar DC wiring and the old RV DC wiring . . . still without really understanding how to do that?

"Might be easier to disconnect existing DC wiring and run a fresh wire from battery to your high-current load."

I don't know what you mean by "high current load?" (Remember, please, I know none of the terminology, abbreviations, etc.) Are you saying a new heavy gauge wire from the batteries/solar/inverter wiring to the interior power panel? If so, that's about 30 feet of wire/cable which gives me more heartburn because of $$$'s. Also, I have no clue about what gauge that might need to be? The 3600 kw genset to battery wire is labeled 2 AWG. The old wire from the power panel to the battery is not labeled, but appears to be smaller (?) than 2 AWG, which confuses me because that is the 120V wire, right? A quick amazon.com search gets me 30' of 2 AWG + lugs for $90. More, of course, if a larger AWG is needed?

"Could be a good upgrade for higher wattage inverter, anyway."

My 3000-watt inverter is not wired into the power panel or system (yet), and may never be? I bought 2 super heavy-duty 25' outdoor/weatherproof extension cords that are plugged into 120V outlets in the back of the inverter. I installed two 20 amp GFCI plugs, one on each side of the main living area for microwave & kitchen appliances on one side of the RV, and for TV, computer, fans/heaters (small) on the other side of the RV. Surprising to me, it is working so well I'm not sure I'll ever bother to figure out connecting the inverter directly to the power panel? If it is connected into the power panel and all of the RV wiring, it will just increase my parasitic amperage draw for wall plugs, etc. I don't ever use?

"Use a separate small fuse to patch in each other circuit. If one of those has a short it'll just blow its own fuse."

Honestly, I have no idea what this means? What type of small fuse, and what's small. What does patch mean? Each other circuit?

If you are referencing the DC fuses in the power panel, then are you saying remove the 15 amp fuses and put in a smaller (5 amp?) fuse and see what happens when I use each circuit? I don't understand, however, what "each other circuit" means.

"But to trip a 175A breaker or blow the battery fuse, probably fault is in the heavy wire not the branch circuits. Maybe the run to the fuse box."

That I do understand and it is what I kinda' guessed and why I asked the question about why the 15 amp DC fuses did not blow? However, the "run to the fuse box" for that cable is inside the flooring of the RV and inaccessible except at the battery compartment and up through the floor at the power panel. So, my only points to check it are the two opposite ends. I am about to go check all the connections looking for loose or damaged wire, that's easy. How do I check to see if that wire/cable is somehow shorting out somewhere in the "run" with no other access to it?

(Note: I read one place that mice can chew on wires in RV's. Over the past 6 months, I've killed two mice in this RV, one about two weeks ago. I guess it is not outside the realm of possibility that one of those mice had some plastic wire covering dinner and started a short problem?)

I am going to go start checking every visible large wire (higher current) connection I can find and look for damage on as much of the wires as I can see.

After that, I'm having a beer. Tomorrow, after a good night's sleep, I'll get back to trying to figure out the rest of the actions and fuses and tests mentioned in the many previous posts.

Thank you, thank you.

Jim
jesfl
High current load, that would be your inverter.
Pretty much everything else qualifies as a low current load.
Mice do like wires for some reason.
How far is your inverter from the battery? If it is 30 feet like I think you are saying, you would greatly benefit from moving one or the other (battery or inverter). High current 12v should be kept as short as possible. Usually 3 or 4 feet.
 

jesfl

Solar Enthusiast
Thanks again to all for the continuing help.

I'm taking a day or two off for other issues. My mind is boggled with all this new stuff and electrical system problems. It is all still very frustrating because of my lack of basic knowledge and difficulty understanding some of the terminology and abbreviations use.

However, one thing is really troubling me.

A couple of months ago, I had a 100 amp ANL fuse blow in the wire from the power panel to the batteries/solar. I didn't think much about it, Just replaced it and went on. There were no apparent recurring issues.

Then when the 175 amp breaker flipped a few days ago. Then the 175 amp fuse blew. It flashed to me that my only previous fuse blow 2 months ago occurred around the time the batteries started going funky and wouldn't charge? Now I know from everyone's help that the BMS units all were killed.

Lightbulb on ! ! !

I now have concluded the 100 amp fuse blow and the death of all three BMS in all three batteries MUST have been directly connected. To me, it explains how all three BMS units/batteries could die simultaneously against all theoretical odds. I'm just not knowledgeable enough to instantly connect the dots when those things happen.

(At my low Ah use rate, it took probably a week or more, for the 450 Ah of power in the batteries to go completely dead. At that time, with the system working pretty much "perfectly," I, complacently, wasn't even bothering to check battery status because I felt indestructible with endless solar and battery power. Another big mistake. Although, the damage to the BMS already had been done, most likely?)

Now, because of the 175 amp breaker/fuse blows, some of you are pointing toward the main wire/cable from the inside power panel/converter/transfer switch to the batteries?

However, if it is a problem or short in the main power pannel-to-batteries wire that caused the 175 amp breaker/fuse issue, wouldn't the 100 amp ANL fuse then is inline before the 175 amp'ers have blown first or simultaneously? It did not. It is still good.

Therefore, logically to me, doesn't that rule out that power panel-to-batteries/solar wire as the culprit for the 175 amp breaker/fuse issue?

If yes, then my focus needs to be on other larger wires/cables for a short problem? Not that power panel-to-batteries/solar wire? Am I correct with this assumption?

One other unrelated (I think) point.

Several of you have asked about or mentioned wire length.

Facts: The positive wire from the (single, 200Ah LiFePO4) battery to the 3000W inverter is a total of 21 inches of 4/0 AWG. I just remeasured. The positive cable runs through a master battery on/off switch and then/also the 175 amp breaker (now dead, temporarily replaced with a 175 amp bolt-on AMG fuse, until I receive a new, high-quality breaker.)

The negative wire, of necessity, is 30 inches of 4/0 because it runs through a shunt for the inside voltage meter/monitor. All of my wiring in the solar system is very oversized, probably unnecessary so.

I am pretty confident neither wire length, nor wire size, nor the quality of connections is part of any equation that caused my recent 175 amp breaker/fuse problem.

Thank you again to all for your comments and information.

Jim
jesfl
 

Hedges

I See Electromagnetic Fields!
Various fuses and breakers can blow/trip in either order.

Fuses are thermal, takes time to deposit the energy to heat up.
Breakers typically use magnetic to trip fast for currents > 5x their rating.
Breakers may use thermal expansion for slow trip of moderate overloads, or a hydraulic shock absorber resisting moderate magnetic force.

The only way wire size causes trip is if it limits current so a motor fails to start and sits there drawing excessive current.
Poor connection at a fuse or breaker can raise temperature, bringing it closer to tripping.

Having both fuse and breaker trip, assuming loads are high enough to do it, suggests a short, so that's what you need to locate.

Tripping of 175A breaker means current from battery through breaker exceeded that. The only way wire to charge controller could be involved is if it also goes through that breaker (but it should have a smaller fuse which is likely though not guaranteed to go first.)
 

Just John

Photon Sorcerer
Thanks again to all for the continuing help.

I'm taking a day or two off for other issues. My mind is boggled with all this new stuff and electrical system problems. It is all still very frustrating because of my lack of basic knowledge and difficulty understanding some of the terminology and abbreviations use.

However, one thing is really troubling me.

A couple of months ago, I had a 100 amp ANL fuse blow in the wire from the power panel to the batteries/solar. I didn't think much about it, Just replaced it and went on. There were no apparent recurring issues.

Then when the 175 amp breaker flipped a few days ago. Then the 175 amp fuse blew. It flashed to me that my only previous fuse blow 2 months ago occurred around the time the batteries started going funky and wouldn't charge? Now I know from everyone's help that the BMS units all were killed.

Lightbulb on ! ! !

I now have concluded the 100 amp fuse blow and the death of all three BMS in all three batteries MUST have been directly connected. To me, it explains how all three BMS units/batteries could die simultaneously against all theoretical odds. I'm just not knowledgeable enough to instantly connect the dots when those things happen.

(At my low Ah use rate, it took probably a week or more, for the 450 Ah of power in the batteries to go completely dead. At that time, with the system working pretty much "perfectly," I, complacently, wasn't even bothering to check battery status because I felt indestructible with endless solar and battery power. Another big mistake. Although, the damage to the BMS already had been done, most likely?)

Now, because of the 175 amp breaker/fuse blows, some of you are pointing toward the main wire/cable from the inside power panel/converter/transfer switch to the batteries?

However, if it is a problem or short in the main power pannel-to-batteries wire that caused the 175 amp breaker/fuse issue, wouldn't the 100 amp ANL fuse then is inline before the 175 amp'ers have blown first or simultaneously? It did not. It is still good.

Therefore, logically to me, doesn't that rule out that power panel-to-batteries/solar wire as the culprit for the 175 amp breaker/fuse issue?

If yes, then my focus needs to be on other larger wires/cables for a short problem? Not that power panel-to-batteries/solar wire? Am I correct with this assumption?

One other unrelated (I think) point.

I would certainly expect the 100 amp fuse to blow before the 175 amp breaker or fuse. So likely whatever the problem is, it is unlikely to be on the other side of the 100 amp fuse. By "other side" I mean the side of the circuit that the 100 amp fuse is protecting (whatever is on the end of that circuit, sounds like your power panel for smaller DC loads).

Several of you have asked about or mentioned wire length.

Facts: The positive wire from the (single, 200Ah LiFePO4) battery to the 3000W inverter is a total of 21 inches of 4/0 AWG. I just remeasured. The positive cable runs through a master battery on/off switch and then/also the 175 amp breaker (now dead, temporarily replaced with a 175 amp bolt-on AMG fuse, until I receive a new, high-quality breaker.)

The negative wire, of necessity, is 30 inches of 4/0 because it runs through a shunt for the inside voltage meter/monitor. All of my wiring in the solar system is very oversized, probably unnecessary so.

I am pretty confident neither wire length, nor wire size, nor the quality of connections is part of any equation that caused my recent 175 amp breaker/fuse problem.

Yes, that length or wire sounds very good, when you are talking about a 30 foot run of 2 gauge wire, is that from your generator to the battery? I would think that is for starting the generator, not charging? The good news is that your fuses and circuit breaker are protecting that large gauge wire from damage, which is what they are supposed to do. The bad news is that intermittent problems are the hardest to track down.
 
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