Blown battery fuses

Bracha

About two weeks ago, I was boon docking and on day 3, I lost power.  A fuse at the battery blew.  I took out my AGM batteries and replaced them with two 100ah renogy LiFePO4 smart batteries.  I installed them the day before yesterday, turned on the bat connect switch on and ....POWER!  Last night, I went out to check them....when I turned on battery,...a
all fuses at the battery blew!  They are brand new and charged!   I still have a separate issue....when batteries are disconnected and plugged into shore power, I have AIR, but no 12V appliances.  This lead me to believe the converter.was bad, but when I pulled the converter fuse...the fuse was good, but the converter started.  All the other fuses are good....

pthomas745

Really need the model and year of the trailer.

"Pulled the converter fuse" means: what fuse?

What exactly are you using to monitor the battery when you say "they are brand new and charged?"  Is your "charged" measurement taken with the battery switch off and the trailer disconnected from any charging?

Your batteries may be lower than you think, and the surge to charge the batteries is causing the battery fuses to blow.

You say "AGM batteries" which is a clue that you have a 400?  If so, the other item that can blow and cause the symptoms of "not working on 12V" is the Gloso circuit breaker.

Look over this thread that discusses these types of issues. It also has a description of what the Gloso does.

https://tab-rv.vanillacommunity.com/discussion/11062/did-we-just-kill-our-brand-new-batteries

Bracha

pthomas745 said:

Really need the model and year of the trailer.

"Pulled the converter fuse" means: what fuse?

What exactly are you using to monitor the battery when you say "they are brand new and charged?"  Is your "charged" measurement taken with the battery switch off and the trailer disconnected from any charging?

Your batteries may be lower than you think, and the surge to charge the batteries is causing the battery fuses to blow.

You say "AGM batteries" which is a clue that you have a 400?  If so, the other item that can blow and cause the symptoms of "not working on 12V" is the Gloso circuit breaker.

Look over this thread that discusses these types of issues. It also has a description of what the Gloso does.

https://tab-rv.vanillacommunity.com/discussion/11062/did-we-just-kill-our-brand-new-batteries

Firstly, I have a 2022 T@b 320s.  Secondly, I just installed two brand new Lifepo4 batteries as I describe...NEVER BEEN USED.  Fully charged separately from camper!  Checked with charger, multimeter, And smart app!  They ARE NOT LOWER THAN I THINK!!!

THE FUSE REFERS TO THE CONVERTER POWER FUSE!
I also say, I replaced the AGM WITH LIFEPO4 

KK1L

@Bracha Folks are trying to help and asking questions to fill in information which is unclear. The impression from your response is that you are being slighted. Don't at all take it that way. Debugging a problem remotely and let alone by written description only is difficult. Be patient with the questions. You know exactly what you know from living it and being present. We only know what is written.

Bracha

No helpful response except batteries are low and this is NOT the case.  I have been trying for two weeks to solve the problem and no solution accept people telling me to charge the batteries.  I have a useless camper just sitting and I am not an electrician 

Bracha

You are just piling on

KK1L

 @Bracha I am gonna try and summarize, comment, and ask questions. Let us know any misunderstanding.

• With AGM batteries you had the same fuse and powering issues
• Replaced AGM with LiFe4PO and the problem(s) persisted

Recent Problem summary

1. installed charged LI batteries and had correct function in the camper
2. opened the battery disconnect switch (disconnected) and left trailer be for a while (I am inferring this)
3. later came back and closed the disconnect switch (connected) and "all the fuses at the battery blew"
4. also with batteries disconnected and camper connected to 120V (shore power) no 12V is available in the camper, but 120V items are powered and work properly

Questions/clarifications

• Can you list "all the fuses at the battery" which blow? Which ones are still intact?
• Do you have a Smart Shunt to monitor current/voltage at the batteries?
• I read back to commentary you made in other threads that you have an IP22 charger. Is that correct? If so can you describe how that is wired? Did it replace the stock charger? I get the impression the fuse blow issue happened before adding the IP22...is that true?
• Can you list any electrical system devices you added or are not "stock"?
• The 12V not working when on shore power could very well be related to the fuse blow issue. Please clarify which fuses are blown and which are not. That will help with further debug.
• Do you have a voltmeter to make measurements?
• Are the fuse and no 12V issues new to the camper? Did you recently purchase it and the problems existed, or have you had the camper a while and they suddenly appeared? If it is a sudden occurence can you describe what lead up to it?

Bracha

All issues began when my e break pin came out and drained the batterries.  I was able to recharge the AGM batts.  I went boondocking for a few days....on the 3rd day, I lost power and noticed the fuse on my group 24 was blown.  Instead of charging the batteries again, I replaced them with the 100ah LiFePO4 batts.  The Ip22 charger is not wired to the camper.  I have had the camper for a year and modified nothing, but the batteries.  When batterries disconnected, I have 120v shore power, but only have 12v shore power when I remove the converter 30 amp power fuse.  The converter is auto detect.  The batteries were disconnected for 24 hour from the time of the working to blowing each fuse on each battery.  There are 3.  All fuses on converter panel are fine.

Bracha

Just took a voltmeter to my batts.....13.5 and 13.8 measured.

Horigan

Seems like there is a short in the 12V circuit somewhere, possibly between the battery and the converter panel.  If it were me, I would turn off all 12V appliances/lights, disconnect both battery cables and measure the continuity between the cables with a mult-meter.  It should be open circuit.  Then start replacing fuses, one at a time, and measure the continuity.  I suspect you'll find a reduction in resistance (not open circuit) when you replace one of the fuses.  For that system trace the positive wire and see if it is chafed or otherwise shorted to ground.  It could be the main positive battery wire to the converter.

Bracha

Can a faulty break away switch cause these problems?

Bracha

I have two batteries.  How do I test continuity with all those wires.  Even if I find a problem, if it isn't a fuse or a breaker, how do I fix?

KK1L

•  I have 120v shore power, but only have 12v shore power when I remove the converter 30 amp power fuse.  

Looking to clarify this statement. I am missing something. When the 30A fuse is removed it will disconnect the 12V output of the converter from the 12V circuit, so then only the batteries would provide 12V. If the fuse is in place there should still be 12V present from the batteries even if the converter is not working. If you put your voltmeter on one of the cigar outlets and measure the voltage under these conditions...

1. no shore power
2. shore power 30A fuse in place
3. shore power 30A fuse removed

• Just took a voltmeter to my batts.....13.5 and 13.8 measured.

So can I assume you measured them with them disconnected from the trailer? Is that correct?
If yes, then it is interesting that one of the batteries is so much more discharged than the other
If no, then there is current flowing to cause a voltage drop.
Oh...do you have both batteries connected in parallel at the same time or swap them as needed? I have been assuming you have them wired in parallel.

@Horigan is offering a reasonable step to take. I was going to offer something similar once we get some symptoms and conditions established. Maybe there is something up with the breakaway switch, but I hesitate to jump to root cause ideas before getting the data.

Here is a partial wiring diagram I found on this forum from @Bayliss for the 320BDL for reference. I have a 400, so cannot rely on what I see in my camper.


 

KK1L

• I have two batteries.  How do I test continuity with all those wires.  Even if I find a problem, if it isn't a fuse or a breaker, how do I fix?

I would recommend waiting on continuity testing. It is harder to do, since it requires disconnecting stuff. You can get an idea of the integrity of the wiring (and if current is flowing) by measuring the voltage drop from one point to another.

Let's work on the symptoms and diagnostics first. How and what to fix comes last.

Bracha

I only have 12v power on shore if the converter power fuse is removed.

Bracha

And the batteries are disconnected.  I can't even turn the bat switch on without blowing fuses.

Bracha

My batteries are in parallel.  Same configuration as from factory

Bracha

I can't keep this camper if it is this difficult to troubleshoot and fix problems.  I can't even find someone to come assess.

KK1L

Sorry you are so frustrated. There is nothing special about diagnostics for your camper that any other would not share. I would be surprised if any dealer would send a tech to make a house call. If you willing to tow the camper to your dealer that might be your best best. I am not exactly sure what you are expecting from the fellow campers on this forum. Doing what we can. I have a ton of debug experience tinkering since a teenager and my 30 years with IBM visiting customers with troubles and now Marvell Semiconductor. I have at least an hour into your issue so far. Debugging remotely is a back and forth affair. It should be methodical. It is typically not quick, and depends highly on the skill set of the person with boots on the ground...you.

"Same configuration as factory" is hard to pin down, since there are variations year to year and even within a model year. We are not all intimately familiar with the variations, so be patient when we asked. If it is one thing I have learned when debugging is to assume nothing.

Back to debug...Having 12V present while on shore power with 30A fuse removed and batteries disconnected is something I am struggling to understand. Without the fuse the converter is not feeding 12V to the camper. Without the batteries connected (switch disconnected) they would not feed 12V to the camper. This is what I am missing...where is the 12V coming from? It is the reason I asked about measuring at one of the cigar outlets in the camper. When you say you "have 12V power" how are you determining this?

KK1L

Staring at the diagram from @Bayliss and thinking about your measurements and comments it does make sense that the breakaway switch could be the root of your troubles. You could just replace it, or if you want to prove it is bad you can disconnect it at the junction box terminal 6 where the red wires connect. Or you could disconnect it at the GND side terminal 1. Either should make your problem go away. Note: I am not advocating that you disable it and continue to use the camper This would be to verify in a non-damaging way if it is the problem.

Both paths you are having trouble with lead to the breakaway. Opening the 30A fuse breaks that path. When you connect the batteries the fuse blows which breaks that path. The problems started when you popped the breakaway. In another thread you mention it looks melted. It is entirely consistent that this is shorted out and needs replacing. It is a single point of failure (SPOF) which fits the symptoms.

If you were to measure the voltage at a cigar plug or one leg of the 30A fuse with the 30A in place you would quite likely read a voltage well below 12V, but not zero.

Horigan

If you don't want to crawl under the front of the trailer to access the junction box, you could unmount the breakaway switch from the trailer frame so it's not connected to trailer ground.  Then see if things work okay.  If they do, that would point to an internal short in the breakaway switch.

KK1L

@Horigan Mine has two wires. @Bayliss diagram also. Google shows most do. I am not sure disconnecting from the frame is enough. Easiest is probably measure V at a DC fuse with the 30A in place. If it pulled down well below 12V that would say. Heck could also then pull the pin on the breakaway and see if it changes. No change would indicate it is bad too.

Horigan

Good point.  Didn't look to count the wires.

Sharon_is_SAM

@KK1L, @Horigan - what about a short in the battery switch?

KK1L

@Sharon_is_SAM Good thought. that would not fit the symptom of needing to pull the 30A fuse. The switch could not force a short path to gnd, and the battery appears to disconnect correctly.

sequimite

Unless the brake disconnect switch is shorted to ground, seems like it would simply apply the brakes and would take some time to blow the fuse. If the switch was melted, it very well could be shorted to ground.

Bayliss

I wasn't going to jump in here, @Bracha, but I find troubleshooting electrical problems both interesting and challenging.  Part of the problem here is that the issues involved have been discussed in three (one now closed) different discussion threads.  Regardless, whenever trying to discover the source of any problem, I always try to think back to what happened just before a particular problem began.

First off, there has been some very good input from others here, particularly @pthomas745 and @KK1L.  To try to build on those questions/suggestions, I went back and reviewed some key information you have provided and will reiterate them in an effort to help you get this particular issue resolved.  I have included some questions I have, or inquiries as to clarification that may help:

May 23rd:  "I have a T@b 320s 2022.  My batteries completely drained after the breakaway switch pin came out.  My dealer said my batteries would recover after one to 3 days of charging.  Even with dead batteries, shouldn't I still have shore power for lights etc. With the battery disconnected?

     Q1:  How did the pin come out?  Were you able to put it back in?  Did the switch appear damaged/melted at that time?  Any fuse(s) blown at that time?

MAY 24th:  “I only had shore power when I removed the fuse for the converter.  I checked the fuses on the batteries and 2 out of 3 were blown....”

     Q2:  Which fuse "at the converter" did you remove?"     

     Q3:  Specifically, which "2 out of 3 fuses" were blown?  (The 30-amp fuses at the two batteries?  Or, was one of those the 30-amp fuse at the converter?)

MAY 24th:  “Replaced all the fuses ( convertor and batteries). Back in business, all systems ago!”

     Q4:  When you say you replaced "all" the fuses, are you referring to every fuse in the converter, as well as the 30-amp fuses at the two batteries (one fuse each), or just the two fuses that blew earlier?

MAY 31st:  “This past weekend I was boondocking for three days.. the fuse on the group 24 battery (I have a 24 and 31), blew on day 3.  Since then, when I turn bat cut off switch on, the fuse blows.  I also cannot have shore power unless the converter fuse is out and it is not blown.  Could these problems relate to the e brake switch?.  I was checking the brakes and I am having a hard time pulling the pin out and the switch looks damaged a little melted...”

     Q5:  What, if anything, happened between the return to full 12V power on May 24th and your most recent trip around May 31st that may have caused the fuse to blow?  Specifically, do you recall anything unusual happening, electrically, during the three days before the fuse on your Group 24 battery blew?  What happened or led you to discover that the Group 24 battery fuse blew?

     Q6:  When you say, "Since then, when I turn bat cut off switch on, the fuse blows," can you clarify whether you first replaced the 30-amp fuse for the Group 24 battery before that happened, or are you referring to a different fuse blowing?  If so, which fuse?

     Q7:  Did this happen more than once?  (i.e., did you replace the fuse(s), and then when you again turned the battery disconnect switch "on," the fuse(s) blew again?

JUNE 9th:  About two weeks ago, I was boon docking and on day 3, I lost power.  A fuse at the battery blew.  I took out my AGM batteries and replaced them with two 100ah renogy LiFePO4 smart batteries.  I installed them the day before yesterday, turned on the bat connect switch on and ....POWER!  Last night, I went out to check them....when I turned on battery,...a all fuses at the battery blew!  They are brand new and charged!   I still have a separate issue....when batteries are disconnected and plugged into shore power, I have AIR, but no 12V appliances.  This lead me to believe the converter was bad, but when I pulled the converter fuse...the fuse was good, but the converter started.  All the other fuses are good....

     Q8:  Is the incident you are describing here (dated JUNE 9th) the same incident you described on May 23rd?  I ask, because you initially said the batteries completely drained "after the breakaway pin came out," but you most recently describe that "a fuse at the battery blew" (and thereafter, you switched to two 100Ah Lithium batteries, which resulted in again having power.)

     Q9:  After you had your 12V power back, am I correct that you turned the battery disconnect switch "off" (thus cutting off power from the batteries to the trailer) and that when you later went to check them and turned the disconnect switch "on," the fuse at each battery blew?

     Q10:  When you say "all fuses at the battery blew," which fuse(s) specifically are you referring to?  I ask, because there should only be one 30-amp fuse for each battery.

Based on the information you have supplied thus far, it does seem that the breakaway switch is damaged and likely shorting out.  If not, and assuming there are no other apparent shorts in the wiring, I suppose I would next be looking for a problem with the converter.  Maybe the answers to the above questions will lead in another direction.  

A FEW MORE GENERAL QUESTIONS FOR YOU:  Which Power Center/Converter do you have in your trailer?  Have you checked the 40-amp "reversed polarity" fuse in the converter to confirm it is OK?  AND, have you confirmed that none of your 120V AC circuit breakers are tripped?

Lastly, have you considered contacting a Mobile RV Repair service to have them come out and try to diagnose the issues you are having with the 12V system?

Sorry for the long post.  I hope you get this figured out.

Bracha

Today, I went under camper and saw two red wires hanging down on the passenger side behind the wheel.

Bracha

Taking the camper to a tech at my dealer..... Turning out, not to be something I can fix on my own.

Bracha

I have learned a lot, here, though.

Bracha

Bracha said:

Today, I went under camper and saw two red wires hanging down on the passenger side behind the wheel.