Melted Battery Charger Fuse

[SGIDAVE]

Hello,

I have the Promariner Pronautic 12-20P which was factory installed in my 2013 R21EC. It looks like this

Although it has THREE outputs, I presently use just TWO. One goes to the Group 24 Starting battery; the other to the House bank (2 6V golf cart batteries in series). The wires from the charger incorporate the usual spade-type fuse at the battery connection as per ABYC requirements. The fuse holders contained 20A fuses. When I turn off my 'main' battery switch, this has the effect of isolating the two batteries by eliminating the Blue Sea ACR from the circuit.

I noted on my Balmar Smartguage that the House bank was not returned to 100% SOC after a 'normal' overnight charge session. So, I investigated. To my horror, I discovered a partially melted 20A fuse at the house bank; the start bank fuse was normal-appearing. This is what the fuse looked like

I have never seen this happen. I've never 'felt' the fuses for heat as charging was underway...never thought about it. I've monitored BATTERY temps...but anyway, I took the fuse pigtail from the unused 3rd charging wire and crimped it into position so as to replace the suspect fuse holder. I placed a fresh 20A fuse and commenced charging. The Pronautic did its ususual 'self-test' with normal results. It then started charging at 20A output as indicated on it's output display. Within 5 minutes, the house bank fuse (the one I just replaced) was too hot to hold onto. YIKES! I shut it down.

More investigation led me back to the owners manual for the charger (available on line if you can't locate yours). To my surprise, the manual states on page 11 in the "Installation" section

Choose a fuse that is 10 amps higher than the charger output (e.g. 60 amps, choose a fuse of 70 amps)

So, I placed a 30A fuse into the holder (which is it's maximum - it is made of 12 AWG wire) and commenced charging. This time, the fuse became warm but never hot. I feel this situation is within specs. Given my relatively large 'house' bank in comparison to the small group 24 starting bank, MOST of the charger's max output is delivered (appropriately) to the house bank.

I offer my findings as a strong warning to check the fuse sizes in your charging circuits. In my case they were too small and could have resulted in a fire.

dave

 

[Stevan47]

Hi Dave: I recently had the same charger as yours installed, under warranty, as my previous, older model ProMariner melted down soon after puyrchasing the boat. All good there and the new one works well. I do not have a house bank of batteries, just the normal two battery charging bank. None of my fuses seem to have become hot while charging, but I will conduct some checks over the next few days anyway. Should I have any concerns, noting that I do not have the additional house bank of batteris? Would appreciate your thoughts. Stevan.

 

[baz]

Stevan: I have the same battery setup as you do. I will certainly be checking my fuses and the battery charger for anomalies after reading the OP. As I'm going to the Roche Harbour meeting this week where Ranger Tug's tech people will be attending I'll ask them about this potential issue the OP raised.

 

[Andrew Custis]

I think that modifying the batteries and the way they charge could have a significant effect on how the system now works. The main reason I say this is because your boat is a 2013 which was built nearly three years ago. If there was an issue with wiring from the factory and or fuse size, I would sure think this would have cropped up long ago. From the factory there was a jumper installed between the 2nd set of charger wires and third set when a third bank is not used. Did you remove that jumper wire? Also, I've never heard of a larger fuse providing better protection than a smaller one. I think what you end up doing when jumping the fuse size up is you place more heat in the wiring itself than the fuse holder as before. I suspect you have another issue going on and should not ignore that.

 

[knotflying]

I agree with Andew, something is wrong here. Firstly, I have never seen a fuse melt like that. I would think that if it exceeded its rated amperage it would blow before the entire case would melt. Secondly, if you are using 12ga wire a 20 amp fuse should be the maximum amperage. Upping your fuse to 30 amps will be heating up your 12 ga wires over capacity.

 

[CAPTCRUNCH]

Kinda surprised the fuse holder appears undamaged.

 

[Binare]

The manual is pretty clear.

10awg wire and a 30amp fuse.

Looks like it was wired with 12awg wire and a 20amp fuse.

That pretty much says that this device was not wired to manufacture specs, it is a rated device, it has gone through an equipment approval and is legally installable equipment IF it is wired correctly, in this case, it was not.

Using a 20amp 12AWG fuse holder is completely incorrect and yes, it will show problems over age, just google these crappy little holders melting, they make poor connections and add a ton of resistance where the crimp meets the fuse, creating lots of heat within the fuse holder, which will, over time, cause exactly this problem.

There is absolutely no reason not install equipment that is properly rated any other way than what the manufacturer recommends.

Why the jumper between bank 2 and 3? that is not recommended wiring.

The manual for this product states:

4. Empty Charger Banks - In the event of an empty charger bank there is no need to use a jumper as
done with traditional chargers. Simply leave the DC positive unloaded and the unit will perform correctly

So again, why install it any other way?

If I was the OP I would ditch the gimpy little inline 12gauge fuse holder, use a stud and nut fuse holder (also recommended by manufacturer) and replace all the wiring with the correct recommended 10gauge wire.

 

[Jake]

The manual is pretty clear.

10awg wire and a 30amp fuse.

Looks like it was wired with 12awg wire and a 20amp fuse.

That pretty much says that this device was not wired to manufacture specs, it is a rated device, it has gone through an equipment approval and is legally installable equipment IF it is wired correctly, in this case, it was not.

Using a 20amp 12AWG fuse holder is completely incorrect and yes, it will show problems over age, just google these crappy little holders melting, they make poor connections and add a ton of resistance where the crimp meets the fuse, creating lots of heat within the fuse holder, which will, over time, cause exactly this problem.

There is absolutely no reason not install equipment that is properly rated any other way than what the manufacturer recommends.

Why the jumper between bank 2 and 3? that is not recommended wiring.

The manual for this product states:

4. Empty Charger Banks - In the event of an empty charger bank there is no need to use a jumper as
done with traditional chargers. Simply leave the DC positive unloaded and the unit will perform correctly

So again, why install it any other way?

If I was the OP I would ditch the gimpy little inline 12gauge fuse holder, use a stud and nut fuse holder (also recommended by manufacturer) and replace all the wiring with the correct recommended 10gauge wire.

Sorry I this is a bit off topic but it is just this kind of thing which keeps me (a non-mechanical type) from upgrading to a larger boat made by any manufacturer. Enough things go wrong just because things go wrong but when you add in things that weren't done correctly at the factory it becomes very frustrating. And I am not inferring anything directly with Ranger Tugs. At least they have fantastic factory support to solve many problems. Just saying.

Jake

 

[Binare]

Sorry I this is a bit off topic but it is just this kind of thing which keeps me (a non-mechanical type) from upgrading to a larger boat made by any manufacturer. Enough things go wrong just because things go wrong but when you add in things that weren't done correctly at the factory it becomes very frustrating. And I am not inferring anything directly with Ranger Tugs. At least they have fantastic factory support to solve many problems. Just saying.

Jake

I'm also not pointing fingers at anyone, just stating a simple fact, how this particular piece of equipment is wired... is not according to the recommended specifications.

The big deal for me is that if something like this did cause a fire and wiped out your boat, do you think the insurance company would pay? highly doubt it... they would be directing you to seek out a lawyer and contact the person who you paid to install it.

I deal with UL ratings on equipment all the time, I do have some knowledge of how insurance companies react to improperly installed equipment in cases of loss.

 

[knotflying]

Clear something up for me. Is the wiring going to the batteries 12 gauge? If they are you need to change that wiring to 10 gauge to handle the load.

Regarding some of the manufacturer's questionable installations; having been in construction I had a saying, "You can have all the best engineers and architects design something perfectly and it all falls apart with Wally Wheelbarrow in the Field". You need a strong TQM program. This costs money, but in the long run it saves money, time and aggravation for the manufacturer and the client.

 

[SGIDAVE]

Clear something up for me. Is the wiring going to the batteries 12 gauge? If they are you need to change that wiring to 10 gauge to handle the load.

Hello Mike and others,

There is 12 AWG running to each of the banks. The manual DOES say to use 10 AWG; however I show below where 12 AWG is safe and well within specs.

The fuse holders are rated for 30A; The wire from which they are made is not labelled - it looks like 12 AWG. I agree with Binare that these can 'go bad' that is develop corosion, etc inside which increases resistance and produces heat.

Look at the table below. Focus on the 105 C. rated cable and you see that 12 AWG UL 1426 boat-cable is rated for 45A outside of engine room.

There are no 'jumpers' neither used or needed as correctly stated by Binare.

After reviewing the ampacity charts you see that the 12 AWG wire is OK for the 20A load; the 30A fuse holders are within specs. (but they are nearly 3 years old)

So, my fuse melted for unknown reasons. Yes, I have upgraded my house bank. I have not changed the charging wiring from the way I bought the boat used. My 21EC is unique but my situation, wiring-wise, is likely NOT unique.

I offer my thread as a SUGGESTION to feel your charger wire fuses as charging is under way to make sure they aren't getting HOT.

dave

PS - Here is a very good tutorial showing a BEAUTIFUL installation of a charger like ours (rebranded under the Sterling name)

 

[Binare]

Dave,

Equipment specs if above bare minimum code are always recommended. There is a reason they have suggested that above and beyond what any general code is given.

Those fuse holders whether within spec or not, are pure junk. Take the plastic dipped coating off the crimp connectors on the one that melted and I guarantee youll gonthrough your boat and replace every last of them 🙂

In your example he was recommended 8awg and used i stud and nut fuses, i personally think 8awg is a little overkill, but 12awg is just not acceptable for a charging circuit period!

You also do not read electrical tables like that, regardless of temp rating, you use the 90c column for most installations, including this one. It is also based on an ambient air temp of 30c, if you expect higher, there is a formula to derate the ampacity, there are also rules which conform to what a free air single conductor is, such spacing between wires and the type of installation.

Its very dangerous to look at a table like that and assume you know all the required information to read it, the manufacture of that charger provides the correct information required to install it, to put it plainly... Its just ignorant to install it any other way.

 

[Capt. Wanabe]

I would like to throw in my two bits worth. I don't think the wire gauge size had anything to do with the melt down. The fuse seems adequately sized for the wire. The fuse, if performing correctly, should have protected the wiring from any overload. The fact that it melted the plastic housing indicates an external point of resistance or short that allowed that kind of heat. Below I posted pictures of an installation that I was responsible for that I think is similar. I upgraded my inverter/charger to a Promariner 2000 PS that has a 70 amp charging capacity and a 200 amp inverter capacity. I upgraded the associated wire size to 1/0 awg and made the crimped connections with a high quality tool. Connections were then labeled and heat shrink wrapped with appropriate material. I checked the installation and it seemed OK so left for the weekend. When I came back I discovered the battery side terminal on the anl fuse block was toast. The fuse bar itself was not blown. Now I believe the mistakes were/could have been: 1) The wire itself may have been damaged when I stripped it with a knife. Don't do that. Electricity travels on the outside of the wire and any scratches or burrs may create dangerous resistance. 2) The fuse was oversized. The circuit should have a fuse rated at 110% of the expected and sized load. My fuse was 120%. 3) The fuse block itself may have been damaged or defective. I have not yet tried the re-install but will see how it goes.
Bottom line is that even if sized correctly the installation has to be perfect and the material above reproach.

 

[knotflying]

Excellent points.

 

[Binare]

1) The wire itself may have been damaged when I stripped it with a knife. Don't do that. Electricity travels on the outside of the wire and any scratches or burrs may create dangerous resistance.

Actually you are supposed to strip with a knife, it's called penciling, what you are not supposed to do is "ring cut" the conductor, think of it as whittling the wire. Electricity does travel on the outside of the conductor at high voltages (think powerlines), it's called the skin effect, doesn't happen at 12 volts.

2) The fuse was oversized. The circuit should have a fuse rated at 110% of the expected and sized load. My fuse was 120%.

Oversized fuses apply to a few things, such as motor loads. In this case it doesn't apply and you also don't know the load in any case. Yes your fuse is oversized however, you can go up a size if there isn't one available at the size required. Available doesn't mean you just don't have one, it means if they make one. I highly doubt the fuse size caused this. See below.

3) The fuse block itself may have been damaged or defective. I have not yet tried the re-install but will see how it goes.

The fuse block really couldn't have affected the wire like this, it's basically two bolts. Much more likely that it was a bad crimp, or you ringed the wire when stripping it, or the conductor was dirty, greasy etc. when crimped. Try using a copper brush on the conductor and the surfaces of the fuse and the ring terminal where they contact, also anti-ox is always a good idea in this environment.

Looks like it could even be a defective fuse, I'd check the resistance of it. I'd also use flat washers under your locking washers and get rid of the flat washer between the fuse and the ring terminal, the right side of your fuse is correct, the left is not, do both sides the same as the right side.

Also looks like the wire could have been loose, causing arcing and sparking.

Bottom line is that even if sized correctly the installation has to be perfect and the material above reproach.

That is 1,000% correct!

 

[SGIDAVE]

Binare wrote:

I'd also use flat washers under your locking washers and get rid of the flat washer between the fuse and the ring terminal, the right side of your fuse is correct, the left is not, do both sides the same as the right side.

Here is a tutorial detailing the improper use of a flat washer UNDER a lug on a battery terminal. The Surveyor who wrote this tutorial says the SS flat washers are POOR conductors and, when placed BETWEEN the surfaces meant to 'conduct' they add resistence and heat. (Causing slight melting of the battery case at the post in this case - see tutorial).

Binare, do you think the way Cpt Wannabe installed the LEFT side of the fuse assembly (with the washer BETWEEN the cable lug and the fuse) added resistance then heat and contributed to the melt down? Or, is that nonsense?

Cpt Wanabe I'm not picking on you - just trying to learn how to avoid more melt downs :shock: As I wrote in to you previously, I can't find actual instructions on the ORDER in which the pieces go on the studs for ANL fuse assemblies. Not even on Blue Sea website where they usually have good 'support' info.

dave

 

[Binare]

Here is a tutorial detailing the improper use of a flat washer UNDER a lug on a battery terminal. The Surveyor who wrote this tutorial says the SS flat washers are POOR conductors and, when placed BETWEEN the surfaces meant to 'conduct' they add resistence and heat. (Causing slight melting of the battery case at the post in this case - see tutorial).

Just to be clear, I was suggesting placing the washer under the locknut, not between the ring terminal and fuse.

Binare, do you think the way Cpt Wannabe installed the LEFT side of the fuse assembly (with the washer BETWEEN the cable lug and the fuse) added resistance then heat and contributed to the melt down? Or, is that nonsense?

Certainly not nonsense, definitely a very high possibility that was the issue. Stainless steel(typical material a washer is made of) has 45 times the resistance of copper.

Before anyone asks why the washer wouldn't be burnt like the copper, copper conducts heat 30 times better than stainless steel.

I can't find actual instructions on the ORDER in which the pieces go on the studs for ANL fuse assemblies. Not even on Blue Sea website where they usually have good 'support' info.

There really is no order, personally I put the fuse on last, if I ever need to change it, I don't need to remove anything else.

On a battery or stacking ring terminals off a busbar, you want your highest amp draw closest to the battery or bus bar, then your second highest... so on and so forth.

I use something like these for this type of application:

https://www.bluesea.com/products/5191/M ... 30_to_300A

They cost more than nut and stud mounts but amount to less mechanical connections and thusly, less failure points.

 

[Capt. Wanabe]

Above advise greatly appreciated!

 

[Binare]

Above advise greatly appreciated!

Anytime. Electrical is daunting, I am a Master Electrician who has worked in Industrial, Commercial as well as Marine in all systems up to 34,500 volts. I love sharing what I have learned, even if I do come across as an Ahole once in awhile. I take electricity very seriously, it not only can cost money but also lives. I've seen what misinterpretation, misguidance and unfortunately ignorance can cost people and it is definitely not pretty.

 

[Capt. Wanabe]

So I looked up the thermal and electrical conductivity of the metals in question and it looks like Binare wins the Trivial Pursuit prize for chemistry! I must admit I didn't believe you as the disparity between copper and SS simply seemed to huge to be correct but according to the tables you are right on. Which would then make me wonder why they would sell SS washers with a fuse block like that. I am now just about convinced it was the misplaced washer that caused the resistance. SGIDAVE has very sharp eyes to have picked that out. Thanks for noticing!