Inline battery fuse holder
- Thread starter Pack Mule
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Iggy
Guru
What is the size of the charger? How many amps? If possible I would use a breaker or the same type of fuses that your boat currently uses. The less styles of fuses you need to carry the better.
ancora
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Installing a "smart" charger to replace a resonant charger. The specs call for a fuse on every cable to the batteries, yet for the 21 years we've owned the boat there were none. The battery charger circuit has it's own breaker. What gives?
C lectric
Guru
Most, even my now quite old charger have a built in C.B./Fuse so the wiring is protected from the charger side.
THe real danger is from the batteries themselves.
If the supply cable between the charger but after the built in C.B/Fuse is shorted then the batteries become the main power source. Depending upon the battery size they can supply thousands of amps. Not for very long but long enough to fry the charger wire and turn it into a bunch of smoke, maybe a fire.
If the problem is bad enough under short circuit conditions the battery itself can explode. Thus the need for a C.B./Fuse as close to the battery as possible.
I used the small square block fuse mounter right on the battery terminals, three of them. THat requires an adapter but now my system is protected just in case a short develops. Blue Seas or Ancor but made by Bussman Fuses, now Littlefuse Co.
In my case I have 3 8D Gel batts. with a 150A fuse mounted right on the terminal with # 4 AWG wire running to a buss bar for distribution. THere is enough battery and fuse capacity to carry all loads but if a short develops in the wiring after the battery connection the fuse is small enough to blow without frying the wiring yet not be subject to nuisance trips.
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C lectric
Guru
PackMule,
to answer your question.
I suspect a 15 or 20A fuse will be too small. I would suggest at each of the battery enda you use a fuse about 20% to 25% larger than the full charger output. That will protect the wiring from the batteries in case of the above yet avoid nuisance trips. You will need a strong mount for the fuse holder.
You should also be using a wire sized for the full charger output to each battery in the case of multiple banks.
to answer your question.
I suspect a 15 or 20A fuse will be too small. I would suggest at each of the battery enda you use a fuse about 20% to 25% larger than the full charger output. That will protect the wiring from the batteries in case of the above yet avoid nuisance trips. You will need a strong mount for the fuse holder.
You should also be using a wire sized for the full charger output to each battery in the case of multiple banks.
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ancora
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In my case, the boat is so old, to bring it up to ABYC standards would be cost prohibitive. There are some things I just have to accept and this is one of them.
Comodave
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+1. I use a Blue Seas MFBF 3 fuse holder for my 3 bank battery charger. It is a 60 amp charger so I used 75 amp fuses and cable rated for 75 amps to the battery bank.
kchace
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This past winter I cleaned up the wiring around my batteries which had individual fuses and went with MRBF 3 fuse holders and it really helped organize and clean everything up while keeping all branches properly protected.
Ken
Any reason why a manual reset circuit breaker would work?
I have used one like this for charging a towed vehicle behind our motorhome. If it trips it eliminates the need to have / find a spare fuse.
http://www.uneeksupply.com/INLINE-2...UAL-RESET-12V-20A-4-6-8-AWG-GAUGE_p_6619.html
I have used one like this for charging a towed vehicle behind our motorhome. If it trips it eliminates the need to have / find a spare fuse.
http://www.uneeksupply.com/INLINE-2...UAL-RESET-12V-20A-4-6-8-AWG-GAUGE_p_6619.html
I looked at using the BS MRBF Fuse & holder on a planned batty bank but noticed the hole for batty lug is 3/8" and my batty lugs are 5/16"... anyone found a work around?
Comodave
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I believe they make both 5/16” and 3/8” ones.
I've searched every way I know but can only find 3/8" hole for 3/8" stud.
C lectric
Guru
What kind of battery terminals do you have?
Usually the 3/8 stud is for a Positive wire with a 3/8 hole in the wire lug.
Usually the 5/16 stud is for a Negative wire with a 5/16 hole in the wire lug.
Usually the 3/8 stud is for a Positive wire with a 3/8 hole in the wire lug.
Usually the 5/16 stud is for a Negative wire with a 5/16 hole in the wire lug.
Battys I'm looking at have 5/16 posts on both and was looking at using the MRBF style.
Its seems odd the holder has 3/8 hole for batty but then uses a 5/16 ring terminal to fit the stud for the fuse end.
Its seems odd the holder has 3/8 hole for batty but then uses a 5/16 ring terminal to fit the stud for the fuse end.
Comodave
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I looked and you are correct, I only see them in 3/8”. I thought they made them in both sizes but they don’t.
C lectric
Guru
Actually a C.B. would also work. I was suggesting the MFDF fuses because they can be mounted literally on the battery post. One of the reasons I went with them. I had considered C.B.s but I do not have a lot of room to play with.
I have used washers to make up for a mismatch of bolts and holes. I used either a copper washer or a silicon bronze washer. Yes, the conductivity is some what lower than the properly sized connection but it is so small that it is of little consequence unless the current flow is absolutely huge.
As for the 5/16 bolt through the actual fuse I don't think it matters as there is lots of clamping force. Most of the current flow will be between the fuse metal and the cable terminal. THe bolt is adequate for the current it will see.
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Thnx for responses - to close this out here is the reply I got from Blue Sea Tech Rep that is consistent with C lectric's coments...
"Cooper Bussmann the maker of the MRBF Fuse holder does not offer a 5/16” version.
The holes are very close and most installers have no issues using the 5191 on a 5/16” stud."
That is likely what I will end up doing as the capacity/ capability to handle the ampere interrupting capacity (AIC) is of prime consideration.
"Cooper Bussmann the maker of the MRBF Fuse holder does not offer a 5/16” version.
The holes are very close and most installers have no issues using the 5191 on a 5/16” stud."
That is likely what I will end up doing as the capacity/ capability to handle the ampere interrupting capacity (AIC) is of prime consideration.
sbman
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The AYBC recommendation is to have overcurrent protection within 7" of the connection to the DC system. If connected directly to the batteries and the wires are more than 7" long then you'd want to have a fuse or circuit breaker mounted within 7" and then run to the charger. (31.5.2.3.1)
Correct
The Blue Sea MRBF units mount right to the batty stud terminal and comply with ABYC 7" reqmt easily.
In addition the high amp ones also comply with ABYC Amperage Interrupt Capacity (AIC) for main connections to batty.
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Sofa King Fishy
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Agreed~ Easy & effective.
diver dave
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I do industrial electronic design including various types overcurrent protection, but my real job is getting my sailcat ready for the ocean.
Its French designed, which could be a book in itself. [emoji856]
In anycase, a lithium house bank is going in with 150A terminal fuses on each pos post. I like the design of these guys, and with parallel batts, seems to be warrsnted. My question is why the NEG side engine disconnects, and why dual pole breakers on some loads, like the autopilot?
Even some radios have NEG side fusing( ssb and vhf).
Its French designed, which could be a book in itself. [emoji856]
In anycase, a lithium house bank is going in with 150A terminal fuses on each pos post. I like the design of these guys, and with parallel batts, seems to be warrsnted. My question is why the NEG side engine disconnects, and why dual pole breakers on some loads, like the autopilot?
Even some radios have NEG side fusing( ssb and vhf).
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