[C320-list] Problem purchasing Battery Charger inline Fuses

[DAVE Swanson]

Jeff,

I ran into a similar problem this last spring when I upgaded my battery bank to Trojan T-105 GC batteries (450Ah) and installed a new Sterling Ultra Charge Pro 40A Charger. 

I recall reading that you should size your charger for approximately 10% of your battery capacity, hence I upgraded my perfectly fine 2008 Charles 30A charger to the 40A Sterling.  I found that my stock inline charger fuses for my 2008 C320 Mk II were the KTK-40 A Buss fuses that you mentioned.  These KTK fuses are kind of expensive and I could not find them in a 50A rating.  I also read that you should size the in line charger fuses for 125% of the rated charger capacity, hence my 40A stock KTK fuses for my stock 30A charger.  

Consequently, I was finding it difficult to located an equivalent KTK 50A fuse for my inline fuse holder for my new 40A charger.  Then I came across the same AGU glass fuses that you note.  These apparently are used in car stereo systems to protect current hungry amplifiers and subwoofer in these booming car stero systems.  These AGU glass fuses fit the stock in line fuse holders that my KTK-40 fuses used to fit in and they are very inexpensive.  So, that is what I am using currently in my new battery charger and GC battery upgrade.  I also have spares on board due to their low cost and availability.

I also have expensive Blue Sea ANL fuses within 8 inches of each battery positive post in accordance with AYBC.  I don’t quite remember their rating though.
upgraded
Anyway, i am using the AGU glass fuses in my set up.  They seem to work fine.

Dave

 
> On Sep 15, 2015, at 5:22 PM, Jeff Hare <Catalina at thehares.com> wrote:
> 
> Hi All,
> 
> We originally had FNM-30 amp slow blow midget inline fuses from the factory
> for our ProMariner 20-3 charger.  We upgraded our ProMariner to a Charles 40
> years ago and never gave a thought to the inline fuses at the time.  We
> never had a problem until Thor struck this summer and blasted those little
> guys to pieces.  So, we replaced our blown Charles 40 with a new Charles 50
> charger and all I had was more 30a slow blow fuses.  That seemed to work
> fine.  The charger is a 3 bank charger that will produce up to 50a on one
> leg, 25a on two legs, or 17a on 3 legs.  Catalina wires the 320 for 2
> batteries so the third charger leg isn't normally used anyway.
> 
> But the largest fuses I can find like these are KTK-40 amp fast acting
> fuses.  I looked (I think) everywhere for higher rated ones in the same
> physical size.  No luck.  But I was finally able to find AGU type glass
> fuses rated at 50and 60 amps (fast acting) that LOOK like they might fit the
> factory inline fuse holders.  Has anyone used AGU fuses in the charger
> inline fuse holders?
> 
> So all that got me thinking that to be safe (ie: protecting myself against
> Warm Beer Syndrome), I need 50a inline fuses because, so if one of those two
> were to blow or one leg were connected to a fully charged battery and the
> other connected to a discharged battery, I'd likely blow the remaining fuse
> the next time the charger kicked in. . and suffer the aforementioned WBS.
> 
> Anyone know what kind of fuses fit these holders that are >= 50a?
> 
> -Jeff
> 
> PS:  This all came to be, because someone on the dock shut off my breaker by
> accident and the fridge drained my batteries. AND I had forgotten to replace
> one of the two blown charger fuses when installing the new charger.  53amps
> through a single 30amp fuse isn't an ideal match.  I fired up the engine
> with the new AmpTech 125 alternator / Balmar MaxCharge regulator and watched
> the current hover around 100amps charging current for over an hour (or
> basically until I was about deaf from the engine noise).
> 
>