Terminal Battery Fuse Question

[aaronorange]

How should I fuse 3 lithionics 130ah batteries wired in parallel when connected to a 3000W Xantrex inverter? I was having issues with the 300a Optifuse. I was told to replace the Optifuse breaker with a Blue Seas disconnect switch. I’m apprehensive not having a fuse inline. Would a 300amp Blue Seas MRBF terminal fuse be sufficient? I currently use a 400amp under the street side bed. I also plan to add the Blue Seas disconnect ether under the SS bed or in the battery compartment. Thanks! 

Edited Wednesday at 05:17 PM by aaronorange

[mossemi]

@aaronorange  I am not sure what this 300A Optifuse is protecting, so without more information it may be difficult to get an answer.  Can you include some pictures?

Mossey

[aaronorange]

Mossemi- Sorry let me try to clarify, The Optofuse was between the 3 lithionics 130ah batteries and the 3000W Xantrex inverter/charger. (OEM from Oliver) My real question is does anyone use MRBF fuses, if yes what amp fuse are they using? Are they using one fuse or one on each positive terminal? Just wanted to see how others are handling the issue with the Optifuse breaker. I understand others are also having problems. 

Edited Thursday at 12:04 AM by aaronorange

[jd1923]

Far better protection than a breaker, get two of these (to have a backup fuse):

https://a.co/d/bdK8VQb

and a fuse holder like this:

https://a.co/d/9V3H8RB
 

[aaronorange]

JD1923, I got ahold of Lithionics and they say MRBF Fuses are ok. They say I can do a single 300a fuse. This fuse attaches to the battery terminal. So protects right from the source.
I also found out Xantrex recommends a 350a fuse max.
 

So the inline 400a I put in for testing will be down graded to 350a if not removed.

 

Thanks everyone for the help as I researched this issue. 
 

 

 

[Ronbrink]

I used both the MRBF and ANL (250A each) with my LFP upgrade, as well as a Victron SmartShunt. I didn’t add a monitor for the SmartShunt, just use the Victron Connect app. I considered adding a battery cut-off switch, but just use the stock 200A blade breaker between the batts and inverter in like manner. I have the Xantrex 2000W in my 2020 OLEll. 

 

Edited Thursday at 10:51 AM by Ronbrink

[jd1923]

9 hours ago, aaronorange said:

JD1923, I got ahold of Lithionics and they say MRBF Fuses are ok. They say I can do a single 300a fuse. This fuse attaches to the battery terminal. So protects right from the source.

I use MRBF fuses for a positive bus I installed and also on my truck battery connecting our DC-to-DC charger. They are simple and inexpensive. And yes go with 350A given your Xantrex manual lists this spec.

The ANL holder may fit better in place of your 300A breaker. If you install at the battery (either location is fine), then you will have to replace the positive cable or put another simple bus-bolt connection in place of your original breaker. 

[mossemi]

@aaronorange  did you replace the OEM 300A breaker with a 400A breaker?

It was not clear to me that the 400A was for testing purposes.  If you haven’t had any issues with the 400A breaker, it may be that the 300A breaker was simply undersized for 390 AH's of batteries.

Mossey

[jd1923]

The fuse rating should be based on the max load amperage plus a safety margin (+25%). Ah of batteries is not a factor except for runtime.

The inverter is the largest load in an RV. Xantrex specs 350A as shown above. Victron specs 400A for the Multiplus II 3KVA inverter-charger. Best to go with manufacturer’s specs. The 400A is likely OK for the Xantrex too, or buy a 350A fuse and keep the 400A as a backup.

OTT installed a 300A breaker which has little margin if your running at a 3KW inverter at capacity. But you would have to run your A/C and microwave on inverter simultaneously to get to near 300A! 🤣

Edited Thursday at 08:27 PM by jd1923