E-box fuse sizes

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dav1d

Member
I'm going to try making my DCDC leisure battery install a bit neater, and as part of this was going to move the fuse that is between the van battery and DCDC charger down in to the E-box (underneath the van battery) like the factory fitted aux battery install (ours didn't come with this option).

Before I go stripping it all out and removing the van battery, can someone tell me what (physical) size of fuse goes in the E-box - is it a midi or a mega link fuse?

From what I understand, I need to fit a fuse in position 3 (SA3).
 
MiDi fuses I think..

The maxi are a lot bigger
 
Electric-ian said:
Can someone confirm fuse 3 is what feeds the taped up spare cables under the passenger seat? Also is the E-box under the battery? What's the process on removal. Tia
Click to expand...
yes and yes and remove the battery, unscrew the screws of the e-box cover and remove the cover.
 
Loz said:
yes and yes and remove the battery, unscrew the screws of the e-box cover and remove the cover.
Click to expand...
And don't forget the trick of removing the blank from the little fuse box and sliding it over so that it stays below when you remove the big plastic cover.
 
rod_vw said:
And don't forget the trick of removing the blank from the little fuse box and sliding it over so that it stays below when you remove the big plastic cover.
Click to expand...
You've lost me lol. Can you explain as I'm yet to remove the battery to find the E-box. Appreciate any tips
 
Electric-ian said:
You've lost me lol. Can you explain as I'm yet to remove the battery to find the E-box. Appreciate any tips
Click to expand...
Apologies to @Loz but in his absence...
  1. Remove the battery, may have a felt 'jacket'.
  2. Remove the parts of the plastic shield between the battery area and the engine, probably three pieces at least one fixed with a nut or bolt.
  3. Remove the metal carrier plate that the battery rests on. Four 8mm (EDIT 13mm) headed bolts I think.
  4. Open the lid of the small fuse box (two 90 degree turn clips) located in the now revealed large flat plastic 'E' box cover.
  5. Remove the plastic spacer that is fitted beside the fuse mounting, yes I know it's not easy releasing the two clips whilst lifting it out!
  6. Remove carefully the T20 Torx screws that hold the big plastic lid in place. Don't drop any as they are a swine to find later!
  7. The big lid will now lift off but the loom to the afore mentioned fuse box will try to hole it back, the fuse mounting should slide to the area where the plastic spacer was and then drop out of the way.
Hey presto you have access to the 'E' Box and all its secret. Treat the contents with respect as your van won't like you making any errors in here.

If you are trying to get additional cable(s) into this box make sure that the entry point is grommeted and sealed, damp in here will cause endless and expensive problems later.

Haynes manual rules apply - assembly is the reverse of diss-assembly.
 
Last edited:
Top man, thanks for the detailed response, it's very much appreciated . I'm hopeful to find the feed to the 2 random cables left under the passenger seat. 1, I think 10mm and 1 possibly 4mm taped up in the loom which are permanent live. I've re-routed to the drivers side, hopefully using as the feed to the 30 amp DC-DC Renogy MPPT charger.
 
Sorry to resurrect this post!
Wire #3, looks to be around 10mm in size and routes to under the passenger seat, fused at 100A.
Could this be larger than 10mm? It seems the rating of a thin walled 10mm cable is 70A, and 16mm around 110A.
We’re these photos taken from a T6 or a T6.1 or would they be the same?
 
Gary_M said:
Sorry to resurrect this post!
Wire #3, looks to be around 10mm in size and routes to under the passenger seat, fused at 100A.
Could this be larger than 10mm? It seems the rating of a thin walled 10mm cable is 70A, and 16mm around 110A.
We’re these photos taken from a T6 or a T6.1 or would they be the same?
Click to expand...

10mm / 100A is correct and the photos are from T6. Wire ampages are for continuous current over long periods but fusing is for short peaks intended to protect against shorts. 100A fuse does not mean the associated circuit is designed to take 100A load for very long.
 
Gary_M said:
Sorry to resurrect this post!
Wire #3, looks to be around 10mm in size and routes to under the passenger seat, fused at 100A.
Could this be larger than 10mm? It seems the rating of a thin walled 10mm cable is 70A, and 16mm around 110A.
We’re these photos taken from a T6 or a T6.1 or would they be the same?
Click to expand...
The wire from SA3 can be either 10mm or 16mm depending on the features of the vehicle. 16mm is used on vehicles with twin secondary batteries (i.e. some Californias) most others are 10mm. The fuse in SA3 can be either 50A or 100A again dependant on features of the vehicle.
 
n10n said:
10mm / 100A is correct and the photos are from T6. Wire ampages are for continuous current over long periods but fusing is for short peaks intended to protect against shorts. 100A fuse does not mean the associated circuit is designed to take 100A load for very long.
Click to expand...
Thanks very much.

rod_vw said:
The wire from SA3 can be either 10mm or 16mm depending on the features of the vehicle. 16mm is used on vehicles with twin secondary batteries (i.e. some Californias) most others are 10mm. The fuse in SA3 can be either 50A or 100A again dependant on features of the vehicle.
Click to expand...
Thanks. Guess I’d better take a look at the fusing on mine. If it’s indeed 50A I take it there wouldn’t be an issue changing it to 100A?
I was hoping the cable would have been 16mm on a 100A fuse which meant I could have used a 75A fuse just before a 50A DC-DC charger (as per Renogys instructions).
Failing that, I’ll fuse at 60A as I was always planning on limiting the charger to 30A through its settings anyway. Would have been nice to run at full load if needed though.
 
Running at 30A Vs 50A will not make a huge difference unless you have a very large battery and regularly depleting it heavily (usually heavy inverter use) and allows everything to run cooler and kinder to the battery for long term health.

Even if you occasionally needed 50A it's better to enable it as and when needed rather than bulldozing charge into the battery every time you run the engine (unless your van is using it for daily work of course)
 
roadtripper said:
Running at 30A Vs 50A will not make a huge difference unless you have a very large battery and regularly depleting it heavily (usually heavy inverter use) and allows everything to run cooler and kinder to the battery for long term health.

Even if you occasionally needed 50A it's better to enable it as and when needed rather than bulldozing charge into the battery every time you run the engine (unless your van is using it for daily work of course)
Click to expand...
That’s the intention - 50A as and when (or even if) needed. 30A for all other times. Not a work van, just a weekend camping van with the occasional week away. Using a 105Ah battery with a Delta for 240 use so no inverter. I reckon our biggest future load will be a fridge.
Thanks
 
50A into a 105Ah battery is pretty brutal - normal charge would be around 0.3C (C being the nominal capacity of the battery)
 
It’s a bit late, but your wires underneath the seat @Gary_M may instead run from SA8.

Whilst I’m there, and to save me removing the battery etc to see, does anyone know the size of the terminal studs in the e-Box? I’m looking to run a 16AWG cable from SA3 to my leisure battery (and leave the smaller gauge SA8 in place to run the power-latching doors etc, that being fused at 50a)

EDIT TO ADD
Just found this thread - M5
 
Ads_Essex said:
It’s a bit late, but your wires underneath the seat @Gary_M may instead run from SA8.

Whilst I’m there, and to save me removing the battery etc to see, does anyone know the size of the terminal studs in the e-Box? I’m looking to run a 16AWG cable from SA3 to my leisure battery (and leave the smaller gauge SA8 in place to run the power-latching doors etc, that being fused at 50a)
Click to expand...
I went ahead and used the large red cable under the seat to supply a Renogy 50A DCDC charger limited to 30A and it’s been working perfectly fine. Any idea what the disadvantage would be if this originated from SA8 instead of SA3?
 
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