Retrofitting a 200Ah LiFePO4 bank into a Transit-based MH — wiring layout questions before I commit

Been planning this for a few months and finally pulling the trigger on a Fogstar Drift 200Ah 12V as the heart of a new leisure bank in my Transit-based van build. Currently running a knackered 110Ah AGM that barely holds 50% SoC by morning, so it's well overdue. Pairing it with a Victron SmartSolar MPPT 100/30 feeding from two 175W panels on the roof, and a Victron Orion-Tr Smart 12/12-30A for the alternator side.

The bit I'm wrestling with is the wiring topology. I've read conflicting things about whether to run the Orion and the MPPT outputs to the same busbar before hitting the battery, or to wire each charge source directly to the battery terminals independently. Victron's own docs seem to suggest independent connections are fine, but I've seen people argue that running everything through a single positive busbar with appropriately rated fusing is cleaner and easier to fault-find. My cable runs are around 1.5–2m from the charge sources to where the battery will sit under the bed.

Also curious about fusing strategy — I've got a 60A MIDI fuse planned for the MPPT output, 40A for the Orion, and a 250A ANL on the main battery positive before the busbar. Does that hierarchy make sense, or am I over-fusing anywhere? The loads side will be a separate negative busbar and a Victron SmartShunt 500A inline on the negative before everything ties back to the battery.

Has anyone done a similar dual-source setup with Fogstar's Drift range specifically? Keen to know if the BMS plays nicely with both charge sources cutting in simultaneously, particularly whether it causes any nuisance trips on the BMS over-current protection when the alternator kicks in hard after starting.

WildWanderer | Posts: 847

@Charlie1981 Solid choice on the Fogstar Drift — cracking battery for the money. One thing worth flagging before you finalise your layout: make sure your fusing is as close to the battery positive terminal as physically possible, ideally within 300mm. With LiFePO4 you can pull some serious current and unprotected cable runs are no joke if something shorts.

Also worth double-checking your alternator charging situation early doors. The Drift's built-in BMS handles a lot, but if you're planning to charge via the Transit's alternator, a DC-DC charger (B2B) like a Victron Orion is pretty much essential — modern smart alternators really don't play nicely with lithium without one.

What's your planned solar setup alongside it? That'll probably influence where you position things in the van.

YEL_Marine | Posts: 312

@Charlie1981 Good shout on the Fogstar — they've got solid QC from what I've seen. One thing people often overlook on Transit builds specifically: the chassis earth return path. Before you commit to your negative busbar location, check how far you are from a decent bodywork earth point. Transit floors can be awkward with the ribbing, and a poor earth introduces all sorts of gremlins — especially once you've got an inverter in the mix.

Also worth thinking about your fusing between battery and busbar — I'd go ANL rather than a blade fuse at that capacity. Keeps things tidy and is far easier to service in a tight bay.

What's your charging setup looking like? B2B from the alternator, or solar as primary?

SaltyRigger | Posts: 23

@Charlie1981 Quick one — have you thought about where the BMS will sit in relation to your fuse placement? With LiFePO4 the common mistake I see is people fusing too far from the battery terminals. ABYC/best practice says within 500mm ideally.

Also curious what you're planning for a DC-DC charger from the alternator — are you going the Victron Orion-Tr Smart route or something else? I'm in a garden office setup rather than a van but went through similar decisions with my Fogstar bank, and the Orion made a massive difference to how reliably the battery topped up.

What's your planned inverter load? That might affect whether 200Ah is actually enough for your use case or whether you'll wish you'd planned for a second battery from the start.

Alan1992 | Posts: 156

@Charlie1981 Nice one, the Drift is a solid bit of kit. Something worth considering that hasn't been mentioned yet — think carefully about your fusing arrangement between the battery and your busbars. With LiFePO4 you can pull some serious current compared to your old AGM, so make sure your main fuse (I'd go ANL style, close to the battery positive terminal) is rated appropriately for your cable gauge rather than just your load. A lot of people size the fuse for the loads and forget the cable itself needs protecting. Also double-check the Drift's maximum continuous discharge rate against what your inverter might demand if you're planning to add one later. Would save you rewiring down the line!