MODULARITY COST AND REPLACEMENT WORKSHEET
Purpose: compare a supported modular configuration with a fixed alternative over the same fleet size and period. Use documented part compatibility and supplier quotations; the worked example below uses invented nominal USD amounts.
Fleet size / comparison horizon / currency:
Device, module and revision / supplier compatibility evidence:
Approved procedure, tools and person allowed to replace the part:
Software mapping, dock, battery, seals, warranty and support horizon:
Spares by site and delivery time:

COST MODEL
N = number of devices
P = modular premium per device
S = incremental initial spare stock and tools
T = incremental training
F = fixed-route repair cost per qualifying event
HF = productive hours lost per fixed-route event
M = replacement module consumed or replenished per modular event
L = modular technician labor cost per event
HM = productive hours lost per modular event
R = assumed cost per lost productive hour
E = qualifying events during the horizon
A = N*P + S + T (incremental starting cost)
B = (F + HF*R) - (M + L + HM*R) (saving per qualifying event)
Net saving = E*B - A. Negative means the modular option costs more in this model.
If B is positive, whole-event break-even = round A/B UP to the next integer.
If B is zero or negative with a positive starting premium, event savings do not repay that premium.

FICTIONAL THREE-YEAR EXAMPLE
N=40, P=$120, S=$600, T=$400. A=$5,800.
F=$300, HF=2 hours, M=$90, L=$15, HM=0.5 hours, R=$30/hour.
Fixed event cost=$360; modular event cost=$120; B=$240.
E=20: net saving=20*$240-$5,800=-$1,000.
Break-even=$5,800/$240=24.17 events; at least 25 whole events.
E=30: net saving=$1,400.
Initial spare inventory and consumed/replenished parts are counted separately. No residual value is assigned to stock. Financing, tax and equal costs are omitted. Adapt to your accounting method. Exclude failures the module cannot fix and avoid double-counting downtime already covered elsewhere.

YOUR BASE / FEWER-FAILURE / LONGER-REPLACEMENT / SHORTER-SUPPORT CASES
Inputs and evidence:
Starting premium:
Saving per qualifying event:
Event count and net result:
Residual value, financing, tax or other added adjustments:
Operational benefit accepted even if net cost is higher:

REPLACEMENT PILOT
Saved task state / exact parts and procedure:
Elapsed interruption including fetching spares and setup:
Correct keys, trigger, dock and charge checks:
Correct test transaction verified in business system:
Problems, lost settings and corrective action:
Owner of compatibility matrix and service records:

Yenra guide and source context: https://yenra.com/modular-mobile/
Prepared October 6, 2026. Planning aid; hardware procedures were not physically tested.