SDMO Generators: 7 Questions Buyers Ask Me (Answered by Someone Who's Made the Mistakes)

If you're shopping for an industrial diesel generator, you've probably typed "sdmo-generator" into a search bar and spent an hour trying to figure out what the Kohler SDMO badge actually means. I was in the same spot in 2017 — a junior buyer who thought a kilowatt was a type of fence.

Seven years later, I've helped spec generator sets for warehouses, machine shops, and small manufacturing plants. I've also made some expensive mistakes: about $40,000 in wasted budget, if you count the rework, the rushed freight, and the generator that sat on a trailer for six weeks because I forgot to order a transfer switch. So this is the FAQ I wish someone had given me back then.

1. Are SDMO and Kohler the same company?

Yes. Kohler acquired SDMO in 2005, and SDMO now operates as Kohler's industrial diesel generator arm. Depending on the market, you'll see the same basic machine sold as SDMO, Kohler, or "Kohler SDMO." One engineering family, one warranty, one support network.

This matters because I've watched buyers treat "Kohler" as the premium option and "SDMO" as the budget one — and pay more for the same product. The badge doesn't set the spec. The spec sheet does.

2. Is a 70 kVA Kohler SDMO generator big enough for my facility?

Let's get the math out first. At 0.8 power factor, a 70 kVA generator delivers about 56 kW of usable power. That's enough for a good-sized auto workshop — lifts, lighting, office loads, and maybe an air compressor if it's not cycling constantly. Whether it's enough for your facility depends on your load profile, not on the brochure.

My first big mistake was sizing a client's backup set for "everything at full load at the same time." No facility runs like that. You need to account for starting surges: a 10 HP motor can draw two to three times its running current for those first few seconds. The compressor kicking in is what trips the generator, not the total.

And check the rating basis. ISO 8528 separates prime and standby ratings. A "70 kVA" nameplate might be the standby rating — or rather, probably is, because vendors lead with the bigger number. For continuous running, you need the prime rating, usually about 10% less. That single detail has embarrassed more buyers than you'd think.

3. Is a single 200 kVA SDMO generator better than two 100 kVA units?

If your peak running load sits somewhere in the 130–160 kW range after demand factors, a single 200 kVA SDMO generator is the simpler call: one fuel line, one transfer switch, one maintenance schedule.

But here's the counterintuitive part. Everything I'd read as a junior buyer said bigger is safer. In practice, bigger was the source of the problem. A diesel set that loafs at 15% load for long stretches can wet-stack — unburned fuel and carbon build up in the exhaust, and the engine degrades in ways that don't show up until you need it most.

NFPA 110 requires emergency systems to be periodically tested under load. Doing that test gets a lot harder when your 200 kVA set can't safely be loaded by the building it powers. So think about your actual load range before you buy future spare capacity.

If your site needs 24/7 uptime, two 100 kVA units with one acting as N+1 backup might be the better spend. If you're in a "keep the lights on" situation, the single 200 kVA set is usually enough — and cheaper.

4. Diesel vs gas generator: which one really costs less?

Short answer: it depends on your usage pattern, fuel availability, and how much you value independence from the grid. Long answer:

Diesel sets have heavier engines, longer service intervals, and can run on stored fuel. Natural gas sets are cleaner, quieter, and cheaper to run per hour when gas is at normal commercial rates. But gas generators only work where a gas line exists, and during a wide-area grid event, gas supply can drop exactly when you need it.

Looking at Q2 2024 U.S. EIA data: commercial natural gas averaged roughly $10–11 per thousand cubic feet, and on-road diesel around $3.80 a gallon. Running a 200 kW generator for eight hours at those prices costs on the order of $430 in diesel versus $170 in gas. Fuel alone, gas wins.

When I put diesel and gas projects side by side at actual sites, though, I saw why the spreadsheet lies. The gas set's skid costs more. Installation varies with the utility. And if your operation's value comes from being able to run with no grid connection at all, diesel's fuel independence can be worth thousands in avoided downtime.

So the honest answer: calculate your annual run hours, check local fuel prices in the EIA data, and then weigh the worst-case outage scenario. That last step is where the real cost shows up.

5. Can a 20k portable generator replace a standby generator?

I get asked this a lot. A "20k portable generator" is a serious piece of equipment — it can run several essential circuits and keep a small site going through a short outage. But it's a different tool, and I say that as someone who once recommended one to a client and watched the plan fall apart.

The problems: no automatic transfer switch. Someone has to physically roll it out, connect it, and switch the loads. Most portable units run on a tank you can carry, and a 20 kW set at full load burns around 1.6 gallons per hour — so a standard 30-gallon tank gives you about 19 hours before a refuel in the rain.

And for a business, the question isn't "can it power something?" It's "can it power what matters, automatically, when nobody's around?" A standby generator with an ATS comes on within seconds and runs as long as the fuel lasts. That's the reliability you're paying for. Portable units have their place, but replacing a standby unit at a facility isn't it.

6. What about the Jackery 300 solar generator? It's way cheaper.

I almost bought a Jackery 300 solar generator for our site office myself, so I won't trash the idea. They're genuinely useful for camping, for charging laptops, for keeping phones alive. But let's be clear about what "300" means: 293 watt-hours of total capacity.

Plug a 1,500W space heater into a Jackery 300 and it's empty in about 12 minutes. A 70 kVA Kohler SDMO generator would run that heater indefinitely without noticing. To put it another way: one hour of the 70 kVA set at rated output is roughly 190 full charges of the Jackery 300.

Is there a place for a Jackery 300 in a B2B facility? Sure — as a backup for communication equipment in an office, or as a lighting source during an indoor outage. As a replacement for an industrial generator? No. Trust me on this one: for a facility, capacity and automation matter more than the label.

7. What's the most expensive generator mistake you've seen?

Comparing quotes by unit price alone. I've been that buyer.

In 2019, I approved a generator purchase that was about $4,000 cheaper than the next proposal. I felt smart for a month. Then came the rigging, the extra conduit, the commissioning that was never in the quote, and a controller that needed replacing after a surge event — I want to say that controller was about $3,400, though the exact number's hazy. The final cost landed roughly $11,000 above the supposedly overpriced alternative.

So now I use a simple TCO checklist before I compare any two quotes:

• Unit price — the first line, not the last
• Freight, rigging, and installation (concrete pad, conduit, wiring)
• Fuel system — day tank, sub-base tank, or connection to bulk fuel
• Automatic transfer switch and controls
• Commissioning and load bank testing — get it in writing
• First-year maintenance, parts, and labor
• Warranty terms — what's excluded and who pays freight on claims
• Downtime cost per hour if the set fails

Add those up and the "cheap" quote starts looking very different. I wish I'd learned that before the $40,000 lesson, not after.