Battery Check for Diesel Pickups
Most heavy-duty diesel pickups carry two batteries wired together, because a diesel needs a lot of current to crank and to run its glow plugs or intake heater in the cold, and our battery check at participating locations tests both. The Car Care Council suggests testing at three years old and before every winter; Minden averages about 75 nights a year at 20 F or colder (NOAA 1991-2020 normals).
4.7 stars from 952 Google reviews
- No appointment needed
- Service while you wait
- Since 1983
- 4 Northern Nevada service centers
- 4.7 stars, 952 Google reviews
A cold diesel is the hardest thing a battery does. Before it cranks, the truck warms the cylinders with glow plugs or an intake grid heater, which can draw a lot of current for several seconds, and then the starter has to turn over a high-compression engine through cold, thick oil. Two batteries share that work. When one of them gets weak, the other carries the load and wears out faster.
When to test
Test at three years, then every fall, per the Car Care Council. For a diesel in the Carson Valley, earlier is better: Minden logs about 188 freezing nights a year and Carson City about 146 (NOAA 1991-2020 normals). If the truck is plugged into a block heater overnight, the batteries get some help, but they still need to deliver on the mornings it is not plugged in.
Why both batteries matter
In a dual-battery truck the two batteries are connected in parallel. A weak one can drag the healthy one down, and a test of the pair together can hide the problem. Where both can be reached, the technician tests each one separately and gives you both results.
- Each battery tested on its own where reachable
- Cranking capacity versus the rating on each label
- Charging voltage with the engine running
- Cables between the two batteries checked for corrosion
the visit
Pull in with the diesel oil change and stay with the truck. At participating locations the batteries are tested during the maintenance check, and the results are explained before you leave. What you do about a weak battery is your decision; nothing is changed without your okay.
Signs to watch for
A slower crank on cold mornings, a wait-to-start light that stays on longer than usual, dimming lights when the heater grid cycles, or a battery warning on the dash. Those can also point to a charging or glow plug issue. We tell you what the numbers suggest and stay within what we test.
Towing and the charging system
A diesel pulling a fifth-wheel or a horse trailer also feeds the trailer's lights, brake controller and sometimes a breakaway battery through the truck's wiring. That steady load means the alternator works harder on long hauls, and a battery pair that is already tired gets less chance to recover. A charging voltage reading taken during the check tells you whether the system is keeping up before a long summer trip across the desert to Elko or Winnemucca.
Sources
- carcare.org/car-care-guide/ (Car Care Council car care guide, inspection and replacement guidance for filters, wipers, batteries and fluids, read 10/15/26)
- ncei.noaa.gov/products/land-based-station/us-climate-normals (NOAA 1991-2020 normals, Reno-Tahoe airport, Carson City and Minden stations: hot days, freezing nights, precipitation, snowfall, read 10/15/26)
- leg.state.nv.us/nrs/nrs-487.html (NRS 487.6875, written estimate and authorization before additional work, read 10/15/26)
Your service center: Reno Northwest
- Call(775) 787-1000Mon-Fri 8 am-5 pm, Sat 8 am-4 pm, Sun closed
- Address6100 Mae Anne Ave, Reno, NV 89523
What a customer said
My wife went in to buy a new battery for her car and they encouraged her to go to the dealer to get the warranty. When she checked and there was no warranty, they tested her battery and did not charge her even though she would have bought a new battery. Lastly, they fixed the XM radio for her for free. Although these were simple things, a lot of shops would have taken advantage of my wife's lack of knowledge of cars and charged her for these. This is a sign of honesty to me.
Related
Drive in. No appointment. Drive out.
Locally owned in Northern Nevada since 1983. No appointment, no pressure: we tell you what the inspection found and you decide.
About usStraight answers
Questions people ask
Still have a question? Call your service center or drive in; there is no appointment to make.
Do you test both batteries on my diesel?
Yes, where both can be reached in the bay, each is tested and the results given to you separately.
Is the battery check at every service center?
It is offered at participating locations. Ask when you pull in.
Does the block heater mean I do not need a test?
A block heater helps cold starts but does not show you battery health. A fall test still makes sense.
Four service centers, no appointment
Drive in today. No appointment needed.
No appointment needed at any of the four service centers. Questions first? Send the form and the service center you pick answers during business hours.
4.7 stars from 952 Google reviews
- No appointment needed
- Service while you wait
- Since 1983
- 4 Northern Nevada service centers
- 4.7 stars, 952 Google reviews