How To Keep 2 Group 31 AGM Truck Batteries Warm In Winter - Diesel Pickup

Updated 01/21/2026 | Published 11/04/2025

Products Featured in This Question

Zerostart Battery Heating Pad - 120V - 160 Watts

(4)

$93.87

Zerostart Battery Heating Pad - 120V - 80 Watts

(4)

$57.61

Question:

I have a pair of Group 31 AGM batteries in my diesel pickup. Would the Zerostart 160-watt heater pad be the right one for those?

asked by: Randy

Expert Reply:

Yes, Randy - the Zerostart 160-Watt Pad Blanket for batteries # ZE27FR is built exactly for Group 31 batteries. It’s a 72-inch wrap designed to fit those large cases and will raise the battery core about 60–70F above outside temps so you keep full cranking power in the cold. Just don’t use it on lithium or ABS-cased batteries. This setup will allow both of your batteries to stay warm if they are next to each other. If they aren't, you'll need two smaller ones like # ZE87FR.

Do you already have a block heater on that truck, or will this be the first step in your cold-start setup?

expert reply by: Andrew N

ZE27FR heater blanket around two batteries
(click to enlarge)

Randy

11/13/2025

Yep, already have a block heater. Truck’s a 2019 Silverado 2500HD Duramax. It’s got two Group 31 batteries, one on each side of the engine bay.

Andrew N.

11/13/2025

@Randy Perfect, thanks for clarifying. Since those batteries sit on opposite sides, you’ll want a separate heater pad for each - either two 160-watt # ZE27FR pads for maximum heat, or two 80-watt # ZE87FR pads if you’d rather go lighter on power draw. Both options will keep the cores around 60–70°F above ambient, which is huge for cranking power in that Duramax. Do you usually plug into a timer, or just let the heaters run overnight when it’s bitter cold?

Randy

11/13/2025

@AndrewN I usually plug it in after dinner and let it run all night. It gets down to –20°F here pretty regularly, so anything helps.

Andrew N.

11/13/2025

@Randy Oh wow! And I thought Missouri winters were brutal lol. Keeping both batteries warm along with your block heater will make that 6.6L fire right up even on the worst mornings. That’s a tough setup for some brutal weather - sounds like you’ve got it handled!