Fieldsheer Mobile Warming Tundra review: the spec sheet everyone else should copy
Of roughly seventy garments converted for this site, this is the one whose maker publishes the most and whose numbers hold up best under arithmetic. The honest catch is that none of that makes the battery bigger.
By Scooter M. · Published October 3, 2026
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The Tundra runs a 7.4 V, 4,000 mAh pack — 29.6 watt-hours — into five zones including both sleeves, with four settings published as "90° up to 135°" and a runtime against every one of them: "2+ High, 3+ MedHigh, 4+ MedLow, 8+ Low". Invert those and you get about 14.8 W on high and 3.7 W on low, or roughly 3.0 W per zone — a figure that matches Fieldsheer's three-zone garments computed from entirely separate numbers. The documentation is the best in the category. The pack is mid-sized, and that is the real constraint.
What Fieldsheer publishes, and why it is unusual
Here is the Tundra's product page in Fieldsheer's own words: "5-Zone Heating System - 2x Chest, 1x Back, 2x Arms", "4 Adjustable Heat Settings (90° up to 135°)", "2+ High, 3+ MedHigh, 4+ MedLow, 8+ Low", and "Powersheer XL Lithium-Ion (7.4V 4000mAh)" with the model number MWCB74V04021.
Count what that is: four settings, each with a runtime. A temperature range. A zone map with placement. The pack's voltage, capacity and part number. No other garment on this site publishes all five of those on one page, and most publish two of them.
The specification, converted
| Setting | Fieldsheer's claim | Implied draw | Per zone (5 zones) |
|---|---|---|---|
| High (up to 135°F) | 2+ hours | up to ~14.8 W | ~3.0 W |
| Medium-high | 3+ hours | ~9.9 W | ~2.0 W |
| Medium-low | 4+ hours | ~7.4 W | ~1.5 W |
| Low (from 90°F) | 8+ hours | ~3.7 W | ~0.7 W |
Energy is 29.6 Wh — our multiplication of Fieldsheer's published 7.4 V and 4,000 mAh, because Fieldsheer publishes watt-hours for none of its eight packs. The implied draw is that figure divided by each stated runtime.
Quick picks
Tap any row to jump to the full write-up below. The energy column is the pack’s capacity times its voltage — the number this category does not print.
| # | Product | Best for | Energy | Price |
|---|---|---|---|---|
| 1 | Fieldsheer Mobile Warming Tundra Men's Heated JacketThe most granular spec sheet of any garment on this site: five zones, four settings from 90°F to 135°F, a runtime for … | Four settings, each with its own temperature AND its own runtime | 29.6 Wh | $199.99View on Amazon |
| 2 |  Fieldsheer Peak Unisex Bluetooth Heated VestThree zones, four settings with temperatures, nine-plus hours on low and full MW Connect app control — at the lowest p… | The cheapest way into Fieldsheer's app control | 16.7 Wh | $139.99View on Amazon |
| 3 |  Venustas Men's Heated Silent Hunting Jacket (Next Camo G2)74 published watt-hours, five zones including both arms and ultra-silent fabric — the most complete hunting-specific s… | Heated sleeves in camo, on the biggest pack here | 74.0 Wh | $199.99View on Amazon |
#ad — buy links are tagged and earn us a commission at no extra cost to you. Prices come from a live feed; where none is available the button reads “Check price” rather than showing a number we cannot stand behind. How we are funded.
Fieldsheer Mobile Warming Tundra Men's Heated Jacket
The most granular spec sheet of any garment on this site: five zones, four settings from 90°F to 135°F, a runtime for each of them, and the battery's model number printed on the page.
#ad Price as of October 17, 2026. How we are funded.
The numbers
- Energy
- 29.6 Wh
- Maker's stated energy
- 7.4 V, 4,000 mAh — 29.6 Wh by our arithmetic
- Settings
- Four, with temperatures: 90°F to 135°F
- Claims
- A runtime for every one of the four settings
- Heated sleeves
- Yes — two of the five zones
- Heat zones
- Two chest, one back and two arms, per Fieldsheer
- Settings
- Four adjustable settings, published as 90° up to 135°F
- Care
- Machine wash cold on gentle only, tumble dry low, per Fieldsheer
On wattage: No wattage published, but Fieldsheer's own numbers invert cleanly: 29.6 Wh over the stated 2+ hours on high is up to about 14.8 W, and over 8+ hours on low about 3.7 W. Across five zones that is roughly 3.0 W per zone on high — and the three-zone Peak vest works out at about 2.8 W per zone from its own separate figures. Fieldsheer's runtimes scale with zone count instead of being copied across the line, which is the opposite of what most makers here do.
On the pack: 7.4 V and 4,000 mAh, which multiplies to 29.6 Wh — our figure, because Fieldsheer publishes watt-hours for none of its eight packs. Note the naming collision: the Tundra page calls this the "Powersheer XL", while Fieldsheer's battery catalog gives that name to a 6,000 mAh pack. Buy spares by model number (MWCB74V04021), not by name.
What we like
- Four settings with both a temperature range and a runtime for each — the most complete garment disclosure here
- Heated sleeves, which most jackets in this price band skip entirely
- The implied per-zone draw matches Fieldsheer's own vest figures, so the numbers were calculated rather than copied
- Bluetooth app control with battery level and per-zone settings
What we do not
- Fieldsheer publishes watt-hours for none of its packs, so the 29.6 Wh here is our multiplication rather than their number
- The same pack name is used for two different capacities depending on which page you read
- 2+ hours on high from a 29.6 Wh pack is short, and that is Fieldsheer's own claim
- Softshell construction — wind and water resistant, not an insulated winter coat
Who this suits
Someone who wants heated arms and wants to see exactly what each setting costs them in hours before they buy.
Who should skip it
You need insulation as well as heat. This is a stretch softshell and the warmth budget is 29.6 Wh.
Spec sources: Fieldsheer — Tundra Jacket Men's ("5-Zone Heating System - 2x Chest, 1x Back, 2x Arms"; "4 Adjustable Heat Settings (90° up to 135°)"; "2+ High, 3+ MedHigh, 4+ MedLow, 8+ Low"; Powersheer XL Lithium-Ion 7.4V 4000mAh, model MWCB74V04021; MW Connect app; machine wash cold gentle; 1 year warranty) · Fieldsheer — Battery Technologies (lists eight packs across three voltages: Powersheer 12V, 7.4V+ Plus, 7.4V Standard Li-Ion, Soft Touch 7.4V, 7.4V Heated Glove Battery, 3.7V Premium Sock Battery, 3.7V Standard Sock Battery, 3.7V Thawdaddy — with no mAh, Wh or runtime figure for any of them)
Fieldsheer Peak Unisex Bluetooth Heated Vest
Three zones, four settings with temperatures, nine-plus hours on low and full MW Connect app control — at the lowest price Fieldsheer charges for any of it.
#ad Price as of October 17, 2026. How we are funded.
The numbers
- Energy
- 16.7 Wh
- Maker's stated energy
- 7.4 V, 2,250 mAh — about 16.7 Wh by our arithmetic
- Settings
- Four, 90°F to 135°F, with a runtime for each
- Charging
- USB-C input
- Shell
- Lightweight polyester with breathable mesh lining
- Heat zones
- Two front and one back, per Fieldsheer
- Settings
- Four adjustable settings, published as 90° up to 135°F
- Care
- Machine wash cold on gentle with the battery removed, per Fieldsheer
On wattage: Not published. 16.7 Wh over the claimed 2+ hours on high is about 8.3 W, or roughly 2.8 W per zone — the same per-zone figure the five-zone Tundra implies from completely separate numbers. That consistency is the strongest evidence we have that Fieldsheer's runtime claims are calculated rather than decorative.
On the pack: The 7.4 V, 2,250 mAh Powersheer pack, about 16.7 Wh by our arithmetic, charging over USB-C. A small pack, but this is also the lightest garment Fieldsheer asks it to run.
What we like
- Four settings with temperatures and runtimes at the least expensive point in the line
- USB-C charging rather than the micro-USB still found on some Fieldsheer packs
- Bluetooth app control, including battery level, at this price
- Light enough to layer under a shell without bulk
What we do not
- 16.7 Wh is a small energy budget however well the claims are calculated
- 2+ hours on high is the honest ceiling
- Mesh-lined polyester offers little warmth of its own with the heat off
- Fieldsheer publishes no watt-hours for this or any other pack
Who this suits
Someone who wants app-controlled heat under their own coat and does not want to pay jacket money for it.
Who should skip it
This is your outer layer. It is a liner-weight vest and the shell contributes almost nothing.
Spec sources: Fieldsheer — Peak Bluetooth Heated Vest (3-zone heating system, 2 front and 1 back; 4 adjustable heat settings 90° up to 135°; 2+ high, 3+ med-high, 4+ med-low, 9+ low; 7.4V Powersheer 2250 mAh; USB-C charging input; MW Connect app) · Fieldsheer — Battery Technologies (lists eight packs across three voltages: Powersheer 12V, 7.4V+ Plus, 7.4V Standard Li-Ion, Soft Touch 7.4V, 7.4V Heated Glove Battery, 3.7V Premium Sock Battery, 3.7V Standard Sock Battery, 3.7V Thawdaddy — with no mAh, Wh or runtime figure for any of them)
Venustas Men's Heated Silent Hunting Jacket (Next Camo G2)
74 published watt-hours, five zones including both arms and ultra-silent fabric — the most complete hunting-specific spec sheet we have converted.
The numbers
- Energy
- 74.0 Wh
- Maker's stated energy
- 74 Wh at 7.4 V — published by Venustas
- Arms heated
- Yes — 2 of the 5 zones
- Fabric
- Ultra-silent, FELLEX insulation, Next Camo G2
- Sizes
- S to 4XL
- Heat zones
- Left and right chest, left and right arm, and mid-back, per Venustas
- Settings
- Three — low, medium and high. No temperatures published
- Care
- Machine washable, per Venustas
On wattage: No wattage published. Venustas's own figures invert to about 3.7 W for the whole garment at the 20-hour claim — roughly 0.74 W per zone across five zones. That is a very low draw, which tells you the 20-hour figure describes the LOWEST setting on an insulated garment rather than anything you would run in real cold. Venustas does not say which setting it refers to, and we will not assume.
On the pack: Venustas publishes "74Wh" directly rather than making you multiply a milliamp-hour figure by a voltage it never states. At 74 Wh this is the largest apparel pack on this site — nearly double a standard 7.4 V 5,200 mAh pack, and twice what the TIDEWE hunting jacket carries. On a long sit that is the number that matters most.
What we like
- Venustas publishes the watt-hours itself, which almost nobody in this category does
- 74 Wh is the largest apparel pack on this site — twice what the TIDEWE hunting jacket carries
- Ultra-silent fabric is a genuine hunting specification, not a marketing adjective
- Two of the five zones are in the arms, which most heated jackets skip entirely
- A three-year element warranty is advertised — though Venustas marks that term "Venustas Official Website Only", so check before assuming it covers a retail purchase
What we do not
- No temperatures and no per-setting runtimes — the 20-hour claim is one number with no setting attached
- Two of your five zones go to the arms, which on a motionless sit is not where you lose heat
- Heated sleeves add bulk at the shoulder and inner arm, which is where a stock or a bowstring goes
- Costs meaningfully more than the same brand's hunting vest on the identical battery
- No wattage published, so the draw is our inference from their runtime claim
Who this suits
A hunter who walks in a long way, or genuinely gets cold arms sitting, and wants camo and silence as well as heat.
Who should skip it
Your hunting is mostly sitting still. Two of the five zones are heating the part of you that needs to move freely, and the same brand's vest spends those zones on your neck and lower back instead.
What the jacket is
A four-way-stretch softshell, wind and water resistant, with two of its five zones in the arms — which is the Tundra's actual distinguishing feature. Heated sleeves are rare at this price, and most of the category spends every zone on the torso.
Control is a waterproof touch button on the chest plus Bluetooth to a phone or smartwatch through Fieldsheer's MW Connect app, which also reports battery level. Machine wash cold on gentle, tumble dry low, one year warranty.
The two things we would change
The watt-hours are ours, not theirs
For all the granularity, Fieldsheer publishes a watt-hour figure for none of its eight battery packs. Its Battery Technologies page lists packs across three voltages — 11.1 V, 7.4 V and 3.7 V — with no mAh, no Wh and no runtime on it at all. Every energy number on this page is our multiplication of figures taken from the garment page. The Fieldsheer brand page has that conversion in full.
The pack name is not reliable
The Tundra's page calls its 4,000 mAh battery the "Powersheer XL". Fieldsheer's own battery catalog gives that name to a 6,000 mAh pack and calls this one the 7.4V+ Plus. If you buy a spare by name you may get a different capacity than you expect. Order by the model number printed on the page: MWCB74V04021.
The energy, converted
Watt-hours, and what they buy
Energy is capacity times nominal voltage. The ceiling draw is the pack’s own published output current times its voltage. The implied draw runs the maker’s advertised hours backwards. Nothing here is measured — check our working.
| Product | Capacity | Volts | Energy | Ceiling draw | Shortest runtime | Implied draw at the claim |
|---|---|---|---|---|---|---|
| Fieldsheer Mobile Warming Tundra Men's Heated Jacket | 4,000 mAh | 7.4 V | 29.6 Wh | Not published | Not derivable | 14.8 Wat 2 h high (up to 135°f) |
| Fieldsheer Peak Unisex Bluetooth Heated Vest | 2,250 mAh | 7.4 V | 16.7 Wh | Not published | Not derivable | 8.3 Wat 2 h high (up to 135°f) |
| Venustas Men's Heated Silent Hunting Jacket (Next Camo G2) | 10,000 mAh | 7.4 V | 74.0 Wh | Not published | Not derivable | 3.7 Wat 20 h manufacturer's headline claim |
“Not derivable” means the manufacturer does not publish the figure the sum needs. We leave it blank rather than estimating it, borrowing a number from a similar model, or rounding one into existence. These are ceilings, not promises: cold, wind, movement and pack age all push real runtime below them. Run your own numbers.
Fieldsheer Mobile Warming Tundra Men's Heated Jacket
- Energy in the pack
- (4,000 mAh ÷ 1000) × 7.4 V = 29.6 Wh
- Most the pack can deliver
- Not published — no output current stated, so the ceiling cannot be computed.
- And the draw the maker’s own claim assumes
- 29.6 Wh ÷ 8 h = 3.7 W — which is the low (from 90°f) figure.
29.6 Wh is mid-table. It is more than ActionHeat's 22.2 Wh USB platform and less than Gobi's 36.5 Wh, well under a Venustas hunting jacket at a published 74 Wh. Two-plus hours on high is Fieldsheer's own figure and it is honest; it is also short.
Who it suits
- Anyone whose arms get cold. Two of five zones in the sleeves, which most heated jackets at this price do not attempt.
- People who ration deliberately. Four settings with a published runtime for each is exactly what you need to plan a day, rather than guessing between low and high.
- Buyers who want to check the maker's work. The claims invert cleanly and cross-check against Fieldsheer's other garments.
- App users. MW Connect reports battery level, which a remote-only system cannot.
Who should skip it
- Anyone needing insulation. This is a stretch softshell, not a winter coat. Fieldsheer's own Ventani has PrimaLoft fill if that is what you want.
- Long days on one charge. 29.6 Wh at 14.8 W is two hours. Buy a second pack or plan around the low setting.
- Anyone who wants the maker to state the watt-hours. Fieldsheer will not, for any pack it sells.
- Spare-buyers who shop by name. The Powersheer XL naming collision is a real hazard.
The alternatives worth weighing
Against the Fieldsheer Peak vest: the same four-setting control and temperature range at a much lower price, three zones instead of five, and a 16.7 Wh pack instead of 29.6. If you do not need heated sleeves it is the better value within the same brand and the same app.
Against the Venustas Silent Hunting jacket: 74 published watt-hours against 29.6, also with two arm zones, and a three-year warranty on the elements against one. Venustas publishes far less about settings and temperatures but carries two and a half times the energy. If the day is long rather than precisely planned, that is the trade.
Against ororo's dual-control jacket: ororo puts the arms on a separate switch, so you can stop paying for them mid-day. Fieldsheer gives you four power levels across all five zones; ororo gives you the choice of which zones run at all. Different answers to the same problem, and ororo's is the better one if your arms are only sometimes cold.
The verdict
If this site gave an award for making our job easy, the Tundra would win it. Fieldsheer publishes the zone map, the temperature range, a runtime for every setting and the battery's part number — and when you invert all of it, the numbers agree with each other and with Fieldsheer's other garments. That is rarer than it should be and it deserves to be rewarded.
What the documentation cannot do is add energy. 29.6 watt-hours is a mid-sized pack and two hours on high is two hours on high. Buy the Tundra because you want heated sleeves and a maker who tells you the truth about what they cost — then buy a second battery, because the truth is that one will not cover a full day.
Our criteria, and what we did not do
- Watt-hours calculated from Fieldsheer's own published voltage and capacity, and labeled as ours throughout, because Fieldsheer publishes none.
- Every runtime claim inverted into watts and then divided by the published zone count.
- Cross-checked against two other Fieldsheer garments on a different pack size to test whether the per-zone figure holds.
- Pack identified by model number, not by the name on the page, because the names collide.
- We have not worn this jacket. How we work.
We have not worn, tested or owned any of these products, and we say so on every page rather than in a footer. What we do instead is compile the published specifications and do the arithmetic. The full method.
Frequently asked
- How long does the Fieldsheer Tundra last on a charge?
- Fieldsheer publishes a figure for each of its four settings: 2+ hours on high, 3+ on medium-high, 4+ on medium-low and 8+ on low, from the 7.4 V 4,000 mAh pack. Inverted against about 29.6 watt-hours those give roughly 14.8 W, 9.9 W, 7.4 W and 3.7 W respectively.
- Does the Fieldsheer Tundra have heated sleeves?
- Yes - two of its five zones are in the arms, in Fieldsheer's wording "2x Chest, 1x Back, 2x Arms". That is unusual at this price; most heated jackets spend every zone on the torso.
- How many watt-hours is the Fieldsheer Tundra battery?
- About 29.6 Wh, which is our multiplication of the 7.4 V and 4,000 mAh Fieldsheer prints on the garment page. Fieldsheer itself publishes no watt-hour figure for any of the eight packs in its range.
- Are Fieldsheer's runtime claims accurate?
- They hold up better than most under arithmetic. The Tundra's claims imply about 3.0 watts per heating zone; Fieldsheer's three-zone Peak vest and Ventani jacket, on a different pack with their own separate claims, imply about 2.8 watts per zone. Numbers that agree across three garments and two pack sizes were calculated rather than invented.
- Which battery does the Fieldsheer Tundra use?
- A 7.4 V, 4,000 mAh pack, model MWCB74V04021. Order spares by that model number rather than by name - the Tundra page calls it the "Powersheer XL" while Fieldsheer's battery catalog gives that name to a 6,000 mAh pack.
- Is the Fieldsheer Tundra warm enough for winter?
- As a shell on its own, no - it is a four-way-stretch softshell with no insulation, so it is a layering piece. The heat tops you up rather than replacing a coat. If you want insulation in the same brand, the Ventani carries PrimaLoft fill.
Sources
- Fieldsheer — Tundra Jacket Men's ("5-Zone Heating System - 2x Chest, 1x Back, 2x Arms"; "4 Adjustable Heat Settings (90° up to 135°)"; "2+ High, 3+ MedHigh, 4+ MedLow, 8+ Low"; "Powersheer XL Lithium-Ion (7.4V 4000mAh)" model MWCB74V04021; MW Connect app; machine wash cold gentle, tumble dry low; 1 year warranty)
- Fieldsheer — Battery Technologies (eight packs across three voltages — Powersheer 12V, 7.4V+ Plus, 7.4V Standard Li-Ion, Soft Touch 7.4V, 7.4V Glove Battery, 3.7V Premium Sock, 3.7V Standard Sock, 3.7V Thawdaddy — with no mAh, Wh or runtime figure for any)
- Fieldsheer — 7.4v Powersheer XL 6000 mAh Battery & Cable (the 6,000 mAh pack that shares the "Powersheer XL" name used for the Tundra's 4,000 mAh pack)
Related
Reviews
One product at a time, full spec table, and an explicit note that we have not worn it.
Fieldsheer and Mobile Warming: the best garment specs in the category, on top of a battery page that tells you nothing
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Heated jackets for men, ranked by what the battery can actually do
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ororo heated apparel, and the 2x battery spread hiding inside one brand
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Heated jackets for hunting, and the arms question nobody asks
One brand sells the same hunting garment as a jacket and a vest - same battery, same five zones. Only the placement changes, and for a long sit that is the whole decision.
Spare and replacement batteries, converted before you buy
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Watts, volts and the number on the label that is not quite true
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