Free Economy ShippingProduct Specifications for PriorityStart! ProMax HD 12-Volt Automatic Battery Protector for Cars & Trucks
| BM Part #: | 12V-PMAX-HD |
|---|---|
| Voltage: | 12 Volt |
| Length: | 5" |
| Width: | 3" |
| Height: | 1.25" |
| Shipping Weight: | 3.00Lbs |
| Warranty: | 1 Year Factory Direct |
| Product Manual: | Download |
- Handles over 1600 starting amps.
- Handles approximately 400 continuous amps.
- Disconnects at 11.7V; times out after approximately one (1) minute.
- Reconnects with 0.2mV load change (brake pedal, light switch, etc.).
- High intensity LED light indicates connect/disconnect status.
- Temperature range: -40°F to +185°F.
- This item is covered by the Replacement Only Return Policy.
- 1,600 Starting Amps: Delivers heavy-duty cranking power built for trucks, fleets, and multi-accessory vehicles.
- Automatic Disconnect: Cuts battery drain the instant voltage dips below 11.7V, protecting your starting power.
- Instant Reconnect: Tap the brake pedal or a light switch and you're ready to start immediately.
- LED Status Light: A bright top-mounted indicator shows connect or disconnect status at a glance.
- No-Wire DIY Install: Three simple clamp connections mean no cutting, splicing, or professional installation required.
- Heavy-Duty Build: Reinforced gears, contacts, and housing withstand tougher loads than the standard ProMax.
Product Description
Nothing ruins your day like a dead battery. If you're constantly jumping your car, truck, or fleet vehicle, chances are a parasitic drain is silently draining the battery every time you park it. The PriorityStart ProMax HD is an automatic battery protector that stops that drain cold, so your engine is always ready to start.
This heavy-duty model is built for vehicles that ask more of their battery — trucks, fleet vehicles, and anything running two-way radios, GPS units, dash cameras, or dual-battery setups. It's the upgraded version of our standard PriorityStart ProMax, reinforced to handle bigger loads without missing a beat.
What's Actually Draining Your Battery
When your engine is off, small drains add up fast:
- Lights or accessories accidentally left on
- Alarm systems and security modules
- Aftermarket electronics like radios, GPS, or dash cams
- Minor shorts in older wiring
Jump-starting fixes the moment, but it stresses your alternator and shortens battery life every single time. The ProMax HD watches your battery voltage around the clock and cuts the drain before it ever gets that far.
No more waiting on a tow truck. No more explaining to your boss why the work van won't start. Just install it once, and let it run in the background.
Built to Last, Not Just to Work
The HD upgrade isn't cosmetic. Every internal component, from the gears to the contact discs, is reinforced to carry a heavier electrical load and hold up to years of daily use in demanding vehicles.
Simple Enough for a Saturday Afternoon
Three connections. No cutting, no splicing, no trip to the mechanic. Most customers have it installed and working in about 15 minutes, right in their own driveway.
Ready for Winter, Ready for Anything
Rated from -40°F to 185°F, the ProMax HD keeps working whether you're parked in a January cold snap or an August heat wave.
Don't let a parasitic drain cost you another battery, another tow, or another bad morning. Add the PriorityStart ProMax HD to your cart and start every time, guaranteed.
Frequently Asked Questions
What's the difference between the ProMax HD and the standard ProMax?
A: The HD handles more power (1,600 starting amps and 400 continuous amps vs. 1,000/250 on the standard model) and uses reinforced gears, contacts, and wiring. If you're running a truck, fleet vehicle, or multiple high-draw accessories, the standard ProMax may be all you need for lighter-duty vehicles, but the HD is built for tougher jobs.
Will this work with my dual-battery or multi-accessory setup?
A: Yes, in most cases one ProMax HD unit handles a dual-battery configuration. Because setups vary, we recommend keeping any high-draw accessories (like winches or high-amp radios) wired directly to the battery rather than through the unit itself, since those should bypass the protector's top post.
How is it installed? Do I need a mechanic?
A: No mechanic needed. It's a simple 3-step DIY connection: attach your vehicle's positive cable to the unit, connect the unit to your battery's positive post, then attach the ground wire to the negative post. Most installs take about 15 minutes with basic hand tools.
Will it drain my battery or reset my radio and clock?
A: The unit itself draws a negligible amount of power (9-12 milliamps, similar to an LED). However, once it disconnects your battery to prevent drain, your radio and clock settings will reset, just as they would after any battery disconnect.
Can this fix a battery that's already old or dying?
A: No. The ProMax HD is a low-voltage disconnect switch, not a charger or battery booster. It stops new drains from happening, but it can't restore a battery that's already damaged or at the end of its life. For best results, install it with a healthy battery.
Cross Reference & Compatibility
Customer Reviews
I bought this product in hopes it would help aid in trucks parasitic battery draw. The product has been working as described. I recommend this product for piece of mind.
I installed and have tested the heavy duty version of Priority Start! on my 2001 Toyota Land Cruiser because it appeared to have a parasitic battery drain problem. Since the vehicle has no mechanical key alternative to its battery-powered locks, I installed an "always-on" momentary switch in the Priority Start! ground wire. If the Priority Start! is activated, shutting down the battery at 11.7 volts as advertised, I am now able to press the switch, which would momentarily disable the Priority Start!, thereby reconnecting the battery long enough to unlock the doors and enter the vehicle. I then will be able to start the car with the remaining voltage in the battery guarded by the Priority Start!, as the instructions indicate. In a chat session, an advisor at Priority Start! suggested this modification (the always-on, momentary-off switch) to compensate for avoiding the potential of getting locked out of my vehicle if the battery is shut down by the Priority Start!, which is its purpose. To prevent tampering from potential thieves, I mounted the momentary switch in an accessible but secret location outside the vehicle. Sorry, I'm not telling where that is.
My main concern with automatic kill switches, such as Priority Start!, was that if I had the vehicle parked in an airport parking lot for two or three weeks, the likelihood of the parasitic battery drain activating the battery shutdown by the Priority Start! would be relatively high. Flying in late at night, I might be greeted with a car with a good battery, but I would be unable to unlock the car because the Priority Start! had disabled disconnected its battery. No fun at midnight in an airport parking lot.!
Many newer vehicles have mechanical backup keys, so for those, there would be no problem.
I give the product a 4-star rather than a 5-star rating only because I think Priority Start! should have built into the device itself a way of working around the potential of getting locked out of electric-lock-only vehicles that have no mechanical back-up method of unlocking. Perhaps they will see this review and consider this as a possible improvement on an otherwise very good product.
I have a parasitic drain on my vehicle. The car has been brought back to the dealer numerous times with the complaint of the battery going dead. The dealership replaces the battery, but does nothing further to resolve the problem. The hassle of having to jump the car when the battery keeps going dead and visiting the dealer forced me to look for a different solution. So I purchased a "Priority Start". Installation was simple and to date I haven't had any battery issues. Hopefully the dying battery issue is resolved.
Easy to install. No problems. The winter will tell me how good this device is.
An improved design. I like the indicator light on top. But will this HD version last longer than the standard version that failed on me did?
Just what I ordered.
No more dirty hands or dead battery.
