Diehard 20071222 battery charger Parts

Charge time on the Diehard battery charger model 20071222 depends on the battery’s size and how discharged it is; we calculate it from the battery’s rating and the charger’s amp setting (commonly 2A or 10A). Use the formula and chart in the owner's manual for the most accurate estimate.

How to estimate charge time (most accurate method)

We use the manual’s calculation method to estimate hours to full charge:

• Find the battery’s Amp Hour (AH) rating (or convert from Reserve Capacity).
• Determine the percent of charge needed (example: 50% to reach 100% equals 0.50).
• Divide by the charger setting (2 amps or 10 amps).
• Multiply by 1.25 for a more realistic estimate.
• Add 1 extra hour for deep-cycle batteries.

Formula:

Hours ≈ (AH × % needed ÷ charger amps) × 1.25 (+ 1 hour if deep-cycle)

Quick example

If you have a 100 AH battery at 50% and charge at 10A:

Battery rating	% needed	Charger setting	Estimated time
100 AH	0.50	10A	~6.25 hours

If your battery is rated in Reserve Capacity (RC)

Many car and marine batteries list RC instead of AH. Convert RC to AH like this:

• AH = (RC ÷ 2) + 16

Then plug the AH value into the charge-time formula above.

Why it matters

Charging too fast or too long can overheat the battery and shorten its life. Estimating time correctly helps you pick the right amp setting, plan your charge window, and reduce the risk of battery damage.

Helpful related DIY reading

For basic electrical troubleshooting while you’re checking the charger, cord, or clamps, we recommend how to use a multimeter to test electrical parts video.

You can also look up parts and model resources by searching 20071222 on Sears PartsDirect.

Last updated: February 2026

For the Diehard battery charger model 20071222, charging starts after you connect the clamps correctly, select the charge rate, and plug the power cord into a grounded 120V outlet. For the exact switch settings and safety steps, follow the 20071222 owner's manual.

How to charge (basic steps)

• Put on safety glasses and keep your face turned away from the battery while connecting clamps.
• Connect the clamps to the battery using the correct polarity for your vehicle.
• Make sure each clamp has a solid, non-slip connection (twist or rock slightly to seat it).
• Select the type and rate of charge using the selector switch.
• Plug the charger into a grounded AC outlet to begin charging.
• When charging is complete, unplug the charger first, then remove clamps in the correct order.

Clamp removal order (important)

Remove the clamps in this order after unplugging the charger:

1. Remove the clamp from the chassis/engine block connection.
2. Remove the clamp from the battery post/terminal.

Extension cord guidance

If you must use an extension cord, use a heavy-duty cord rated for the charger load and keep it as short as practical to reduce voltage drop.

Cord choice	What it affects	What you may notice
Short, heavy-duty	Best power delivery	Normal charge rate
Long or light-duty	More voltage drop	Slower charging, warmer cord

Why it matters

Correct clamp placement, a solid connection, and unplugging before disconnecting reduce sparking risk and help the Diehard 20071222 charge more consistently.

You can also look up model-specific diagrams and any available replacement items by searching 20071222 on Sears PartsDirect.

Last updated: February 2026

The model number for your Diehard battery charger is printed on the rating label and also appears on the front page of the documentation as Model No. 200.71222. Use the exact model when looking up diagrams, manuals, and replacement parts in the [owner's manual].

Where to look on the charger

Check these common spots where Diehard typically places the ID label:

• The back of the charger cabinet near the power cord entry
• The side panel near the handle
• The bottom of the base
• Near the front panel controls (switches and meter)
• On a sticker or stamped plate that lists electrical ratings (120V information)

What the model number looks like

This charger’s model is often shown with a decimal in the printed format.

You might see it printed as	Use it for parts lookup as
200.71222	20071222
Model No. 200.71222	20071222

Tips to avoid mix-ups

Using the correct model number matters because parts and wiring can vary by version.

• Write down the full model exactly as shown on the label
• If the label is worn, confirm the model on the manual cover (it lists 200.71222)
• Keep the model with your notes for troubleshooting items like the circuit breaker, meter, clamps, and control board

Why it matters

The model number ties your charger to the correct wiring diagram, safety instructions, and parts list (for example, items like the AC power cord, output cable, and 35A circuit breaker are model-specific).

Last updated: March 2026