TOPDC BT-501 500 Amp
#4 in Load testersFull review
An adjustable 500 A carbon-pile tester with a built-in test timer, for car, truck and farm batteries.
Amazon $135.99$135.99
The TOPDC BT-501 500 Amp is the better car battery tester overall, rated 3.1 to 2.8. The TOPDC BT-501 500 Amp leads on features or load. The OTC 3181 130 Amp wins on price. The OTC 3181 130 Amp costs $46.62 less ($89.37 vs $135.99).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
OTC 3181 130 Amp
#6 in Load testersFull review
A rugged fixed-load tester for quick pass or fail checks on 6 V and 12 V batteries, including side-post ones.
Amazon $89.37$89.37
Which should you buy?
- Choose the TOPDC BT-501 500 Amp for features or load (500 A load vs 130 A load).
- Choose the OTC 3181 130 Amp for price ($89.37 vs $135.99).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every load testers car battery tester; a clear win is highlighted. How we rank explains each one.
| Factor weight | TOPDC BT-501 500 Amp | OTC 3181 130 Amp |
|---|---|---|
| Overall rating | 3.1/5 | 2.8/5 |
| Price 25% | 57 $135.99 | 75 $89.37 |
| Battery coverage 25% | 37 up to 1,000 CCA, 6 V batteries | 20 CCA range not published, scored as the bottom of the scale, 6 V batteries |
| System tests 20% | 40 tests the charging system | 50 system tests not published (neutral score used) |
| Features or load 20% | 70 500 A load | 11 130 A load |
| Warranty 10% | 0 warranty not published, scored as none | 0 1-year warranty |
Specifications
| TOPDC BT-501 500 Amp | OTC 3181 130 Amp | |
|---|---|---|
| Testing | ||
| Type | Carbon pile | Fixed load |
| Battery voltages | 6/12 V | 6/12 V |
| System voltages | 12 V | - |
| Rating range | up to 1,000 CCA | - |
| Load current | 500 A | 130 A |
| Charging system test | Yes | - |
| Features | ||
| Display | Analog | Analog |
| Build | ||
| Warranty | - | 1 year |