Description
Length is the first thing to check with the US AGM 4D. At just over 20.5 inches long but under 9 inches tall, it is a low, wide slab that suits a battery bay or box where headroom is tight and floor area is not. The sealed AGM build also means it can sit on its side, which gives you more ways to orient it than a flooded battery would.
Published runtimes are 146 minutes at 75 amps, 209 minutes at 56 amps and 540 minutes at 25 amps, from a 246Ah (20-hour) rating. Next to the US AGM 8D, which has almost the same length and height, you give up 62Ah of 20-hour capacity and gain a narrower case (9.45 in versus 10.6 in) and about 26 pounds less weight. That is the real choice: the 4D is easier to lift and place, while the 8D is the one to buy when you need every available amp-hour.
Because electrolyte is held in glass mat rather than free liquid, there is nothing to top off, and U.S. Battery states the case does not leak. It is a 12V unit, so a 24V bank needs two of them in series.
Specifications
| Model | US AGM 4D |
| Voltage | 12V |
| Capacity @ 20hr | 246Ah |
| Capacity @ 5hr | 206Ah |
| Minutes of Discharge @ 75A | 146 |
| Minutes of Discharge @ 56A | 209 |
| Minutes of Discharge @ 25A | 540 |
| Length | 20.55in (522mm) |
| Width | 9.45in (240mm) |
| Height | 8.82in (224mm) |
| Weight | 143 lbs (65kg) |
| Case Material | ABS, heat sealed |