How many cells, what voltage, how much internal resistance — and the thing that actually matters: how far the voltage drops when the amplifier pulls on it. That is what decides whether your amp delivers what it promises.
| Property | What it means for SPL |
|---|---|
| Very low internal resistance | This is the whole point. At high current the voltage barely drops, so the amp actually delivers its power. |
| Huge current delivery | A single cell will hand over many times its capacity in amps continuously, and more in bursts. Lead-acid cannot touch this. |
| Thousands of cycles | Lasts far longer than lithium-ion, and does not mind fast charging. |
| Cold tolerance | Can be charged below freezing — this is where it beats conventional lithium. |
| 2.3 V cells | Six cells make 13.8 V, which is exactly car voltage. A lucky number. |
| Low energy density | For the same watt-hours it is heavier and bulkier than lithium-ion. In exchange it does not go up in flames. |
| Hard to charge fully | The alternator's 14.4 V is only 2.4 V per cell across six — that is not full. You need a dedicated charger or a boost converter. |