B500K for AC500 vs EcoFlow DELTA Pro Ultra Series Smart Extra Battery
Compatibility note: expansion batteries only attach to their own brand's stations — this one pairs with BLUETTI systems, the other with EcoFlow's. Read this as a value and longevity comparison (which ecosystem is cheaper to expand), not a choice between interchangeable parts.
- Price today: BLUETTI is $250 cheaper ($2,049 vs $2,299).
- Cost per Wh: $0.40 vs $0.38 — EcoFlow DELTA Pro Ultra Series Smart... gives you more battery per dollar today.
- Rated cycle-cost estimate: 10.0¢ vs 10.9¢ per lifetime kWh (manufacturer cycle ratings).
| B500K for AC500 | EcoFlow DELTA Pro Ultra Series Smart Extra Battery | |
|---|---|---|
| Price today | $2,049 | $2,299 |
| Deal status | Normal price — matches recorded low | Normal price |
| Capacity | 5120Wh | 6000Wh |
| $/Wh | $0.40 | $0.38 |
| Chemistry | LFP | LFP |
| Rated cycles | 4,000 cycles to 80% | 3,500 cycles |
| Output | — | — |
| Solar input | — | — |
| Weight | 99.21 lbs | 111.8 lbs |
| Expandable | — | to 90000Wh |
| Standalone use | No — link port only | — |
| Recharge without station | No — only through the station | — |
| Recorded low | $2,049 (2026-07-07) | $2,099 (2026-07-07) |
| View at BLUETTI — $2,049 | View at EcoFlow — $2,299 |
Full tech-spec comparison all specs
| B500K for AC500 | EcoFlow DELTA Pro Ultra Series... | |
|---|---|---|
| Battery | ||
| Chemistry | LFP | LFP |
| Capacity | 5,120Wh | 6,000Wh |
| Rated cycles | 4,000+ | 3500 |
| General & physical | ||
| Weight | 99.21 lbs | 111.8 |
| Warranty | 4 years | 5 years |
Also published by B500K for AC500
| Cycle retention | 80% |
|---|---|
| AC outlets | 0 (link port only) |
| USB-C ports | 0 (link port only) |
| USB-A ports | 0 (link port only) |
| 12V / car output | 0 (link port only) |
| AC input | None — recharges via the station only |
| Solar (PV) input | None — recharges via the station only |
| Car input | None — recharges via the station only |
| Dimensions | 20.47 × 12.87 × 12.15 in |
| Operating temperature | -4°F to 104°F |
Also published by EcoFlow DELTA Pro Ultra Series...
| Expandable | Yes |
|---|---|
| Max expanded | 90000 |
Like-for-like specs both brands publish are shown first (✓ = better value); each brand's remaining published specs follow. Core figures are editorially verified; the rest come from each manufacturer's tech specs.
Price history — B500K for AC500
Price history — EcoFlow DELTA Pro Ultra Series Smart Extra Battery
Prices recorded daily from the official BLUETTI and EcoFlow stores. Deal statuses compare each product to its own 90-day history — methodology.