Short answer: the DR-FZ100 is a dual-slot charging case, so the slot count is the storage count — two NP-FZ100 packs at most, and a third will not go in. A camera body will not fit at all: an A7 series body with a pack inside is far larger than the interior, so this is not a matter of trying harder but of different orders of size. As for small items such as cables and memory cards, whether they fit depends on the internal layout of the particular unit, and the method at the end of this article lets you check that yourself.
A note on approach first: this article deliberately avoids figures such as interior length, width and height in millimeters, or the weight of an empty case to the gram. Those numbers should come from the unit in your hand and its documentation, and they can differ between batches. What can be given is the structural logic, comparable orders of size, and a two-minute procedure you can run yourself.
Why two packs and not three
The DR-FZ100 was designed around charging two packs at once, so the slots, contacts, latches and indicator lights all come in pairs. Each slot has a defined seating structure and a pack must latch home to count as seated. A third pack has no matching position and would simply sit on top — which means it will not charge and will press on the contacts and shell when the lid closes.
Some people reason that they will not seat it, just lay it in the lid. That achieves nothing: the lid only presses down properly when both packs are latched in their slots, and a loose pack shifts in transit and knocks against the latches and contacts. Half the value of the case is that you drop packs in and they charge, and close the lid and they travel.
So the storage ceiling is two. If your normal pattern is four packs in rotation, the right arrangement is two in the case and two in use, not one case holding four. The DR-FZ100 category has a two-camera article covering how to schedule four packs.
Why a camera body cannot go in
This does not need dismantling to settle; comparing dimensions is enough. Take the A7 series: the body alone, without a lens but with pack and card, is roughly 130mm wide, 96mm tall and 75mm deep, with bodies such as the A7S III a little thicker. The interior of a dual-slot case, by contrast, is designed around two packs of about 38.7mm width and 22.8mm thickness side by side, so its overall length and depth are both under a hundred millimeters.
| Item | Order of size | Against the interior | Verdict |
|---|---|---|---|
| One NP-FZ100 pack | About 38.7 × 22.8 × 51.5mm | Matches one slot exactly | Yes, two of them |
| Two packs side by side | About 78 × 22.8 × 51.5mm | Matches two slots | Yes, this is the designed capacity |
| A7 series body, pack installed | Around 130 × 96 × 75mm | A single dimension already exceeds the interior | No |
| Body plus a small prime lens | Tens of millimeters deeper again | The gap widens further | No |
The conclusion is clear: any idea of storing a camera body in the charging case is a non-starter. It is not a design trade-off but a difference in what the product is for — the case deals with how packs charge and travel, not with how a body is carried. Carrying a body means a camera bag or an insert.
A third pack, memory cards, cables
A third pack
No, for the reasons above. If you genuinely need to carry three or more packs in one container, choose a multi-slot charger or a separate battery case rather than forcing a dual-slot unit.
Memory cards
It depends on the unit. Some leave a small pocket or mesh sleeve on one side that holds one or two SD cards; others are pure slots with no spare volume. The way to tell: load both packs and see whether the remaining gap takes a hard card case — usually it will not, and a bare card will slide into the gap beside a slot.
It is better not to put bare cards in a battery case at all. Card contacts are more delicate than battery contacts, mixing them risks scratches, and pulling a card out tends to bring a pack with it.
Charging cables
Most dual-slot cases expect the cable to stay outside; there is no room to wind one inside. Forcing it in presses on the lid and loosens the latch over time, so a cable tie is the better answer.
The two-minute self-check
- Seat both packs and confirm they latch home with the indicator lights behaving normally.
- Close the lid and press gently on it, feeling for springiness or a localised bulge. A bulge means it is already full — add nothing more.
- Pick the case up and shake it lightly, listening for anything shifting. A rattle means something is not secured.
- Open it and look for clear gaps around the interior, and check whether those gaps run through to the slot area. Small items in a through-gap will slide into the contacts.
- If you intend to add a card or an adapter, put it in, close the lid, shake again and repeat steps 2 and 3.
This turns whether something fits from a guess into a test. Any arrangement that needs force to close should not be used long term.
A more practical arrangement
If you regularly carry four packs or more, split the two jobs: one dual-slot case for charging, a separate container for carrying. The case then only has to charge, not carry everything, and it lasts longer — repeated overloading and lid pressure is the most common cause of a distorted body.
The other direction is to depend on the case less. Packs with a built-in USB-C port, such as the TNP-FZ100, need only a cable and a power bank on the road, and each pack can live in any compartment rather than being collected in one place. Once you have several packs, that approach usually wins on volume. The weight and volume comparison between the two routes is in the direct-charge battery category.
One more point that gets overlooked: the rules for flying with lithium batteries are built around carrying them with you. How you pack does not change compliance, but spreading packs across several bags makes counting them at security slower. Kept together in one case, you get through faster. The rules are in this article.
FAQ
Will the DR-FZ100 take third-party packs?
Usually yes. Any pack built to the NP-FZ100 outline varies very little in size and latches in normally. A few third-party packs with a thick protective shell or extra structure can be tight; do not force them, and check first whether it is a shell tolerance issue. The compatibility list is collected in the FZ100 series overview.
Can I put the loaded case straight into a camera bag?
Yes, but not at the bottom under heavy items. The shell is rigid with limited crush resistance, and sustained pressure loosens the latch and distorts the contacts. The top layer or a side pocket is better.
Does an empty case take up much room?
More than two bare packs — that is what the rigid shell buys you. If you only carry two packs and have no need to charge on the go, bare packs are lighter. Whether to bring the case comes down to protection and charging versus volume.
Can packs and a body share one bag?
Yes, but the packs are better off in their own soft pouch or hard case. Loose packs mixed with a body and lenses pick up metal debris on the contacts and get their shells scratched by mounts and screws. That applies equally to OEM and third-party packs.