Buyer guide
Charging a construction site battery
A battery is only as useful as its charging source. The unit sets one limit, the site sets another, and the lower of the two decides how the arrangement performs.
Two limits: the unit and the site
Every charging arrangement has two ceilings.
| Limit | Set by | Typical question |
|---|---|---|
| What the unit can accept | The battery system’s charging input rating | Is the unit able to take what the supply offers? |
| What the site can give | The spare capacity of the connection or generator | How much is left after the site’s own load? |
The lower of the two applies. On most sites that is the second one.
The Ampd 200 brochure lists a maximum charging power of 205 kW, and the Ampd 400 lists 410 kW. Those are unit limits. They do not describe the supply available on your site, and they do not imply a charging time.
Charging from a grid connection
A grid connection is the simplest source: steady, quiet and available around the clock. The question is how much of it is spare.
As a rough illustration, a three-phase connection limited to 100 A per phase at 400 V can carry about 69 kVA in total. If the site is already drawing 40 kVA, around 29 kVA is left for charging at that moment. When the site load drops overnight, most of the connection becomes available.
That pattern suits a battery well. It charges steadily when demand is low and discharges on the peaks, so the connection is used evenly instead of being overwhelmed for a few seconds at a time.
The reference units on this site are IEC variants for three-phase supplies. The voltage range and connection arrangement are in the product comparison. Confirm your site voltage, phase and frequency early; they are among the first things a technical review needs.
Charging from a generator
Where there is no connection, a generator charges the battery. The generator runs for part of the day at a healthy load, charging the battery and supporting any heavy demand, then stops. The battery carries the site in between.
The brochures list one supported configuration: a single unit connected with one generator, with ComAp or DeepSea microgrid controller compatibility. They give a recommended maximum generator capacity of 350 kVA for the Ampd 200 and 650 kVA for the Ampd 400.
Tell us the generator’s make, model and controller if you know them. Compatibility of the controls is checked as part of the assessment.
The energy balance decides whether it works
Storage does not create energy. Over a day, the charging source has to supply everything the site uses, plus losses. If it cannot, the battery starts each day lower than the last.
An illustrative check, assuming 85% of the energy put in comes back out:
| Spare supply | Energy returned per day | Site demand | Result | |
|---|---|---|---|---|
| Case A | 60 kW for 24 h | about 1,224 kWh | 90 kW for 10 h = 900 kWh | Keeps up |
| Case B | 30 kW for 24 h | about 612 kWh | 90 kW for 10 h = 900 kWh | Runs down |
In case B no size of battery fixes the problem. A larger battery only delays the day it runs out. The answer is more supply, less demand, or a generator to top up.
Why there is no standard charging time
Charging time is the energy to be returned divided by the power actually available for charging. Both change from site to site, and the second changes hour by hour as the site load rises and falls. A figure quoted without those inputs is not meaningful.
Optional charging equipment
Some charging features are optional and are not part of the standard specification.
- Serial charging system. Listed as an optional feature, rated at 40 or 80 kW on the Ampd 200 and 40, 80 or 120 kW on the Ampd 400. This is separate from the main charging input above.
- Direct DC MPPT controller. An optional controller for direct DC solar input. Its rating is given on the product pages.
Certain standards in the brochures apply only to units fitted with these options. Neither option establishes compatibility with a particular charger or solar array without further documentation, so name any equipment you intend to connect.
What to tell us about charging
- Grid connection capacity, in kVA or amps per phase, and how much is typically in use.
- Generator rating, model and controller, if there is one.
- Site voltage, phase and frequency.
- Working hours, and the hours when load is low.
- Any hours a generator must not run.
- Whether you are interested in serial charging or solar input.
“Not sure” is fine for any of these. Get a site power proposal and the charging arrangement is worked out in the technical review.
Source: Ampd 200 IEC brochure, Rev 1.3, dated 29 April 2026; Ampd 400 IEC brochure, Rev 1.3, dated 29 April 2026. Manufacturer-published figures for the IEC variant, not independently tested. Specifications can change, so the current data sheet for your territory is confirmed in a project proposal.
Product figures on this page: Ampd 200 Brochure IEC Rev 1.3, dated 29 April 2026; Ampd 400 Brochure IEC Rev 1.3, dated 29 April 2026. Manufacturer-published, not independently tested.
Questions buyers ask
How long does a site battery take to charge?
There is no single figure. Charging time depends on how much energy has to be returned, how much power the grid connection or generator can spare while the site is also drawing load, and the unit's own charging limit. It is worked out for the project, not read from a data sheet.
Can a small grid connection charge a large battery?
Yes, provided the connection can supply the site's total daily energy, plus losses, in the hours available. A small connection charges slowly. If the site uses more energy each day than the connection can deliver, the battery will run down however large it is.
Does the maximum charging power on the data sheet apply to my site?
It is the most the unit can accept, not what your site can provide. Actual charging power is limited by the spare capacity of your connection or generator, which is often much lower.
Are solar input and serial charging included as standard?
No. On the Ampd 200 and Ampd 400 IEC brochures, the serial charging system and the direct DC MPPT controller for solar input are listed as optional features. They are specified and quoted separately.