A coffee machine, a blender, a display fridge and a card reader all want 230 V, and a food truck has a 12 V battery. The arithmetic for choosing the inverter and the battery bank is short, and getting it right is the difference between a trading day and a flat battery at lunchtime.

Step 1: add up the watts that run at the same time

Look at the label on each appliance and list the watts. Then think about which ones are on at the same moment, because that is what the inverter has to deliver:

Espresso machine (single group)	about 1,200–1,500 W while heating
Blender	500–1,200 W, a few seconds at a time
Display or under-counter fridge	80–150 W running, four to five times that for a second when the compressor starts
Induction hob (one ring)	1,800–2,000 W on full
Card reader, lights, speaker, phone	10–60 W each

A coffee cart runs the machine and the fridge together: about 1,400 W steady, with the fridge compressor’s start on top. A 2,000 W pure sine wave inverter such as the KISAE SW1220 covers that with a 4,000 W surge in hand for the motor starts. Pure sine wave matters here: compressor fridges, espresso machine pumps and anything with a microprocessor run exactly as they do on the grid, where a cheaper modified-sine inverter makes them hum, overheat or trip.

Step 2: turn watts into amps from the battery

At 12 V, every 1,000 W the inverter puts out draws about 94 A from the battery (1,000 W ÷ 12 V ÷ 0.89 efficiency). A 2,000 W load pulls about 190 A. That is why cable size and fuse rating are not optional: KISAE’s manual asks for AWG 2/0 (67 mm²) cable with a 300 A fuse on the SW1220, with the battery no more than 1.5 m from the inverter. The 1,000 W SW1210 wants AWG 2 (34 mm²) and a 150 A fuse.

At 24 V the current halves, so cables, fuses and losses shrink. If the system is 2,000 W or more and you are building the truck from scratch, a 24 V bank with the KISAE SW2420 is the tidier design, and 24 V DC fridges and LED lighting are easy to find.

Step 3: size the bank for the trading day

Amps × hours gives amp-hours. The espresso machine heats hard for a minute, then cycles; across a six-hour trading day a single-group machine plus a fridge typically averages 300–500 W, call it 35 A at 12 V, so about 200–250 Ah drawn from the battery. Fullriver rate the DC series to 80% depth of discharge, so you need a bank of about 300 Ah: two DC160-12 in parallel, or two DC145-12 if the fridge is small. A truck that also runs an induction hob or a second machine moves to a 24 V bank of four batteries. Measure your own day with a battery monitor for a week before you finalise it; most owners find their average is lower than their fears and their peaks higher.

Step 4: how it gets charged

While driving: a KISAE DC-DC charger from the vehicle alternator, sized at about 20% of the bank’s capacity (a 300 Ah bank wants about 60 A, so the DMT12100).
At a pitch with mains power: an inverter-charger such as the KISAE Abso IC122055 (2,000 W with a 55 A charger) replaces the inverter and the mains charger with one unit. It takes the same AWG 2/0 cable and 300 A fuse as the 2,000 W inverter, and its 55 A charger suits a bank of about 275 Ah. Plug in and it passes the mains straight through to your sockets while recharging the bank; unplug and it switches to inverting by itself, with no flicker to the card reader.
Solar on the roof: 200–400 W of panels keeps a fridge running through the day and takes the edge off the battery; see solar and alternator charging.

The checklist

Pure sine wave inverter rated above the watts that run together, with surge headroom for compressors.
Battery bank sized at the day’s amp-hours divided by 0.8.
Cable and fuse to the manufacturer’s table, battery within 1.5 m of the inverter.
A way to put the energy back: DC-DC while driving, inverter-charger on mains, solar on the roof.
A battery monitor so you see the state of charge during the day.

Send us your appliance list and trading hours on LINE @drakeco ou WhatsApp and an engineer specifies the inverter, bank, charger, cable and fuses for you, free, usually within one working day. Lead times for KISAE inverters are confirmed with you before you pay.

สรุปเป็นภาษาไทย

ขั้นที่ 1 รวมวัตต์ของอุปกรณ์ที่เปิดพร้อมกัน เช่น เครื่องชงกาแฟ 1,200–1,500 W บวกตู้เย็น 80–150 W (คอมเพรสเซอร์ใช้กระแสสูงตอนสตาร์ท) อินเวอร์เตอร์เพียวไซน์ 2,000 W เช่น KISAE SW1220 รองรับได้พร้อมเซิร์จ 4,000 W

ขั้นที่ 2 ที่ 12 V ทุก 1,000 W ดึงกระแสจากแบตประมาณ 94 A คู่มือ KISAE กำหนดสาย AWG 2/0 กับฟิวส์ 300 A สำหรับ SW1220 และแบตห่างจากอินเวอร์เตอร์ไม่เกิน 1.5 m ระบบตั้งแต่ 2,000 W ขึ้นไปควรพิจารณา 24 V

ขั้นที่ 3 เครื่องชงกาแฟกับตู้เย็นตลอดวันขาย 6 ชั่วโมงใช้ประมาณ 200–250 Ah หารด้วย 0.8 ได้แบงค์ประมาณ 300 Ah เช่น Fullriver DC160-12 สองลูก ขั้นที่ 4 ชาร์จกลับด้วย DC-DC ขณะขับ อินเวอร์เตอร์-ชาร์จเจอร์เมื่อมีไฟบ้าน และโซลาร์บนหลังคา ส่งรายการอุปกรณ์มาทาง LINE @drakeco เราคำนวณให้ฟรี