How much current does the battery supply during levelling, and how many Ah are needed?
No current figure is published on the product page for the KTS200's D3501-1142 jacks, so it would not be right to attribute a numerical ampere value to the system. What is decisive when planning is this: 12V DC electric levelling jacks draw short but high-current loads, and the house battery must be fully charged at the moment of levelling.
The right approach is to establish the capacity planning logic instead of guessing a number.
Character of the load: Levelling is not a continuous but a short operation. The manufacturer describes the total cycle time as «usually a few minutes». However, during that time the jack motors run under load; that is, the current drawn is not small, it is only short-lived. Energy consumption (Ah) is therefore limited; what is really critical is the battery's ability to supply instantaneous current.
Capacity planning:
- On lead-acid/AGM batteries, limit the depth of discharge to about 50% to preserve life. The practically usable capacity of a 100 Ah battery is about 50 Ah.
- While typical cycle life at 50% depth of discharge is of the order of 500-1000, going down to 80% roughly halves that number.
- In LiFePO4 batteries the usable capacity ratio is markedly higher.
- As a battery ages, its internal resistance rises; the same current demand causes a larger voltage drop.
For the cable, cross-section and protection values specific to your system, consult the company that installed your RV's electrical system or the AXI support line.
Full coverage of the topic: How to choose levelling jack capacity