Knox Krypton bP — Battery Is Not Connected (Warning, Not a Fault)

What it means: bP is a warning, not a fault. Knox Krypton hybrids are rebadged Voltronic Power InfiniSolar units — an identification that comes from retailer listings and an exact specification match, never from Knox itself — and the InfiniSolar V IV "Warning Indicator" table lists bP against "Battery is not connected", with a flashing icon. That distinction is the whole point of this page. Warnings flash and the inverter keeps running; faults sit solid with the red light on and the inverter stops. bP means the unit cannot see a battery bank and is telling you so, while continuing to run your house from solar and the grid. On a Knox model that was sold and installed as a batteryless grid-feeding inverter — and Knox markets several Krypton models exactly that way — bP is not a problem at all. It is the display accurately describing a system that was never given a battery. On a system that does have a battery, it is the same message and a real one: you have no backup, and the next load-shedding slot will prove it.

Why does Knox show bP?

The Pakistan factor

bP causes more unnecessary panic in Pakistan than almost any other Knox indicator, because the batteryless hybrid has become a mainstream product here. Knox markets several Krypton models on exactly that basis — batteryless, grid-feeding, dual output — and a household that bought one for net metering and daytime savings will see bP from day one, permanently, and quite correctly. Dealers get calls about it every week. Before you let anyone quote you for a repair, check whether your system was ever meant to have a battery. The version that does matter is the household that installed a bank for load shedding and then discovers bP on the evening the grid goes down. The usual causes here are mundane and preventable: a battery isolator left off after a technician's visit, a DC fuse that blew months ago and was never investigated, or a terminal lug that has worked loose through a summer of thermal cycling. There is one pattern worth naming plainly. On homes that have been upgraded from a tubular bank to lithium — now very common across Lahore, Karachi and Rawalpindi — bP after an upgrade often means the new pack's BMS has disconnected itself, not that a wire is loose. If the pack has gone dark, the correct response is to find out which protection fired. Deep discharge is the usual answer, and a lithium pack that has been taken flat and left flat is a warranty conversation with the battery supplier, not something to be revived by repeatedly cycling the isolator.

How to fix it (safe to try yourself)

  1. Safe for a homeowner — first, establish whether you are supposed to have a battery at all. Several Knox Krypton models are sold as batteryless grid-feeding units. If yours is one of those and no bank was ever installed, bP is normal, nothing is wrong, and there is nothing to fix. Check your invoice and the model on the label before spending money.
  2. Safe for a homeowner — confirm what you are looking at. Is the indicator flashing, or is it solid with the red fault light on? Flashing is this warning. A solid red fault with a numeric code is a different situation — code 56, "battery is not connected well or fuse is burnt", is the fault-level version and it has its own page.
  3. Safe for a homeowner — check the obvious external switch. If there is a clearly labelled battery breaker or isolator outside the battery enclosure, look at whether it is off or has tripped. Switching a deliberately-left-off isolator back on once is reasonable. If it trips straight back out, stop and call an installer; something is drawing fault current.
  4. Safe for a homeowner — look at the bank without touching it. A visibly disconnected lead, a scorched fuse holder, green or white corrosion on a terminal, or a lithium pack with no lights on all tell you something. Photograph it and hand the photograph to your technician.
  5. That is the end of the homeowner path. Do not tighten a battery terminal, do not clean a terminal, do not replace a DC fuse, do not reseat a pack in a rack and do not open a battery. Battery terminals are live at all times, whatever the inverter is doing, and a 48 V bank will deliver enough current through a dropped spanner to weld it.
  6. On a lithium bank, do not treat a BMS reset as the fix. If the pack's BMS has opened its output, it did so for a reason — over-voltage, under-voltage, over-current or temperature — and clearing that protection without knowing which one fired simply re-arms whatever caused it. A reset is appropriate after a qualified engineer has read the BMS log and dealt with the cause, not before.
  7. Qualified installer if the system has a battery and bP persists. He should check the isolator, the DC fuse, terminal torque and lug condition, the cable size, and — on a lithium bank — the BMS state and its communication with the inverter.

References