How fast an Ohme charger should charge
A single phase Ohme delivers up to 7.68 kW, which is 32 amps. Ohme is clear that this is the ceiling, not a promise. The rate you get depends on your electrical installation, your charger type and your car. On a smart charge Ohme may also slow the rate on purpose as part of its dynamic charging, to manage grid demand and, in Ohme’s words, reduce strain on the battery. That is not a fault. The question on this page is why a Max Charge, which asks for full speed, is still coming in at half.
Ohme’s own slow charging guide lists the causes, and we check them in this order.
The car’s own AC charging limit
Some plug in hybrids and smaller EVs can only take 3.7 kW on AC, however fast the charger. Ohme cannot beat that. Your handbook, the EV Database website or your dealer will tell you the car’s maximum AC rate, and it is worth remembering AC and DC limits are different. A car that takes 150 kW on a motorway rapid may still be a 3.7 kW car at home. Some cars also carry a “reduced AC charging” or eco setting that halves the rate.
Two more car side causes catch people out, and we see both. The first is the taper. Every EV slows its charging as the battery gets close to full to protect the cells, so a car that was pulling 7 kW at 60 percent may show 3 kW at 95 percent. That is the car, not the charger, and it is normal. The second is the car’s onboard charger, the unit inside the vehicle that turns the AC from the wall into DC for the battery. It sets the ceiling for AC charging, and when it develops a fault the car will take less than it should from every charger, not just yours. If the car is slow at a friend’s charger or a public 7 kW post as well, that is where to look.
The wrong vehicle in the Ohme app
Ohme uses the vehicle profile in the app to work out charging speed and schedules. If the profile is a 3.7 kW car and yours is 7 kW, the charger may hold to the profile. Settings, My EVs, check the Max AC charging speed matches your car. If your model is not listed you can create a custom vehicle. Ohme notes you cannot remove a car while it is the primary EV, so add the right one first, switch to it, then remove the wrong one.
A maximum current set at installation
Installers can cap an Ohme’s maximum current for safety, and Ohme gives the example of a looped supply where the DNO guidance means a 16 amp limit. Check it in the app under Settings, My Charger, Advanced Settings, Charger configuration, Max Charge Current. If it reads 16 A that is deliberate, and only your installer should raise it, once they have confirmed the supply can take it. If your installer has gone, that is one of the things we can assess.
Load balancing cutting the rate when the house is busy
If a CT clamp was fitted on your main supply cable and load balancing enabled, the charger backs off whenever the house gets near its load limit (60, 80 or 100 amps depending on the property). Kettle, oven and shower on together and the charger will slow, then speed back up when they go off. Ohme calls this a normal safety feature and it is. You can watch it in Advanced Settings, where the clamp reading is shown.
Load balancing with no working CT clamp
This is the one that catches people, and Ohme is explicit about it. If load balancing is enabled and the charger is not getting a reading from the CT clamp, it limits itself to 16 amps as a precaution, roughly 3.7 kW. That happens when load balancing was switched on but no clamp was fitted, when the clamp is on the wrong cable or not connected properly, or when the clamp has failed. Check during a Max Charge under Settings, My Charger, Advanced Settings, CT Clamp Reading. The number should move as the house uses power. If it sits at zero, the clamp is the problem.
The Home Pro manual says the same from the installer’s side. If the clamp is removed or faulty with load balancing active, the unit reverts to a reduced rate. This is a short fix, and it is one we see.
The Home Pro firmware version that capped Max Charge
Ohme published a dedicated notice about Home Pro firmware v2.62, which limited Max Charge to about 16 amps and 3.5 kW. The app pops up a “charging slower than expected” notice, session stats halve, and the power screen shows 3.5 kW on Max Charge. The check is the firmware version on the Home Pro info screen or in Advanced Settings. The fix is to unplug the car, switch the charger off at its breaker on the fuse board for two minutes, switch it back on and let it update. If it is still on 2.62 after half an hour, request an update from Ohme.
The cable itself can halve your speed
Every Type 2 cable carries a small resistor in the plug whose only job is to tell the charger how much current the cable can safely take. The charger reads it and never goes above that number.
A three phase cable declares a lower number than a single phase one. It is built to carry around 16 amps down each of three cores, which adds up to 11 kW on a three phase supply. Put the same cable on a single phase home charger and only one core does any work, so you get about 3.7 kW. The charger is doing exactly what the cable told it to.
Nothing is broken and nothing is unsafe. A three phase cable on a single phase charger is simply telling a 7 kW unit to run at half speed. It is not the commonest cause of a slow Ohme, but it comes up often enough that we ask about the cable early whenever an ePod is slow.
This only applies if you supply your own cable, so it affects the untethered ePod and not a tethered Home Pro. If your ePod has always charged slowly and the app settings all look right, borrow a different cable and try again. If the speed doubles, you have found it.
Our view
There is no single answer to this one. On the units we see it is most often the car, either what it can take on AC or a setting inside the vehicle, and after that a cable, a maximum current set at installation, or load management holding the rate down. We look at all of them, because it is rarely the same thing twice. What it usually is not is a broken charger. This is one of the few Ohme problems that is normally fixed without touching the hardware at all. If you have run through the six and it is still slow, tell us the clamp reading, the max current setting and the firmware version, and we will know before we come out.
