Battery problem update

[Chocky]

We live in a relatively mild climate but the Puma is sold across Eu including some very cold places like Finland. The 48 volt battery will not give up enough charge to power the BISG in winter conditions so a 12 volt starter must be used. Ford did indeed design the system just like all other OEMs do.

Why on earth would the 48v battery not hold enough charge!? It should be a far superior battery to the 12v battery. Can you provide any “technical “ description or evidence of this, not marketing stuff.

I have found some information on the basic level mild hybrid systems and it looks like that’s fitted to Puma etc, so that is why it still has the 12v starter. Not very efficient systems at all and the bms controls the charging of the 48v battery as the 12v charging is derived from the 48v generator/battery via the DC-DC converter or does it have a separate 12v direct source charging facility from the hybrid unit, who knows, information on it is crap

I said not give up enough charge. The 48 volt battery could be fully charged but in the cold you cannot pull enough amps from it to drive the BISG. The 48 volt battery bms will handle cell balancing, lithium plating protection and any functional safety requirements at the battery level. The Ford ecm will control the vehicle 12 volt charging strategy as the DC-DC is pretty dumb.

[4251]

We live in a relatively mild climate but the Puma is sold across Eu including some very cold places like Finland. The 48 volt battery will not give up enough charge to power the BISG in winter conditions so a 12 volt starter must be used. Ford did indeed design the system just like all other OEMs do.

Why on earth would the 48v battery not hold enough charge!? It should be a far superior battery to the 12v battery. Can you provide any “technical “ description or evidence of this, not marketing stuff.

I have found some information on the basic level mild hybrid systems and it looks like that’s fitted to Puma etc, so that is why it still has the 12v starter. Not very efficient systems at all and the bms controls the charging of the 48v battery as the 12v charging is derived from the 48v generator/battery via the DC-DC converter or does it have a separate 12v direct source charging facility from the hybrid unit, who knows, information on it is crap

I said not give up enough charge. The 48 volt battery could be fully charged but in the cold you cannot pull enough amps from it to drive the BISG. The 48 volt battery bms will handle cell balancing, lithium plating protection and any functional safety requirements at the battery level. The Ford ecm will control the vehicle 12 volt charging strategy as the DC-DC is pretty dumb.

Lithium batteries are now commonly used for starting, I don’t buy that one, proper mild hybrids use it all of the time! A DC-DC converter is a passive device it doesn’t need intelligence. The current control is carried out before or after it.

[Stoopo]

From Ford:

HOW DO MILD HYBRIDS WORK?
Mild hybrids combine an electric motor and 48-volt battery with a conventional engine. The electric motor seamlessly integrates with the engine and uses stored energy to provide extra torque. The system monitors vehicle usage to determine whether to use or charge the battery.

When your MHEV is coasting or braking, the electric motor acts as a generator. Energy is collected and stored in the 48-volt battery, ready to assist or supplement the engine.

Yes this is about all I can find from Ford too, but it’s a super basic none technical and pretty useless marketing description. The schematic I posted is how most mild hybrid technology works

“Most” being the operative word. I’m pretty sure the Ford system is different.

[Stoopo]

The problem is you can't charge the 48v battery externally, if it went flat you wouldn't be able to start the car at all as some owners of other makes have found.

But the Puma is started by the 12v battery.

[DesertIslandBlue]

Correct me if I’m wrong but I was under the impression that the 12v battery starts the engine via the 12v starter motor only when the engine is cold.
The 48v system starts the engine via the BiSG at all other times.
Apparently this is because the BiSG uses a belt and the extra torque required when cold causes belt slip.
Not sure what happens when the 48v battery is flat but the electronic trickery hopefully would allow a cold start via 12v but would switch off the stop/start until sufficient charge is present in the 48v system?

[Stoopo]

Correct me if I’m wrong but I was under the impression that the 12v battery starts the engine via the 12v starter motor only when the engine is cold.
The 48v system starts the engine via the BiSG at all other times.
Apparently this is because the BiSG uses a belt and the extra torque required when cold causes belt slip.
Not sure what happens when the 48v battery is flat but the electronic trickery hopefully would allow a cold start via 12v but would switch off the stop/start until sufficient charge is present in the 48v system?

Exactly that I think.

[Chocky]

Correct me if I’m wrong but I was under the impression that the 12v battery starts the engine via the 12v starter motor only when the engine is cold.
The 48v system starts the engine via the BiSG at all other times.
Apparently this is because the BiSG uses a belt and the extra torque required when cold causes belt slip.
Not sure what happens when the 48v battery is flat but the electronic trickery hopefully would allow a cold start via 12v but would switch off the stop/start until sufficient charge is present in the 48v system?

You're mostly spot on. It's not when the engine is cold but actually after every key start.
If the 48 volt battery is depleted then start/stop is inhibited until it is replenished either by regen braking or the engine.

[DesertIslandBlue]

Correct me if I’m wrong but I was under the impression that the 12v battery starts the engine via the 12v starter motor only when the engine is cold.
The 48v system starts the engine via the BiSG at all other times.
Apparently this is because the BiSG uses a belt and the extra torque required when cold causes belt slip.
Not sure what happens when the 48v battery is flat but the electronic trickery hopefully would allow a cold start via 12v but would switch off the stop/start until sufficient charge is present in the 48v system?

You're mostly spot on. It's not when the engine is cold but actually after every key start.
If the 48 volt battery is depleted then start/stop is inhibited until it is replenished either by regen braking or the engine.

Thanks @Chocky

[Stoopo]

Glad we sorted that out

[4251]

Correct me if I’m wrong but I was under the impression that the 12v battery starts the engine via the 12v starter motor only when the engine is cold.
The 48v system starts the engine via the BiSG at all other times.
Apparently this is because the BiSG uses a belt and the extra torque required when cold causes belt slip.
Not sure what happens when the 48v battery is flat but the electronic trickery hopefully would allow a cold start via 12v but would switch off the stop/start until sufficient charge is present in the 48v system?

You're mostly spot on. It's not when the engine is cold but actually after every key start.
If the 48 volt battery is depleted then start/stop is inhibited until it is replenished either by regen braking or the engine.

It will mostly be replenished by the engine starter generator, but intelligently when coasting and slowing, same as vehicle charging systems have done for over 20 years. If it relied on regenerative braking it would be useless.