Talk Morgan Forums Morgan Sports Cars Morgan Plus Four, Supersport & Plus Six (CX & CXV Generation Vehicles) Plus Six, Battery problems.

I replaced my cars battery last year with the correct size AGM battery all seems fine until a few months ago I stopped for fuel, when I came to restart the engine it struggled to turn over and the fault light came on so I stopped and turned off, I turned it back on and it started with no fault lights.

It did the very same thing this morning again at a fuel station, this time it stared on the 3rd attempt and the engine fault light stayed on, the car drove normally when I arrived home I turned the engine off and plugged in my OBD diagnostic tester only for the fault light have reset.

So tested the battery 12.5 v and kept monitoring the voltage it went down to 12.3 v within 30 minutes not enough to start the car, left it another hour came back battery back up to 12.5v and the engine started

12.5v appears to be low for an AGM battery, apparently I should be seeing 12.7v +, now before I go out and buy another battery as anyone else experienced this issue?

I would sling a meter on the battery and check its being charged and see what the actually battery voltage drops to when you crank it. This will tell you if it's a charging issue, th battery or a poor connection to the starter. AGMs aint cheap! Good luck

Mine failed after 18 months. The AA guy said it wasn't unusual with AGM batteries. Whilst on the ctek it charged fully but when cranked showed 10.5 v.

Possibly not the battery at all, it could be related to this problem, I have contacted the factory for comment.

BMW is recalling over 87,000 U.S. vehicles (and thousands more worldwide) from 2020–2024 due to a fire risk caused by a faulty starter motor that can overheat, even while parked. Affected models include various 2–7 Series and X3–X6, plus the Toyota Supra. Dealers will replace the starter for free, with owner notifications beginning March 2026.

It is reported by MSCC.

There is a post on the cx user bulletin board but for p4 not p6
If you can't access the bulletin board please send me an email to info@folkmog.net

Messafe from Morgan Motor Company re 2020-21 Plus Fours
Post by Gill Bevan [20169] » Fri Dec 05, 2025 4:37 pm

Hi all we have been asked to pass on this message to 2020-2021 owners from John Bower:

We have a warranty campaign running to replace the starter motors on early Plus Four cars. These are cars built between May 2020 and February 2021. attached is a list of the cars affected in the UK. Even though these cars are out of warranty, we would still replace the starter motors free of charge to any owners.

We really recommend that these starter motors are changed.
Any Morgan owners with affected cars can contact their preferred Morgan dealer and get their cars booked in for the job. We have sent starter motors out to all of the dealers who sold the original cars, but it is always best to contact the dealer first and make an appointment.

The job is not long, but the dealer will tell the owner how long they need the car for. Within a day assuming the new starter motor is still available with them.
Attachments

I saw that John, published also in Miscellany. Yes, just for the specified Plus Fours. Yet the BMW recall is also for the Supra, which I thought had the six pot B58. Checked on google and it seems that the Supra in some markets can have the B48 engine as an entry level model.

BMW B58 engine vehicles in the USA (and thousands more worldwide) from 2020–2024 due to a fire risk caused by a faulty starter motor that can overheat, even while parked. Affected models include various 2–7 Series and X3–X6, plus the Toyota Supra. Dealers will replace the starter for free, with owner notifications beginning March 2026.
This video explains the details of the BMW starter recall and the risk involved:
Related video thumbnail
0:37


WISH-TV
YouTube• 28 Sept 2025
Key Details of the BMW Starter Recall:
Hazard: The starter motor can overheat due to internal wear, leading to a potential short circuit and increased fire risk.
Safety Advice: Owners are advised to park their vehicles outside and away from structures until the repair is completed.
Symptoms: Drivers might smell smoke or notice the engine is hard to start.
Affected Models (various 2020-2024): 2 Series, 3 Series, 4 Series, 5 Series, 7 Series, X3, X4, X5, X6, Z4, and Toyota Supra.
Remedy: Dealers will replace the starter motor for free.
Timeline: Owner notification letters are expected to be sent around March 24, 2026.

Mike - let us know what response you get from MMC re the Plus Six, please.

Any idea why AGM batteries are used - I believe they are for stop/start applications and had no idea one was fitted.
Unable to drive the car for 3 months or so due to an operation so car wired up for maintenance and my charger kept indicating a fault after reaching 100% charge.
Being oblivious to battery technology I had no idea the charger had to be changed to an AGM setting.

My bad, 72 years and still learning!

2024 Plus Four Auto

Mike given the minimal age of the battery I would place it on a smart charger overnight set to AGM and possibly winter rate given present overnight temperatures. After waiting an hour to settle down after charge you should see 12.7 volts, maybe more due to residual surface charge. If its less and/or later drops as quickly as you suggest it's likely a u/s battery. Note that standing battery voltage is only relevant an hour or more after use or charging and is only then an indication of the state of charge on remaining capacity which could be a small fraction of as new. You could have a battery showing 12.7 volts standing but unable to start car when starter demands an unsupportable current draw due to minimal capacity.

As a side issue the reported starter problem is alarming in that it happens whilst vehicle is standing and needs to be investigated. Surely it would have triggered a recall though by BMW on their affected cars. It would be interesting to hear MMC's comments on this issue.