Powersports battery w/BMS, 4.0Ah, 13.2V, “A” polarity, Case Type 2, Length 4.45" Width 2.28" Height 3.50". Shorai Batteries require a charging system output of 13.1 Volts or higher at idle, and must not exceed 15.2 volts at maximum output
In my DS7 2023 model vehicle, its name is in the right rear trunk compartment. This battery is 4 amps. main starter battery 70 amps. I think the fault is due to battery difference. One is a liquid battery, the other is a lithium battery, the charging voltage is incompatible.
I’m not sure about the difference in battery types.
I was told both batteries are lead acid ?
I would of thought the car would work out difference in voltage/amps and charge as necessary ?
I do think though your main battery must be faulty if its dropping to 8v when not running.
From what I was told the smaller auxiliary battery only supports the main auxiliary battery during start/stop or when if other features are taking a bit of a drain on the main auxiliary battery.
So it says in your boot what types of battery the car should have ?
If it says liquid (acid) for one and lithium for the other I would stick to that.
I cant see it being a manufacturing error putting wrong batteries together as there would be recalls everywhere ?
Its odd though why your main one is dropping so low.
I’ll try to see what type my central battery is .
Thank you for your help. Also, when the problem is fixed, I will share it here. In my opinion, the battery in the front is a liquid type battery, when the power of this battery drops below 50%, 11 volts cannot charge the dry type battery in the back. The rear battery requires 13.1 volts to charge. The spare battery is not charged because it is not charged while the vehicle is in motion. There is a problem that cannot be fixed. I tested the front battery in the cold morning and measured 10 volts. Besides, it does not charge and all the energy is consumed. I think that if I renew the battery in the front, it would be a short-term solution. Regards.
The back up battery, the dry one in your boot is there to support the main battery (wet one) at the front, so it doesnt get its charge from the main wet battery.
Both batteries get their charge from the alternator.
If the dry battery was getting its charge from the wet acid battery it would mean that it’s constantly under load starting the car, supplying power to the cars other electronics and supplying a charge back to the dry battery.
So I’m not sure the system works as you describe, but I’m might be mistaken.
I was always led to believe that the smaller battery, in your case the dry one is there to support the main battery not the other way round ?
Personally I think your front main battery is faulty so its just not holding it’s load, I dont think it’s dropping because its charging the dry battery.
This is why some features go into hibernation mode, when the main starter ( auxiliary) battery drops in voltage.
It’s a complicated system.
It could be. I stopped my car and after 1 minute, a sound was heard from the relay next to the battery and the voltage started to drop. The rear battery and the front battery fall together. The relay makes a bridge connection in vehicle standby mode. My thought. I will try using a higher charger with lower amperage. It was plugged in for 16 hours and did not exceed 13 volts. Happy New Year to you too.
So,
I’ve just checked the main battery voltage on my E Tense, the car has been sitting for 5 days, it was 12.1v, but oddly it crept up to 12.5v if I left the tester attached.
Bearing in mind that my tester puts the battery under load when carrying out a test I would of thought the voltage would drop not go up ?
Possibly the back up battery supporting the main battery ?
Today I delivered my vehicle to DS service for this problem. I stated that the main engine battery could no longer hold a charge and I went for a replacement. They said they would deliver your vehicle in the evening. Then they called and said they would charge the vehicle for battery replacement and test it, but it wouldn’t hold a charge so they should try it, I’m sure the two batteries are different. I don’t even think it is AGM, two different batteries are not the solution. It will be in the service for 4 days, we will wait and see, he may tell me that it has been repaired like you. This seems like a short-term solution in cold weather…
My car has been back to the service dept at least 5 times over the last 3 months and its still not solved.
They tell me every time the batteries are good ?
I’ve never asked what type of battery the support one is, I will do when it goes back in.
We are waiting for the Stellantis engineer to have feedback from the headquarters in France.
I’m going to put mine on a slow trickle charge today just to see if the charger picks up any faults.
I’ll update here later.
BTW, the manual says if any of the accessory batteries need to be changed it has to be done by a dealership because the negative is not accessable on the main battery and the positive not accessable on the central back up battery.
I’ve had a quick look and it does seem as if its a dealership job, at least on the DS4 E Tense anyway ?
The central battery is hidden away under the central armrest, and even if you manage to expose it the positive terminal is not exposed, so its definitely not intended to be charged like the front main battery, and even that one has the negative terminal hidden away.
I think on the DS7 there are some resetting of systems necessary
What a reset. In my opinion, the vehicle is in sleep mode and it should not be activated to charge the spare battery. The problem cannot be solved unless the alternator supports the two batteries with separate voltage. I’m sure the problem won’t be fixed.
I agree.
I think my issues are that the car is going into hibernation mode (sleep) prematurely.
This is one of the things the dealership are looking into.
Anton is saying we need to reset some features after carrying out a battery recharge.
But I think this is only necessary if the battery is disconnected.
Oh right sorry.
100% certain features will need resetting if the battery is changed.
The BMS will need setting for a new battery, along with the usual user settings.
So, after a slow overnight trickle charge the max voltage showing on my tester is 12.42v !
The charger does a number tests during the charge to see if the battery is in good condition, one of the tests is to see if it holds a charge.
There were no faults found !
Personally I think 12.42v after a full charge is a bit low , but I’m not sure if thats because the car’s BMS will only allow ?
I’ve read that a cars BMS only allows around an 80% capacity on batteries, leaving room for any overload ?
If you measure the voltage unloaded, it will probably show 14 or more just after fully charged, and it`s normal to drop when loaded, also with a tester. Depends how much load the tester puts on. It will probably be described in the tester user manual.
Backup and main battery incompatibility. The main battery is the liquid lead battery on the engine side, the dry type battery in the rear trunk. Cold cranking amps - CCA Incompatible
Master, I may be wrong because I used the translation. We are talking about 12 volt battery charging for charging, aren’t we? On the road via 220v, the hybrid charger is independent of the 14 kW under the rear seats of the vehicle and the 12 volt batteries. The accessory battery is in the DS7 rear bumper and the main starter battery is in the engine compartment. I know that BMS only controls the drive battery. The 12 volt system is also controlled by the ecu-ecm, which controls the charging system of the internal combustion engine, fuel, ignition, etc. Our vehicle is a plug-in hybrid. Does BMS have a function in the 12 volt system?
I want to tell you this. In the different plug-in hybrid system we use, the ecu-ECM charges, the main control is there, everything is under its control. Let’s not think of it as a battery powered vehicle. I will share with you the 12 volt battery information and photos that I will request from the service when returning the vehicle. I love my DS car like you, but the problem is beyond nonsense.
