LiMA Defect? How to Check Correctly.

Hi,

Hopefully, no one will kill me for asking a question about a gasoline engine, or for having missed something already written in the search results.

Citroen AX '93, 1.1i engine, 150,000 km, with a 44Ah battery.
The battery is completely discharged after about 10 days of inactivity. (The starter doesn't turn over, and the voltage drops to 2 volts during the starting attempt.)
When I plug them into the charger, the effective charging current drops from an initial 3 amps to 0 amps after 10 hours.
I'm guessing, perhaps naively, that the battery might be faulty, as it seems to only hold a maximum of 15Ah based on a rough estimate (charging current of approximately 1.5A for 10 hours). What do you think?

I then went to ATU, and they checked the battery and the alternator. They claimed that the battery was fine, but the alternator wasn't charging it. Unfortunately, I wasn't present during the inspection, and the mechanic couldn't explain to me exactly what he had done.
"However, I then switched on all possible consumers while the engine was running (lights, rear window heater, etc.), and the voltage at the battery terminals was between 13-14 volts, depending on the load. This is noticeably higher than the battery's resting voltage (12.8V), so the alternator should be supplying power, meaning it shouldn't be broken, right?"
Am I wrong?

Okay, I can't measure any current drain from the battery when the ignition is off (specifically, 4mA), so battery discharge due to leakage currents is probably not the issue.

edit: How do you professionally test the function of the alternator?

Thank you for your responses.
Georg.

If you suspect the battery is the problem, try connecting your ASV battery.

Since you don't have any leakage current, the AX shouldn't be draining your (still) working battery.

If the AX starts nicely, then the AX battery is probably dead.

m;

Hello Martin,

Okay, the ASV battery simply doesn't fit in the AX in terms of size. Furthermore, it's obvious that it would also start the car nicely with that battery, just like it does with the AX battery that was freshly charged from the outlet. And I also don't want to hang my ASV battery onto the AX for a long-term test, possibly in the trunk or something , because 10 or more days is a bit too long for that.

There must be a faster and better way to decide whether it's either...
- the bra
or
- the battery
is, which is in the bucket.

Best regards, Georg.

Georg_G wrote:

There must be a faster and better way to decide whether it is either... - the bra or - the battery is, which is in the bucket.

Hi Georg,

Get yourself a digital multimeter or a precise analog multimeter with a good scale range (resolution) in the 10-15 volt range.

The cables and connectors/terminals between the alternator (LiMa) and the battery must not be corroded, have sharp bends (which could indicate partial cable breaks), etc.

With the engine running, the alternator should produce approximately 13.8 to 14.5 volts, largely regardless of the electrical loads that are turned on (with a fluctuation of less than 0.2 volts).
And this continues until almost the entire Christmas tree is lit. Then, the voltage can drop slightly while idling, but it should stabilize back to around 14 volts by approximately 1300 rpm.

EDIT:
Even with varying engine speeds (acceleration), the voltage should fluctuate only minimally, with the exception of idling under high load (see above).

If the LiMa system doesn't do that, then it's more or less broken.

and the mechanic couldn't explain to me exactly what he had done.


ATU - avoid!


However, I then switched on all possible consumers while the engine was running (lights, rear window heater, etc.), and the voltage at the battery terminals was between 13 and 14 volts, depending on the load.

edit: How do you professionally test the function of the alternator?

Exactly, see Ulf's description.


Citroen AX '93, 1.1i engine, 150,000 km, with a 44Ah battery.
What do you mean?


battery out.
sulfated, dried, or precipitated as active mass.

Testing a battery is very simple: fully charge it, connect one or two H3 bulbs to it, and see how long it takes for the voltage to drop to 10.8V. One bulb draws approximately 4.5A (two bulbs draw 9A), so a 44Ah battery should last for at least 4 hours.
Short, high-current tests are not necessarily indicative of capacity. It takes more than just applying a high current for 5 seconds to determine that. Even a battery with 10Ah of remaining capacity can easily handle that.


CU Gremlin.

: How does one professionally check the function of the alternator?


In addition, you could check the ripple voltage, preferably using an oscilloscope. Besides the voltage, as Ulf already mentioned, you could also check the charging current under load at various speeds.

Regards,

Tobias.

Hello,


Thank you for the responses.

In this case, it's likely that both the battery and the alternator are faulty. The on-board voltage has been fluctuating significantly (1 volt) depending on the load. And the battery also fails quickly when subjected to the test described by Gremlin.
Luckily, there's still a matching bra lying around...

Thank you and best regards,
Georg.

Hello Georg,

My own one wasn't performing as well as it used to, so I decided to measure it and compare it to two other TDI engines, one of which was only 2 months old.
When idling (with everything turned on), the alternator's (even the new one's) output reaches its limits, and the voltage can drop to below 13.5 volts, possibly even lower, but:

No matter what you turn on in the car, if the engine speed exceeds 2,000-2,500 RPM, there should be at least 13.8 volts, otherwise the battery will not charge properly.
Here are my results. My LiMA (likely referring to a specific test or measurement) isn't doing so well anymore, but it achieves a score of 13.9 above a certain threshold (likely 2000). The new one scores 14.1, which is still acceptable.

Did I read that wrong, or is your battery 9 years old? If so, it's 3 years past its lifespan. Replace it. It's almost nothing compared to the cost of the alternator.

Regarding your question about the Lima test:
1. Use the clamp ammeter and apply a reasonable load to the battery. It should, at a higher motor speed, roughly deliver the amperage rating indicated.

Or:

If you load the vehicle's electrical system with a current draw close to the alternator's rated output, it should still maintain a voltage of around 13.8 volts (by increasing the engine speed).

Okay, so: If it's a 50A alternator and you're only drawing 40A from it, and it's maintaining a voltage of 13.8V (even 13.6V would still be okay), then leave it as is.

If the voltage drops below a certain level, the battery will no longer charge. If it drops below 13 volts, the battery will start to discharge.
Since car batteries are not cycle-resistant, they tend to fail very quickly.

I would advise against the discharge test. A new car battery can only withstand about 30 of these cycles before it becomes unusable. While it might still have some capacity, it will become highly resistant and won't be able to turn the starter motor anymore.

The only way to find out is to measure - reduce the current to 200-300 Amperes and measure the voltage. I don't have any values for this, but any workshop should be able to do it.