Help battery charge new battery and not old alternator
 

Need help Asap! My car showed battery charge and i first thought the battery was bad, so i got new one today i did the voltage test through the climate and it showed 11.5 then i tried again it still got 11.5 with the car on is that too low? Brand new battery and like 6months old alternator! Its an 430E.. Btw i just drove 500km without problem then i shut it off and turned the car on the problem came

Why not correctly take the battery voltage with a volt meter directly at the battery--what does that read---if it still reads 11.5 then you need to take the car somewhere for a load test---that test will pin point the fault rather that cod fishing and purchasing not needed parts such as you have done till now!!

The battery was old.. The previous owner told me its old, but the alternator was new thats why i just went and got new battery without thinking.. Im stranded 500km away from home and everything is closed tomorrow

Sounds like there's a fault in your charging system, most likely a component on your alternator like the voltage regulator. Even though it's new, it could have failed. The alternator needs to be tested. You probably drove the entire way on a battery charge but ran the battery down. If you completely recharge the you'll be able to drive for a while until it runs down again. You can get further if you conserve electric power by shutting lights and AC (fan) off. It does take some time to completely recharge the battery though.

Yeah im trying to find someone where i am to test it, but everything is closed today :/ im saving what i got in thr battery to drive to mechanic tomorrow

Battery/Alternator issues
 

Retired auto tech here. To check charging system properly, battery MUST be fully charged and then measure the voltage at the battery and note it. Surface charge should be approx 12.5 to 13volts +-
Keep voltage meter on battery and start the car. Check the voltage. If alternator is working properly it should keep voltage at least at surface charge, but usually slightly higher. THEN turn on accessories that eat up voltage: A/C, high beam headlights, heated seats if equipped, emergency flashers, radio, wipers, etc. Now check the voltage at battery. Alternator should maintain at least 12.5 volts with everything on. Usually will keep voltage in the 13+ volt range. If it is below 12volts, alternator is suspect. Alternators have internal voltage regulators with brushes built in. If Alternator is suspect, voltage regulator can be replaced inexpensively on Bosch units, but Valeo regulators are more in the $70/80 range. Consider the mileage on the alternator in either case. Sometimes it's more cost effective to get a good quality rebuilt unit. Eeuroparts has the Bosch 120amp rebuilt for around $150 but there is a core charge you pay up front and get it back upon return. I have a 2000 E320 with Valeo unit. My car has close to 180k. Alternator is working fine (I recently ran the test) but I'm replacing it as a preventive measure. After much research, I decided to get one from Autozone. It's a Duralast 120amp part #15443 and it happens to be a Valeo. Lifetime warranty and it was only $140 with free shipping. Tax added was $17, but I took advantage of a promo code and am getting an Autozone $35 gift card. Net cost is approx $123 with lifetime warranty. If it fails, at least I can take it back to local Autozone and have a replacement in a day. On line vendors offer 1 or 2 year warranties, but I would have to pay for return shipping and wait a week to get another one. My research found that some/most on forums say you can replace Valeo with Bosch, but Autohauz info said you can't. I think a Bosch would work fine provided you get the correct amp unit. Some vendors sell 115amp and personally I would never use a lower amp unit. Higher but not lower. I think I lucked out in finding the Autozone info on another Mercedes forum thread because if I search Autozone for a 2000 E320, it shows the Bosch 115amp. Searching for a 2002 E320 gave me the part #15443 which turns out to be a Valeo 120amp so given the deal and proximity of Autozone I ordered mine today. Just got an email from Autozone indicating my alternator is on the way. I'll update after installation. Note: Autozone is charging a $70 core charge up front on top of the prices I quoted above, but local Autozone said they would refund me upon return of the old unit. I hope this info helps you!

Battery/Alternator issues
 

Forgot to mention that based on the info you wrote, I'm assuming your battery is good since it is relatively new. Charging the battery with a slow charger overnight should restore the proper surface charge to the battery. If for some reason the battery voltage is below 12.5 volts after overnight charge, I would suspect the battery. Remember, you cannot run a proper charging system check with a bad or undercharged battery.

James, I bought my replacement alternator at AdvanceAuto for about $120 a few years ago. I'm pretty sure it was a Valeo as well but not certain. I do remember it was different from the one I pulled and there was a note that came in the package stating it may be different from the one it replaces. I pulled the bad one out first and brought it with me so I wouldn't be charged a core charge, good thing because the new one didn't come with a pulley and they lent me and impact drill and socket in the store so I was able to swap the pulley off the old unit. It came with a lifetime warranty as well. Ordered it online and it was in stock in one of their stores not far away.

My AutoZone rebuilt alternator is coming tomorrow. If it looks good I plan on installing it Saturday. Will do a follow up post when done.

The problem is fixed, it was the alternator old ties of serp belt where in the alternator (previous owner had accident the serpenite belt fell off.. So new 150amp alternator and brand new battery!

Autozone rebuilt Alternator update
 

It's been over a week since I installed the Autozone rebuilt Alternator. My car had a Valeo and the replacement was also a Valeo. Exact match and swapping out was just under 1/2 hour. I checked the voltage output before and after replacing the alternator and both withing specs. I was very impressed with the quality of the Autozone rebuilt. As I mentioned in this thread, I replaced mine as a preventative measure. Placing the old/new side by side and spinning the pulley revealed that my original had a slight bearing noise and spun much more freely than the replacement. Not bad for 180k!
I have not returned the core yet since I wanted to be sure the rebuilt is going to continue to perform correctly. But in another week or two, I'll take the old one to the local Autozone and collect my $70 core charge refund. I've already replaced the serpentine belt, idler pulley and tensioner, checked water pump and ps pump and all is good. Next project: Front shocks, half shafts and ball joints. Also have front and rear flex discs on the list.
Love this car and don't mind spending a few bucks to keep it running correctly.:zoom: