I need to replace my main H8 battery. I usually buy AGM batteries. Should I also replace my starter battery which is H5 with AGM as well? Does it matter?

 

Hello @silvertonesx24 ,
I went AGM for both, not an issue, they are both lead acid batteries, and the C-TEK 7002 charges the five types of lead acid batteries.

Johnny

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Thanks Johnny. What symptoms will I have if the starter battery is bad? Struggling starts? I don't have a load tester but I'm starting to get main battery symptoms. Dash warning, EPC light came on randomly, it died while ON the tender, etc. I'm familiar with how Mercedes dual battery system works but not sure if the Bentley is the same or not

 

@silvertonesx24 ,
If the starter battery is dying or dead, then yes, poor cranking power, but, depending on your year vehicle, the emergency start procedure may be automatically engaging, therefore no need to turn the key to the left, the house battery dying or low will give you issues, keyless entry may not work, power soft close doors will not close, or even the trunk release will not work by remote or the "B" on the boot, yet the trunk release button on the drivers door will.

This is a nice tool to use to test each battery, along with the charging system, it will give the state of charge, state of health, it is a load tester also, not a bad price either.

Johnny

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OK thanks, I just ordered something very similar. I noticed that my battery was under warranty, so I took it in. They "charged it up" (thanks, I can already do that) and I made them test the CCA and they said it was fine.

I have my own load tester on the way today and will test it myself to verify.

The battery has now died twice while being kept on the Battery Tender, and the Battery Tender won't charge past 90 percent. I can start up the car just fine via the key, of course as that is a separate battery. Then I can get in the trunk, etc. Pretty useful feature from Bentley!

Either I have a bad drain somewhere, or something is wrong with this battery and they are trying to get out of replacing it.

 

Well my battery load tested just fine. I must have a parasitic draw somewhere. First to test and see if it happens if the car is locked or unlocked.

 

Looks like my problem was my Grom BT3 draining the battery. I noticed my car said "No CD" so I unplugged the grom, and suddenly the battery tender was able to charge to 100%

 

you were lucky to find the source of problem...

btw - what is your guys best practice to find the parasite current? you do the time consuming playing with removing fuses and looking at ampermetter? or other approach?

 

I would have watched an amp meter (waiting 5 minutes or so for everything to shut down on the car). I just started with the Grom as it's the only thing on my car that's aftermarket besides the radar which I know is accessory power only.

Plus, I knew by my battery tender, that it was always in a charging state, either 80% or 90%. Once I pulled the Grom, it was finally able to get to 100%

First thing I always do is pull the amplifier/infotainment fuse. Seems like a good 80% of drain problems start there.