[Munster]

After replacing my N70 Battery and Falcon alternator because of failures of both, the new battery is as flat as after sitting in the garage for two weeks. I haven't been able to drive it following an operation.

Can anyone give any ideas why a brand new battery would go flat when there was no drain on it?

[Gwagensteve]

Unless the battery was faulty from the shop, it can't go flat without there being some current draw.

Steve.

[henno]

Was the battery disconnected? I bet there was some drain on it.

[droverdave]

Well not much you can do but charge it up and see how it goes. If is stuffed, take it back for warranty and get another.

Did you drop it? you can drop cells that way, which might make it look like its "flat".

[Munster]

I do have dual batteries, the second battery is fully charged.
I have it on charge now, I'll check it tomorrow to see how it's going.

[Gwagensteve]

How are the dual batteries controlled? Random discharging of dual batteries due to problems with their control systems is all too common. One of reasons I dislike dual battery systems.

Steve.

[Munster]

Matson 140amp controller. The batteries were connected all the time. This problem seems new, because the original battery went from 12.5 volts to 3.66 volts overnight. The Matson is about 4 - 5 years old.

[Munster]

Gwagensteve wrote:

How are the dual batteries controlled? Random discharging of dual batteries due to problems with their control systems is all too common. One of reasons I dislike dual battery systems.

Steve.

Steve,

What's your preferred system for controlling dual batteries?

[Gwagensteve]

In truth, my preferred system is a single battery of the required capacity.

My defender has dual batteries fitted by the previous owner. I'm waiting for that system to die and wipe out one or both batteries. Seems to happen to every system eventually.

[Munster]

My new battery is a N70 with 810 CCA. You are right, I don't think I need the extra battery as I hardly ever run a fridge in the Zook.

[killazook]

The n70 is a big battery for a zook
In my jimny i have the stock battery and run a 40l engel fridge and the battery runs it for over 18hours without a problem and still starts easy

[Munster]

I also run a 9500lb winch.

[Munster]

After a lot of disconnecting and testing I discovered the falcon alternator (Mitsubishi) was discharging the battery when the ignition was off. I got another alternator from the auto leccie but it was the same. I have put the original Vitara alternator back and the problem is gone.
Apparently my car doesn't like the falcon alternator.

[whincup]

i had the exact same problem. i ended up using a relay to control the volt sense wire from alternator to battery. trigger the relay off the ignition power wire (black/white trace), the other side earth. problem went away. may have been a faulty alternator because i've since replaced the alternator & removed that relay, but its a cheap/easy option for you to think about...

however, if your using the standard wires (not the charge cable, the other 2) this probably wont make a difference