Thread: Low Battery level and dual batteries

Originally Posted by jonesy63

What would a hard reset achieve? When the terminals are connected back to the suspect battery, it is not going to change the battery.

I don't know, hence the question.

Scarry: in my case (2011 D4, dual traxide), it takes pretty much a day of running to get a full charge into the crank (which I think shows on my voltmeter as about 12.7 -13V while running). When its charging up, depending on state of initial charge, my voltmeter (OK $10 cigplug, but ...) shows up to 14.7V while running.
Like you, I use the ctek to trickle mine up about monthly, but I use the trailer plug. All seems neat and sweet, so far - 1 year. The OEM battery warning goes off at about 11.5V (standing), which is when I plug in the ctek.

Originally Posted by lpj

I don't know, hence the question.

Let me make it simpler:

1) Dead battery
2) Hard reset
3) Battery is still dead!

Hard reset - does nothing in this situation. The BMS is saying low voltage - working correctly.

Hi Paul and Trevor, 11.5v - 11.7v is too low for a cranking battery.

You should not allow it to get below 11.9v if you want a long life span.

Also, a long drive every so often is not going to return your battery to a fully charged state.

It will allow the battery capacity that is still usable to be fully charged but a battery that is used for short trips or sits around unused for long periods, requires numerous long drive so that each time you drive, once the battery is fully charged, the alternator can then condition the battery.

It’s the conditioning that will S-L-O-W-L-Y bring your battery back to maximum capacity.

The alternatives, as you both have posted, use a battery charger and leave it on the battery for around 8 to 10 hours after the battery charger goes into float mode.

Just like when charging via an alternator, a battery charger needs time to recondition the battery and you need to repeat this charging cycle to get the battery back to full “health”.

This chart will help with determining battery charge capacity, but note, SoC only indicates the State of Charge of the USABLE capacity, and not the battery's original total capacity.

Originally Posted by jonesy63

Let me make it simpler: 1) Dead battery 2) Hard reset 3) Battery is still dead! Hard reset - does nothing in this situation. The BMS is saying low voltage - working correctly.

Gee thanks. Perhaps I didn't express my genuine question properly. In any case, you have missed the point of what I was asking. I can't see how your response has helped at all. I thinks it's clear from the posts that the battery is dead.

This forum is for "support and community"

Thanks and I'll now bow out of this little game of yours.

Originally Posted by lpj

Gee thanks. Perhaps I didn't express my genuine question properly. In any case, you have missed the point of what I was asking.

lpj, I think I understand your question. When a fault happens that is monitored by the car electronics, the computer stores a fault code. Some of these codes clear automatically when the fault situation goes away, others are stored for future analysis - and clearing - by the dealer.

The low voltage fault code could well be stored until cleared by a dealer who can investigate the reason for the fault code and if necessary take action. It may be possible to clear that fault code by a hard reset.

I don't know the answer to your question, but I think I do at least understand the question.

Thanks Tim,i can tell how low the cranking battery is by how long it takes the charger to go on float.

What i should do in future is get out the fluke and use your chart which is probably more accurate.

Since i have been charging the battery with the new charger,i have not seen the light on the SC80 flashing,where before it was often on.

Another reason to have an SC80 as it is a good warning everything is not OK.

Originally Posted by lpj

Gee thanks. Perhaps I didn't express my genuine question properly. In any case, you have missed the point of what I was asking. I can't see how your response has helped at all. I thinks it's clear from the posts that the battery is dead.

This forum is for "support and community"

Thanks and I'll now bow out of this little game of yours.

Apologies - yes, I missed your intended question. No games intended, I totally misunderstood what you were confused about. (BMS message versus clearing error stored error codes).