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Is there a way to safely charge a car battery with this equipment? If not, why?

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Simon:
If it's an actual battery management system like some modern cars have then fair enough, it takes care of itself like restarting the engine if you are sitting in traffic running you electric air conditioning and the battery gets low. But run-of-the-mill vehicles that just connect everything in parallel don't run that high. My last car ran 13.8V I had a constant display on it.

tautech:

--- Quote from: Simon on October 21, 2019, 07:33:36 am ---If it's an actual battery management system like some modern cars have then fair enough, it takes care of itself like restarting the engine if you are sitting in traffic running you electric air conditioning and the battery gets low. But run-of-the-mill vehicles that just connect everything in parallel don't run that high. My last car ran 13.8V I had a constant display on it.

--- End quote ---
Understood, however I'd never trust a dashboard meter to be particularly accurate let alone the average vehicle owner having the knowledge to properly interpret it. Charge failures need prompt alert to the driver and I wouldn't care for anything other than a red charge light alert.

Still, that 13.8 V display is typically the lowest max you want to see a FLA charging system maintain.

Mechatrommer:
older battery having trouble reaching 13.8V let alone 14.4V. i monitored few battery and with 14.4V charger, some of them can constantly suck 0.25-0.5A and get hot. hot battery is not a good sign (hydrogen discharge) i boomed one of those 60AH'er right next to my ear while welding its rusty holder to a car with it sat right next, and being (over?) charged (13.8 - 14.4V) overnight. i got a warning of pissing smell, and read about hydrogen discharge a night before, and remember did a hydrogen pop experiment in school decades ago. a real stupid move i didnt take the hints, now i know and the puzzles now all connected together nicely and it will stick in my head pretty well i guess. sometime i believe a little bit of knock on our head or ringing bell echo from the ear can improve memory retention and attention, even on aging brain.

Simon:

--- Quote from: tautech on October 21, 2019, 08:02:14 am ---
--- Quote from: Simon on October 21, 2019, 07:33:36 am ---If it's an actual battery management system like some modern cars have then fair enough, it takes care of itself like restarting the engine if you are sitting in traffic running you electric air conditioning and the battery gets low. But run-of-the-mill vehicles that just connect everything in parallel don't run that high. My last car ran 13.8V I had a constant display on it.

--- End quote ---
Understood, however I'd never trust a dashboard meter to be particularly accurate let alone the average vehicle owner having the knowledge to properly interpret it. Charge failures need prompt alert to the driver and I wouldn't care for anything other than a red charge light alert.

Still, that 13.8 V display is typically the lowest max you want to see a FLA charging system maintain.

--- End quote ---

It was a CAN bus display so it would have been either taking it from CAN bus data or i would hope that someone that can design a CAN bus device would be clever enough to measure voltages to 0.1V!

T3sl4co1l:
Simon, about an hour later and battery voltage rose to the set 14.25V (as it turns out) and current started to decline.  After about three more hours, it was still taking 1.5A charge, where I decided to cut it.

Doing the full charge at 13.8V will certainly (for the wet lead acid formulation) result in an incomplete charge state, and getting there will take exponentially longer than doing it at a slightly higher voltage.

Tim

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