If you want to charge a battery right up 14.4V but don't leave it too long. You can float charge at around 13.5V. i would not try to put 400W or nearly 40A into a typical 40A car battery. i think the charge rate is usually arout 5-10A.It's also for the lols because I kept one that is not dead yet, and for general interest about the technology of battery charging (I don't need it for anything particular yet, so it's mainly general research, if it was for a real project, I'd probably try to find an always-on charging system anyway).
as suggested how about a comercial charger? they would be as cheap as the whole combo you have.
I do not think that you car alternator, let alone in cars equipped with start/stop system cares about your 5-10A charging limit, bhaha!
No, you don't understand, nor know.
Car alternator output is usually set to about 14.4V. There is no point in charging using 13.5 or 13.8V. That would take for ages to charge the battery.
You 5-10A charging current limit is just a silly talking. Alternator is like "zero fucks given" to your current limits.
Say, can I just set the module to 14.4V and the current limit to something high-ish and then monitor if the current it draws is dropping, or is there another way (if there is even a way)?
Lead Acid generic specs
-----------------------
At a comfortable temperature of 20°C (68°F), gassing starts at charge voltage of 2.415V/cell. When going to 20°C (0°F), the gassing threshold rises to 2.97V/cell.
Battery status -40°C (-40°F) -20°C (-4°F) 0°C (32°F) 25°C (77°F) 40°C (104°F)
Voltage limit on recharge 17.1 16.2 15.3 14.7 14.1
Float voltage at full charge 15.3 14.7 14.1 13.8 13.5
or lower or lower or lower or lower or lower
gasing at 20*C for V >= 14.4V
nominal, no load = 12.6V
floating charge = 13.5...13.8Vwhy does the alternator need to charge the battery that much? the battery is only used to start the engine and if the power demand is in excess of the alternator. The alternator will have a current limit but that is not what controls the battery charging it is to protect the alternator. The charge is controlled with the voltage and hene it is NOT 14.4V, go and measure your own vehicle if you don't beleive me!
why does the alternator need to charge the battery that much? the battery is only used to start the engine and if the power demand is in excess of the alternator. The alternator will have a current limit but that is not what controls the battery charging it is to protect the alternator. The charge is controlled with the voltage and hene it is NOT 14.4V, go and measure your own vehicle if you don't beleive me!
what vehicles use AGM batteries?Motorcycles and scooters.
Yea, and all a battery does these days is start an engine which takes less than 50Wh and is quikly replenished.
Yea, and all a battery does these days is start an engine which takes less than 50Wh and is quikly replenished.
Under ideal conditions, perhaps. It also has to be able to start a cold engine in adverse conditions. Try it at -18C. 60% of the battery capacity is gone because it's cold. The oil in the engine is a cold thick fluid, so every moving part takes way more energy to move. In fact, that's so important that those are the conditions car batteries are rated under. The CCA (cold cranking amps) is how much current a very cold charged battery should be able to deliver for up to 30 seconds. When it's new.
Now try it at -40C. Yes, I've really had to start vehicles at those temperatures. Better to stay inside if it's not important, to tell the truth. People who deal with such climates regularly have engine and battery heaters. And replace batteries much sooner than those in warm climates.
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.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.
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.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.
Well, so what? It's taking current at a lower voltage because it's in a discharged state. As the concentration of Pb-->PbO2 and PbSO4-->Pb rises, the cell potential also rises. (In fact it's up to 13.74V already.) When all surfaces are fully charged, the voltage levels off somewhere around there (when under some degree of charge, because again, overpotential). I'm going to float it at 14.2 for a while (preferably 12-24 hr, not sure if I'll get that much time on it tonight) to ensure a full charge (desulfation, to the extent that it can be performed at all).You don't get a maintenance charge until 15V (gassing charge) where you'd get any benefit from desulphation and really you don't want to go there with the modern sealed FLA.
Tim
Well my car tonight according to a cheapo USB charger went as high as 14.5V dropping to 14.3-14.4. However I did leave the dash cam on all weekend and do short journey's so assuming the alternator can be controlled maybe it knows that the battery is low (started at 12.3V). I'll see how it performs over the next week
I thought the old "generators" or dynamos were supposed to be smooth DC.
In reality the 3 phase that get rectified are pretty goodEspecially when solid state regulation came in. Still, early alternators had electromagnetic regulation with all their EMI but to the greatest degree they were reliable until silicon technology advanced sufficiently to give reliable replacements.
What car maker does have 100mA drain? Such ECU would not pass even the basic LV124 tests. ;D
This ^ :-+
I can tell you from experience with large vehicle fleets that charging systems in vehicles are not all that interested in the best charging profile for the batteries and the use of either solar or regular charging of batteries with a mains charger to make sure that the batteries regularly reach 100% SOC will increase the life of the batteries sometimes by 25%.
Another point of reference i have with battery charging in telecommunications dc systems i have is with sites that had unreliable power the batteries would last longer. Getting discharge / charge cycles as opposed to batteries that never or rarely got cycled. Typically the batteries that where discharged to some extent would last 7 years vs 5 years for batteries that where on a float voltage consistently. This obviously is on a curve batteries that where cycled regularly and to deep discharge had a shorter life. We had a policy of not using automated discharge cycles to mitigate the risk of having reduced capacity if a power outage was to happen during that cycle.
what vehicles use AGM batteries?