| Electronics > Beginners |
| Is there a way to safely charge a car battery with this equipment? If not, why? |
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| tautech:
--- Quote from: Simon on October 21, 2019, 10:10:52 am ---I thought the old "generators" or dynamos were supposed to be smooth DC. --- End quote --- Well as smooth as you can get with a carbon brush commutator and an electromechanical regulator. ::) Old vehicles often didn't have radios so when you fitted one all sorts of suppression was required so to not have to a crackling whistling mess varying with RPM. Sure some of it was the ignition points but all of it, certainly not ! If you've every had the lid off one of the old points regulators to make a charging cutoff voltage adjustment the chattering points make it plainly clear where all the interference was coming from. --- Quote ---In reality the 3 phase that get rectified are pretty good --- End quote --- Especially 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. |
| Simon:
Yes i studied dynamo regulators closely when I cansidered designing a replacement. |
| floobydust:
--- Quote from: Yansi on October 21, 2019, 06:28:32 pm ---What car maker does have 100mA drain? Such ECU would not pass even the basic LV124 tests. ;D --- End quote --- Subaru are notorious for high parasite drain and mysterious dead batteries, across many models. 2015-2017 Subaru Legacy, Outback TSB Number: 11-176-17, NHTSA ID: 10125883, TSB Date: Dec.15, 2017 Failing Component: Electrical System: Battery Summary: This bulletin announces availability of reprogramming files to optimize the ECM for control of battery charging functions. Depending on vehicle use conditions, the battery state of charge value may differ slightly from the actual value. The new logic will enhance charging system control and result in improved battery life. TSB Number: 11-174-17R, NHTSA ID: 10131689, TSB Date: Aug.8, 2017 Failing Component: Electrical System: Battery Summary: This bulletin announces the availability of reprogramming files to optimize the ecm and address the following customer concerns: * check engine light coming on (with DTC p05a0 stored in memory). * potential battery discharge (dead battery) |
| Marck:
This isn’t really relevant to the original question but might be useful And its nice to be able to contribute with something i actually know about and have some experience. Some modern commercial vehicles will reduce charge voltages at idle to reduce emissions. This was a common issue 10 years ago when i was designing radio installations for emergency response vehicles. The best work around for this was to have the manufacture of the vehicle disable the feature either in the ECU or having the alternator modified to supply a normal charge voltage at idle. More modern systems now will measure accessory current use to maintain acceptable charge profiles quite often we see problems where installers will connect accessories before the measurement point causing problems with charging. Simply moving the connection point can resolve some problems Another problem this caused was very low voltages at start up which would cause problems with all sorts of equipment causing them to freeze up or worse. The best work around in 24 volt systems was to use a dc-dc converter and run the radios / accessories at 12v. This added another point of failure but was often the best bandaid fix where they wanted to keep the serviceability of the vehicles standard so no complexity was added to normal vehicle systems. For 12v systems in cars and such the other option was to introduce a delayed power up of the accessories for about 30 seconds to allow voltages to stabilise post engine start. Some of these vehicles would drop well below 10V during start up the issue here was that the voltage would cycle 8V - 11V - 8v during the couple of second start sequence and cause issues with the power up of the equipment. Some vehicles will wake up ancillary systems when they detect the keys proximity to the vehicle so people that park their cars close to where they are moving around with keys in bags and pockets can see problems if the vehicles are not regularly driven and the batteries are getting older. I have read about this being an issue with some BMW models. 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. M |
| tautech:
--- Quote from: Marck on October 22, 2019, 12:04:33 am --- 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%. --- End quote --- This ^ :-+ Also acquired from 45+ yrs of owning and operating several classes of vehicles. I try to do an annual freshening charge right to the max charge V of that class of battery to where you can see the drawn current drop right away to a couple hundred mA or less. Any cheap SMPS bench PSU with voltage and current metering is perfectly suitable for this. --- Quote ---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. --- End quote --- Interesting and it makes perfect sense. Having done a recent solar powered installation for community data provision when setting up the charge controller for a series/parallel bank of four 165 Ahr SLA's there were several options for battery maintenance based on the battery type used. https://2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com/wp-content/uploads/2014/02/150V-TS-MPPT-Operators-Manual.pdf P12 It is important to select the battery type that matches the system battery to ensure proper charging and long battery life. Refer to the specifications provided by the battery manufacturer and choose a setting that best fits the recommended charging profile. DIP Switches 4 - 5 - 6 Battery Absorp. Float Equalize Equalize Type Stage (Volts) Stage (Volts) Stage (Volts) Interval (Days) off-off-off 1 - Gel 14.00 13.70 off-off-on 2 - Sealed* 14.15 13.70 14.40 28 off-on-off 3 - Sealed* 14.30 13.70 14.60 28 off-on-on 4 - AGM/Flooded 14.40 13.70 15.10 28 on-off-off 5 - Flooded 14.60 13.50 15.30 28 on-off-on 6 - Flooded 14.70 13.50 15.40 28 on-on-off 7 - L-16 15.40 13.40 16.00 14 on-on-on 8 - Custom Custom Custom Custom Custom * “Sealed” battery type includes gel and AGM batteries Battery Type - The most common battery type associated with the specified charging settings. Absorption Stage - This stage limits input current so that the Absorption voltage is maintained. As the battery becomes more charged, the charging current continues to taper down until the battery is fully charged. Float Stage - When the battery is fully charged, the charging voltage will be reduced to the Float voltage setting. Equalize Stage - During an equalization cycle, the charging voltage will be held constant at the specified voltage setting. Equalize Interval - The number of days between equalization charges when the controller is configured for automatic equalizations (settings switch 7). Then in addition there's Equalisation management as follows: Switch 7: Battery Equalization Choose between manual and automatic battery equalization charging. In the manual equalization setting, an equalization will only occur when manually started with the push-button or when requested from the equalize menu on the TriStar meter. Automatic equalization will occur according to the battery program specified by settings switches 4, 5, & 6 in the previous step. In both settings (auto and manual), the push-button can be used to start and stop battery equalization. If the selected battery charging setting does not have an equalization stage an equalization will never occur, even if requested manually. You'd hope it all works as expected as the price of the battery bank was $$$ :scared: |
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