Author Topic: Is there a way to safely charge a car battery with this equipment? If not, why?  (Read 1556 times)

0 Members and 1 Guest are viewing this topic.

Online tautech

  • Super Contributor
  • ***
  • Posts: 17479
  • Country: nz
  • Taupaki Technologies Ltd. NZ Siglent Distributor
    • Taupaki Technologies Ltd.
I thought the old "generators" or dynamos were supposed to be smooth DC.

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
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.
Avid Rabid Hobbyist
 

Online Simon

  • Global Moderator
  • *****
  • Posts: 14441
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Yes i studied dynamo regulators closely when I cansidered designing a replacement.
 

Offline floobydust

  • Super Contributor
  • ***
  • Posts: 3352
  • Country: ca
What car maker does have 100mA drain?  Such ECU would not pass even the basic LV124 tests.  ;D

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)
 

Offline Marck

  • Contributor
  • Posts: 49
  • Country: au
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



 

Online tautech

  • Super Contributor
  • ***
  • Posts: 17479
  • Country: nz
  • Taupaki Technologies Ltd. NZ Siglent Distributor
    • Taupaki Technologies Ltd.

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%.
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.

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:
Avid Rabid Hobbyist
 

Offline Marck

  • Contributor
  • Posts: 49
  • Country: au
Most of our DC systems are Eaton but we recently in the last few years used some Tristar gear for some solar installations.  We found them quite good but with a slightly higher failure rate than the mains powered Eaton equipment but the cause of those failures could be put down to the duty cycle being much higher with daily discharge cycles.  Don’t get me wrong we are only talking about 2 issues across 5 sites in 4 years.  We just started trialing  Victron inverter / chargers Thats because we also need inverters to run an air conditioner and one other piece of mains powered equipment along with the nice http based UI that we can access remotely to keep an eye on things and ease of gathering trends. This means that we only need to keep one spare device that replaces 3 seperate units a mains charger/inverter/solar charger. Set up in pretty much a plug and play setup.  By no means am i suggesting that the Tristar gear is not as good as the Victron stuff its just ease of serviceability for us. Time is the only real judge of performance for most of these things.

Most quality battery manufacturers will specify an ideal charge profile based on the battery and typical operating temps in sites that are not temperature controlled they quite often recommend  a change in charge voltages for temps outside a specific range.  Most of the better chargers will have a temp probe that can trigger a change in charge profile for excursions outside the optimum. 

Good luck with your service power is always a expensive and difficult thing to get spot on for long trouble free service.

Just another bit of advice on the batteries that claim much more than 150 AH capacity in the standard long tall form factor used in these installations.  Quite often these claimed capacity’s are at a lower discharge rate compared to the competition.  A reasonable rule of thumb is if the battery dose not weigh more the capacity may not be as claimed. On average a good quality 150AH battery will weigh around 47 kilograms each if the claimed capacity dose not come with extra lead in the battery unless they have some design advantage its time to dig into the spec sheet and see whats going on.

Its almost at the stage where Lithium is the correct choice for new installations.  The increase in available discharge capacity the increased cycle count and the huge weight savings the lifecycle cost is almost at breakeven point.  The only thing that is holding back the revolution is the cost of failures smudges the cost benefit line a bit.  A out of warranty replacement of a battery is double that of lead acid.  And at this point there is not quite enough long term data on any particular manufacturers lithium service life to adopt that risk.   For any existing installations that wont allow constant voltage charging and will require upgrades of chargers and such its a little further away.  But my personal opinion is that within 5-10 years we will not see many  lead acid battery installations being used in telecommunications.


Now we are way off topic.
M



 

Offline Tomorokoshi

  • Frequent Contributor
  • **
  • Posts: 839
  • Country: us
what vehicles use AGM batteries?

What cars use AGM batteries? Mine do!

Just charged up some spare batteries using my HP 6114A power supply. Set to the recommended charging voltage of 14.4V and set the current limit to 1A. Then I slowly adjusted the voltage down to keep the trickle current to around 100mA.

This all started because one of the batteries stopped taking a charge after being used for around a month. That was maybe 3 years ago. Took it to the store where they used the battery tester, declared it failed, and so I was able to submit a warranty claim for a free replacement.

I never got around to getting rid of the failed battery, and before I got the coupon for the replacement I bought another one of a different brand and construction. Through a series of mishaps I now have all three batteries not installed in a car.

Anyway, as part of topping off the two known-good batteries I connected the failed battery to the HP 6114A. No current. Well, that being the case, I instead used the HP 6186C 300V / 100mA Current Source to charge it. At 10mA it drove to something like 100V.

Over the course of a few hours the voltage dropped to maybe 15V, so I charged with the HP 6114A instead. For the most part it topped off at the same voltage as the other two, and after 4 weeks the two good ones are 12.8V, and the "bad" one is 12.7V.

I don't know what the failure process was and I don't know what may have fixed it. I have not signficantly load tested it yet.
 

Online tautech

  • Super Contributor
  • ***
  • Posts: 17479
  • Country: nz
  • Taupaki Technologies Ltd. NZ Siglent Distributor
    • Taupaki Technologies Ltd.
@ Marck
The installation we did was purposely kept all DC and powers just a DC POE switch that in turn powers all the Ubiquity data transmission HW. NO freaking inverters !
Here's a link to some pics of the installation with a link to the docs of the DC POE switch we used:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2698096/#msg2698096

The 4 batteries are German SLA's and mighty heavy buggers @ some 55kg ea !  :scared:
Yep and we used the Tristar solar controller battery temp sensor.  ;)

Anyways, IMHO it's over designed to hell as any one bit of HW draws under 30W max ea and there's 900W capability from the panels for a measly ~100W max load.
Avid Rabid Hobbyist
 

Offline Marck

  • Contributor
  • Posts: 49
  • Country: au
That Ubiquiti gear is good value for money. We recently used a couple of the Air fibre 24hd links for temporary coms over about 2Km.  A solid gigabit link and lets say very rough one eye closed  alignment.

That looks like a neat little switch.  Here that would probably cost hundreds of $$.  The US gets all the good cheep toys. 

M
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf