www.elektronik.si

[reber]

Očitno je servisant enostavno spregledal dejstvo, da se debata vrti okrog omejene napetosti, kar pomeni, da napetosti ne bomo presegli, kar avtomatično pomeni zmanjšanje toka. Akumulator se niti slučajno ne bo segrel na omembe vredno temperaturo, vse bo ostalo v mejah normale in dovoljenih vrednosti. Ker tukaj primeri dokazujejo, da akumulator le ni tako občutljiva stvar, se ni potrebno pretirano bati.
Res pa je, da bi polnjenje z velikim tokom povzročilo škodo akumulatorju, če bi to polnjenje nadaljevali predolgo, vendar bi v tem primeru presegli 16V in celo 17V kar sploh ni v redu. Ker pa debata že od začetka teče v smislu omejene napetosti, ne vem zakaj taka panika ...

Primer: če hočem akumulator 100Ah polniti s 50% tokom, bi ga teoretično napolnil v dobrih 2 urah ... vendar bi po nekaj minutah že presegel 13V, po nekaj 10 minutah bi presegel 14V, verjetno celo dosegel in presegel 15V, kar pa je že preveč, saj v tem času akumulator še ne bi bil 50% poln, kar pomeni polnjenje še vsaj 1 uro s 50% tokom .... Po dodatni uri polnjenja s takim tokom bi se akumulator že pošteno segrel, elektrolit bi že vrel, napetost pa bi bila že krepko čez 16V, verjetno tudi krepko čez 17V. Tako polnjenje bi akumulator uničilo v nekaj ciklih.
Spet se vrnimo k bistvu vprašanja te teme: napetost je omejena, torej bo tok avtomatično sam padel ... v čem je tukaj problem?

[servisant]

[reber]

... klub vsemu, pa bo življenska doba obeh akumulatorjev praktično enaka lahko celo različna v prid naključnemu akumulatorju.

[pajo]

Sealed Lead-Acid Standard-Charge
For applications which can allow a recharge period of 24 hours or more––any period from an extended “overnight” charge to a “float charge”–– the standard-charge is the regimen of choice. The reasons for this include:
• No charge termination required.
• Frequently requires no temperature compensation.
• Small power supply required to provide the chargingcurrent.
• Small charging circuit power components.
• Low overall charging system power dissipation.
• Excellent battery life due to low charging stress.An SLA standard-charge is relatively straightforward to implement. In “cookbook” form, such a charge requires:
• Charging Current: Limited to 0.25C or less.
• Charging Voltage: 2.25V/cell to 2.30V/cell, plus charger
overhead.
• Charging Temperature Range: 0°C to 40°C.
• Charging Time: 24 hours or longer.
• Charge Termination Method: None required.
• Secondary Charge Termination Methods: None required.
• Special issues which may require further consideration are: wide temperature range charging, wide temperature range discharging, and accurate gas gauging under varying conditions of use.
Sealed Lead-Acid (SLA) batteries are generally charged using a constant voltage source with a deliberately imposed current limit (essentially a current-limited voltage regulator), or a charger which will, in terms of the electrochemical
effects seen by the battery, act as if it were such a source. The charging regimen which this gives rise to is known as “Constant Voltage,” or more commonly, “Constant Potential.” For the purposes of this document the term “Constant Potential” (CP) will be used. The reasons for using a CP charge regimen are various, but the three principal ones are these:
• Charge acceptance (the efficiency of conversion of
previously removed electrical energy back into chemical
potential) is reduced as the charging current through
an SLA cell is increased.
• Once full charge is achieved, continued charging current
through an SLA cell will have an irreversible oxidizing
effect upon the positive plate of the battery, ultimately
reducing battery capacity.
• Most importantly from the standpoint of designing a
practical charger, there is no reliable way to know an
SLA cell’s state of charge based upon its terminal
voltage or its temperature.

Sealed Lead-Acid Fast-Charge
In many cases, 24 hours or more will constitute an excessive recharge time. Portable instrumentation is an excellent example–– even if the battery pack in an instrument can be “swapped out” for external recharge, it is often needed again before the day is out, fully charged and Figure A4. The battery temperature at which actual capacity is 85% of standard capacity is approximately 0°C.
Similarly, adjustment to the indicated capacity may be desired if the continuous discharge current will be at a rate significantly greater than 0.1C. It may be desirable to take these effects into account if gas gauging is to be done over
extended temperature ranges. If correction parameters for AN64-29
Application Note 64 ready for use. In this case the sophisticated fast-charge
techniques which the LTC1325 makes practical are the way to go. A fast-charge regimen implies:
• Significant recharge within one hour; 100% recharge
within three hours.
• Suitable means to determine charge termination point.
• A backup charge termination method to ensure best
battery life.
• Highly efficient use of available charging energy.
• Increased product value through better battery utilization and greater customer satisfaction.
An SLA fast-charge is very similar to an SLA standardcharge. It is recommended that the section on standardcharging of Sealed Lead-Acid batteries be read before
reading this section. There are only three significant differences between the two sections:
a) The charging voltage is increased (to increase the charging current).
b) Temperature compensation is definitely required at a rate of » –5mV/°C, preferably from a sensor mounted near or on the battery case.
c) Fast-charge termination is required.
• Charging Current: Vendor-dependent. The vendor used
as a reference suggests 1.5C.
• Charging Voltage: 2.45V/cell to 2.50V/cell, plus charger
overhead.
• Charging Temperature Range: 0°C to 30°C.
• Charge Termination Method: Current Cutoff.
• Charging Time: Three hours; 60% of charge is typically returned within the first hour.
• Secondary Charge Termination Methods: Timer.
• Special issues which may require further consideration are: wide temperature range charging, wide temperature range discharging, and accurate gas gauging under varying conditions of use.
The primary termination method, “Current Cutoff” (CCO), looks at the absolute value of the average charging current flowing into the battery. When that current drops below 0.01C the battery is charged and needs only a trickle current of about 0.002C. The backup method should be a 180-minute time-out, according to the recommendations of the vendor suggesting 1.5C as a high-rate current.
During fast-charge the battery will get warm and some venting may occur. It is prudent engineering to allow for these contingencies in the mechanical design stage of the equipment in which the battery will reside. The manufacturer of the SLA battery to be used should be consulted for specific guidance. In all other regards, the techniques for the fast-charging of SLA cells and batteries are the same as those used for standard-charging these devices. A simple circuit, coupled
with a straightforward software servo loop, provides a high performance SLA battery charger and gas gauge as well as significant built-in fault detection and protection mechanisms.

povzeto iz:
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1021,P1275,D4153

[Iztok]

[reber]

Akumulatorji Topla so to večkrat naredili, da so praktično novi kar umrli. Prav tako sem slišal za TAB da se dogajajo čudne stvari. Prav nasprotno pa imam izkušnje z TAB motion, ki ni štartni akumulator, je pa primeren za čolne, razne akumulatorske stroje (čistilci, sesalci, ...) za solarne sisteme, ... UPS, ... in imam dobre izkušnje. Lahko da imam srečo, lahko pa so umrli akumulatorji samo slučaj. Prav tako poznam kar dosti primerov, kjer akumulator Topla v traktorju ali avtu deluje čisto normalno.
Očitno je, da vsi akumulatorji le niso enaki, in da vsi akumulatorji le niso natančno pregledani na končni kontroli.
Prav tako bi bilo verjetno dobro, da nov akumulator preizkusimo in da akumulator kupimo šele ko ga rabimo in ne 2 meseca prej.

[mucek4]

Na vikendu imam celotno napeljavo iz rabljenega avtomobilskega akumulatorja in preko razsmernika. Zadnjič sem šel k naključnemu avtoelektričarju in rekel, če ima kakšen rabljen aku zame. Po tem sem mu povedal zakaj in je rekel. Saj ne rabiš močnega, saj nimaš velikih tokov. Rekel sem mu da bi bilo bolje večjega, saj mi ga ni treba vsake 14 dni nositi domov in polniti, on pa da je večji samo za večje začetne tokove, da pri manjših tokovih ne bo zdržal ni dalj časa.

Torej je res, da bi pri porabi 3A (11W + 20W varčna žarnica + radio + poraba inverterja) akumulator 35 Ah zdržal isto časa kot recimo 55 ali celo 85 Ah? Moje sicer pomanjkljivo znanje pravi da ne, želel bi pa vaš odgovor..

Hvala.

[Domenius]

Tvoje znanje ima prav. Čeprav se tudi avtoelektričar ne moti v vsem - več Ah, večji zagonski tok.

[protoncek]

[jur]

[Iztok]

[lado]

Avtomobilski akumulator ni najbolj primeren za takšno uporabo-namenjen je za plitvo praznjenje ob velikih tokovih, kar pri tebi ni slučaj.Še več, globoko praznjenje takšnega startnega akumulatorja ga sigurno poškoduje....Zato raje nabavi kakšen solarni ali trakcijski akumulator in ti bo zadeva bistveno dlje delala...

Razlika med startnim in trakcijskimi akumulatorji je v osnovni konstrukciji.Startni ima debelejše elektrode (manjša notranja upornost) in posledično zmore velike tokove ima pa zelo malo aktivne mase v ploščah zato ne prenese globokih praznjen...
Trakcijski je pa ravno obratno -tanše elektrode in veliko mase...(so tudi precej težji ob isti kapaciteti)

Zato bi bilo najbolje dobiti kak solarni akumulator VARTA, SONENSHINE,...EXIDE..
je pa tudi res da so precej dražji--za to izbiraj kaj imaš rajši neprestano prenašanje polnjenje,iskanje drugih še uporabnih akumulatorjev...ali...

lp

lado

[protoncek]

moj nečak ima na vikendu npr. dwa akkumulatorja po 120 Ah in sončne celice, mislim da skupaj 60 W. Poraba je par žarnic, ena varčna...definitivno pod 10 A ker več regler ne da. Namesto enega cca 80 Ah solar akku (recimo v conradu preko 80.000 SIT ) je raje dal omenjena dwa rabljena, ki sta dobra, samo ne zmoreta več velikih zagonskih tokov. Mu je kolega zrihtal za(stonj) malepare.
Delata že dwe sezoni, pa če koj crkneta se splača.

[mucek4]

[protoncek]

mucek-->po moje se ti dolgoročno bolj splača kupit 12V varčno žarnico...ti razsmerniki majo mal izgube, tukaj se pa vsak amper pozna. Res pa je da so 12V šparlampe drage...a si mogoče kaj meril koliko ti kuri razsmernik pri priključeni (recimo 15W) žarnici...da vidiš koliko so izgube?