Ducato / Elektroblock battery charging

Discussion in 'Tech/Mech General' started by Stealaway, Aug 14, 2015.

  1. Stealaway

    Stealaway Funster

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    It seems that the Elektroblock only charges the domestic battery's at a maximum of 18 A with the engine alternator.
    The alternator seem to be 150 A, it should be able to charge the battery's faster?
    Has any one found an way of increasing this?
     
  2. Lenny HB

    Lenny HB Funster

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    18Amp is the mains charger rating, the Elektroblock has circuitry that charges similar to a B to B, the amount of charge will depend on the charge level of your batteries, the manufacturers wiring and type of battery.
    On our last Hymer once when the batteries were flat I clocked 44 amps (Gel batteries), Gel's when flat have a very low internal resistance hence the high current draw not good to it to often if you want your batteries to last.
     
  3. Stealaway

    Stealaway Funster

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    Thanks for that its good to know, how do you measure the charging current?
    It seems to take about 3 hours to charge the battery's from 12.2v to 12.8v on tick over.
    On my 2 hour journey back yesterday it took them to 13v.
     
  4. tonyidle

    tonyidle Funster

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    Charging time: if (for example) you have a 100Ah battery and you discharge it for a while, perhaps amounting to 5A drawn over a period of 8 hours you will have used 40Ah. To replace this by charging you will have to charge at 5A for 8 hours, 10A for 4 hours, etc. In fact owing to the battery not being 100% efficient you will need to put in around 20% more Ah than you took out. The amount of current that the battery will accept when being charged depends on three things: the battery terminal voltage, the battery internal resistance, and the voltage of the charging source. The output of your vehicle alternator will be in the range of 14.2v to 14.5v. If the battery is in 'normal' discharged condition its terminal voltage will be around 12v leaving 14.2v - 12v = 2.2v. Under normal conditions this voltage and the battery's internal resistance will only allow (probably) a 5A charge meaning it will take 8 hours (+ 20%) to fully re-charge it. Devices such as the battery-to-battery charger allow a higher charge by raising the alternator output voltage well above 14.2v and have monitoring circuitry to ensure no over-charging. Lead acid battery operation is incredibly complex and my simple explanation doesn't do it justice. Suffice it to say that no matter what standard charging source is in use it takes days, not hours, to fully re-charge a 'flat' battery. Hence the popularity of clever boosters such as those sold by Sterling and others.
     
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  5. JeanLuc

    JeanLuc Funster

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    Very helpful explanation Tony - thanks. However, my understanding is that a Schaudt EBL already contains some voltage boosting circuitry that improves the charge rate when the alternator is doing the charging (as LennyB mentions above). Although I believe people do use additional B2B chargers together with an EBL, it is not something to embark on without a full understanding of how the two systems might interact / conflict surely? If I have discharged as much as your example shows above, I often see a charging current of 20-30 amps from the alternator. My set-up is an EBL99 coupled with IT992 control panel - no additional B2B unit.
     
  6. Lenny HB

    Lenny HB Funster

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    To measure the charging current if it is not shown on your control panel you would need to fit a battery monitor prices vary from £20 to well over a hundred, also fitting involes a lot of labour as you have to fit a shunt next to the battery and run cables to the meter.

    Not advisable to fit a B to B with an Elecktroblock, and won't give you that much improvement.

    You should never leave a diesel just ticking over, one of the easier ways to wreck your engine also if you have a DPF (Diesel Particulate Filter) it will ruin it and could cost up to a couple of grand to replace. Also an alternator will not give it's full output on tickover.

    Tony's explanation is good, I have 2 x 95 A/H batteries and I wouldn't expect a full days driving to get them anywhere near fully charged if they were flat.
    Simplifying Tony's explanation, if your batteries are flat, to start with you with get an initial charge from the Elektroblock of around 20 amps as JeanLuc says, but after 15 - 30 minutes of charging the internal resistance and terminal voltage of the battery will rise which has the effect of reducing the amount of charge the battery can take, as Tony says to about 5amps.
     
  7. stevec

    stevec Funster

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    Just a point of information for those doing Ah calculations. Manufactures generally rate the Ah of a bsttery using a discharge rate of 1/20th of the capacity.....so a 100Ah battery will give 5 amps for 20 hours. Higher discharge rates will give proportionally less time, so you won't get 100amps for 1 hour. On the other hand it will give 1 amp for more than 100 hours. Of course not forgetting the 50% rule!

    Incidentally I shall be buying an LRM1218 for my Burstner EBL99 shortly. It has two analog outputs which indicate the charge current going to vehicle and leisure battery. Schaudt won't divulge the relationship beteen analog voltage and charge current but i will do some tests before fitting it unless someone knows it already.
     
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