Add or replace leisure batteries?

Discussion in 'Tech/Mech General' started by steve.lorimer, Oct 14, 2009.

  1. steve.lorimer

    steve.lorimer Read Only Funster

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    Hi folks

    I'm currently on a trans-Africa expedition. At the moment I've got 3 x 110 Amp/hour batteries in my truck, and after a year on the road, they're getting a little tired (ie: after many quite severe discharges they are not holding charge too well, or at least I get that impression - perhaps I'm just using too much charge and need to just increase the total Amp/hours capacity in my truck.) I'm in Nairobi in Kenya at the moment, and can get some new leisure batteries here.

    My questions are thus:

    1. If I buy some new batteries is it ok to connect them in parallel with the old batteries to eke out what life is left in the old batteries, or will the old batteries damage the new batteries, and therefore should I replace the old batteries in their entirety?

    2. Is there a way to tell how much life is left in the old batteries? Will a battery outlet be able to tell me this? At what point should I consider replacing the old batteries?

    3. If it's ok to add the new batteries in parallel with the old batteries, should I get new batteries with the same Amp/hour rating as my old batteries, or is it ok to mix and match Amp/hour ratings?

    Many thanks in advance for your help!

    Regards
    Steve

    (details on our journey if you're interested: www.overafrica.org)
     
  2. superk

    superk Read Only Funster

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    My thoughts would be to ditch the old ones rely on the new otherwise the old ones will drag the new ones down.

    :Smile:
    Keith
     
  3. Tony Lee

    Tony Lee Read Only Funster

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    It is possible that just one of your three batteries is failing.

    A quick way to tell is to charge all three of them up as close to full charge as possible (you have a three stage charger??) and then disconnect all three batteries from the system and from each other.

    Measure each voltage and record it and measure them say 30 minutes later.

    Then if possible connect the same load up to each battery in turn - say by switching on all the lights - for say 15 minutes on each in turn. Measure the voltage at the end of the 15 minutes before disconnecting.

    If any one of the three is significantly lower than the other two - by more than half a volt - it might be worth connecting just the other two and seeing how they perform without the other low one.

    If that test isn't particularly conclusive and you are sure the problem is with the batteries, then it may be better to just get three new batteries - and since you may be a bit of a battery murderer (or rather your system might be) - there is probably not much point in getting anything other than the cheapest starter batteries you can find.
    You haven't given us any info on your electrical setup so we can't really give any definitive advice.
     
  4. steve.lorimer

    steve.lorimer Read Only Funster

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    My power system

    Hi Tony

    Thanks for your response. Here is a break down of the system:

    Power producing
    • 3 x 110Ah batteries
    • 2 x 120W solar panels, producing only when sunny (which in Africa is almost all the time) +/-7A produced at midday, +/- 4A produced at 9AM and 5PM. Solar panels are controlled using a Steca PR10 30 charge regulator
    • Truck alternator, producing 10A when truck is running (I have a 10A 24/12V converter connected to the truck alternator)
    • Mains charging, producing only when at campsites providing electrical hookup

    Power consuming
    • National Luna freezer - 12V - 2.5Amps average running current. 1.53 - 2.6 amp/hour average power draw (I'd say on average it runs for 1 hour in every 2 hours, during the day)
    • Sound system - 400W amplifier (100W x 4 channels), used +/-3 hours per day, when truck is not running
    • Laptop computer - 12V 4.6A charger, used +/-3 hours per day
    • Surflo pump - can draw 7A, but it only runs intermittently (ie: when a tap is opened – we don't use it for the shower a lot)
    • LED lights - minimal consumption, only on for +/-4 hours per day

    What do you think?

    Thanks again
    Steve
    www.overafrica.org
     
  5. steve.lorimer

    steve.lorimer Read Only Funster

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    Current drain at rated output for the amp is 24A. That's one issue there I think!?
     
  6. pappajohn

    pappajohn Funster Life Member

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    if used at full power, which i doubt unless you're deaf, then thats 72amps per 3 hour day:Eek!:

    330amp battery reserve with a usable 130ish amps (discharged to recommended 60% of full charge)

    your sound system is using over half your battery power over 3 hours, if they were new, which they aint:Doh:

    your solar panel should just about keep up with the drain if its good sun for 10 hours per day but, as you said, it drops to maybe 4amps by late afternoon so will never keep on top of it.

    time to ditch the radio/amp and buy a windup one:BigGrin: evidently they're in abundance in africa.:Eeek:
     
    Last edited: Oct 15, 2009
  7. pappajohn

    pappajohn Funster Life Member

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    a bit about paralleling batteries....
     
  8. steve.lorimer

    steve.lorimer Read Only Funster

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    It would be interesting to know what current drain the amp causes in practice, coz we hardly ever listen to the music at full blast. I'd guess a far lower current drain?

    My reasoning is this: I completed the entirety of the west coast of Africa (which is not at all set up for tourism, so there was practically never a chance to hook up to mains) with the 3 batteries I currently have. At one point, in Congo-Brazzaville, we got stuck for 2 weeks fighting with the Angolan embassy to get visas for Cabinda. During those 2 weeks we sat virtually all day every day in the truck, waiting for word from the Angolans, and the South African embassy who took up the fight for us (to no avail, but that's a long story... if you're interested, read here: http://overafrica.org/journal/congo-brazzaville---the-exodus.aspx)

    Anyway, as you can imagine, we spent a lot of time listening to music while we twiddled our thumbs (probably in the order of 5 or 6 hours a day I'd guess.) There was a fair amount of rain around, being at the equator and just before the onset of the rainy season, so the solar panels weren't producing a huge amount of charge. At no point did our battery charge die. The solar panels were capable of keeping up with the current drain.

    With that in mind, I'd say that perhaps the way we use the sound system is ok, and it's one or more batteries that have died. It would also probably be worthwhile getting a higher-current rated 24/12V converter for the truck's alternator, but not hugely necessary.

    Any thoughts?

    Thanks
    Steve
    www.overafrica.org
     
  9. steve.lorimer

    steve.lorimer Read Only Funster

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    A question about chargers

    I've got a 15A 24/12V converter that drops my alternator output when driving my truck, and charges my 12V leisure system.

    I've heard that "good" charging systems alter the current according to the state of the batteries' charge. Not so good charging systems just push a fixed current into the batteries, and when fully charged, the batteries can get damaged by that excessive input of power. That got me wondering.

    I've just got a basic converter that shoves the 15A into the batteries when I'm driving. Perhaps that's not good for the batteries, although that leads me to wonder about what happens with a car's charging system. When the alternator is running it's generating quite a large amount of amps (my truck's alternator generates 24V/55A, most 12V alternators generate in the order of 100A). What happens to the vehicle's batteries when that huge amount of current is pouring into the batteries while driving? Surely they too would be damaged?

    Is my basic 24/12V converter not doing me any good, or am I barking up the wrong tree (or just plain barking!?)

    Thanks
    Steve
    www.overafrica.org
     
  10. derekfaeberwick

    derekfaeberwick Read Only Funster

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    What about a Genny?

    Just be careful not to make the lions angry!:Rofl1:

    A serious suggestion none the less.
     
  11. steve.lorimer

    steve.lorimer Read Only Funster

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    Hi folks

    So I've given my batteries to a solar & battery place in town to be properly tested. They've just called to say that after 3 days of charging (each being charged separately), the batteries still won't get fully charged. What does that mean? Are they just buggered? Do I need to get some replacements?

    Thanks
    Steve
     
  12. steve.lorimer

    steve.lorimer Read Only Funster

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    Steca charge controller

    Hi folks

    I bit the bullet and bought some new batteries - E-Solar AGM batteries.

    Now, something interesting (perhaps!) As previously mentioned, I have a 24/12V 15A converter which converts my 24V alternator output into 12V for charging my batteries. Similarly I have a 220/12V converter which converts a 220V mains hookup into 12V/15A for charging my batteries. Neither of these are "smart" chargers - they don't vary the voltage or current according to the batteries state.

    Now I also have a Steca PR2020 solar charge regulator, which IS a "smart" charger. (From their website: The auto-adaptive state of charge algorithm results in optimal battery maintenance and control over the module output) I was wondering if you know if it's possible to connect the outputs from my other charging systems (alternator and mains hookup) to the solar input of my solar charge regulator to take advantage of the smart charging?

    Many thanks for all your help, it is much appreciated!

    Best regards
    Steve
     
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