Time taken to charge batteries VS alt size.

Discussion in 'OnBoard Electronics & Controls' started by DennisRB, Apr 16, 2010.

  1. capt littlelegs
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    capt littlelegs New Member

    I think I would generally agree with the battery article although it is a bit too much of a sweeping statement, there are some good leisure batteries etc. but you notice they mention advanced chargers which is what Sterling make, these tend to overcharge batteries and so are not suitable for sealed batteries etc.! Unfortunately you never really know what you are buying, some are really cheaply made and don't last. My bro-in-law's cousin has a UK battery factory, Lincon Batteries and he recommended me a while ago the type used by the RNLI (lifeboats), they stood up to a lot of punishment but unfortunately they were not cheap and now he doesn't list them anymore.
     
  2. jonr
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    jonr Senior Member

    > Right now it only sits at 12.5 volts when batteries are low and it will slowly go up to high 13's after hours of charging.

    This is mostly likely caused by voltage drop over the wires. It is most accurately solved by using an alternator with remote sensing - ie, it adjusts to the voltage delivered to the batteries, not to a set voltage at the alternator.
     
  3. capt littlelegs
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    capt littlelegs New Member

    If this were the cause then the most sensible approach would be to use the the correct cable to avoid the voltage drop. Remote sensing causes other problems and cannot compensate for poor wiring.
     
  4. pistnbroke
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    pistnbroke I try

    well dennis batteries is batteries...if you ever been to a battery factory the plate groups all come down the production line and get put into different cases or have different labels put on ....1y 2y warantee etc ..same battery...the only different types are spiral wound
    Personally I buy my (exide ) batteries at K mart or big W.....if you get someything with a 2 year warantee ....dont buy 4 on one receipt get individual receipts ..you can take them back in 18 months if they go bad and get a new one . Tell them you had it on your car..I never had a problem .
    If disconnected you can usually leave a battery unused for 3to 4 months
    and if you get your wind/solar sorted longer ...how many watts is your solar?
     
  5. jonr
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    jonr Senior Member

    > the most sensible approach would be to use the the correct cable to avoid the voltage drop

    Nobody has yet invented a cable that doesn't cause voltage drop when you draw more current. You can reduce the problem with larger cables but not eliminate it. That's why they sell alternators with remote voltage sensing.
     
  6. capt littlelegs
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    capt littlelegs New Member

    No they sell remote sensing alternators to people with cheap installations. Any significant voltage drop at the battery is only evident at high currents with inadequate cables when the regulator has no effect (remember it is only a voltage limiter it can't increase it under high load!) so the correct cable for the maximum load will have no significant voltage drop at high currents and practically nothing at lower currents near full charge when voltage limitation matters. Remote sensing as a cure for poor wiring will do nothing but cause problems such as overheated cables with reduced current and overvoltage in other places plus a risk of losing the remote connection and uncontrolled voltage!
     
  7. DennisRB
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    DennisRB Senior Member

    I got my mate to take the batteries all off. I have them now. They are sealed lead acids. There is no AH ratting. They look cheap. I put one on charge an the charger said it was full and it was only taking about 1 amp.

    When I got them the engine had run for about 4 hours to charge them. After standing for over 12 hours the voltages on all 4 batteries was 13.1V plus or minus 0.05 of a volt. So this makes it seem like no battery is more stuffed than any others. Also the high voltages on them is good inst it?

    I haven't done the load test yet with the headlamp. I asked my mate how big the wiring was and he pointed to some small cables laying around the garage. So I think that is probably the problem.
     
  8. CDK
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    CDK retired engineer

    For better assessment we need something you can quantify, like size or weight, not just 'sealed' and 'cheap looking'.
    The only remote diagnosis from the facts supplied, is that none of the cells are shorted.

    The lack of labels is a bad omen, but they might have been removed. I met a guy who peeled the label of his beer bottle faster than he drank the beer; when confronted he said he wasn't aware he did that...

    Now first do the headlamp test!
     
  9. pistnbroke
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    pistnbroke I try

    personally I would have left the charger on the batteries.
    The voltage is good and as CDK says indicates that that you probably dont have one bad cell/

    No labels is a good sign ...probably a top quality unit sold at a discount without warrantee as it had been in stock too long ...so they took the labels off .if they have hydrometer built in not cheap probably AC Delco . dont go by looks ..cheap looking women are often the best performers.

    Any sign of being able to prise off a lid ?

    60w headlamp bulb will tell the story . If it stays on 12 hrs (above 10.8) I would not bother going further test another and re charge the first.

    50 mmsq or even 75 for your new harness and switches on each batt neg ..from withworths about $8.99 ea green knob
     
  10. DennisRB
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    DennisRB Senior Member

    The batteries have labels all over. Just no listing of AH, unless someone else can figure it out from this.

    Sealed Calcium. ROCKET (global & yuasa battery co)
    CCA 650 RC 155
    SMF DCM27
    6 month warranty

    Size 300 x 170 x 210mm

    I will take pics. I did leave the battery on charge for 2 days. It was taking about an amp or so at around 14.3V. My charger is basic, and I cant really increase it more unless I put it on engine start mode which will pump about 6amps but at 15.9V.

    There is a sign of a lid on there. I have not tried to prise it off. I will wait until I show some pics. I don't want to damage anything.

    Edit just found this on the batteries http://www.apollobatteries.com.au/pdfs/SMFDCMtechBulletin.pdf
     
  11. pistnbroke
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    pistnbroke I try

    yuasa biggest battery maker in the world spec is 95 ah. sealed deep cycle .flame arrestors /vibraation proof etc ... The reserve capacity is how long it will supply 25A and in this case you would need a starting type battery of 135 ah to get 155 min...so I think the batteries are big enough.
     
  12. DennisRB
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    DennisRB Senior Member

    I have the head lamp high beam drawing 5.2a @ 12.75v. (Note to myself time was 13:37). The test wont matter if I stop and start it again in the morning will it?

    So RC 155 means it will supply 25a for 155 minutes? And usable capacity is 95ah? How is the 95ah measured? Will drawing 5a until battery voltage is 10.8v be along the lines of how the ah rating is achieved? Because I am sure if you then reduced the current draw down to 0.5a you would get quite a few more ah out of it until it went back down to 10.8v.
     
  13. pistnbroke
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    pistnbroke I try

    oh its working again ...

    yes RC is how long will supply 25 A ..suppposed to be how long you can run your car if the alternator fails under worst conditons ..light wipers heater etc..

    Remember a battery is called a 12v battery because it spends most of it dischrge voltage at 12 v ,,,,

    RC has replaced AH as the makers were filddleing it ...Just saying 95 AH means nothing .....95 AH at the 10 hr rate means 9.5A for 10 hrs to 10.8v.

    But the figures look better at 20 hours because you get 1.14 times as much out of the battery ie in your case its 108 AH (20 hr rate)
    They also had a 5 hr rate ( .83 of the 10 hr rate)
    The faster you run it down the less you get out .....
    Bit silly to leave it overnight ..why not stop when you go to bed and start again in the am ...after all if the battery does not fall flat on its face in the first 2 hrs its probably ok .....
     
  14. DennisRB
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    DennisRB Senior Member

    My point was regarding stopping overnight and starting in the morning :) (unless you read my first post which I changed within 1 minute) Thanks for the clarification on the ah thing. I understated the concept of ah, but as you say the lower the test current the more ah you get. Thats why I was wondering if my 5a load would be a similar load to how they came up with the rating.

    Anyhow. The batt I put on charge died in 2 hours. :( I put the next one on the load test, but I didn't charge it. I think they were all pretty much charged since the voltages are still 13.1V after 2 days. The one I charged was only 0.1v higher than the ones I didn't put an extra charge on.

    I put the flat one back on charge. Is there any hope for these batteries? Did they die from under charging?
     

  15. pistnbroke
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    pistnbroke I try

    I think they are sulphated (no cure ) but the only way to tell is take the top off and get a hydrometer in ...if it wont go over 1150 after a full charge they are sulphated...( good is 1250 )....when you charge you move the sulphate from the plates to the acid ...if its stuck in the plates ...scrap ..sulphated. ,,,,,,,and dont compress the bulb on the hydrometer when you take the reading or you can distort the reading !!!

    Sulphation is caused by being left part charged or discharged for a long time

    batteries are like women ...money money money

    Oh yes the sterling power is dead on in my opinion ....batteries is batteries like eggs is eggs
     
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