[modeleng] Re: Battery problems correction

Patrick Coppens wrote:
> Alan Stepney wrote:
>   
>> OK, for todays silly suggestion, check the charger.
>>
>> There is a possibility that the rectifier has gone short circuit, and 
>> putting, say, 20+ volts AC into the battery wont make it very happy.
>>
>> http://www.alanstepney.info
>> Alan Stepney's Model Engineering, steam, and workshop pages. 
>>
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>>   
>>     
> As an electronics engineer, I tend to agree, with some of you, who 
> state,that the battery has been producing an excess of H2 and some other 
> gases, that come with charging a battery of this kind.
> It is unlikely, that the vent would not become "unblocked" when gas is 
> produced.(and these batteries have an added "safety valve")
> What is likely in my opinion, is that the load current was rather high, 
> and that the amount of gas produced was higher then acceptable.
> On top of this, you are dealing with volatile gases that are heated up! 
> this occurs because of the loading.
> All this together, is still an unlikely scenario, though.
>
> I suspect, that because of the frequent moving in and out of the battery 
> (out and in the car) that some plate(s) lost part of their (lead) charge 
> and shorted.
> If you add that to the above, you might get a result as shown in the 
> pictures.
> On the other hand, most deep-cycle batteries, (I have worked with this 
> type more then the others, but they are basically the same) I have seen 
> in this state, were simply connected wrongly to the charge current....
> And that, will kill a battery every time....
>
> Also, there is something to be said, in connecting batteries in series, 
> only if they are of the same brand and type. Every manufacture makes his 
> batteries according to his specifications, and the "internal resistance" 
> will differ, with the brand and type.
> A difference in "internal resistance" will eventually cause degradation 
> of the plates (and loose bits!) and internal short circuits. (one 
> battery is using current from the other, as it passes trough the plates, 
> as it were..)The internal resistance starts to differ more and more as 
> the battery heats up, and the problem gets worse...
> So beware! If it is really needed to switch two batteries in series (Pb 
> batteries) make sure that they are both new, and of the same make and 
> time. Try and charge them when switched in series, with a 24 V charge.
> If the choice is there, a long and slow charge is always far better then 
> a slow "burst" charge (or whatever they call it these days!)
> If possible use "deep-cycle" batteries (the type used in caravans and 
> the like) These are designed for erratic discharge and will last longer 
> for the kind of application suggested in this case.
> As a new battery needs to be bought for this application anyway, you 
> might consider a 24V one and be done with all the possible trouble 
> mentioned above...
>
>
> Cheers
> Patrick
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>   
correction :
slow "burst" should of course be fast "burst charge"!!!



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