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A question about battery charging voltage

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ghaly

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I have read in the previous elementary question, that mention: a lead acid battery will gas if the charging voltage is 15 V even before it is fully charged, while it is written on the battery cycle use 14.4 - 15 V.

While I am sure almost all lead acid batteries has the same charging constant voltage range.

I know the lead acid battery will gas only if it is fully charged regardless of the charging current.

If the charging voltage is 15 V , will the battery gas before it is fully charged ?.

I need answers from many of you.
 

lw1ecp

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If this is helpful for you, the battery on my car says "Do not exceed 14V charging voltage at 1500RPM". This is a regular maintenance-free model. I recall a previous one I had asked not to exceed 14.4V. And power car audio ICs such as the TDA2002 are rated at 14.4V so I imagine the IC manufacturer takes this value as typical of a battery being charged from the car's alternator.
The only way to reach 15V with a not-fully-charged battery is with a very high charging current, much more than the alternator's. Please take a look at a commercial battery charger from a respectable maker: if for a given Ah it states some maximum charging current, then it should be safe regardless of the voltage, until it reachs full charge. Of course, if you are talking about a car battery, it is not designed to be charged by a powerful off-board charger frequently, only in case of emergency.
 

chuckey

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Its all to do with the life of the batteries, telephone exchanges trickle charge at 13.8V and get a life of greater then 50 years from their batteries. Modern American cars use 15V and the life of the battery is three years. If a battery gases at a charging current of 1 amp, it is charged. I would think that at higher charging currents, the parts of the plates that are fully reformed will gas, but the battery plates are only partially reformed, so the battery is only partially charged.
High frequency inverter chargers which will have some HF ripple content produce an effect called "microcharging". The HF part of the current does not distribute its self equally over the plates, so some bits of the plates get reformed before others, then these parts start to gas and you loose water. This was told to me by a battery rep who I called in, as we had something like 140 batteries in use in professional equipment which appeared to be dying.
Frank
 
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