Trying to charge 12 v 5 ah battery using 12v 1.5 ah charger

[333rocky333]

Take the 12 volt battery and pos to pos and neg to neg connect it to your car battery and leave for around 15 minutes to 1/2 hour.
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Eric, with respect, you seem to know your stuff, but just wondering how safe is that, when I was younger i recall accidentally shorting a car battery and the thing virtually exploded, and the wiring catch fire, maybe unlikely to happen but what if you connected a battery that may be internally shorted

 

[securespark]

An alternator belt may slip if it is loose, hence why some cars scream when you rev them, because the battery is sucking in 100s of amps.

Thought the scream was the belt slipping?

 

[bernardgreen]

Take the 12 volt battery and pos to pos and neg to neg connect it to your car battery and leave for around 15 minutes to 1/2 hour.

That is a low hazard operation when the batteries are about the same size ( same amperehour capacity ) since the charged one cannot over charge the un-charged one. It can however result in a dead cell boiling out.

It is a very hazardous operation if the charged battery's capacity is several times the capacity of the small un-charged battery. The smaller battery can be severely overcharged and while a boil out is un-likely ( but possble ) damage to the battery can occur.

 

[ericmark]

I accept there can be a danger putting batteries in parallel which is what we do every time we use jump leads. But that danger is small if some care is used in the main do it some where with air flow.

The anti-reverse protection on chargers is a problem when the battery is completely discharged one has to find a way to defeat the system to get the battery to start charging. The same applies to the Delta V chargers for AA cells I have a cheap charger to start them off then put in Delta V charger.

So other than putting the two batteries in parallel what methods would use suggest without buying a complete new charger to kit start the charging process? Remember I stated 15 minutes so one should see if something really un-towards was happening.

 

[bernardgreen]

Connect the batteries with a current limiting device in one lead. A 12 volt car headlamp bulb wll limit the current , it will also indicate by glowing if there is a significant current flowing due to dfferent voltages. How dim or bright it is will give an idea of how much current is flowing. When (if ) the head lamp gets very dim then replace it with a 3 volt lamp. Use a meter first to check the difference in voltage is less that 3 volts.

 

[flameport]

Thought the scream was the belt slipping?

It is, totally unrelated to the battery charging.

You need to get grips with reality, how does a car alternator limit charging current?

By regulating the voltage output, usually about 14 volts.

there isn't a limiter.

Yes there is.

An alternator belt may slip if it is loose, hence why some cars scream when you rev them, because the battery is sucking in 100s of amps.

Wrong.
Loose belts WILL slip, the noise is due to the slip, no alternator in any car would put '100s of amps' into the battery, and if it did, the battery would be destroyed along with most of the other electrical systems in the vehicle.

 

[ericmark]

Loose belts will slip, once the slip they will wear the V and then even a tight belt will slip. You can get large alternators This link shows a 200A model but I would expect the batteries would use something like this

to control the charging of likely two banks of batteries it becomes rather specialist. We are looking at the other end of the scale Something like this

A very simple charger no protection it just works. At about £8.