Charging batteries from batteries

[dandman]

Great, thanks for the input. The amperage reading is .7 of an amp from the feeding battery. When I put a 10w 12v bulb across the feeding battery directly, its voltage decline is hugely different to when it is feeding the other batteries but I am doing this ever so slightly differently to just connecting them in parallel. Any thoughts on why the battery may be acting differently?

[e2matrix]

Great, thanks for the input. The amperage reading is .7 of an amp from the feeding battery. When I put a 10w 12v bulb across the feeding battery directly, its voltage decline is hugely different to when it is feeding the other batteries but I am doing this ever so slightly differently to just connecting them in parallel. Any thoughts on why the battery may be acting differently?

What is the " ever so slightly differently to just connecting them in parallel " ?   That may be a key factor.  Overall judging a battery's power by it's open circuit voltage reading is not a good way to determine it's available power.  Rather it's all about watts as in amps times volts.  Are these lead acid batteries?  I'm not an expert on this but I'm sure some others here may be able to tell you the best way to determine if you have something anomalous here.  Getting accurate measurements of actual power used and power added to other batteries can be more difficult than it seems.

[dandman]

I am introducing a degree of resistance. These are standard lead acid batteries 2 x 600cca and 1 x 500cca. I understand its about watts. If I discharge at 2.1 amps over 30 minutes then recharge for 2 hours to return to the original voltage and repeat the same thing 3 times over the same time periods. Is that not an accurate enough measure of watts used watts reinstated through charge?. The anomally or query is about the apparent lack of discharge rate of the feeding battery in this situation as opposed to under normal circumstances?. I am pretty sure I could recharge a torch battery more than twice the total value of the 2 batteries used.

[nightlife]

 I dont think you understand what I said. You have to load test the battery's to know how may amps they contain. I am assuming you are working with 12 volt car battery's, am I right? If so, the .7 amp reading you have must be what the dead batterys are drawing from the charged battery.

[dandman]

Yes I am using 12v, lead acid car batteries. I dont know how to load charge a battery. So Im relying on deductive reasoning and what what knowledge I do have. Please see my last reply and let me know if that rationale is sufficient?. It will also give an indication of why I believe there is an anomally in readings of amperage versus actual energy used from the feeding battery. Thanks for bearing with me but I am self taught and do appreciate the feedback.