Natural Discharge

[mat1]

Many affecting factors i know, but what is the natural discharge rate for a battery, amp hrs ?
Say for example a 100ah battery.
Ball park figure will do.

Thanks

Mat

 

[Damian]

All batteries will self discharge over a period of time naturally whether the battery is used or not. This means that the battery capacity will go from 100% down to 0% over a time period regardless if the battery is being used or not. Again recharging the battery corrects this naturally occurring reality.
Battery self discharge rate varies based on the chemistry type used and the temperature the battery is at: higher temperatures increase the self-discharge rate. This explains why batteries left inside cars on hot days must be recharged more frequently!
Battery self-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery. Battery self-discharges does decrease the overall shelf-life of batteries and causes them to initially have less than a full charge when actually put to use.
Here are average self discharge rates for the following chemistries:
NiCd
NiMH
Lead Acid
Li-ion
Li-ion polymer
Reusable Alkaline
Self-discharge / Month (room temperature)
20%
30%
5%
10%
~10%
0.3%

The rate at which batteries self discharge depends on the type of battery, state of charge, charging current, ambient temperature and other factors. Lithium based batteries suffer the least amount of self-discharge (around 2–3% discharge per month), while nickel-based batteries are more seriously affected by the self-discharge rate.
To reduce the rate of battery self discharge during storage then store the battery at lower temperatures to reduce the rate of self-discharge and preserves the initial energy stored in the battery.

 

[mat1]

Crikey should have listened more at school.
So,
5% of 100ah = 5ah natural discharge per month
5ah/ 30 days = 0.16ah per day
or 0.2ah to round it off.

I was trying to work out if a theory posed to me was correct, and it appears so.
That is for trickle charge and battery maintenance only, whilst in storage, choose a solar panel 10w per 100ah.

Mat

 

[RayS]

Can't match Damians knowledge, but another possible factor is the cleanliness of the battery top. Unless this is clean and dry, there is the possibility of a discharge path through the grime, allowing a retrun path from positive to negative. unless really wet and dirty, this is likely to be a very small value, but will certainly not increase the value Damian has given.