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Stand by charging method for a Car battery

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New Member
Hi All,
i would like to keep a 12 volt 60Ah Calcium Car Battery on stand by mode.
what i have in my mind is to charge the batterry while it is on stand by.
but not sure which charging method is better for battery life.
should i keep the battery under constant trickle charge or should i charge the battery by monitoring its voltage till it gets certain point ( say 14.4 volts ) and stop charging. then wait till the battery voltage reduce till 12.5 volt to start recharging.

if the trickle charge is better what will be the charging volts and amperes
( i think 1 A is ok for this battery since C/100 = 0.6 amp. and considering
few leds ( aprx. 15 leds ) will always be on while the battery on stand by mode

thnks for any assistance.


Active Member
I need to solve a similar problem with a lead-acid (supposedly deep cycle) battery that I'll use on occasion at my camp. We have 110 vac all season but I want the backup as well as the 12 vdc to run radios, etc.

I figured that there must be some well verified knowledge on how to best "maintain" a battery. I discovered this site -


The information seems reasonable and I suspect that there is more information like it. Things that appear to be important - for a lead-acid battery:

Knowing battery condition in terms of charge - fully charged, discharged, etc.

Temperature of the electrolyte.

Charging current/voltage and subsequently the changes that are seen in current/voltage as the battery charges.

It looks like, for best battery life/performance, that there is an appropriate amount of charge (in terms of voltage or current) to be applied for a given condition of battery. A battery charging scheme incorporates some intelligence may or may not be justified. It would appear that a PIC or some other simple controller could be the heart of a very effective battery charger.

I'll share whatever I come up with in the future even if it is to copy what others have already done (as I am sure they have).


Active Member
Sarac - on the way home last night I talked with (via ham radio) a friend who made a living servicing battery systems for telephone systems and he helped reinforce some of what I've learned - that the stuff on the site does matter. He did say, however, that as the battery gets close to full charge it is somewhat self regulating (lead-acid anyway). We had to end the conversation at that point but will pick it up again soon so I can ask him to tell me how the "self regulating" characteristic would imact my plans.

I have seen the acid boiled out of batteries but I'm not sure if it's the result of application of extreme overvoltage or some other thing that suggests there are limits to the "self regulating" characteristic that he's described. I'll share more when I talk with him.
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