@eetcowie: "Marine batteries are often of the deep-discharge type."
As a boat-owner (Happiness is a Trojan that doesn't leak) I've seen two types of Marine batteries. Some deep-discharge batteries are used for accessories on larger boats or electric trolling motors on small boats (e. g. Bass Boats). They aren't designed to start a large gas or diesel engine. Newer batteries in the last 10 years or so seem to be designed to handle engine starting as well as deep discharge. If you are going to use a battery for starting, always check the CA (Cranking Amps) or CCA (Cold Cranking Amps) to make sure it can survive the load without destroying the cells, and also check the discharge rate for deep discharge (amps discharged over a period of time). Marine starting batteries often use the CA value instead of the CCA; not many are (fool)hardy enough for below-freezing cruising!
A fully-charged deep-discharge marine battery, a 12V auto-receptacle three-way splitter, and a small inverter are quite handy when a blizzard or a storm (hurricane, thunder storm, or a derecho) takes out the power. Only when the storm blows over is it time to crank up the generator!
The final summary, will probably be pricing per kg of weight or by volume (L). I already include the price in each battery type, in WattHours per $, so it makes it easier to compare technologies for each kind.
While looking up information on solar power for recreation vehicles I came across some great information on wet cell lead acid, and although archaici technology I "m guessing the principles remain similar to other technologies.
Lifetime vs. depth of discharge, multi-stage charging vs. voltage and current vs temp, optimal maximum charging current, etc
Look up Trojan T 105, this is the workhorse golf cart battery (good for RV too!)
Between the 2 page datasheet and 24 page user guide you'll learn the basics about flooded batteries.
I will cover more on the memory effect later, but for now, Max, there may not be a substantial memory effect on the type of battery in your device. Suffice to say that for each chemistry and construction combination, there exists an optimum charging and discharging electrical and physical environment that will yield the greatest service life. But a high service-life comes with trade-offs in other performance areas -- this is no surprise, since "...you don't get something for nothing", they say. I tend to have the thinking that when something is really good, I ask myself about what does it compromise? Some comedian once said, "You can't have everything. Where wuould you put it?"
@eetcowie: The 'memory effect' was initially denied by manufacturers, but eventually they reversed their stand after good science showed that certain chemistries had a preference for a terminal voltage where the battery spent most of its time...
Will you be elaborating on this later in the series, and also telling us how to mitigate against it? For myself, in th ecase of my iPad, I usually let it run down to around 10% and then charge it all the way back up to 100%. By comparison ,in the case of my notepads, it's onlt every "now and again" that I turn them on without plugging them into the wall first -- is this OK?
The 'memory effect' was initially denied by manufacturers, but eventually they reversed their stand after good science showed that certain chemistries had a preference for a terminal voltage where the battery spent most of its time. It results in a loss of capacity, since the battery quickly drops its terminal voltage after discharging, to the 'memory' point. To compensate, manufacturers began recommending that batteries always should be discharged to the end-of-cycle point (not partially discharged and recharged). This idea ran counter to system designers wishes, since most of the energy-transfer losses happen at the end of the rated-discharge cycle. What you mentioned, though, happens often enough about the pattern of cycles and optimum performance, even outside of the memory effect. Some manufacturers now include mention of how their batteries perform with regard to the memory effect, in order to differentiate their product from the competition.
NASA's Orion Flight Software Production Systems Manager Darrel G. Raines joins Planet Analog Editor Steve Taranovich and Embedded.com Editor Max Maxfield to talk about embedded flight software used in Orion Spacecraft, part of NASA's Mars mission. Live radio show and live chat. Get your questions ready.
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