Monday, Feb 01, 2010 at 22:37
no worries fugwurgin, glad to be of help.
Before seeing the battery dealer, arm yourself with a little battery knowledge:
A great majority of small and medium size lead acid batteries sold (flooded, AGM and GEL), have their grids made from lead calcium alloy.
Flooded ones are more prone to stratification, self discharge, sulfation and shedding of active material compared to AGM.
These affect every cell inside the battery to a varying degree, leading to cell mismatch in the series string.
If this mismatch is left unchecked, it'll lead to even more mismatch.
It's a bit like wiring small and large capacity batteries in series and trying to charge all of them in one go.
The easiest way to counter this problem is by heavy overcharging the battery, which ensures every single cell will actually receive a full charge.
This high voltage charge is called equalisation charge, which de-stratifies the electrolyte and fully charges every single cell, but on the other hand this leads to more water break up into its gasseous building blocks.
Because most flooded batteries offer service caps, you can top them off with distilled water occasionally to make up for the loss.
For this reason, NEVER buy a 'maintenance' free flooded battery which can't be topped off because it's been made so cheaply that even the six threaded caps would have added too much cost to the manufacturing process.
Enter the world of VRLA AGM batteries, and never worry about having to equalise and refill them because they don't stratify and usually aren't very susceptible to cell mismatch. In fact, the boost charge voltage of around 14.7V is already high enough to do a mini equalisation on all cells. Their little gas generation is taken care of by a process called recombination under slightly elevated internal pressure.
AGM batteries offer superior deep cycle capabilities, less self discharge/sulfation, and can accept more charge in a shorter time. They usually also last two to three times longer than a flooded design.
Their only drawback is that they are a bit more picky about being recharged properly.
Thus, get a charger which matches their charging requirements as closely as possible to get the best out of them.
Remember your (VRLA AGM and GEL) battery is only as good as your charger.
Use your alternator to float charge them at 13.8V while on trips, and give them the occasional boost charge with the right mains charger.
Keep the battery as close as possible to 25 degrees when boost charging, even if the charger offers temp compensation.
Disconnect them when back
home and store them under the house or somewhere else cool.
Permanently float charging them @ 13.8V will cause dry out in summer when the temperature corrected float charging voltage could be as low as 13.3V.
If you'd like to find out more about this perfect combination, stay tuned.
Best regards, batterymeister
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