Date: Mon, 3 Oct 2011 17:13:42 -0700
Reply-To: Rocket J Squirrel <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Rocket J Squirrel <camping.elliott@GMAIL.COM>
Subject: Re: Vitrifrigo: two corrections to my earlier post
In-Reply-To: <2BF2B0E3A6E64C4DA8E8A236FEBC1751@troyb5bff49d63>
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And Rocket's info came from that Dennis Haynes. To give the man his due.
--
Jack "Rocket j Squirrel" Elliott
Bend, Ore.
1984 Westfalia. A poor but proud people.
1971 "Ladybug"-brand utility trailer ca. 1972 from a defunct company in
San Clemente, Calif., now repurposed as The Westrailia.
Sent from my kitchen.
On 10/03/2011 02:11 PM, Troy wrote:
> Al:
>
> I think you're citing common wisdom about batteries and charging. Low and slow has been the common wisdom for many years, or as long as I can remember at least (I'm in my 50's). I searched various forums, and a lot of people still believe this is best, then again a lot of people still think that putting batteries on concrete is detrimental--it's not.
>
> I looked at Smart charger technology, and this consist of charging a battery in 3 states, the bulk state, the absorption state, and then the final float state. In the bulk state, approximately 80% of the battery capacity is replaced at maximum voltage and current. This is then followed by a 14.4 V absorption state until the battery reaches approximately 98% of its capacity, and finally the charger drops off to the float state (around 13.8 V) and then tops the battery up the last couple of percent.
>
> So, what current is best? Interstate and Trojan both recommend charging up to about 20% of the amp hour rating. Smart chargers will use this high current (up to the chargers max) until 80% of charges reached, but I'm not sure what happens with a car alternator. Since the car alternator is capable of even higher amperage, we can (and probably should) make a conscious choice to limit that current by wire selection. So, if we have say a 125 amp hour battery, we probably don't want to choose a wire that is capable of handling more than about 25 amps (wire length must be factored in as well). That probably means about a 10 gauge wire from the alternator to the starter. Now, if your deep cycle battery is of higher capacity, or you have a long run of wire, then one could go with a larger wire gauge.
>
> One thing I learned is that I could probably go to a larger Smart battery charger. Mine has a maximum of 8 amps. It also appears that common wisdom has changed as to what rate is best. Several people in boating forums have cited extended battery life by using higher amperage charges. Smart chargers are also being designed to deliver high currents, and finally at least 2 manufacturers (Trojan and Interstate) are recommending higher charging current. Rocket's info seems right on.
>
> So, this is what I learned today:)
>
> Troy
>
> ----- Original Message -----
>
>
> Hi Troy, yeah yeah search the internet for how lead acid batteries work and what the charging characteristics are. too little time to show you but it all has to do with the available surface of the plates which is the location of the ion exchange that makes the critter work. High current batteries need more active surface to deliver the high rate of reaction that produces the energy, deep discharge/low rated current batteries need thicker plates and a slower charge rate. Don't take it from me, I'm not a chemist. Search for flooded cell battery theory and operation and let us know what you find.
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