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Old 09-21-2011, 08:54 AM   #17 (permalink)
California98Civic
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Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,299

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
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charging well

Looks like you were writing the below while I was editing last night's post with the update that the battery reads 13.5 on the steering-column-mounted voltmeter. Since the manufacturer calls 12.8 full charge and recommends exceeding it by 8% regularly... I think I am there. But you had also commented earlier that my alt, when engaged, seemed to be behaving as if it never "thought" the battery was fully charged. I think you are right... what is the threshold at which the alt considers the battery too low. I'll bet anything below 12.8? So this deep cycle has design features that confuse the parameters of the alt's design? Interesting.

Anyway, you ask how much the battery cost: $114 and then about 12 more on post adapters. It was an odd choice... but if it works in my application, I'll be very happy for having risked the cash to have gotten the alt delete without sacrificing my weight-reduction goal of under 2000lbs.

Quote:
Originally Posted by oil pan 4 View Post
If you have any doubt you didnt get a full charge it might be a good idea to run the alternator for part of the drive if you can.
An ampmeter could tell if the battery is drawing alternator power for charging. You could use an amp meter to see if the battery got charged at night. You could give the battery some alternator power and if it soaks up every amp the alt puts out then you know it didn't get charged the night before.
At that point about all you can do is run the alternator and lose some fuel milage or get a bigger charger.

How much did that battery cost?

I am thinking that little deep cycle battery could hold around a half kilo watt hour of use able capacity so its going to want quite a bit of power.
The battery may not be able to get a full charge off a normal 14.4 to 14.5 volt starting battery charging electrical system. I have never thought about charging hard cycled deep cycle battery on a normal car system.

I don't consider my 44lb starting batteries full until they are at 15.1 or 15.2 volts and drawing less than 2 amps. A smaller deep cycle like that should be full around 15.2 volts drawing under an amp.
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See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.



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