Monday, February 1, 2010

RE: [Electric Boats] DIY activation charger

 

Or pick ‘em up for under 5 bucks at goodwill.

But we should clarify a couple things here:

 

1)      That 65watt supply only dishes out about 4amps---and 4 amps is but 2% of the typical amphour rating (220ah) of a lead acid battery on many of our e-boats.  Folks need to know that you won’t see the bubbling described below unless your battery is already been charged to its absorption or float level.

2)      Be careful about sparks when you’re engaging/disengaging clip leads on a battery that’s burping H2.  Fortunately, at but 4amps, there’s not much of a spark risk, but beware.

3)      Finally, some of these laptop supplies are more robust than others.  While many probably don’t mind pushing 4amps into 6v instead of 18v, some might overheat or blow a fuse or worse.  If you have 6v batteries in a string, it’d be a little less risky to apply the power supply across 2 of the batteries in series at a time.

 

-Myles

 

From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of aweekdaysailor
Sent: Monday, February 01, 2010 5:58 AM
To: electricboats@yahoogroups.com
Subject: [Electric Boats] DIY activation charger

 

 

This is to help de-stratify the electrolyte, such as after topping off a battery - otherwise the fresh water just floats on top. [This is for wet lead-acid, not sealed or gel]. Good to do periodically anyway.

I have a bunch of old laptop chargers - they all put out somewhere between 15 and 19 volts and about 65watts, so I just added clips in place of the plug (use a voltmeter to establish +- - usually + is the inner wire). After about 10min, the electrolyte was bubbling nicely. The charger gets a bit warm as it will definitely put out maximum amps when confronted with a large battery, but for these short periods of time, should be fine.

Don't leave it plugged in, wear gloves and goggles, open the caps, and don't do this in an enclosed space - explosive H2 could build up. This is just to run for a few minutes to mix up the electrolyte. If you don't have one lying around, Amazon has them for about $7-$12 ea (HP chargers are a good bet)

Cheers,

-Keith

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