I made a high wattage resister from some old standing rigging that had started getting meat hooks. I noticed that it is 3/16 stainless steel which has a high resistance. The wire rope was 19 strand. I unwound one strand and measured it as about 1 ohm per meter of length. I bent the strand into a shape that was compact but did not self intersect and short out. It also allowed good air circulation to carry away the heat. I did a test where I passed about 7 amps through it at 10 volts of voltage drop for 70 watts. I could feel the heat coming off of it like a small electric space heater. I can make resisters of just about any desired amount of resistance and power dissipation ability and do it very cheaply this way.
Will
Will
On Jun 13, 2016, at 21:20, oak oak_box@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
It can be a challenge to find high enough wattage resistors that won't fry when you try to discharge a battery.One thing that I found that works reasonably well is to go find some halogen headlight bulbs for cars - they're designed for 12V, and generally draw up to 7 amps apiece. Several of those wired in parallel will do the trick (though they can be a bit pricey).John
From: "John Acord jcacord@gmail.com [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Monday, June 13, 2016 7:21 PM
Subject: [Electric Boats] Re: AGM Battery Anomaly
JohnMike,Another thing you can do to help your battery is to isolate it and do a deep discharge followed by a full charge. You will need a low resistance high wattage load though. For a 100AH 12V battery I use a couple of 1.2 ohm big ceramic resistors in parallel. 20 amps is a good discharge rate and battery heating is moderate. Recharge at at least that rate.
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Posted by: Will Marsh <willmarsh3@gmail.com>
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