Posted by Sherman in Idaho [72.47.153.28] on Sunday, April 20, 2014 at 13:21:43 :
In Reply to: Re: How do they fail? posted by jerryinidaho [64.234.49.226] on Saturday, April 19, 2014 at 16:12:27 :
That's something I'd probably try if I picked up one that was otherwise solid for free. I couldn't begin to tell you how to do it by email though. It would depend on how it was designed. All you really need is the transformer, rectifier, and meter, and if it's a small one that won't put out more than 5 amps, you don't even really need the meter. Most of the new ones are too clever for their own good. What I really dislike about the "smart" ones is that they will declare a battery dead and beyond salvation, when it actually could be charged just fine if you could manually kick the voltage up high enough to get it started. Also, they will sometimes cut off the charge too soon. They seem to assume a perfect battery that just happens to be a bit low. If the cells are unbalanced, which often happens as a battery gets old (the only way to tell is with a hydrometer), a voltage measurement will show full voltage while the weak cell is still too weak to provide cranking current. The "smart" charger will cut off the charge, just based on the voltage being high enough, whereas if you did it the old-fashioned way, you'd continue to charge until the gravity was up to full on all the cells. Then you'd add water to the cells that got over-charged, and your battery would be good to go. A "smart" charger simply has no way to deal with that kind of thing, so it will have you replacing batteries that really don't need to be replaced.