Discussion in '6.9L IH & 7.3L IDI Diesels' started by Tony Stottler, Jan 19, 2021.
" Heavy duty battery charger"
Anyone with more info, please let me know if this is a old wives' tale.
I had heard.. if possible, with dual batteries, connect to the positive terminal of one battery(#1), and the negative terminal of the other battery(#2). (to balance the voltage drop across the batteries)
That would be a good idea, but for a trickle charger pumping in an Amp or two, the voltage drop across those 2/0 cables will be nil.
Associated still makes the model "US20" you can find them for around $300 online, my Carquest store sells them for like $325 and they are the "dumb" charger. Commercial quality for sure.... We started selling them and using them since Schumachers quality is so bad lately and they quit making manual chargers. We have had great luck with them at the store, and in my personal shop working on almost exclusively heavy truck.
Snicklas is spot on. The new smart chargers will not juice a dead battery most of the time. They stopped making "dumb" chargers a good 15 years ago or so. I recently picked up this beauty (pun intended) for 80$ so I can stop borrowing my buddy's vintage schumacher. Doesnt have a trickle setting unfortunately but has higher cranking capacity than his. Alternatively, you could try finding a Forney welder/charger machine. Supposed to be absolute tanks, run on 220v and operate as a stick welder, soldering station and battery charger.
I can't stand smart chargers at all. I'm sure analog chargers have been at fault for many many fires because people forget them on. But at work we have 2 $750 associated 12/24v 250amp big bastards. Any time I see a old analog charger at a garage sale or sitting around I grab them up and clean them up.
I should of mention the one i have is 90 amp constant charge and I believe 200 amp for starting.https://www.amazon.com/55-AMP-MONSTER-BATTERY-CHARGER/dp/B00K1NQRSK
Thanks, Larry, that us20 looks like what I want. There is an Advance Auto store in Fairbanks that carries Carquest, I'll check with them on that model. Shipping to Alaska is a deal breaker for big things, so mail order is out for something big and heavy like that. One of those old Forney machines would be really cool, but there probably aren't any in the Interior.
This is what I have. It's been a great charger.
My junkyard friend saves old dead smart chargers for me to fix and return to him. I take out the smart board and discard it. Then I rearrange the wires, and write "not used" on the face plate by the now disconnected switch. The chargers enjoy a new life as dumb units. Once in a while I need to replace diodes. That's easy and inexpensive. My junkyard friend loves them. As you guys pointed out: they will charge a really dead battery. Blue skies.
Can you please teach me to do this. I regularly find smart chargers at my local transfer station destined to be shredded into scrap. Most supposedly power up but read constant faults or other issues.
If there is a transformer, you can use it to make a dumb charger. The AC power should go in one pair of transformer terminals. There should be two or three or more terminals on the other side of the transformer which provide lower voltage AC. If there are three or more, that let's you choose different voltage ranges/charge rates. Higher voltage means faster charge.
The outputs from the transformer need to go through a diode bridge to make DC. If there are multiple outputs, you will need a single pole, multi-throw switch to choose which output goes to the bridge. The output of the bridge is DC, route that to your batteries. For extra credit, route it through a DC ammeter.
If there is a small transformer and capacitors, it may be a switching power supply. That may not work .
If you can source a cheap, large transformer that puts out around 14-16 volts on the secondary terminals, you can get some power diodes and make a charger. I can't find a cheap control transformer around here, so I'm out of luck. I've thought about building one from an old Miller Thundervolt welder I have, by putting some power diodes in and some fractional-Ohm, 150W resistors in series with the output, so the output voltage will drop as the current rises. That one would be tricky, because I'd have to use a couple of SCRs to regulate the output voltage, which is around 30V-40V open circuit.
Edited to add: this Horrible Fright ``charger'' looks like a nice little charger kit. It probably has the right transformer, the diodes and the switches. If the transformer works, any other problems would be cheaply fixable.
Hey! Finally a topic where I can add a little more knowledge. I have both dumb and smart chargers, my smart chargers are two Battery Tenders and a Battery Minder. They will not boil out a battery, and they are not designed to jump start your truck.
I did find this out this past summer; if you have a dead battery, you can charge it by jumping it with a good battery and putting the smart charger on it, it will see 12 V and start to charge, then disconnnect the good battery and let it trickle charge.
You can charge multiple batteries with a smart charger if the voltages are matched
and, never hook the polarity of the charger backwards, only bad things will happen.
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