Charge an extra battery

[wanderinthru]

Dealing with the 75, C 30, 465. Looking for a temporary "fix" to keep my welding machine starting battery (12 v dc) charged.
Is there anywhere in the truck charging system I can hook to with an 8, 10 gauge wire that can be attached to the + side of the welder battery to keep it charged? Where it will only be hot when the truck is running, or key on?
This is temporary because plan is to build it a new bed, at which point will add a second battery to the truck and run cables back to start the welder. Why, because how I want the welder mounted it will be a pia to get to the battery. Nor do I see a reason to add an alt to the welder if its mounted on a truck that already has one. I digress.

Thanks guys..and Taylor
Shakey

 

[Ricko1966]

If I was trying to charge a second battery,I wouldn't be using wire of that gauge,your wire will be your limiter as to how much draw you can put on your alternator and truck battery. Personally I would use a common 4 or 5 prong fog light relay. Put 30 to battery positive 87 to second battery positive 85 to a switched power source 86 to ground wired up with 14 gauge and a 15 Amp fuse in wire 30. Your second battery will charge anytime you are driving the truck. On your way to the job site on your way to the store etc. If second battery isn't junk this should be all you need it should cost about 10 bucks

 

[75gmck25]

My ‘75 K25 has the optional 2nd battery. There is a charge wire running from the junction near the brake booster over to a relay on the driver side inner fender. Then from that relay the wire runs over to the 2nd battery. When the ignition is on there is brown activation wire coming out of the fuse box and that turns on the relay and connects the 2nd battery to the charging system. It’s designed to isolate the camper power (2nd battery) when the truck is not running.

 

[wanderinthru]

If I was trying to charge a second battery,I wouldn't be using wire of that gauge,your wire will be your limiter as to how much draw you can put on your alternator and truck battery. Personally I would use a common 4 or 5 prong fog light relay. Put 30 to battery positive 87 to second battery positive 85 to a switched power source 86 to ground wired up with 14 gauge and a 15 Amp fuse in wire 30. Your second battery will charge anytime you are driving the truck. On your way to the job site on your way to the store etc. If second battery isn't junk this should be all you need it should cost about 10 bucks

Well that's what I want, but? What is all these 30, 87, 85, 86? Prongs on the relay. This welder starts before it makes a full rotation so battery get's very little draw, it's a good battery, just need to keep it up. Really appreciate you Ricko, but remember your alot smarter than I am!

 

[Ricko1966]

OK most of those relays will be labeled right on the bottom terminal 30 85 86 87 and 87 a if your local parts store doesn't have a relay numbered like that let me know I'll get you a pic of one and a pic of the terminals.

You must be registered for see images attach

 

[wanderinthru]

My ‘75 K25 has the optional 2nd battery. There is a charge wire running from the junction near the brake booster over to a relay on the driver side inner fender. Then from that relay the wire runs over to the 2nd battery. When the ignition is on there is brown activation wire coming out of the fuse box and that turns on the relay and connects the 2nd battery to the charging system. It’s designed to isolate the camper power (2nd battery) when the truck is not running.

I'll see if I have such. As I told Ricko, this battery will never need much.

 

[Grit dog]

As stated a circuit through a relay is the way to go for a set it and forget it solution. But with the possibility of overcharging the welder batt.
Also I’m not a fan of using, tapping into or taxing the wiring and fuse systems in antique vehicles any more than absolutely necessary.
The super simple solution which there’s nothing wrong with is just hook the welder battery in parallel with the truck battery (and a simple inline fuse on the + wire is a good idea).
If the welder has no parasitic current draw, then you never have to worry about discharging the truck.
However mismatched batteries different uses, could pose an overcharging issue with the welder batt. So since you only need charging sometimes
Run the hot parallel wire to the welder battery or starter and just run it thru the cab with a simple disconnect switch. Leave it off until you want to top up the welder battery and then turn it on for a while.

Another option is a small DC DC charger but doesn’t sound like you have the drawdown to make good use of it’s benefits.

 

[wanderinthru]

As stated a circuit through a relay is the way to go for a set it and forget it solution. But with the possibility of overcharging the welder batt.
Also I’m not a fan of using, tapping into or taxing the wiring and fuse systems in antique vehicles any more than absolutely necessary.
The super simple solution which there’s nothing wrong with is just hook the welder battery in parallel with the truck battery (and a simple inline fuse on the + wire is a good idea).
If the welder has no parasitic current draw, then you never have to worry about discharging the truck.
However mismatched batteries different uses, could pose an overcharging issue with the welder batt. So since you only need charging sometimes
Run the hot parallel wire to the welder battery or starter and just run it thru the cab with a simple disconnect switch. Leave it off until you want to top up the welder battery and then turn it on for a while.

Another option is a small DC DC charger but doesn’t sound like you have the drawdown to make good use of it’s benefits.

Bet your super simple solution is what I end up doing. Like said it's temporary. Was just going to hook a battery charger to it when I felt it was getting low. Know how that will work out, get back to the shop, phone ring, somebody pulls up I forget end up out in BFE with a water leak or broke piece of equipment and a welder with a dead battery.

 

[Ricko1966]

To ease any worries of overcharging the second battery, now matter how you do this if your charge wire is 14 gauge with a 15 Amp fuse you can never charge at a rate greater than 15 amps,less than aot of battery chargers,as long as your alternator is producing correct voltage,you won't overcharge there either. What Grit dog said with the switch would 100 percent work but you have to remember to flip the switch. The relay I showed 30 and 87 are the switch. 85 and 86 turn the switch on and off. Either way will work fine.

 

[wanderinthru]

To ease any worries of overcharging the second battery, now matter how you do this if your charge wire is 14 gauge with a 15 Amp fuse you can never charge at a rate greater than 15 amps,less than aot of battery chargers,as long as your alternator is producing correct voltage,you won't overcharge there either. What Grit dog said with the switch would 100 percent work but you have to remember to flip the switch. The relay I showed 30 and 87 are the switch. 85 and 86 turn the switch on and off. Either way will work fine.

Ricko going to keep all this in mind. May be a better way when I do it permanent. Could I just hook an Amp gauge in there somewhere, mounted in the cab, to be sure I ain't blowed a fuse or something?

 

[Ricko1966]

You could wire a Amp gauge inline with your charge wire or a volt gauge wired anywhere in the 87 wire and the other side to ground. The volt gauge would constantly monitor welder battery voltage it's a 11v you start the truck if shows 15v you know your charging. You torn the truck off it shows 13.2 you know the welder battery is charged.the downside is the voltage gauge would be a constant small drain on the welder battery no problem of the truck gets used regularly but if you were going to park the truck for an extended time you'd want to take 1 lead off the welder battery.

 

[Ricko1966]

I'm going to take the opportunity here to explain a simple relay for those that don't know. Look at the pic in post #5 if you look at that relay 30 and 87 think of that like a toggle switch when 30 and 87 are apart its like your toggle switch being off when 30 and 87 are touching its your toggle switch being on. The difference between a relay and a simple switch is with a relay the switch 30/87 is turned on and off by an electro magnet. When put power and ground to 85 and 86 it closes your switch.You can turn the magnet on with very little amperage but the switch 30/87 can handle a ton more.

 

[AyWoSch Motors]

What if you just ground the welder to the truck frame, and run a battery cable from your truck's battery to the stater relay in the welder. Get rid of the welder's battery all together and just use the truck battery. Truck will charge its own battery, and the welder wont be putting as much strain on it as the V8 in the truck would.
Worst case if your starting the welder alot and not running the truck, might just have to start to the truck every now and then to charge up the battery.

 

[wanderinthru]

What if you just ground the welder to the truck frame, and run a battery cable from your truck's battery to the stater relay in the welder. Get rid of the welder's battery all together and just use the truck battery. Truck will charge its own battery, and the welder wont be putting as much strain on it as the V8 in the truck would.
Worst case if your starting the welder alot and not running the truck, might just have to start to the truck every now and then to charge up the battery.

Because I don't enjoy walking that much, lol. My shop is on the edge of town, but the places I work off this truck ain't. As I head north from here being 10, 15 miles from a house is not uncommon, plus they ain't home during the day. Have a couple jobs lined up there to do. Cell phones don't work up there, hell may or may not work at the shop. The pens we built and posted pictures of in the Farming and Ranching thread were a 5 mile walk to the nearest black top, is a county road 2 miles away,in the wrong direction, and someone may or may not be going down it. I want the truck to have a good hot battery.

 

[wanderinthru]

I'm going to take the opportunity here to explain a simple relay for those that don't know. Look at the pic in post #5 if you look at that relay 30 and 87 think of that like a toggle switch when 30 and 87 are apart its like your toggle switch being off when 30 and 87 are touching its your toggle switch being on. The difference between a relay and a simple switch is with a relay the switch 30/87 is turned on and off by an electro magnet. When put power and ground to 85 and 86 it closes your switch.You can turn the magnet on with very little amperage but the switch 30/87 can handle a ton more.

As time has wallared all this around in my head. Makes the most amount of sense to go ahead and mount the relay, and a volt meter in the truck. When I do build it a new bed that one wire running to the welder is all I have to worry with.
Heres what I'm thinking, and then a question. Build a little sheet metal box that will hold the relay and the volt meter in the cab, where ever. 8 gauge wire, fused at the truck battery, to the relay. The other needed wires to activate the relay (I'll have to go back and read that again) Leave the relay straight into a fuse, then the volt meter, on it's way back to the welder battery, use 8 gauge here as well, I am in Texas, lol. Am I correct in, a look at the truck, then welder volt meter will tell me if I'm charging? Is there a "better" key on hot, off not wire/ connection to use in the cab? Truck has a CB mounted and wired in, don't work but looks cool, thinking of using that wire? As it has just been written out am I correct to believe when the key is off the 2 batteries will be isolated?
Thanks Ricko, and Grit Dog and everybody (sorry, CRS, esp names, that's why mine is weird so I can remember it)

Just use the chassis as the ground.

Thanks
Shakey