Hello wizards of everything electric, after reading this, you'll either shake your head in pity at me or laugh and say "what a bonehead!"

Long story short, I run a sign shop, have a bucket truck to do installations/service and the boom runs off a "bus battery", (12VDC electro/hydraulic pump). The salesman that I bought the truck from said that the boom battery was charged off the generator, which was not on or included with the truck (the original owner opted to keep the generator). He mentioned that the engine alternator also provided some battery charging while driving. The boom operates flawlessly, except on larger jobs which require lots of boom movement, then the battery starts to fade.

Thinking that I would be ahead of the game, I opted to purchase a generator/welder from Lincoln Electric (Ranger 305G, 11.5KV, 300A DCEN/EP) since I do a fair bit of welding onsite, this should be the be-all-end-all of service trucks. Power for the boom, power for the welding, 120VAC power to spare for tools/lights. Sounds perfect right?

Well......

Looking over the wiring schematic for the bucket truck, I notice that the no mention of any type of power source other than the DC batteries (there's 3 : regular truck battery for the diesel engine, emergency battery, and the bus battery for the boom) that's connected in any way to the DC circuts. That is to say there's no "generator" in the entire schematic. There is a pair of 120VAC 15A receptacles, which terminate at "TO SOURCE OF 120VAC POWER FUSED FOR 15A" but that circut is in no way connected to the DC portion of the schematic.

So, sitting here with my tail between my legs, wondering how hard my wife is going to kick me in the nuts when I tell her that the fancy new $5,000.00 generator I just got for the business doesn't run the boom/charge the battery, I bow to you O wizards of electrons, how the hell can I affordably make this generator charge the bus battery and still energize the (2) 120VAC receptacles?

I should mention that there's a lead coming off the truck near where the original generator sat, with a 240VAC 30A "twist lock" plug. I'm thinking there's a way to wiggle a transformer with a rectifier in there or maybe even splice in a normal battery charger into one of the 120VAC circuts, and jump it straight to the battery?

anyone.....Bueller....

 

Lead acid battery chargers are more than a transformer and diode. You might just get a charger like the one linked - http://www.drugstore.com/qxp205472_333181_sespider/vector/21015_amp_12_volt_battery_charger.htm.

What is the amp-hour capacity of the battery? You might want something bigger than a 15 amp capacity.

 

that's what I was thinking at first, but I have a Schumacher battery charger which is similar, and any time you apply a load to the battery that it's connected to (i.e. trying to start motor that battery/charger is connected to) the charger defaults to "error" so if I was to utilize an off-the-shelf charger, I'd need to find one that doesn't trip off when a load is applied to the battery. I originally intended to run the generator while working the boom, essentially running the boom off the generator power and saving the battery as a means of working where I couldn't run an engine (some jobsites are "quiet zones" and running a diesel engine or a generator for long periods is frowned upon).

I don't know the amp hour rating of the battery, there's a 10A Circut breaker in the schematic, immediately out of the + terminal on the bus battery. I guess I'd have to check the battery itself, it's huge btw, 3 times the size of a normal automobile battery.

 

A quick search of the Interwebz found this brochure on your Ranger 305G:
http://content.lincolnelectric.com/pdfs/products/literature/e6117.pdf

It does appear that you can set the output voltage as low as 14V DC, with selectable Ampere ranges.

There are lots of accessories that you can obtain for your welder/generator.

Lincoln's number is 216.481.8100 - I suggest that you contact them, and explain that you'd like to be able to use your welder/generator's DC output to charge your boom's battery while the boom is in operation; and what would be the best way to do that - do they offer a battery boost/charge kit?

 

I understand where you're headed with that suggestion, but the DC output on the generator is specifically set up for welding, to give you an idea the connections for the DC output are currently connected to 2/0 wire, which are connected to a 300A ground clamp, and a 250A Electrode holder.

My specific proposal was to have a unit wired to the 120VAC connection which would a. Charge the battery, and b. Run a CC of 12VDC to the battery terminals when a load (the boom operation) was applied.

I think I may have found the solution, here's a link to the unit.

http://www.batterystuff.com/battery-chargers/12-volt/marine-chargers/SEC12-45.html

Wondering if that'd do the ticket or if I'm barking up the wrong tree.....

 

Looks like that would do it. It'll run on 120v 12A, which your generator/welder is capable of producing.

Be sure to use the thermocouple on the battery post to maximize your battery life. I'd suggest using lower charging amps to keep your battery/batteries from heating excessively.