[orange4boy]

Here's what I found, but all need an inverter

I swear, I found a 12 - 14.5v buck converter somewhere. I'll keep looking.

There are more 24-14.5 volt units around but that would mean another battery.

16 volt batteries and accessories:993 - Powermaster 16V Battery Accessories

Someone makes a Li 16V battery for racing. Only $1999 special for you. (There are cheaper ones)
https://p10.secure.hostingprod.com/@...1536435320330c

Iota 110 to 13.5V charger/power supply IOTA Engineering DLS Series AC/DC Power Converters and Battery Chargers for 12VDC Systems
Iota Regulated Battery Chargers
EVDL - Ruggedizing an Iota power supply for DCC use

This link is to a DIY16v battery chargerAutomatic 12V Lead Acid Battery Charger

I also thought of using an 18V cordless drill battery just for the coil.

I don't know if all that info will help or hinder. Seems like the cheapest way is probably the inverter/charger combo like I have. All readily available and cheap. I found a 750Watt inverter at a dewalt repair/clearance centre for $25. I got the 50A charger for $60 at the same place. I was using 35A to run everything last night.

Good luck.