I found one interesting ballast 12DC from scrap yard that works with single F48T12 or F72T12 silmline so I installed in F72T12 fixture and it lit up pretty bright same as normal if was compares to 120 AC ballast.

The ballast was made by Falcon company but I couldn't find any in production. I think made in late 1990's but not sure. 

Only I found IOTA company does make 12 DC ballast but listed only up to F48T12. 

Is there a such 12 volt DC ballast ever made can support 8ft (F96T12) ? or never it was?   It would be nice to use with 12 volt system solar.   

I'll try post pictures tomorrow.

I"m sure that the ballast you found, is an electronic HF ballast and converts the 12V DC it gets, into a HF AC. There is no such a thing DC, low voltage and/or battery operated magnetic ballast, and DC operated electronic ballasts (Like emergency inverters), can't retain the DC current to feed the fluorescent lamp with it. The inverter of the ballast can only convert DC to HF AC and 120V AC to HV DC and than to customized frequency AC.
For a 12V DC electronic ballast to operate F48T12 or F72T12 slimlines at full brightness, the ballast need to be operated from a large and high power and capacity battery or from a step down transformer (120V 60hz -> 12V DC).

I think for power rating of 40V or more, the 12V is way too low voltage to be practical, mainly due to the losses in wiring (it would allow only very short interconnection, but that could cover only small distances)
For the higher power loads is better suited the 24V or 48V, so I would guess you could more likely to find a ballast rated for these higher voltages...

What you can do is get some old UPSes. They can be hacked for external 12V (or something else depending on the original battery) and power 120/240V lights (with ordinary ballasts) with that

But some warnings :

UPSes usualy give square or modified (square with added "0 step") wave. Magnetic ballasts may not like this - they may heat more or instant-start the lamp etc. For example in a Switch Start (Preheat) fixture i tried the starter kept glowing dimply and was staying warm after the lamp was started

UPSes are not made to work continuously at full load (they are overloaded by design, only based on the assumption that the battery will go flat before something else blows up) - so load them REALLY low compared to their rated capacity, add in cooling fans, and better heatsinks as needed

Teh 12V battery circuit is not isolated from the 120-240V outputs. Even more, there may be some odd connection - Such as battery being connected to the AC in through some voltage divider for charging, and that being connected to teh AC out through a current sense resistor and maybe some components too..... So if there is a short from the input to the output you can seriously burn up your UPS and even the fuse may not protect it (as the fuse is only on 1 of the wires on either side). So keep the output short and well isolated (from earth etc)

i have never seen a 12v 8' slimline ballast.
no real mobile/remote application for them.

What you can do is get some old UPSes. They can be hacked for external 12V (or something else depending on the original battery) and power 120/240V lights (with ordinary ballasts) with that

But some warnings :

UPSes usualy give square or modified (square with added "0 step") wave. Magnetic ballasts may not like this - they may heat more or instant-start the lamp etc. For example in a Switch Start (Preheat) fixture i tried the starter kept glowing dimply and was staying warm after the lamp was started

UPSes are not made to work continuously at full load (they are overloaded by design, only based on the assumption that the battery will go flat before something else blows up) - so load them REALLY low compared to their rated capacity, add in cooling fans, and better heatsinks as needed

Teh 12V battery circuit is not isolated from the 120-240V outputs. Even more, there may be some odd connection - Such as battery being connected to the AC in through some voltage divider for charging, and that being connected to teh AC out through a current sense resistor and maybe some components too..... So if there is a short from the input to the output you can seriously burn up your UPS and even the fuse may not protect it (as the fuse is only on 1 of the wires on either side). So keep the output short and well isolated (from earth etc)

I remember I did experiment on 50 watt sodium pressure lamp (magnetic ballast) hook up on APC brand name UPS unit It would start up fine and work as normal. But when I tired hook up other cheap china product square wave it would NOT able start up sodium pressure lamp.  I am pretty sure those quality pure sine wave APC UPSes works fine with fluorescent ballast but too bulky putting inside of fluorescent fixture unless it's large inside space.      

I played with it too a bit

Fluorescet TL 36W T8 4ft on Switch Start (Preheat) - The starter remains glowing dimly and warm, oher than that works ok

HPS - some lamps will be cycling, some will be ok

Incandescent - works.... (and makes odd sound if you hear the lamp up close in total silence !)



So i expect magnetic ballasts to eiher work normal or slightly overdrive

Electronic ballasts will be ok anyway

i have several heavy iron old school ups units here on big battery banks.several apc ans several best power.
they run shoplites and preheat dazor bench lamps without issues.sounds different but nothing bad.
but doing this to run a fluorescent from lvdc is very inneficient.
running big lamps from 12v means running very heavy power leads to go any real distance.thats why 24-48v systems are more common.

But the "heavy iron old school UPS" are at first quite inefficient and at second they are limited in power they could deliver for longer period of time. Their "thermal management" rely on the battery to discharge before the transformer reach dangerous temperature. So with higher than original capacity battery it tend to burn out on full power...

Not only the transformer but other stuff too... Switches (transistors) are on undersized heatsinks. So you have to add a fan and derate the power capacity to keep it cool

Also it is bad to use long wires up to the UPS since the current in them is pulsed. The long wires make some isolation from the battery, and the electronics will have more of that pulses too

Some UPSes are not the big magnetic stuff but HF (they use HF to step up, then rectify it, then make 50-60 Hz with H bridge). They should have a capacitor on the input, but sometimes it is way undersized and thats when wiring to the battery begin to matter big time

So keep it close to the battery, and extend the wiring on the other side - The 120-1240v output you can connect to wires as long as you want. Also have thinner wires without 20A going on in them

The architecture with 12 to 325V DCDC (operated at high frequency to save weight, space and losses) followed by the 50Hz generating HB I have seen mainly in products called "12->230V inverter" or so, not as much in UPS. The reason the UPS more often use the classic transformer is, the transformer and surrounding electronic have it's second duty in battery charging, while the HF converter based UPS would need separate converter for that, adding complexity.

But otherwise the HF converter based inverters have way higher efficiency, mainly with inductive loads, as the 12V/325V conversion stage is processing only the real power, the apparent does circulate only between the load and the 325V rail tank capacitor.
And unlike the UPS inverters, these usually handle the long time load well, mainly due to the rather high efficiency.

But there lay another important thing for the HF converter based inverters:
The internal 325V DC rails have to be decoupled by sufficiently sized tank capacitor, as this is the only thing allowing to handle inductive loads (to swallow and then return the apparent power) and with many compact (auto) inverter designs this is way too small for that duty. The minimum is about 1uF per watt for 230V models and 4uF/W for 120V models.

And as with any modified sinewave, avoid the use of loads containing large capacitors across the AC line. Few 100 nF total for EMI filters is OK, but power factor correction capacitor would ruin both the bulk transformer (from UPS), as well as the HF converter based inverters, while more sensitive are the later.
If you want to power anything containing such capacitors, you really need real sinewave output models.

the old apc and best power units are massively overbuilt.
efficiency is mediochre at best.
since most emergency stuff is 12/24vdc this just runs computers and a 1920's desk fan.
now if you want to run long tubes from 12vdc i have plans for them.will run mercury and sodium lamps as well as mh with a simple multiplier stack for ignition.
you customise it with the transformer you wind yourself.
iirc i had it run a f96t12 at about 4.5a on the 12v side.it was running the starting multiplier with only 3 stages instead of 6.

the old apc and best power units are massively overbuilt.

My experience came from repairing the APC made (as no other brand seems to be imported here for the category below 500VA) and it was repeating few times on units made since 1993 till 2006, all burned their transformer (and the battery fuse, but never anything else; load was 200..300W computer) so the in my eyes the rating and thermal management concept didn't changed at all.

With the original rated battery the transformer reached >100degC (a water droplet just started boiling on the iron core - I had no other means checking the temperature) just when the battery undervoltage shut it down, so really not much margin till reaching the core Currie temperature and consequent transformer thermal runaway...

maybe you get the lightweight plastic ones there.ours have heavy transformers and steel cases.some have fans.
the ones built into a plugstrip and the "cs" series are junk.mosfets on chunks of aluminum.light transformers.
its about to melt down at full load right as the 7ah battery is done.trash.
i will let you guess what we think the "cs" means.

We have both types here. There is one 1000VA UPS, and another 1000VA UPS that weight 3x and cost 2x. Guess where is the difference