12 volt radios in 24 volt m35a2

[Irv]

Headsets and the laws

In Washington State, the regulations say that you cannot wear a headset unless it is required for noise protection. The Deuce qualifies, easily. If you get stopped, point to the yellow "Hearing Protection Required" sticker on the dash, and then hand the guy a copy of the rules and regs.

A car stereo driving headphones is not going to draw much power. I'd just tap off of the lower battery and call it a day. I advocate the 24 to 12 converter for anything larger, though. I ran 12v trailer brakes (12 of them) directly off of the lower battery and never got a noticeable charge imbalance (I did watch for that). I was pulling about 10 tons behind the truck. I had two pairs of car batteries. Irv

 

[AN/ARC186]

As far as the WA law goes, (and the same goes for most states) if the headset has built in external microphones for ambient pickup (so you can hear sirens, etc) they are exempt, Peltor makes quite a few that has this feature, including a set sold at walmart for $99.(Peltor 6S) Other manufacturers also have this feature.

Drop a line when you get to WA. We'll issue you your raingear and sunlamp..............

 

[Troll1216]

Mil Spec 24vdc to 12vdc

I did a quick check for for 24/12 vdc mil spec converter... I've been looking for one myself. I found 24 volt to 12 volt DC/DC converters (fully regulated) from 100 to 700 Watts non-isolated and isolated. . Has anyone delt with them?

 

[Troll1216]

Hearing Protection / Intercoms

I checked with a trooper buddy of mine as well as Florida motor vehicle regs and found that it is Illegal in florida to use an intercom or technically even hearing protection (earplugs) while driving. I asked if there was a provision for "large" trucks with the "hearing protection required" sticker and he said that that was a no-go too. He did suggest that the "shooting range" type with the external mic to pick up surrounding sound would be best not to get messed with, but that was iffy (still illegal) at best and would depend on your ability to explain.

This is for Florida, but most states have similar laws, check carefully.

I am going to stock up on flesh colored earplugs!!!!

 

[nhdiesel]

I did what Irv said, and ended up just tapping one battery for my few low-draw 12v items. No two batteries are exactly alike, and drawing under 10 amps from one isn't going to cause any issues at all.

On my trip I used a Sirius radio, charged my MP3 player, powered my GPS and charged my cell phone. I didn't have the MP3 and cell powered at the same time for lack of outlets, and they didn't have to be powered all the time anyway.

I DID use headphones, and took my chances. I'd rather have a small fine than be deaf after 1100 miles in a Deuce. Plenty of cops saw me, never got questioned. I'd say use headphones until/if you get harassed, then find an alternative. I remove my headphones when I'm in town, for two reasons- that's when I need to hear whats outside the truck; and that's where I'm more likely to get bothered about the headphones.

Jim

 

[Troll1216]

Hearing protection

EXACTLY what my suggestion would be, on for long trips, off for town. Tapping the battery seems the best option. I was going to put my HAM radio in it and pull juice that way. This is how my department runs the 12 vdc lights for the trucks we have. They did a seperate 12 vdc power strip in the cab with a throw to disable it if necessary.

 

[treeguy]

I installed a 30 amp 24 to 12 volt converter form OK Offroad, it works great. It runs for $300 I think, check out thier web site, I like it. You can run just about anything except a winch. I also have it wired to a single 12v battery to act as a 12v reserve bank. I also use 2 marine battery switches, one for the engine and another one in line with that to supply the converter.

 

[RAYZER]

If you pull 12v off one batt ,you must isolate the grounds on the accessorys and run the grounds back to the same batt.

 

[Troll1216]

Good call I forgot that...... Could have been bad!

 

[rosco]

Not if you use the grounded battery! But be careful, not to draw too much from it, and cause an inballence - one battery will dead and the other will be boiled dry (over-charged).

 

[duffman1993]

be sure to blare "Blue Oyster Cult & Don't Fear The Reaper" from them speakers.

 

[seaaggie]

I installed a 30 amp 24 to 12 volt converter form OK Offroad, it works great. It runs for $300 I think, check out thier web site, I like it. You can run just about anything except a winch. I also have it wired to a single 12v battery to act as a 12v reserve bank. I also use 2 marine battery switches, one for the engine and another one in line with that to supply the converter.

So, 24V DC output from second battery to the input on the converter. Then, output on the converter to extra 12V battery?

 

[SoundGuy]

The battery is a good idea. If you are using the 30amp 12vdc to charge a battery, you really should put a resistor in there for current limiting to the battery. One shorted cell could make for a bad day as it burns up your unit. A 1/4 Ohm 100watt resistor should do it. This will limit the current the battery can draw to less than what the converter will max out at. This is especially useful if the battery dies. The units usually only put out 13.8 volt, but a dead battery will suck all it can to charge itself. They also make some PWM devices that limit current by fast on off cycles (1000 or more per second). These are more efficient and don't get as hot, but can be a little pricey. (Check ebay)

Also as a note most of the 24vdc to 12vdc converters are sold as a max current rate, but can only support such current for a short time. the real rating you should watch is the continuous duty as not to overload anything. Using current limiting and a battery is an excellent approach.

 

[Stan Leschert]

I use these they are 30amp and have a Memory wire to save your settings

New Car Power Supply Convert Devicer DC 24V to 12V - eBay (item 270545843842 end time Apr-11-10 12:09:01 PDT)

Rob knows what he is talking about. He sent me one and it just works!

 

[nmwildman013]

Newby here. I recently bought a M211 ex-firetruck and they had all the 12 volt radios and other equipment tapped off one battery.

 

[SoundGuy]

Welcome wildman. Yep, works great, for a little while. One battery ends up dying quicker, the other gets overcharged. There are some equalization systems out there that prevent this. You truck may have one.

 

[Stan Leschert]

As previously stated, either get an invertor or a battery equalizer. If you fell rich, just do the tap, and then get ready to replace both 6TL Batteries, fix the generator, and rebuild the regulator. Your choice. Been there, done that, and finally got smart! Under $50 bucks for an invertor, our get out your wallet. You just got broke!

 

[59apache]

why make things so complicated? use a second alternator, a 3rd battery and you're fine! with a cheap 66A alternator you have enough power to use working lights, cb, cooler and so on.

 

[ApopkaFL]

Car Power Inverter Convert Device DC 24V to 12V DC, Car Power Converter, Car Power Adapter

 

[wikallen]

Car Power Inverter Convert Device DC 24V to 12V DC, Car Power Converter, Car Power Adapter

I have 3 of those in my M109a3. Two up front, one in the back. You can find them on ebay for under $11 shipped. Works great on my GPS, Phone, 12volt cooler, inverter, etc.