24v system

[houstonrealtor]

Question. I have a 1988 M998 with a 24v charging system and I'm not at all familiar with 24v systems. I want to install a nice 12v radio (music type) and I figured I would need a 24v to 12v converter but after checking out the batteries I noticed they are 12v batteries so why couldn't I just connect the power from the radio/amp directly to one of the 12v batteries? Am I missing something?

 

[King]

Originally Posted by King Maybe I'm missing the big picture here, but why don't you just tap one battery? I'm only using a single circuit for cell phone inside my Duce, any ground point with the tap provides a simple 12vdc and an inline fuse is easy to add if desired? Just a thought.
If you are just using a single item on the 12v tap, you will be fine.

This a very simplified explanation of what happens. There is much more involved.

The issue comes in when you create a large load on the 12v circuit. By drawing power from the single battery it creates an imbalance in the voltages between the batteries. When the alternator attempts to charge the batteries, it see the lower voltage in the single battery and attempts to charge it at a higher rate. This in turn overcharges the second battery that already is fully charged. The overcharging cooks the second battery and shortens its life.

"We are all born ignorant.....but one must work hard to remain stupid" - Benjamin Franklin
​

 

[Mike82ndABN]

i saw a nice marine boat radio head unit, with 4 speakers, all weatherized and pretty much water resistant, it runs 12/24v. Win-win.

 

[papakb]

Search on eBay for 24v AM/FM radio. There are several to chose from that are designed to be used on tractors and boats that are fairly inexpensive. This eliminates the need to tap off of one battery or run a power dropping regulator.

Kurt
KG6KMJ

 

[Robus1022]

The 24v options are pretty piss poor. I would recommend an alpine running off one battery before a chinese radio in an aluminum can. Marine grade is probably going to be most durable, I only base that on working at an audio installer for 5 years, replacing radios in boats for decades and the easy car radio swap. It seems the 24v radios either have no input or look like(and probably wont last as long as) a dual brand cheapo head unit, which often corrode to **** after a season. I have seen the elcheapo in a boat last 5 years, but i have also seen hundreds of alpines from the early 90's still kicking in saltwater boats. With mass production its a gamble but a decent brand name is worth the $$$ unless you dont mind resoing the job once a year. Enjoy!

 

[houstonrealtor]

The 24v options are pretty piss poor. I would recommend an alpine running off one battery before a chinese radio in an aluminum can. Marine grade is probably going to be most durable, I only base that on working at an audio installer for 5 years, replacing radios in boats for decades and the easy car radio swap. It seems the 24v radios either have no input or look like(and probably wont last as long as) a dual brand cheapo head unit, which often corrode to **** after a season. I have seen the elcheapo in a boat last 5 years, but i have also seen hundreds of alpines from the early 90's still kicking in saltwater boats. With mass production its a gamble but a decent brand name is worth the $$$ unless you dont mind resoing the job once a year. Enjoy!

I'm actually planning on using a iPad mini with a dash mount and running all the speakers off of an amp via bluetooth or 3.5mm jack. Wonder if a 24v to 12v converter would handle that.

 

[Robus1022]

Hmm what I do on my boats is a concealed 4-channel amp, with a 1/8" earphone to rca adapter, most come with a water proof flushmount volume/input. Might work for you. This one is not cheap but I am sure parts express or amazon has a 24v 4-channel amp. http://www.jlaudio.com/mhd600-4-24v-24-volt-marine-audio-mhd-amplifiers-98227

 

[Retiredwarhorses]

Upgrade to a 200amp generator and run the 14v tap to the rear battery, this will fix the imbalance.
this is how it's done from the factory on new HMMWV's with TCM for the 4L80E trans.
the TCM is 12 volts...

 

[houstonrealtor]

Upgrade to a 200amp generator and run the 14v tap to the rear battery, this will fix the imbalance.
this is how it's done from the factory on new HMMWV's with TCM for the 4L80E trans.
the TCM is 12 volts...

Hate to be so ignorant but..... 14v tap??? Is that to make up for the extra power being drawn from that battery? Didn't realize that there was a separate charging wire for each batter. What amp generator does it have now?

 

[NovacaineFix]

Just buy a equalizer, easy to install and solves any imbalance issues when running a 12 volt appliance in a 24 volt environment.

The imbalance like someone else stated can be easy to misjudge until you start going through batteries.

Here is a link to a google search for equalizers:

https://www.google.com/search?q=24v...7.6985j0j7&sourceid=chrome&es_sm=119&ie=UTF-8

These are the same things that buses, coaches and ambulances use to run 12 volt appliances on their 24 volt vehicles.

 

[steelandcanvas]

Just buy a equalizer, easy to install and solves any imbalance issues when running a 12 volt appliance in a 24 volt environment.

Sometimes also referred to as a "DC to DC Converter".

 

[NovacaineFix]

Sometimes also referred to as a "DC to DC Converter".

Yes and no.

A normal DC to DC converter, will do just that, increase or lower your source voltage to a usable voltage for a device.
Like a 24 volt to 12 volt converter will reduce the source voltage in half so that 12 volt accessories can be used without frying them releasing the "magic smoke."

An equalizer has an additional circuit built in to "balance" the charging voltage that would occur from installing a 12 volt circuit into a 24 volt system.

Not saying you're wrong but also saying your not 100% correct.


For that reason of the balancing circuit, there is a dramatic price difference between a straight DC to DC converter and a 24 to 12 volt equalizer.

 

[houstonrealtor]

Yes and no.

A normal DC to DC converter, will do just that, increase or lower your source voltage to a usable voltage for a device.
Like a 24 volt to 12 volt converter will reduce the source voltage in half so that 12 volt accessories can be used without frying them releasing the "magic smoke."

An equalizer has an additional circuit built in to "balance" the charging voltage that would occur from installing a 12 volt circuit into a 24 volt system.

Not saying you're wrong but also saying your not 100% correct.


For that reason of the balancing circuit, there is a dramatic price difference between a straight DC to DC converter and a 24 to 12 volt equalizer.

Which one would be best for my application?

 

[NovacaineFix]

I would say the equalizer because it has the least amount of possibility of causing unseen damage to the 24 volt system and killing your batteries.

If your are doing this on the cheap and the stereo will not be in use 100% of the time, you could use the standard converter and place a cut-off switch in-line with the stereo so that that there is no chance of causing any charging imbalance when the stereo is not in use. Just remember to not leave the switch on all the time. Now you also said amp, so that tells me that there is potential for some serious amperage draw, so again, the equalizer would be your best bet.
I would refrain from connecting it straight to one of the batteries, though it may be the cheapest and most tempting to do, it will create problems down the road.

Just remember, 24 volt systems are basically the same as 12 volt systems with the exception of the voltage of course. The problem arrises when it comes to the batteries, because typically you have to use 2 12-volt batteries connected in series to get the 24 volts. By connecting in series the ground is not always the same for the batteries as the chassis ground when using a 12 volt device in a 24 volt set-up, since you have to connect one of the positive terminals of the batteries to one of the negative terminals.

It only gets worse and more confusing when you add more batteries, like my 818 which has 4 batteries, 2 connected in series and 2 connected in parallel, still 24 volts though. [Head scratching]

I know, it does sound confusing and it is easy to get messed up when talking positive to negative and vice-versa.

One other option, would to use a completely separate battery just for the stereo, but you would have to keep charging it up independently of the other batteries.

 

[houstonrealtor]

Would something like this work? Not sure why it says that it "provides 24/7 battery charge" if the vehicle is not running 24/7....

 

[Retiredwarhorses]

Would something like this work? Not sure why it says that it "provides 24/7 battery charge" if the vehicle is not running 24/7

the pulse tech unit as a kit comes with a solargizer, so when not running, it keeps the electrolytes happy in the battey.
its not a charger though....be careful of these. I had a customer who had the full kit installed with the solar panel, it cooked and blew up one of the batteries. I found that panel was sending out IIRC, 32-36 volts to the batterys while the truck was not even running. I had removed the batterirs and had that voltage on the battery cables.
couldnt find much info on them from there website....I think I even called them, but no help.

 

[NovacaineFix]

Would something like this work? Not sure why it says that it "provides 24/7 battery charge" if the vehicle is not running 24/7....

I wish I could give you a clear answer on that device, but I am not familiar with it, sorry.
I have twin solar panels on my 818, but they are not connected. The unit is supposed to provide a very small trickle charge in a way to keep the batteries up to par, not really a charger, but supposed to maintain them, I guess. With anything, you should always check them weekly/monthly just to make sure things are going as they are designed to be, especially with voltages and batteries.

Good Luck man

 

[papakb]

I've got to agree with Steve about the Pulsetech systems. I called them too and the "technical assistance" person I talked to knew even less about it than I did. While they look like exactly what we could use in our HMMWVs I'd avoid using them.

The Vanner Equalizers are probably the best (and most expensive) way to get 12 volts safely and reliably in our trucks. Tapping off of one battery works but creates an imbalance in the system along with other problems for those of us unfamiliar with power wiring. I've used quite a few different voltage dropping units over the years and they work well. Just make sure you know how much current load you expect to have and pick a unit with at least a 50% safety margin. ie: If you expect to draw 10 amps buy a 15 amp unit. It's just good design practice.


Vanner: http://www.vanner.com/battery-equalizers/

 

[NovacaineFix]

Would something like this work? Not sure why it says that it "provides 24/7 battery charge" if the vehicle is not running 24/7....

After looking online for more info about the Pulse-Tech device, I would steer clear of it and save your $$.

To me, and this is just my opinion from the info I can see online about the product, it appears to be a magic fix-it box with no real promises or guarantees that it really does anything short of providing a break-out box for fuses.
Again, just my opinion.

If the Vanner's products are too expensive, and they probably are, try searching a local junkyard or automotive electrical shops that specializes in large trucks, buses and ambulances, they may have some older units that still work that will save you some $$ and still do what you need.

 

[Retiredwarhorses]

After looking online for more info about the Pulse-Tech device, I would steer clear of it and save your $$.

To me, and this is just my opinion from the info I can see online about the product, it appears to be a magic fix-it box with no real promises or guarantees that it really does anything short of providing a break-out box for fuses.
Again, just my opinion.

If the Vanner's products are too expensive, and they probably are, try searching a local junkyard or automotive electrical shops that specializes in large trucks, buses and ambulances, they may have some older units that still work that will save you some $$ and still do what you need.

I have installed them and put them to good use...they are cheap compared to other chicom junk for more money on the market. They are fully submersible, fused, and have both 12 and 24v feeds....what else do want?
I will keep buying them and using them as long as they are available for this cheap.