will i need a new battery? - PeachParts Mercedes-Benz Forum

iNeon · #1 11-12-2005, 11:43 AM

I have done a series of upgrades to the 240d and was wondering if i will need a new battery.

i have added an amplifier(250w) and a single subwoofer.

also added were a pair of heated seats. i have not wired them to switches and this post is somewhat about that as well.

i was thinking about using rear dome light switches, but they only have two wires run to them, how would i get power?

the heaters are simple 1 setting heaters from a late 80s/early 90s 244 volvo. they only have a black wire and a red wire run to the plugs. at this point, would i need a 3 prong switch to run power to the heater from the fuse panel and then that would send the power to the elements? would i run the hot wire from power to both switches?

i have a vague idea about how this should all be wired, but i am not as knowledgable as you guys wherever this is concerned!

i am also worried about the power drain on my battery, it is not an old battery, but i still wonder how much juice itll have in cold mornings to warm the seats while glowing! maybe that isnt advisable heh heh.

i just know last winter i froze to death every morning waiting for my engine to warm up. now ill have a nice radio and warm seat while im waiting=)

Jim H · #2 11-12-2005, 12:06 PM

Quote:

Originally Posted by iNeon

I have done a series of upgrades to the 240d and was wondering if i will need a new battery...

Probably not, but you might need a higher-capacity alternator. Leave the seats and radio OFF until you have started the engine and the alternator is online.

Quote:

Originally Posted by iNeon

... i was thinking about using rear dome light switches, but they only have two wires run to them, how would i get power?

If you try to operate a heated seat with a dome light circuit, you will overload that circuit and melt the fuse.

You will need to find a circuit with enough capacity. You might be able to find an unused fuse postion in the fuse block. You may have to run wire from the fuse block to the seat switches. The W126 seats have a 16A fuse all to themselves.

Quote:

Originally Posted by iNeon

...now ill have a nice radio and warm seat while im waiting=)

Heated seats are wonderful. Soon you'll be driving in shirt sleeves, setting the temperature a few degrees lower, and being comfortable.

Good luck.

iNeon · #3 11-12-2005, 01:10 PM

i wasnt talking about running the heaters from the dome light, just using the switches from dome lights.

are these switches not robust enough to handle the current needed to heat the seats?

the fuse panel space will be a non issue, the car is a standard 240. no electric sunroof, no electric windows, no electric mirrors or anything extra nice. i think there are even a pair of spaces with nothing even hooked up.

so a simple diagram...ill post it when i am done

*edit*

this is the diagram of how my mind thinks they should be wired. it should all be fairly self-explanatory

#4 11-12-2005, 02:56 PM

That diagram looks good.

The ground on the switches is for the light I assume?

Think of the battery as a water storage tank for a water well.

The tank can be small as long as the well is big enough to feed water equal to the usage by all the people in their houses.

If the well is too small you will slowly use water from the tank and eventually drain the tank. A bigger tank would work but only for a longer amount of time becuase the well is still too big.

So...make sure your alternator can keep up with the headlights, radio, fan, amp, and seat heaters (65amp is most likely inadequet) and go from there.

If you are running a 250w amp and are actaully USING it, then you probably need a bigger "well" unless you use all those things sporadically enough that you won't drain the "tank".

I would shoot for 85A+ unit. See the thread about the AL-129X

iNeon · #5 11-12-2005, 05:03 PM

oh, i just assumed you needed a ground at all points!

like i said, i am not an electrician heh heh

what i will do is run extra fibers from whatever light source powers the normal dash switches and that will take care of switch lighting. i want to have switch icons made at a sign shop, black vinyl with cut-outs. i have seen a number of older mbs with white circles instead of their respective switch icons, so this cannot be hard to accomplish.

i would like an indicator for the seat being on, though.

the amplifier is to fill the sound out, not to rattle the car apart. although, it seems to do an ok job of that as well. i will wait until i need an alternator and then i will upgrade to the higher amp one.

the 240s come with a 65amp and the s class come with an 85?

now i just need to get those switches!

did i mention that pull a part only charged me 8 dollars for two seat heaters? they tried to charge me 16, but i argued that they were one unit, and won

i didnt even take any real tools with me, i had to dissect two seats with a screwdriver

whunter · #6 11-12-2005, 06:13 PM

Do NOT take power through existing fuses.
Run a new line to the battery, fuse it at the battery, and each seat.

#7 11-12-2005, 07:37 PM

Quote:

Originally Posted by iNeon

oh, i just assumed you needed a ground at all points!

like i said, i am not an electrician heh heh

the 240s come with a 65amp and the s class come with an 85?

Sounds like you have it covered pretty well.

The 240D will either have a 55amp or a 65amp. If you are not using your amp to rattle out your teeth, then you will be okay with that load.

Just add up your current draws and see where you are.

iceman3876 · #8 11-12-2005, 08:35 PM

Quote:

Originally Posted by iNeon

i wasnt talking about running the heaters from the dome light, just using the switches from dome lights.

are these switches not robust enough to handle the current needed to heat the seats?

the fuse panel space will be a non issue, the car is a standard 240. no electric sunroof, no electric windows, no electric mirrors or anything extra nice. i think there are even a pair of spaces with nothing even hooked up.

so a simple diagram...ill post it when i am done

*edit*

this is the diagram of how my mind thinks they should be wired. it should all be fairly self-explanatory

Great drawing..what program did you use to produce it??

#9 11-12-2005, 08:45 PM

Quote:

Originally Posted by whunter

Do NOT take power through existing fuses.
Run a new line to the battery, fuse it at the battery, and each seat.

But don't put two fuses in series....thats generally not a good idea

I just saw two fuses...maybe you meant switches sir whunter?

iNeon · #10 11-12-2005, 09:18 PM

i use adobe illustrator cs

my other baby...a 2.0 g5/1gig RAM

i use these diagrams to help my projects go more smoothly. i am an artist by trade, so i think visually; they help me a GREAT deal

here are some others:

one is a custom dash-- i am going to add a computer module(mac mini) and screen to the dash.

another is my car in a two tone paint scheme. i really like this one. its not finished, of course, what project is?!?

the last is a maybach inspired dual sunroof with a wooden coffered ceiling, i have a better image than this, but i cant find it, i think it might be on my ibook. i do want to see this project to fruition, though. with dual stained glass(sandwiched between safety glass) panels and oak beams with nice ambient lighting.

barry123400 · #11 11-12-2005, 09:21 PM

I would seriously consider wiring a solinoid into the circuit to disable the heated seat feature when you turn car off. Otherwise you may forget to turn it off and return to a car with a flat battery. Easily accomplished I think. By the same token the seat heater will not activate before you attempt to start the engine. Also hunters ideal of a separate fused power feed is also an excellent ideal. Really no sense stressing an old wiring system. To visually check if your alternator is getting enough out to power your various add ons I would install a cheap meter that monitors battery voltage. If the load is too great you will observe battery voltage constantly dropping off. Or it will allow you to juggle your electrical load if required. It is also a great early warning system that things are going downhill in your electrical system in general a long time before the alternator light comes on in my experience. The switch to activate the seat should have enough amperage capacity to be trouble free. A light rated switch like the dome light switch could burn up. Would you want the new mercedes the insurance company might provide? On second thought install the lightly rated switch.

whunter · #12 11-12-2005, 09:26 PM

Quote:

Originally Posted by Brandon314159

But don't put two fuses in series....thats generally not a good idea

I just saw two fuses...maybe you meant switches sir whunter?

Protect the battery from short = fire hazard + protect each seat heater, after the switch.
The fuse numbers used in my picture are exaggerated for effect, real AMP readings would be needed to size fuses correctly.

The circuit will work and be safe when the correct fuses are used.

Diagnosis:
Battery fuse blows = a short between switches and battery = replace wire.
LF fuse blows = short in driver seat heater or wire from heater to switch.
RF fuse blows = short in passenger seat heater or wire from heater to switch.

iNeon · #13 11-12-2005, 09:26 PM

i wasnt going to overload any of the fuse circuits. i know there are circuits designed for all the power buttons and things; things i do not have in my car.

i have not done any hacking to the electrical system and i do not intend to!

i just think using the fuse panel and putting them on the circuit they were intended to be on would be the best idea.

the car already has a pair of wires run to the positive battery cable for the constant radio power and amplifier, i do not wish to clutter that part up any more with my add ons. i will remove the fuse panel or buy one from a junkyard and permanantly install a 16 amp circuit there for this system, maybe a pair of them so i feel better.

to add to this... i want the heaters on a switch operated circuit. i do not wish to have heating function with no key in the ignition, ideally it would be only operable in the run position so i could not drain the battery while sitting with the radio on.

thanks guys, this is pretty durn informative!

t walgamuth · #14 11-13-2005, 04:34 AM

i thought that most 240s have a 45 amp from the factory. the 300s have a 65 amp from the factory. they are interchangable though. afte fighting the low alternator output for 25 years on 240s i am now upgrading them routinely when the alternators need replacing (at 275k or so).

tom w

Jim H · #15 11-13-2005, 09:46 AM

Let's make this more interesting and informative. My W126 Electrical manual shows that the switches have OFF, LOW and HIGH postions.

There are 2 contacts and an internal lamp that glows when they are in LOW or HIGH position

It is wired so that LOW postion connects the heaters in series, while HIGH connects them in parallel. This means that the heaters operate on 6V on low and 12V on high, or a 25% and 100% heat setting.

With a simple ON/OFF switch you must decide if you want to wire the heaters in parallel for HIGH heat or in series for LOW heat.

You may want to scrounge some 2-pole seat heater switches from a M-B at recycler, or see what Radio Shack has that will duplicate the functions.