Second battery for cold weather starts? - PeachParts Mercedes-Benz Forum

hangit · #1 02-12-2008, 08:16 PM

Has anyone added a second battery for added reserve to aid in cold weather starts? The past week we have had some -15F nights here in WI and it's all my new NAPA 850CCA battery can do to crank the engine fast and long enough to fire up. I'd like to see pics of the second battery tray mounting if anyone has done this. I'm also running 5W-40 semi-synthetic oil.

My F250 powerstroke has two batteries and has yet to leave me stranded.

Thanks.

John

jkoebel · #2 02-12-2008, 08:17 PM

Option 2 is keep battery inside, on a trickle-charger, and use it + heavy-duty jumper cables when starting, then throw it in the trunk.

hangit · #3 02-12-2008, 08:34 PM

Quote:

Originally Posted by jkoebel

Option 2 is keep battery inside, on a trickle-charger, and use it + heavy-duty jumper cables when starting, then throw it in the trunk.

Not an option when my 17 y/o daughter drives it to school and the car sits in the parking lot all day!

John

jkoebel · #4 02-12-2008, 08:35 PM

Quote:

Originally Posted by hangit

Not an option when my 17 y/o daughter drives it to school and the car sits in the parking lot all day!

John

Get her a bigger backpack?

#5 02-12-2008, 08:38 PM

A single battery is more than enough for -15 starts, I've done it several times before.

Your best bet for two batteries is to mount one in each of the trunk wells and run some 0-gauge up to the starter.

Quote:

My F250 powerstroke has two batteries and has yet to leave me stranded.

Your powersmoke has two batteries because it needs it to start a high compression large displacement engine.

hangit · #6 02-12-2008, 09:17 PM

Quote:

Originally Posted by ForcedInduction

A single battery is more than enough for -15 starts, I've done it several times before.

That may be true, but you only get one crack at it! I am hoping to add a little margin for error. It's my understanding that these old engines don't have "like new" compression so it's important to have good glow plugs (new relay, plugs and freshly reamed GP port in this car), valves adjusted, and a fast crank RPM for proper ignition of the fuel.

John

Skippy · #7 02-12-2008, 10:43 PM

Can you just plug it in?

bustedbenz · #8 02-13-2008, 01:42 AM

Quote:

Originally Posted by Skippy

Can you just plug it in?

Not when his daughter drives it to school and it stays in the parking lot all day

John Deere uses the 2-battery system with great success... but they've got mroe flexibility than we do about mounting them.

One frequently discussed possibility is mounting the battery in the trunk, routing VERY heavy cables (2 gauge or even 0) from the trunk to the front.... etc. There's almost no place under the hood where you can fit one without major modifications. I can't think of a convenient place offhand, if there is one. I've wished for it several times.

***DO NOT TRY THIS AT HOME. SARCASTIC REMARK FOLLOWS.***

You could also buy a battery that, when flipped upside down, lets the posts line up exactly with the battery posts that are mounted under the hood.... store it in the trunk, when start-up time comes just turn that thing upside down, balance it carefully on top of the posts, and crank quickly before it falls off... I mean, how many arcs could you possibly get with a solid post-to-post connection like that?

***

Sorry about that, just an amusing mental picture I got. 1:45 am does that to a person.

The original suggestion of routing cables from the trunk somehow seems like the most practical and workable solution. I'd investigate some kind of box (vented) that would be mountable back there.

#9 02-13-2008, 01:44 AM

Quote:

Originally Posted by bustedbenz

***DO NOT TRY THIS AT HOME. SARCASTIC REMARK FOLLOWS.***

You could also buy a battery that, when flipped upside down, lets the posts line up exactly with the battery posts that are mounted under the hood.... store it in the trunk, when start-up time comes just turn that thing upside down, balance it carefully on top of the posts, and crank quickly before it falls off... I mean, how many arcs could you possibly get with a solid post-to-post connection like that?

In all actual truth, that does not sound like a bad idea. Obviously, a traditional lead acid battery is out of the question but get something sealed and without a liquid inside like an Optima and it could work....

Cervan · #10 02-13-2008, 02:18 AM

Quote:

Originally Posted by ForcedInduction

In all actual truth, that does not sound like a bad idea. Obviously, a traditional lead acid battery is out of the question but get something sealed and without a liquid inside like an Optima and it could work....

just make a mount where the receiver drier goes.. run 0gauge up to the battery posts and there ya go.. You may beable to have a 24 volt system too.. running them in paralell would facilitate this, watchout though ,every bulb in your car may explode

;D

turbobenz · #11 02-13-2008, 02:38 AM

and every relay, circuit board and they wouldnt charge in series either. But I do wonder how fast it would crank on 24 volts, you probably wouldnt need a glow system. But starters need huge current and the internal resistance of two batteries would probably be too high. Yes, i know it would fry the starter

hangit · #12 02-13-2008, 10:08 AM

My thought was to mount a smaller case battery down near the receiver/dryer and hook them in parallel. I don't want a 24V system.

John

bustedbenz · #13 02-13-2008, 10:10 AM

Quote:

Originally Posted by Cervan

just make a mount where the receiver drier goes.. run 0gauge up to the battery posts and there ya go.. You may beable to have a 24 volt system too.. running them in paralell would facilitate this, watchout though ,every bulb in your car may explode

;D

You mean running them in series?

jap · #14 02-15-2008, 09:42 AM

I've thought about keeping a second battery in the trunk and then if i need it, then i can pull it out, take it to the front, quickly wire it up and when I'm done just put it back in the truck to recharge at home later. They are heavy though, your daughter many not be able to do this.

I cant tell you how many times this would have saved me lots of time walking and begging for a jump (back in the "I'm trying to track down all the endless electrical problems" days). But now, it would be just a little insurance.

pawoSD · #15 02-15-2008, 11:27 AM

When I was at Sam's Club a few weeks ago I saw a "vehicle" battery they had there that was about 8x as big as our 100A batteries. I think it was like 700A

Now THAT would keep you cranking.

Don't remember what the CCA was but I am sure it was several times the standard battery of our cars. It probably weighed 200lbs and *would* fit in the trunk of our cars.

Standard terminals and 12V output. That'd be awesome.

If you left your lights on accidentally, you'd probably come back before they killed the battery!