How many volts does it take to run a 6.5?

[DennisG01]

Quick background: Driving around today, in and out of a few stores. Came out from the LAST ONE and the truck wouldn't start - barely even turned over. A guy in a little VW Bug gave me a jump. Boy, did it suck that engine down when I hooked up - thought it was going to stall :rolleyes:

Checked voltage - with engine running - when I got home - 10.8V. I think I may have narrowed it down to a bad alternator power wire. But...

It got me wondering... How low can batteries go and still allow the truck to run like normal? Albeit, the headlights and dash lights did seem dim. Now that I think about it, I think they've been dim for a few days.:o

[6.5 Detroit Diesel]

when my alternator went out, it only took a few starts. then my tach started acting funny. my marker lights barely came on while the truck was running too. the meter was reading under 10 volts

[bobt]

When my alternator went out, my red light on dash (battery icon) stayed on. When just my batteries were bad, they showed output of about 10+ volts and the starter just clicked trying to engage.
Bob

[rameye]

Its my understanding that when the resting voltage of your batts goes below 11 volts upon recharge they will only have 1/2 of the capacity they had prior to the incident.

Thats for lead acid wet cell batteries, gel cells are a different kettle of fish.

[Lightyear]

Check your battery cables and connections at rhe battery terminals, too. The passenger's side end of the long postive cable was so corroded and eroded it wouldn't make good contact, causing strange electron behavior. New cable and she runs like a champ.

[DennisG01]

All the big cables are good and tight - absolutely no visible corrosion anywhere. The alternator power wire is a 4gauge. All cables are 2 years old.

This is my fault that the cable is bad - I made a poor connection from the cable to the lug connector. I pulled it apart and re-did it - I was surprised, the visible bare copper strands were still bright and shiny.

I'll know for sure if this is it after I get both batteries charged up (doing them separately). But, last night when I wiggled that alt wire, my DVM kept fluctuating. So, I'm pretty sure that's all the problem was.


That 11 volt thing has me worried. I'll need to find out more about that.


EDIT: Oh, I'm charging the batteries like this:

First, a "normal" battery charger on the 2 amp setting for about 10 hours.

Second, using a Battery Minder (not "Tender") until it says everything is OK. The Minder is supposed to have the added benefit of being able to fight/get rid of sulphation build-up on the plates.


I very quickly read up a little bit about the 11 volt thing - it appears that sulphation starts to form on the plates below about 11 volts. If that's the concern about under 11 volts, maybe they'll be OK.

[Robyn]

Depending on the type and brand of battery the issues with sulfation can or can't be an issue it's a toss up.

I always use the spiral wound batteries like the Optimas in my rigs.
Far less issues.

The amount of voltage to run the thing is also and IFFFFY proposition. The DS4 injected trucks require quite a bit of power to keep the computer happy.

Some rigs will start having various code issues once the voltage drops bellow 13 and some will run well even to the point that the lights will hardly burn.

An Old mechanically injected 6.2/6.5 will run sweet right up until the power levels drop so low that the fuel shut off can't hold any longer.

Battery cables, corrosion and the many connections on these trucks is a big source of troubles for lots of folks.

Glad you got it sorted out.


Robyn

[DennisG01]

The amount of voltage to run the thing is also and IFFFFY proposition. The DS4 injected trucks require quite a bit of power to keep the computer happy.

Some rigs will start having various code issues once the voltage drops bellow 13 and some will run well even to the point that the lights will hardly burn.


Guess I got lucky this time - didn't get any codes. In fact, the red battery light only came on once when I was back in the driveway. It was very dim.

[Hubert]

I had the passenger side Pos post loosen and the voltage on dash gauge dropped towards 9V and it ran ok. The battery light on dash did not come on.

I don't remember being able to tell a difference really at the time except the head lights were getting dimmer.