CRD RUN-TIME, LOST CHARGING

Gypsy62 · **Posted:** Mon Jan 22, 2018 12:17 pm

I've been messing with serp/pulley combos the past few weeks. Yesterday, I paid the price for my serp-less recreational day-driving. Jeep stalled.
Given that I have fairly precise knowledge of my driving-time & conditions, the snafu provided an accidental revelation that may be useful to somebody...

Available CRD run-time in the event that you lose charging, daytime-driving:
- 1.5 Hours before "Charge Warning" light illuminates (looks like lightning-bolt, located on left-center of cluster). Aggressive-driving.
- After "Charge Warning" lites, .5 Hour before stall.
- Total available driving-time without serpentine/alternator= +/- 2 hours.

Obviously, your available battery-energy depends on:
A. Day vs night driving, & accessory load
B. The quality and state of your battery(s)

I have a healthy 5yr.old Optima 800cca 'yellow-top' battery.
CRD definitely starts to "sound funny", idle crappy. However, I found that it remained rocket-smooth under heavy-throttle.
Mine stalled while parked at idle for almost 1/2 hour at a "Yonke"**.
My buddy was waiting in the jeep and said it was uneventful, no dramatic shaking or "death-howls", just suddenly stalled. I'm not certain how it would have finally pooped-out if underway in city-highway driving.

I have a Kennedy-pump installed. I just-now realize THAT was the main culprit that drew-down the battery!
Any thoughts on how long she'd putter day-driving without an electric pump, given that the tbelt energizes the injection-pump?

* I accidentally discovered that the OEM belt will still provide temporarily-adequate tension with Idler Pulley B removed (w/stock IPA); however, it jumped & shredded next day.
** =MX junkyard, aka "Automotive Salvage Boutique" to quiche aficionados...

Keywords: failed serpentine belt, broken v-belt, alternator died failed, jeep diesel not charging, charge-warning light on illuminated, headlights dimmed, jeep crd stalled

flash7210 · **Posted:** Mon Jan 22, 2018 2:18 pm

It helps to know the amp-hour (Ah) rating of the battery.

Your average lead-acid 700CA car battery is usually about 45 Ah.
In theory, it could supply a current draw of 2 amps for about 20 hours.

So I did a test.
Headlights off. Cabin blower off. Radio off. Battery fully charged. Engine at idle.
Current draw from the alternator was about 15 amps.

So, in theory, a standard car battery should support the 15 amp load for about 3 hours.
However, the more you demand from the battery (amps) the lower your Ah rating will become.

Conclusion: a brand new fully charged battery (45 Ah) will probably be able to support a 15 amp draw for about 1 hour under the best possible conditions.

Deep cycle batteries have higher Ah ratings but lower CCA rating.
This makes them good for use as backup power but poor for starting your engine.
(When my original Optima red top failed, I used a spare deep cycle that I had. It did manage to start the engine but was only good as a temporary fix.)

AGM batteries don't provide much more as far a Ah goes.
The advantage of an AGM battery is low maintenance, no acid to spill out, and longer service life.

WWDiesel · **Posted:** Mon Jan 22, 2018 2:29 pm

As I stated before, lot of variables figure into this time factor!
But bottom line, when the battery voltage gets to around 9 volts, strange things start happening.
Low voltage to the ECM will put you on the side of the road! :roll:

Billybob · **Posted:** Tue Jan 23, 2018 2:59 am

WWDiesel wrote:

As I stated before, lot of variables figure into this time factor!
But bottom line, when the battery voltage gets to around 9 volts, strange things start happening.
Low voltage to the ECM will put you on the side of the road! :roll:

Yep definitely...ECM does not like low voltage and will grind Jeep to a halt. :wink:

CRD RUN-TIME, LOST CHARGING

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