4x4Wire's TrailTalk Forums: Charging: Battery info (ANOTHER OPTIMA BITES THE DUST!!!!!)

After digging into more theory than I remember from my E.E. undergrad and ham radio days.... after asking more questions than I knew existed.... and after waaaay too many telephone conversations with too many battery manufacturer and distributor reps, I narrowed my suspicions for the seemingly too frequent Optima failures to one or more of the following reasons:

1) High engine compartment heat
2) Inadequate battery size (capacity) - particularly in winch applications
3) Improper winch technique (single-line pulls and/or long pulls without giving the battery a chance to rest, cool and recover)
4) Improper alternator voltage resulting in overcharging (particularly with AGM batteries)
5) Optima manufacturing flaws

While all of the above can contribute to premature battery failure, I decided to run some tests on what I could determine for myself to see if I could eliminate anything from the list. What I found amazed me.

With ambient temperature at 65 degrees, today was a good day for testing since batteries are at their best around 70 degrees. I installed 3 meat thermometers in my engine compartment at the following locations:

Location A) Between the inner end of the battery and the heat shield
Location B) In the unshielded area directly in front of the battery
Location C) In the possible alternate battery mounting location directly behind the D/S headlight in the space occupied by the W/S washer reservoir on some models - and where some Dodge (Mitsubishi?) trucks have it as a factory mount (3.0L?).

I took several readings and swapped thermometers around so I could be certain that all were within a degree or so relative to one another.

Here is a summary average of readings taken by location (above) after driving at least 5 miles on the Interstate at 65mph and stopping quickly to get a reading:

Location A: 80 degrees
Location B: 80 degrees
Location C: 120 degrees

Here is a summary average by location (above) taken after warm-up and 30 minute curb idle:

Location A: 140 degrees
Location B: 140 degrees
Location C: 165 degrees

Astounded at these idle temperatures and recognizing that in-gear idling would be even higher and far more damaging to a battery, I decided to check a couple of other cars. By contrast, a Lexus RX330 measures 118 degrees with thermometer sitting on top of the battery, hood down 30 minute curb idle. A 560SL M/B has the battery in the trunk, but has a very crowded engine compartment.... it measured 120 degrees at Position C and 130 degrees at position B (directly beside a big alumionum-block V8 exhaust manifold). Big differences!!

Obviously the comments about high engine compartment heat from the local Mitsubishi shop foreman as a reason for valve train failure now seem to me very reasonable and it appears the same could be a big contributor to battery failure as well.

Remembering the statement (posted here by another poster) from the Optima employee about Optima batteries gassing at 120 degrees, it seems we may have found a main culprit. Also remembering the statement reported to me (and posted here) from the Lifeline rep who claims their batteries perform well at 140 degrees and gas at 150 degrees, I wondered - since the curb idle temperature next to the battery - inside the heat shield - was 140 degrees, what would happen if I took off the heat shield to make room for the largest possible Lifeline battery to accomodate winch stress. I placed the thermometer outside the heat shield, shut the hood and let it idle for 10 minutes. The temperature reached 180 degrees - so taking out the heat shield is not a good idea and one that is guaranteed to fry (maybe even explode) your battery.

Considering that a trail rig as well as a commuter (anyone, actually) spends a great deal of time idling in gear, we will have to face the fact that we have a high underhood idle temperature problem - at least in the Gen1 3.0L.

What to do about it?

The reason Position 3 gets so much hotter (+25 degrees) than the standard firewall battery locate at idle (wonder how batteries last in the D-50s?) is due to the fan's rotational direction and blade orientation. The fan is designed to pull fresh air through the radiator and push the extracted heat toward the D/S because if it pushed it to the P/S it would heat the intake air - not a good thing at all. I considered playing with the fan orientation, but it doesn't seem practical. A larger CFM fan rating might help somewhat. A smaller fan pulley might be able to turn the fan faster at idle. Maybe a temperature controlled variable speed electric unit would help a lot - particularly if it was combined with either a reversed hood scoop or hood louvers.

As for battery location, it's best where it is unless you want to move it to the rear cabin area (not a bad idea at all).

Assuming there to be a measure of truth in what the Optima rep said - and assuming some truth in what the Lifeline rep said, the choice for me is easy.... go with the Lifeline Group 27... Group 31 if it'll fit..... a lot more performance and hopefully less susceptible to heat.

Otherwise, the last choice is to go back to batteries to which you can add water - but the heat is going to drive a lot of gas which will be very corrosive. I noticed my battery pan (metal) is about shot - the only place I have any real rust on the truck.

Anyway, I hope the research effort has helped - I'm glad I did it because I need a new and larger battery and the process has revealed (for me at least) the reason to choose the one I hope will perform the best in this application.

--------------------
'89 G-Raider Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 155k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, 165A alt., Lifeline AGM, Rust-Oleum

Edited by FrankR (03/13/04 10:24 PM)

Post Extras

4x4Wire TrailTalk Forums Index

4x4Wire Mitsubishi Trail Talk Forums

	4x4Wire TrailTalk Forums Index 4x4Wire - National OHV recreation news 4x4Voice - California OHV recreation news OutdoorWire - your link to access news MUIRNet News - Environmental news 4x4Wire on FaceBook