P80 Bastards vs -1998 Voltage Importance on Running

[abscate]

I just finished doing an AC compressor RR and , thanks to kahl, had use of the car using a short serpentine belt that cut out the AC while I worked the job in.

As documented, on the 1999-2000, the short belt spins the alternator clockwise, backwards from the regular belt, so the freewheeling pulley prevents alternator charging with the short belt.

Ive driven the car for a week, and it was very lumpy on cold start, once it warmed up it ran ok. I was a bit worried as it was coding P0300 and then clearing in a hour or two of driving.

Well, now that the car is back on alternator voltage the difference is incredible. The cold start is smooth and stable and it is it's own self again

Conclusion - I think the ME7 coil unplug (and later P2) are much happier cars with strong battery voltage and/or alternator output. The battery was fine for starting in 25F weather but I think these cars really want >13 Volts to run.

[MrAl]

Hi,

I have long suspected that a somewhat lower battery voltage would cause misfiring on my 1998 v70. What you are saying seems to confirm this possible behavior.
I noticed this one day when it was raining and i did not give the car much time to warm up after coming out of a store i had been in for a while. It actually stalled out on me and i was lucky to get it to start up so i could pull over and let it run for a while. This was with the headlights on because it was raining, and i may have had the heater on too and of course wipers.

I have a battery load tester i'll have to throw on there one of these days.

[wizechatmgr]

I know below 12V (think around 11.5-11.7v) my car got to the point the auto transmission would not enable a shift into first. It sat at neutral while in drive and refused to move. Shortly after that it died.

[MrAl]

Hi,

Wow that's strange. I would think those systems should work down to at least 11.0v and if not maybe something is wrong.

[wizechatmgr]

The next time my alternator goes, I'll try to keep an eye on the exact cut-off point.

Suffice it to say anything much under 12v wasn't very useful and the car ran like crud. Jackrabbit/donkey kick response upon demand for throttle.

[abscate]

The Kat was running on a 5 year old battery that would drain to a no-crank condition with 10 minutes of flasher on. It started doing a crank start stall cycle , then popped a P0137 code for rear OXS low voltage phantom code

A new battery is the fix, of course

[volvolugnut]

Why is it our nature to run a battery to complete failure while we do preventive replacement for many other more expensive (less critical?) parts?
volvolugnut

[MrAl]

Why is it our nature to run a battery to complete failure while we do preventive replacement for many other more expensive (less critical?) parts?
volvolugnut

Hi,

I think it is because it is harder to determine when the battery is actually really bad unless something drastic goes wrong like no crank.
Also, people tend to think the battery will last forever (ha ha). Batteries seem expensive too unless you find a good price.

I have a good test but most people probably don't want to do it.
Using a scope, you can watch for a huge dip in the voltage when you go to crank the engine for the first time after sitting. If it dips down to 11v when the battery is new then starts to dip much lower as time goes on, you know something is going wrong.
You can use a regular analog panel meter too for this test as the needle response faster than the typical digital meter even the more expensive ones. The needle will start to dip down more and more as time goes on and the battery ages, as you start to crank the engine for the first time after sitting overnight.

There are still some gray areas though I guess in determining when to replace the battery before you get no crank. That's probably why we wait till the very end. That way we know we really need to spend $200 for a new one.

You know what else is funny, the battery prices for the v70 1998 vary quite a bit as do batteries for other cars. The prices could be 50 percent for some batteries. Does the prince really reflect quality. I used Walmart batteries for years and got the full warrantee period or more out of every one of them. I don't know why I stopped buying them, I think it was because other batteries were offered for purchase closer to home.

I also did a read on the best batteries a short time ago (maybe a month or so). It is surprising that they have much more advanced batteries now. They even have Lithium based batteries (I think it was the LiFePO4 type) which I found surprising, but they do not spec them for every car ever made so you may have to do your own math. I do not know if they make one for the Volvo v70 1998 or not, but you could check the web site. One maker calls it the "Gravity Battery".
Now as to the cranking power, they are probably a little less. The most interesting feature is the lower self-discharge. Lead acid batteries are notorious for relatively high self discharge, while Li based batteries have much less self-discharge, meaning the car can probably sit longer without starting and still crank the engine.
I base this opinion on my experience with batteries of different chemistries over the past 40 years or so. I do not have any experience with Li based batteries used in cars however.

[abscate]

I just got a NAPA H6 for $145 after Napa bucks and a promotion sale. They’d replaced my last one free after I completely abused it on a current drain car, so I rewarded them with more business

Why is it our nature to run a battery to complete failure while we do preventive replacement for many other more expensive (less critical?) parts?
volvolugnut

These great questions of life require patience, meditation, contemplation, and Guinness to bring understanding

Why do we pass a gas station on the freeway with the Idiot Man Light on hoping we can get to the next gas station ?

[MrAl]

I just got a NAPA H6 for $145 after Napa bucks and a promotion sale. They’d replaced my last one free after I completely abused it on a current drain car, so I rewarded them with more business

Why is it our nature to run a battery to complete failure while we do preventive replacement for many other more expensive (less critical?) parts?
volvolugnut

These great questions of life require patience, meditation, contemplation, and Guinness to bring understanding

Why do we pass a gas station on the freeway with the Idiot Man Light on hoping we can get to the next gas station ?

Did someone say Guinness?
If you've got a couple four-packs of the draft who needs a new battery