2000 V70R electrical issue continues

Post by **scot850** » 04 Oct 2021, 16:11

Update. Dealer has charged the battery and after the weekend it is still holding 98% charge.

What output should a P80 alternator be giving for no load and full load? Mine with no load = 13.62V Full load = 13.5V
Should they be higher? I thought it should be around 14+V on no load and 13.8-14.0V on High load?

Either way, my hope that a low voltage output was misplaced. Problem still there when light switch used. Conclusion by the dealer is the DIM is bad. Contacted Xemodex as the only DIM they don't list is the 99-00 P80. They are looking into it. Also contacted another company out in Toronto but yet to hear back from them on DIM repair.

The DIM pcb is still listed but on a 3-4 week back order. Price is in the $600 range with taxes. OUCH! A new pcb can be programmed by the dealer with the correct mileage. Have asked them to confirm if a used one can be re-written or not. Service manager is looking into it but doesn't expect a quick response!

Once I get the car back I will swap out the original DIM with the used one I have and see what, if anything, happens.

Neil.

Post by **misha** » 04 Oct 2021, 16:19

Healthy charging system should have 14.2-14.4v at idle without consumers.

With headlights,heater blower at 1st or 2nd speed(about in the middle on ECC) and radio ON you should have 13.8-14v.

13.5v is too low and not enough to keep the battery charged especially with frequent short trips.

Where from did you got those numbers...battery terminal or directly at alternator?

Post by **RickHaleParker** » 04 Oct 2021, 17:50

scot850 wrote: 04 Oct 2021, 16:11 What output should a P80 alternator be giving for no load and full load? Mine with no load = 13.62V Full load = 13.5V
Should they be higher? I thought it should be around 14+V on no load and 13.8-14.0V on High load?

The correct alternator voltage depends on the Depth Of Discharge (DOD) of the battery and the active electrical loads.

Float charge voltage ( Maintain ) for Lead Acid batteries is 2.25V to 2.30V per cell. A car Starter battery is 6 cells.
( 6 x 2.25V ) to ( 6 x 2.30V ) = 13.5V to 13.8V. Your 13.5V & 13.62V is in the float charge range.

If an alternator outputted the higher charging voltages when the battery was fully charged, the excess energy would convert to heat, boil the electrolyte and destroy the battery.

I still think your issue is diminished battery capacity. Keep it on a float charger and it will get better. Keeping in mind it takes a long time to undo the damage.

If somebody wanted a smarter charging system. One could insert a PWM ( Pulse Wave Modulated ) Charge Controller, the type use in Solar energy applications, between the alternator output and the battery.

PWM ( Pulse Wave Modulated ) Charge Controllers where invented in the 1960s to maximize the lifespan of batteries.
MPPT ( Maximum Power Point Tracker ) Charge Controllers where invented later to maximum the energy transfer efficiency between solar panels and the battery, they do so at the expense of battery lifespan.

When Solar panels where extremely expensive MPPT made economic sense. The cost of solar panels has dropped to the point this is no longer true. Protecting the battery is more cost effective. PWM is the way to go on solar or building a smarter automotive charging system.

PWM Technology is so mature a 100A PWM CC goes for about $15.00. If you think you need more current, two CC can be connected together in parallel for more current if the charging algorithm is the same for both CC.

Post by **scot850** » 04 Oct 2021, 18:28

Don't know where the dealer took the reading from. The mechanic did say that they were ok.

Thanks guys. Appreciate the info. Not sure what type of chargers I have. I know I have a float charger and a trickle charger that charges at 2A or 4A and then maintains once up to full charge.

Like I mentioned, the dealer has some really fancy charging system that took the battery from a reading of 38% charge to 100% in a day and since then (last Friday) it has only dropped to 98%.

I do have one of those 'smart' chargers that is supposed to repair batteries. Not tried it yet. Got it as a replacement for one that fried a battery when the unit failed.

Neil.

850oldschool · Post by **850oldschool** » 04 Oct 2021, 21:09

Erik posted this link in a thread related to alternators and voltage regulators, so you may have already read it:

https://www.landiss.com/battery.htm

I got a lot of good information from it. It seems to explain why the Optima I put in my VW Golf years ago didn't deliver the outstanding performance I had hoped for.

Post by **scot850** » 04 Oct 2021, 23:13

That is interesting. This might be where I recall that 14.2 -14-4V was what an alternator should be putting out when not loaded and dropping to 13.8V on full load. That is why I was confused when the dealer said 13.5V on full load is ok and 13.62V low no was ok too.

I now have another question for them. Many thanks for the info.

Neil.

Post by **abscate** » 05 Oct 2021, 05:27

It seems to explain why the Optima I put in my VW Golf years ago didn't deliver the outstanding performance I had hoped for.

These things are ridiculously oversold for automotive applications.

Post by **scot850** » 05 Oct 2021, 13:19

I agree. Other than the dry battery idea, it does not make any difference over a regular battery other than the way higher price.

Neil.

Post by **scot850** » 06 Oct 2021, 16:07

Got the car back from the dealer. Turbo is worn but service manage says to drive it more and the leak may settle down with use. It is not leaking from the feed or return pipes. There are drops of oil falling from the bottom of the turbo casing. This only started after a 80+ mile country road round trip at about 60-70 mph. It was dry before that.

Anyway, back to the electrical gremlins.

Tomorrow I plan to try the used DIM to see what if anything happens. The dealer can install a new DIM pcb, but they are on back order of at least 3-4 weeks possibly more these days. They can program a new pcb with the correct mileage, but not a used unit. I have formally asked them to check what can be done by Volvo. Don't hold any great expectations, but you never know!

So hopefully by the end of the day tomorrow I may have a working car with a used DIM or a smoldering pile of ashes. Even possible a totally non-functioning car if the DIM myth is correct that swapping it out kills the car to stop mileage tampering!

And the best part? All the work the dealer did on the car which includes a wash and looks like someone spent some time cleaning it inside cost me $90 CDN. That is about 0.5 hrs work charged for.

I am one of the few that advocates for working with your local dealer, but I have to say I have read a lot of horrendous stories of dealers in the US that are next to useless in all aspects. I am clearly lucky that I have 1 I have worked with for 20 years and now working with the new one too. Having got a working relationship has clearly worked in my favour, even though sometimes it has gone wrong, they have mostly redeemed themselves.

Neil.