Battery drains when idling with front & rear aircon running

[grolly6]

During the hotter days of this summer I noticed that when I'm stopped at an intersection with both the front and rear airconditioning turned on my battery voltage starts dropping and continues dropping to the point that I get nervous(~12v) and turn off the rear AC(No other electrical items turned on, just AC). This was happening throughout the summer and I ended up replacing the battery(It was the original one from Japan and it was due for a replacement anyway) but that had no impact on how quickly the battery voltage drops when idling with both AC units running.

Is this kind of behaviour normal for an L400 with the stock 90amp altenator? Or, is this indicative of a weak alternator? Or, could there be some reason my AC system is drawing too much current?

[TardisDeli]

This would be more of an Alternator issue, not battery issue. The alternator takes excess power from the running engine, and that charging power is stored in the battery. If it is raining, or if you have an oil spill that landed on the alternator belt, or if the belt is old or stretched or you hear squealing, then he alternator might not be charging at full speed.

Yes, there is not much excess charging power leftover from 2 AC condensers running and consuming huge watts (plus If you also had radio and headlights on and fan running full speed and maybe a gps on and a video for passengers and maybe a fridge of food and maybe you have an aftermarket stereo amplifier which consumes 5 watts).

All those watts consumed immediately leave nothing to go into battery. So yes you would see the battery reading less than 12, at 11.5 it is no longer charging cuz there aint no juice left over from the amusement ride to go into the battery. it doesnt mean the charging system is bad, it just means "hey dude, can you turn down the fan cuz I'm just a hamster running in a hamster wheel and I am running low on juice".

The Delica, it is a magnificent and wonderful car not an amusement ride.

If you are not having problems starting, nor having dim headlights while running wipers & radio & heater (which indicate possible charging issues), then just don't run both AC at same time.

Cheers christine

[Mr. Flibble]

X2, Alternator.

Probably worth getting it tested. Bushings may be on their way out, or it could be getting old. Then again, it might be fine, but strange charging issues usually crop up as they begin to wear out.

[grolly6]

Thanks Christine/Mr. Fibble,

I did a test again this morning and as long as I'm above about 1,200rpm the voltage needle doesn't do the fast drop. The fan belts all seem to be tight enough(I saw 2 belts side by side on the pulley) and I didn't hear any squeeling. So, for now, when I'm idling I'll turn off the power hungry items.

Anyway, I thought that only the fans would draw electrical power from the alternator and that the AC compressors would be operated via belts off the crank pully. But, with both fans at max I didn't see as much voltage dropping on the gauge as I did when both AC compressors were engaged with full fans. Do the AC compressors require extra electricity(separate from running the air circulation fan motors)?

On a related note, I did see a 120amp alternator for sale by one of the local vancouver Delica importers(It was on Craigslist). He said it came from the Hyundai equivalent to the Delica and is a bolt in. Having 33% extra power may be worth the upgrade for me when I start towing my camper since that camper sucks a lot of power once the running lights and RV battery charger come on.

[MardyDelica]

hi, I do have 120 ampere available last week but out of stock now.
its original Mitsubishi japan not Hyundai.
for what I know there is no 4m40 engine in korea only 4d56.
if you need help for this pls give me a call so I can get you one.
only japan made Mitsubishi.
cheers;
Mardy

[Rising Sun Auto Import]

On a related note, I did see a 120amp alternator for sale by one of the local vancouver Delica importers(It was on Craigslist). He said it came from the Hyundai equivalent to the Delica and is a bolt in. Having 33% extra power may be worth the upgrade for me when I start towing my camper since that camper sucks a lot of power once the running lights and RV battery charger come on.

Hey Grolly6,
I never told you the 120amp new alternator we have in stock came from Hyundai.
It was manufactured in South Korea and we have lots in stock.
Pls read carefully my email.

"there is no 4m40 engine in korea only 4d56" mentioned by someone is totally not related to alternator topic.
4M40 alternators can be made in any country all over the world.

Steven

[yojimbo]

My first thought was actually the battery. The alty will supply enough power, but im not so sure at idle, a google search shows a steep curve above 1100 or so rpm generally. I would guess the battery is tired and thats what you are seeing. In fact, if the draw is greater than the alty output it would happen tp a good battery too, it would just take a lot longer. It would worth meashring the real battery voltage with the engine off, idling, and at 1200 rpm. If you see less than 12.5v off and 14 or so running, then its the battery.

[macro]

I had this exact same thing happen to me. Your alternator needs a rebuild. I pulled mine one night and got it rebuilt and reinstalled the next day. My regulator was fine but the brushes were worn down. With the rebuild in it does make more voltage but I still can't sit around too long with the AC on, I never did get around to see if the engine kicks down enough to compensate for the AC though. The 120A alternator would probably fix that, but a rebuild cost me half what a new one would. I'm probably stating the obvious, but double check your battery leads and also check resistance across your main battery ground. These things can apparently affect the alternator keeping up as well. Take the van into a good auto electric shop and they can tell you for sure and usually for free. Don't get suckered into buying a brand new alternator when a rebuild is half the price and if you're not running a huge stereo and a ton of auxiliary lights all the time it'll be fine!!!

[grolly6]

My first thought was actually the battery. The alty will supply enough power, but im not so sure at idle, a google search shows a steep curve above 1100 or so rpm generally. I would guess the battery is tired and thats what you are seeing. In fact, if the draw is greater than the alty output it would happen tp a good battery too, it would just take a lot longer. It would worth meashring the real battery voltage with the engine off, idling, and at 1200 rpm. If you see less than 12.5v off and 14 or so running, then its the battery.

Just went down to the parking garage: 12.76v when off, after starting the voltage was slowly climbing up from 12.76(engine was cold, glow plugs may have been pulling juice), then a buddy held the throttle around 1200 and voltage was ~14.2(glow plugs probably still active). I replaced the battery around July so I'm optimistic it's OK. But, I did go with a type 24 intead of the larger type 27 battery, and I'm sure that reduced it's reserve capacity and that may be contributing to the more rapid drop in the voltage needle when idling at an intersection with AC on full. But, I'm leaning towards the alternator not being well suited to carrying a heavy electrical load at idle rpm.

[grolly6]

On a related note, I did see a 120amp alternator for sale by one of the local vancouver Delica importers(It was on Craigslist). He said it came from the Hyundai equivalent to the Delica and is a bolt in. Having 33% extra power may be worth the upgrade for me when I start towing my camper since that camper sucks a lot of power once the running lights and RV battery charger come on.

Hey Grolly6,
I never told you the 120amp new alternator we have in stock came from Hyundai.
It was manufactured in South Korea and we have lots in stock.
Pls read carefully my email.

"there is no 4m40 engine in korea only 4d56" mentioned by someone is totally not related to alternator topic.
4M40 alternators can be made in any country all over the world.

Steven

I apologize, I do recall you stating that your alternator was made in Korea and I must have confused things from some posting I read somewhere about the Hyundai stuff.

[grolly6]

I had this exact same thing happen to me. Your alternator needs a rebuild. I pulled mine one night and got it rebuilt and reinstalled the next day. My regulator was fine but the brushes were worn down. With the rebuild in it does make more voltage but I still can't sit around too long with the AC on, I never did get around to see if the engine kicks down enough to compensate for the AC though. The 120A alternator would probably fix that, but a rebuild cost me half what a new one would. I'm probably stating the obvious, but double check your battery leads and also check resistance across your main battery ground. These things can apparently affect the alternator keeping up as well. Take the van into a good auto electric shop and they can tell you for sure and usually for free. Don't get suckered into buying a brand new alternator when a rebuild is half the price and if you're not running a huge stereo and a ton of auxiliary lights all the time it'll be fine!!!

Thanks for the recommendation. I think I may end up going with the larger capacity alternator "just to be safe" since I plan on towing a trailer that can draw a lot of extra current with all the running lights on and the RV battery charger active. Then, I could keep my old alternator as a spare and have it rebuilt should the need arise(Or maybe rebuild it and sell it to cover some of the cost of the 120amp upgrade...)

But, for now, I'll leave my existing alternator in place until I finish the mods I decribed in one of my other posts(Trying to get more power out of the engine for towing the trailer). My money has been flying out fast over the last few weeks(2.5" stainless exhaust, suspension repairs, air bags, multiple gauges, and the trailer itself is having some dry rot in the floor repaired) so I need to regulate the cash outflow for the rest of this month...

[macro]

I was in the same boat. Once I lifted it, I had to replace everything. I couldn't afford a new alternator at the time or else I probably would have gone the 120A route as well. Good luck!!!

[grolly6]

Installed a new 120 amp alternator, no change in behaviour:-(

[vixentd]

If you are idling and wish to see your battery charge register well above 12.5 with the two fans and accessories running you will need to purchase and alternator that is rated for a high amperage at idle.

Basically you could purchase a 150 amp alternator and it would not make a difference unless if was designed to produce high amps at idle. Most alternators are rated at 4000 rpm or higher to produce their rated amps. Your alternator is not producing anywhere near its rating at idle. You can take your old one in to an alternator shop and he can spin it at idle and read the amps for you. You will be shocked how low it produces at idle. You could reduce the pulley size so it will spin faster but it will not make a huge difference.

The car stereo people, police cars, taxis etc. do spend a lot of time idling and need massive amounts of power so they use special alternators.

https://www.dcpowerinc.com/articles/truth-about-idle

The above link will explain.

What you are experiencing will not discharge your battery unless you are idling for an hour at each light. It will bring it briefly down, but as soon as you drive the amps will be added back.

[grolly6]

If you are idling and wish to see your battery charge register well above 12.5 with the two fans and accessories running you will need to purchase and alternator that is rated for a high amperage at idle.

Basically you could purchase a 150 amp alternator and it would not make a difference unless if was designed to produce high amps at idle. Most alternators are rated at 4000 rpm or higher to produce their rated amps. Your alternator is not producing anywhere near its rating at idle. You can take your old one in to an alternator shop and he can spin it at idle and read the amps for you. You will be shocked how low it produces at idle. You could reduce the pulley size so it will spin faster but it will not make a huge difference.

The car stereo people, police cars, taxis etc. do spend a lot of time idling and need massive amounts of power so they use special alternators.

https://www.dcpowerinc.com/articles/truth-about-idle

The above link will explain.

What you are experiencing will not discharge your battery unless you are idling for an hour at each light. It will bring it briefly down, but as soon as you drive the amps will be added back.

Thanks for the insight! I'll chill out on this issue and move on:-)