Need HD battery recommendation for an 04 Grand Caravan 3.8L

Short circuit in alternator. That's why it's always hot, even while parked. Really, put your hand on it.

You might consider fixing the problem rather than just replacing batteries. No battery, no matter how "HD" it is, will survive long when a vehicle's electrical system is at fault.

And what will that accomplish?

Sorry I miss read your post. We've checked the alternator and all diodes are good and there is no short in the alternator either in the static mode or when running under light or heavy load.

Early on did an extensive diagnostic of the electrical system, generator charging and load(s), no obvious problems there. Not saying that it's not a possability but all loads are within specks.

How many batteries has this Caravan had already? The original battery in my '01 Ram lasted about 9 years / 50K miles.

What is the parasitic load reading at 10 minutes, 20 minutes, and one hour?

No parasitic load. If the ignition is off there is no current flow (except the door lock receiver but that's not been a problem even after several days parked). If the switch is in the accessory position or the head lights left on (in the time out period) or the cabin lights are in the time out period not to mention the radio the van won't start (best you get is a click) in 10 or 15 min.

If I run the radio only (~2 amps measured) at the 15 min point it's iffy at the 20 min point it's jump cable time.

We have a rack on the front of the van that's big enough to hold an ice chest for tail gating. Put a HD truck battery there and ran the leads to the van battery. No problem at an hour+ out. Only problem is the HD truck battery won't physically fit inside the hood.

If we leave the ignition key in the lock (off position) the car is dead (starter clicks in less than an hour) Using the HD truck battery the thing will still start 8+ hours later. If we had just a bit more space we could mount the HD truck battery but Dodge has filled that space with necessary 'stuff' that can't be moved. (When it comes to me Murphy was an optimist)

I'm trying to find a battery that will fit and work in our application. Also looking for a mounting position to put in a cabin battery to run the lights/radio etc and save the other battery for starting only. We have that on a Class C RV --- works great especially when someone is playing the entertainment system and wanders away for a few hours.

Don't get me wrong the vans are perfect for our main requirment (our extended family is foster to adopt) so we have a *lot* of grand kids. Maybe next time we should buy a school buss?

Maybe excessive resistance in the starting circuit?

Really sounds like a parasitic load or a bad battery. How have you checked for a parasitic load and have you had the battery properly load tested lately?

Several things. There is a fair amount of electronics that draw power when the key is off. More than the door lock receiver.

With the engine off, key off, AT THE BATTERY what is the exact voltage you read?

With the engine running, in idle, AT THE BATTERY what is the exact voltage you read?

With the engine running, in 2000 RPM, AT THE BATTERY what is the exact voltage you read?

Make these measurements at the battery, using a known accurate digital volt meter.

That is what I'm thinking.

You have problems with the battery clamps and/or the cables and terminals to the starter.

JAM

Sorry for the delay in posting (I've been in the hospital for several weeks.)

It seems most (all?) the aftermarket vendors and in some cases the dealers data bases list several drop in replacement batteries that were classed as ~equals but are not.

In the end we went with the top of the line aftermarket replacement. (no I don't know which one was installed but I do know it works)

Did a bit of digging and while the published specification on all (recommended) drop in replacements are essentially the same. The real world deep cycle charteristics (non published) of available batteries are vastly different.

It seems the drop in replacements batteries all have cca that are slightly different but not significant in the performance but the deep cycle charteristics are vastly different and unfortunately unpublished.

As to the test run. Since the van has been basically down for several weeks my son arranged with a friend that has access to a aircraft power system simulator and test jig. (High buck/high tech aero-space/industrial design state of the art stuff)

In the end they ran a charteristics test of the vehicle as well as several similar models. Ditto various batteries.

The van was found to be performing as expect based both on available specifications and comparison test.

They did a cauterization test of several models (good sample found in the employee parking lot) and found that all of low end recommended drop in batteries none operated the vehicle(s) to cauterization/specification.

Thanks for all who responded.