As long as your current charging system on the Cat engine is checked out OK, should be no problem replacing the 8D batteries. Your Cat engine requires a much higher cranking current than us with the ity bity Cummins engines.

I would look into and separate charging system to charge an maintain the AGM system while parked if you are going to continue using AGM batteries for house batteries.

1 comment, AGM batteries do require that you keep them on a float charge (should be designed for AGM batteries) if it will be a long time between usage.

quote:

I would look into and separate charging system to charge an maintain the AGM system while parked if you are going to continue using AGM batteries for house batteries.

Here from the previous page is what charges the AGM when plugged into shore. It is also charging when the generator is on. Power source, is a battery charger and power supply that uses 110 house current to put out 12 volts. I have checked daily during this past winter. It does maintain 13.2 volts when on and connected to the house batteries.

When I replace the engine batteries, I am not so sure the AGM has enough current to turn over the big CAT. I am considering keeping the engine batteries the standard lead acid.

Our Newell had two 8D engine batteries and 6 8Ds used for house batteries. Replaced the house 8Ds with 12 T-105s. Later on replaced the 8D engine batteries with two group 31s. Never had a problem starting the 8V92 on the group 31s, but never had it in cold weather.

The compartment for the engine two 8Ds had room for 3 group 31s. Original plans were to use 3 batteries but never needed the third one.

In regard to starter batteries:

I also had 2 - 8D Batteries.

When it was time to replace, I only went with one.

This starts my Regency just fine.

It does not like the real cold weather for starting (below 20 degrees in MN).

However, if I plug-in the engine heater for a couple hours, it starts-right-up.

quote:

Originally posted by MWrench:

However, it is generally not advisable to charge AGM batteries and Wet cell batteries tied together. The charging profile for AGM batteries is quite different than wet cell batteries. Wet cell batteries would probably be OK but AGM batteries would not have ideal charging and could be damaged or shortened life.

Thank you to all the contributing members for helping to solve the electrical battery problem.

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In my case I figure the battery mix (advanced glass mat- house and lead acid- engine) along with two charging inputs toasted the lead acid batteries. Thankfully not the AGM batteries which cost over twice as much. Just as a safety precaution I will unplug the house battery charger on long trips while running the generator that charges the house batteries. A solenoid switch near the generator could also turn off the battery isolator. This switch would separate the two battery banks completely.

quote:

Originally posted by ~Mac~:
In regard to starter batteries:

I also had 2 - 8D Batteries.

When it was time to replace, I only went with one.

I did replace my both of my 8D (engine) batteries with Crown Batteries. The one that was resurrected by the Epsom Salts trick posted here was used by itself to start the 3208 Caterpillar. Just thought I would mention since you said you only have one. I am still using two 8D batteries in my coach for the engine starting.

I have a power problem. Last week 80% of my #4 and all of my #2 battery cables fried. I replaced the #4 to the motor and when I started the engine the gauge started jumping around. I think it is the voltage regulator. Can I get some input and see what you think.

Wow... that must have some serious current, like a dead short. Did the batteries survive?

Since you did not specify I have no idea if you have a gas or diesel coach, boat or aircraft.

Give me a bit more to work with and we might be able to help more.

Most alternators have internal regulators. They also have large internal diodes. If the diodes short the alternator will draw full battery current to ground and cause wiring damage. Usually they remain shorted and cook the batteries to death.

Diodes usually fail when overheated. They may fail shorted or open. Perhaps yours shorted first, then got so hot they went open circuit.

Best I can do with the information I have.

I agree with SteveVW - knowing where these cables originate and terminate might help with armchair diagnosis.

Because there should be a fusible link from the battery to the load, as Steve mentioned, the likel culprit is either a shorted battery cell or a bad diode in the alternator.

There is usually no fusible link between the alternator and the battery.