New alternator now wont start

Mayby experiment with a battery charger on low. If you can where you park. Leave it on overnight. But if your out on the road i know thats not possible. Sounds like apu is charging batteries when you start it? Could also unhook batteries when trk is shut down and see if something could drawing them down. Sometimes when a group is unhooked one will be warm to the touch. The group have to be connected. Just disconnected at the point where they go to the trk. The warm one will usually be the bad one. 18 months is not that long for battery life, but you never know.

 

Clean all your connections, check your starter relay. Tight connections aren't always clean and good, so don't let appearances fool you.

 

When replaced my starter, I cleaned all the cables and any connections related. I also have a habit of throwing a slow charged on each battery individually about every 6 months or so. Gives me the opportunity to clean those cables too.

 

Look up how to check voltage drop. With a good dvom (digital volt meter) and a helper it’s easy and fairly quick to completely check the wiring and all connections under load.

 

Buy a battery load tester. Best investment for now. Disconnect all .batteries from each other and indivitauly test the batteries.

 

Cleaning the terminals certainly doesn't hurt, but to save you some time... When in doubt, pouring Coca-Cola on the terminals is a quick way to clean them. Not kidding. This works wonders. Coca-Cola literally dissolves oxidation on battery terminals - one reason I don't drink Coca-Cola much anymore. If this method helps, then it's a safe bet the terminals need more thorough cleaning. If it doesn't, then you might start looking elsewhere.

Something to consider - the weather is getting cooler this time of year. A battery consists of several individual cells and if any one of those cells gets weak, it will not hold a charge, and will drain power from the other cells. Most with even one weak cell will drain overnight in cooler weather. Will tell on it in a heartbeat.

I've had batteries that were fine as long as the temp was above 60 or so, but would drain when temperatures started dropping. It IS that time of year when weather starts to get colder, so I would definitely start checking batteries. I'm with @tommymonza - a load tester would be very helpful here, as it would quickly tell on a battery with a weak cell - quite useful when dealing with multiple batteries in a bank.

It's very possible that overload from charging bad batteries is what took your alternator out in the first place. Come to think of it, not to ask a dumb question, but you DID test the alternator before replacing it, didn't you? It might not have been bad. Just a thought.

 

Yeap. I bought an electronic one from Amazon, it was like $25...been a great tool to have!!!