mercer transportation

I also run https://www.amazon.com/Whynter-FM-4...&qid=1576270048&sprefix=portable+free&sr=8-18 plus a fridge in my truck. I don't run my apu in the winter as I got a espar heater.

 

Then you will go through a lot of batteries if you don't let the APU keep them charged. There's no free lunch here, you have to pay for that energy you use somewhere. If you run the batteries down past their design voltage their lifespan will be greatly reduced. APU will also put some heat to your engine if you have the coolant plumbed to the truck, making it easier on the motor when you start in the morning.

 

Power isn't free ur right but 5 hours on a 10 hour break with interstate batteries is stupid.. I Have my apu to come on at i think 12.4. My APU isn't hooked into my truck so i don't need it to run just to keep the truck charged up. When its running for 5 hours a night that just seems way to much on these batteries when you end up replacing them every year at $100 a pop i would rather add another $100-150 and get 3 years out of em lol

 

Because of your enormous hotel load drain I don't think the Maxwell capacitor is going to extend your battery life. What's killing your batteries in a year isn't starting the engine, it's from being drained on a nightly basis.

As long as you continue to consume that much power you are going to find your batteries just won't last. You paid 10 grand for that apu, use it.

 

I'm not understanding this. What do you mean your APU is not hooked into your truck so not used to keep the truck charged up. Are you saying the APU is not connected to charge your batteries?

12.4 may be a little high since nominal voltage is 12.6 resting. I can see how that would keep coming on all the time. If you are replacing batteries every year there may be some other underlying problem, or you just have too much load and really need to be using the APU whether you want to or not. Batteries can only do so much.

 

You are correct on all points. The Maxwell has nothing at all to do with extending battery life. Dual purpose batteries designed for trucks (available at any truck dealer), not deep cycle is the correct choice. Maybe change the charge cutoff to 12.2 and reduce the cycling of the APU.

 

Actually in a more typical operation without the extreme hotel load battery drain, battery life should be extended. Cranking over a big diesel takes a crap load of juice. It's a lot of power consumed very quickly. That's hard on batteries even in ideal circumstances. A capacitor on the other hand is more of a trickle drain. It slowly draws the energy so it's much easier on the batteries. That alone should extend battery life.

 

Pete, I'm not real sure what you're really trying to accomplish here. Seems to me you're tripping over dollars trying to save dimes. Just let the APU do it's job. It's designed to start up to charge the truck batteries before they get too low. You already have a solution to the problem you're wanting to spend more money on trying to fix. Doesn't make sense to me.

 

Also if your batteries are in bad shape and are not accepting a charge, that will destroy the alternator on the APU.

How many amps for all the hotel loads combined? That information is needed to assess you actual needs. Also inverter and things normally powered off that.

 

If it were me.....
Go with the capacitor for starting.

2 deep cycle batteries hooked up to ONLY the fridge/freezer on a solinoid with a relay that charges them when the truck is running.

2 regular batteries for your electronics...ecm,radio memory,ect.

I have a similar setup on mine, but without the capacitor. I have 1 deep cycle battery that runs my espar all day and night before it needs to be recharged. I have a voltage gauge on it in my sleeper so i know when i need to charge it up. Its on a relay that comes on when i turn the key. No problems in 6 years

Look up mictuning mic-dv-077 on Amazon. Plugs right into your rocker switch hole