Off the shelf engine generator shutoff

[booster]

As I look at all the oddities of upgrading our batteries and engine charging rate, it is obvious we will be bouncing off the high spec of the coil type separator we have. It is rated at 200 amps, and I have never been overly fond of it because it runs hot and uses a lot of power when on, a real killer for trying to charge the starting battery off solar, for one thing. I have kept it because it is easy to modify it to be able to turn it off from the driver's seat, with indicator light to know if it is on or off.

I took a look at Blue Sea, which I hadn't done in quite a while, and it appears they have decided to directly address the issue, although they list it as another purpose. They have added a dedicated switch, with status indicator lights, to their 300 amp ACR relay. It is electronic control and uses very little parasitic power, so now that it can be driver controlled, it looks to be the near perfect (a bit spendy, though) solution for those that want to be able to shut off engine charging once the batteries get full to protect them from overcharge on long drives. Bonus is that you can also lock the ACR on to start the van if the starting battery is dead.

https://www.bluesea.com/products/762..._-_12V_DC_500A

[avanti]

The ML-ACR is a nice item (like all Blue Sea products), but I'm not convinced it is worth the cost. A simple isolation relay combined with a Trik-L-Start seems to me to have no real disadvantages. As you say, the relay is easy to control, and the Trik-L-Start eliminates the need to power it for solar charging of the chassis battery. When the engine is running, the power consumption is insignificant.

[booster]

I guess I have gotten used to the convenient, at least to me, way our current setup works. It is a two way separator, so it can sit in normal mode almost all the time, charging the coach off the engine when it is running, and the starting battery off the shore charger when plugged in, all automatically only when the charge voltage is present. The only time it is changed is when we are driving, and the amperage to the coach from engine drops low enough to show that the batteries are full. I then shut it off to prevent overcharge. The solar will continue to run the coach power from there on, and it won't overcharge by design. The only think I don't like about ours is the heat, power drain, and 200 amp capacity, other than that, I really wouldn't change how it works.

[avanti]

But, the setup I describe is just as automatic. The isolation relay is automatically closed when (and only when) the engine is running. The Trik-L-Start monitors the chassis battery and the state of the coach charging systems (whether solar or shore power) and trickle charges the house battery whenever appropriate. Seems perfect, and much cheaper than the Blue Sea device, even if you upgrade to a 300amp relay.

Admittedly, you still have the heat issue--but only when the engine is running.

[booster]

Do you have a way to shut off the relay when you are driving to prevent overcharge?

That and being able to charge the starting battery with the solar without wasting the parasitic are main issues for us. With the switch on ours, or the Blue Sea, you can just turn off the separator (ACR) when you are on solar only, and no power goes to the starter battery (which is good for over a week easily) or the parasitic (on our current setup) if you want to put all the solar to the coach batteries.

[avanti]

Originally Posted by booster

Do you have a way to shut off the relay when you are driving to prevent overcharge?

Not yet. But, all it takes is a simple (low current) switch between the "engine running" signal and the relay coil. it is on my list. I DO have a "boost" switch that powers the isolator relay coil from the coach battery, for emergency "jump starts".

That and being able to charge the starting battery with the solar without wasting the parasitic are main issues for us. With the switch on ours, or the Blue Sea, you can just turn off the separator (ACR) when you are on solar only, and no power goes to the starter battery (which is good for over a week easily) or the parasitic (on our current setup) if you want to put all the solar to the coach batteries.

The Trik-L-Start is essentially an intelligent "bridge" over the isolator contacts. It senses when (a) there is charging current available in the coach (from whatever source) and (b) the chassis battery needs charging. When both of these conditions are met, it steals a small amount of current from the coach charger and sends it to the chassis battery. It looks like this:

For under $50, it is hard to beat.

[booster]

Once you add the cutoff switch, you will have a very similar setup to what we have now. With the separator we have, I was able to tap into the wiring between the electronics and the coil of the relay, so I can have it be full automatic all the time, and can shut if off either when stopped and on shore power, or when driving. The shutoff on shore power is kind of like your trickle charger in limiting unwanted losses from the coil. We would be OK with what we have, but it will be short of capacity at 200 amps, and getting rid of the parasitic losses gives more options of using the solar more efficiently.

To me, the most important part of the system is being able to shut off the charging while driving to prevent battery damage.

[avanti]

Originally Posted by booster

To me, the most important part of the system is being able to shut off the charging while driving to prevent battery damage.

I agree. My current project involves using the serial output from our Trimetric to generate a display that I will be able to show on the nav screen. That, combined with the aforementioned switch will make proper management very easy.

[booster]

That will be pretty cool when you get it to work. We toyed with moving the Trimetric to the front, so I could see it while driving. The obvious benefit is that you get the actual amps to the battery, which is the most important in charging. The downside for us, was that I also wanted to be able to see how much power the alternator was putting into the coach total. This is useful for seeing how much power the microwave or other high load item is taking out if we run the engine during use. Since we don't have a 4/0 cable from the engine (2 X #4), I need to know if we are good enough to be able to charge low AGM batteries (440ah worth are the plan), and run the microwave, without over loading things.

I finally decided on an inductive pickup ammeter from the engine to the coach. I get a good indication of turn off time when it hits zero-meaning that the solar (which runs a bit higher voltage, has taken over and will finish the battery charging and running the coach).

[booster]

I went back and started looking at some of the other relays and ACRs that Blue Sea has as some other pics showed remote switches also.

It appears they are adding switches with LED indicators to more all the time. This one may be a bunch better for us, as we really don't need the automatic charge connection for much of how we would use it. It is full manual control and made like the 12 power relay in the coach, so NO parasitic losses when open or closed. Only a pulse when switching. Doesn't change state when powered up or down.

https://www.bluesea.com/products/770...enoid_-_12V_DC

I also got to thinking again how it would be nice to be able to see the actual battery charging current along with the total to the coach. Looking closer, the inductive ammeter that we have has another set of inputs, so we would be able to add another pickup on the battery cable to get the same reading as the Trimetric gets, and it will be on the same ammeter in the cockpit. I probably will add a pickup when I do the new battery bank, as it will be easy then to do.