Battery bank isolator wiring question

[lockmup68]

Two banks of four batteries, one chassis set, one house set. I have a Blue sea ML-ACR isolator  which supports dual engine/alternator input. 

So the alternator will charge both banks when truck running. What I’m trying to figure out is how to wire When the generator is running AND the truck is running. The generator does NOT have an alternator to charge a battery. It charges via an intellipower 9200 with Charge Wizard (AC to 12v DC converter). 

Here is the instruction diagram for dual motor wiring: 

For the generator side, is it as simple as wiring into the run side of the ON switch for the generator? We have to attach the run side of the key for the truck as the primary. 

I hate wiring stuff. As many know, the wiring on this truck had a lot of interesting things going on. It appears that the manual solenoids that we’re used powered OPEN every time the key was on, allowing both banks to be charged at all times from the alternator AND also to be charged from the Intellipower at the same time when the generator was running. No wonder the batteries were fried. 

Appreciate your help. 

Edited May 17, 2019 by lockmup68

[Steve from SoCal]

Perhaps the simplest thing would be a NC relay from the intellipower when the generator is on it drops out the intellipower to battery.    That would be an AC relay powered by the generator when it is running.

Steve

Edited May 17, 2019 by Steve from SoCal

[jkennell]

You can have multiple charging sources at the same time to a battery bank w/o causing problems.   In general, there is no issue with having an alternator, a solar charger, and a generator/Inverter all hooked up to charge the batteries, as long as the regulators in all the charging systems are working correctly.   

Overcharging/fried batteries is not caused by having lots of charge sources, its caused by having too high of a charging voltage from any source.  

Very occasionally, interactions between multiple sources may cause issues, but its rare.  Usually, the sources all kinda just balance each other until the batteries are fully charged at which point they all stop charging. (Very simplistic view, and yes, fancy hi-cost charge controller systems MAY cause the batteries to last longer....).     

I have helped design power systems, and its not at all uncommon to have a battery bank hooked up to the solar charge controller and the generator driven chargers at the same time.  

I say all this not to try to stop you from whatever you feel would improve the system, but rather to suggest that you should check your existing system for proper operation first.  If you fried the batteries, I'd strongly recommend checking the charge output of each source (alternator, etc) separately for overvoltage before you fry another set.   For instance, if your truck alternator running at 16V (regulator wide open)  redoing the charge circuit isn't going to prevent it from overcharging the next set.

Others are free to disagree.  I know several on here have much deeper understanding then I do of battery banks and all that goes into maintaining them.  I just don't want you spending a lot of time and money on a bunch of stuff and then finding that the problem was as above.

[lockmup68]

Thanks. I think it was a faulty solenoid and the batteries were over six years old, so I might be overthinking this. Alternator is also new. 

It is a new isolator, so that should be good  new alternator which is within spec. We’ll check the intellipower converter  

 

[rickeieio]

3 hours ago, lockmup68 said:

It is a new isolator, so that should be good  new alternator which is within spec.

I'd check it anyway.  I've had too many bad "new" elictrical parts.

We're now waiting on a replacement for the controller on our new Bigfoot system.  First one didn't work, right out of the box.  And Bigfoot has apparently had a run on them, as they have none in stock, until sometime Monday.

[Scrap]

I think the simplest way is to just manually turn your ACR rocker switch to off when running truck and generator at the same time.  That'll uncombine the batteries and the truck charges/maintains its side and the house charges/maintains its side.  But you can't forget.  

To do it automatically you'd need to make a relay setup that takes IGN from the truck, IGN from the generator, then when they both have 12V it sends that signal to the Isolation #1 input of the ACR so it uncombines the batteries when both of them are turned on.  It'll have to be a relay system so it doesn't backfeed the two IGN circuits.  How to wire that I'd have to think about it for a bit....

[Scrap]

Get a 12V sealed relay or similar:

https://www.amazon.com/ONLINE-LED-STORE-Waterproof-Harness/dp/B01N66W2XF/ref=sr_1_5?keywords=12v+sealed+bosch+relay&qid=1558197179&s=gateway&sr=8-5

• 85:  To Ground
• 86:  To Generator IGN
• 87a: None
• 87:  To ACR Isolation #1
• 30: To truck IGN

If the generator has more on time than the truck then you'll want to swap 86 and 30.  If you do that, however, you'll hear the relay click every time you key on the truck.  That may get annoying after a couple years.

[RandyA]

Jkennel's advice to just hook um up and let them run together is the less complex approach.  Like he wrote, (or did he?) one of the charging sources will become dominant depending on the top voltage to the battery bank.  For example, one charging source may cut off and float at 12.6 while the other kicks in a bulk mode occasionally at around 14.5.  That's fine - the same as with just the single source charger.  Remember a charger does not "push" anything into a battery, the battery condition determines how much it takes from a charger.  It is a voltage thing at the battery plus the internal resistance of the battery followed by the current limits of the charger at the said voltage (I = E/R).  Scrap also has good advice if you want to take one charger out of the equation, but it will require the additional wiring you said you dislike.  Just for info I now have my MPPT solar, the Progressive Dynamics 80 amp 4-stage converter/charger and the Xantrex RS2000 with a 100 amp converter/charger I got from Henry all combined at my 300 Ah battery bank. The PD converter is the dominant charger.  I had to do something similar to what Scrap outlined to cut off the PD when the Xantrex was in inverter mode.  You don't want to charge the batteries from the inverter you are taking battery power from! Oh, be sure your wire gauge is appropriately sized for the expected maximum current.  Anything less will cause a drop in charge voltage to the batteries.