fusing both batt w charging relay what issues to expect?

[blueh20]

I am running3-100w renolgy solar panels on top of my 2014 ford E250 van which go to a 40 amp renolgy commander controller then to a 255 ah lifeline batt.

Also have a Blue Sea systems charging relay ml-acr connected between house batt and starter batt with 2/0 wire pos and neg, 15' each way.
The house batt is the main batt and starter batt is aux.

Running a blue sea 100amp fuse panel(fused with 30amp breaker) for led lights, arb fridge and a flojet that pulls 7.5 amps max. All wiring is complete loops back to panel.

Theoretically my Blue sea charging relay is suppose to let the "house" battery start the vehicle in case the "starter" battery goes dead. Havnt tried it yet.

I just put a 150 amp marine type fuse on each positive battery post in case my 2/0 positive wire"between batteries" ever grounds out on the frame, my alternator puts out about 80-100 amps.
I am just about ready to start the vehicle up with the new fuses in place, what to expect?

I assume though if the house battery ever did try to start the vehicle with those fuses in place that the cranking amps would blow both fuses immedietally, is this correct????

if so is their anyway to have the house battery start the vehicle while still having some kind of " frame shorting" protection ?


thanks for your input.

[blueh20]

littlebill, thanks for chiming in, I just learned ALOT about my charging relay in your post. And hope you can teach me some more.

"realistically you should never have a dead starter battery, that said if you do, i would recommend waiting a minute or so in override before attempting the start"

But how would I know I had a dead starter battery before I turned the key on and tried to start the engine.
Does the relay automatically/instantly send power from the house battery to the start battery if needed, or does it require a manual switching?

"in this case using the override switch will allow the relay to connect the banks and start the motor".

What position would I turn the over ride switch too? Does that "override" switching include pushing the button "down"?

In using the over ride switch, would I just let the batteries coexist for 15 minutes or so, then turn the switch off so to disconnect the two batteries before starting so I dont blow my 150 amp fuses? OR try and start the vehicle while they are both bonded together?
thanks

[blueh20]

landyacht318, thats a lot of info, its going to take some time for me to understand that whole post, I guess, if you would be so kind, to please tell me what to start with first,grounding issues? alternator wiring issues? altenator to charge house battery by NOT going thru start batt issues? ford regulator issues? charging of the lifeline batt issues? How to insure lifeline gets 51 amps all the time issues? etc.

I have know idea about lifelines venerable reputation!. To me, just parts the original owner had purchased.
Seems as though the original owner didnt skimp on buying quality products, but seems as though maybe he didnt set the system up completely correctly to insure all works as it should.
Grounding issues seems as though a good place to start?
OR alternator heavier gauge wire?
I am all ears, thanks for helping

[blueh20]

red31, I dont have a purpose for the ml-acr, it was in the system when I bought the van, I am almost wondering, after all of these posts , maybe I should take it out of the van ?

You mentioned "backward wiring", I just re wired the system as the original owner had it wired, I drove the van around wired the original way for 3 months, all seemed to work well, kept the arb fridge at 34deg, seemed to work, so just put it back together the same way, while adding fuses/breakers/wiring etc.

"Will solar charging cause the backward wiring to combine the batts?"
I dont know the answer to that, I was told( by original owner) that the solar and altenator would charge both batteries, I hear the charging relay switching(loud click) often, so its doing something.

"Or do you plan to manually combine?",
as I am slowly learning more about this system from these responses, I am hoping that the relay will require a manual change to send power to the starting battery when needed to keep from blowing my 150 amp fuses on both battery pos posts. I dont know enough yet to plan on anything in this system.

what does the "backward wiring" mean,
thanks for responding

[LittleBill]

i don't think some people on this thread understand how this relay works.

its a voltage sensing bi directional relay, meaning the minute the charge voltage from the alternator/solar/grid goes above a certain voltage the banks are connected. thus if your connected to grid/generator/solar, and your charger is working, there is no way for the starter battery to go dead considering its getting charged, when the voltage drops under 13v the banks disconnect, in this case using the override switch will allow the relay to connect the banks and start the motor

realistically you should never have a dead starter battery, that said if you do, i would recommend waiting a minute or so in override before attempting the start

[blueh20]

mchero, I dont know enough about the charging relay yet to know how it works, I was under the impression that if the starter battery was DEAD the relay would instantly throw the house battery into play to start the vehicle and blow my 150 amp fuses.

But if the relay only lets me manually direct house battery amps to the starter batt then I am good to go, just let the house battery charge the start batt for 15 minutes , then turn the relay off and try and start.

I am trying to understand how the relay works, but the website doesnt go into enough detail for a 12v newbie.

[blueh20]

wow, fantastic responses folks, thanks so much, whole bunch of info here, and might I add, confusing for this newbie..
Am going to try and respond to individual posts one at a time because You all made good points, and some of those points I dont understand very well.
And I am going to explain my situation a little better and where I am coming from on this issue.
Am a total newbie to 12v wiring-solar-lifeline batt- charging relays- grounding12v--auto alternators and so on. Am a retired general contractor commercial and residential,thats 110-120-220 I am ok with that.

I purchased this van set up with all of this solar setup already setup in a box in the back of the van,panels on the roof, nothing else in the interior, just a shell. Solar system/parts are 1 year old.
I took it all out and started a camper conversion and am almost done with the convert.
Yesterday is the first time I fired the van up in 3 months, so I threw a fire ext on the pass. seat and drove it to see if the solar system/fuses I added,breakers added, wiring off of fuse block added,manual battery isolation switches added,etc., well it all worked, no fire and the fuses/breakers didNOT blow, the mt50 solar display and the xantrex all seemed happy.

NO, I dont really understand the system, did ton of research on the web and crossed my fingers.
Now I need to learn more.

[mchero]

Perhaps not doornail dead as one put it but dead enough to blow a fuse. I have more experience on the diesel side. Your getting some excellent info. so ill just step back and watch.

[landyacht318]

How is your house battery grounded?

Since you are asking it to take power from engine battery to recharge, then all the current for house battery, engine battery and likely all the stock vehicle loads is now on the original alternator to engine battery cable, which was not intended to carry all this current.

You might consider either upgrading this OEM cable, or adding another thick parallel circuit from alternator + to engine battery, fused of course.

I prefer taking juice for house battery right from alternator (+) output stud rather than from engine battery.

If you are relying on the frame ground, well the original engine to battery ground is also going to have to carry the extra current of a depleted lifeline battrey, a large depleted lifeline AGM, which can suck up EVERYthing your alternator can make, especially the voltage regulator, which controls alternator output, is seeking 14.2v+. I recommend if you are using a frame ground, to add another ground from frame to an alternator bracket mounting bolt, and take extra steps to insure these remain low resistance and tight.

I would recommend not idling parked to recharge, as underhood airflow is quite limited when not moving, and a hot alternator is not a happy alternator, and it will get quite hot feeding a depleted lifeline 8d.

Also keep in mind your ford's voltage regulation is not always going to be asking for 14.2 to 14.4v, as lifeline wants when anything but 100% charged.

Lifeline wants your 8d battery to get no less than 51 amps when depleted to 50%, and you should not expect your alternator to meet this at idle, or perhaps at speed if your headlamps and blower motor are on.

Deeply cycled AGMS will get tickled to death by too light of charging currents, a bunch of low and slow solar, even to full every day, pisses them off. Your solar will barely do 20 amps in ideal conditions.

Its an expensive battery, you might want to ensure that it gets that 51+ amps from 50% SOC when you have grid power available and that you can hold it at 14.2 to 14.4v until amps taper to 1.275amps.

If you cannot properly feed that lifeline AGM, then do not expect it to live up to its venerable reputation.

A voltmeter on your dashboard revealing the Lifeline voltage. is wise, even though it will likely be dissappointing and ignorance is bliss until it is time to buy a new battery.

I have a hall effect sensor ammeter whose display is on my dashboard so i can see what my battery is accepting from the alternator when driving. Wonderful tool. The more amps the battery is accepting the lower its state of charge.

[DrewE]

As a practical matter, I think you'd be pretty unlikely to blow one of the fuses under most circumstances. It's rare that the starting battery would be completely doornail dead, and the current that flows is determined by the charge acceptance rate of the battery at whatever voltage ends up there...which will be lower than the resting voltage of the house battery, both due to voltage drop in the wiring between the two and due to the voltage of the house battery drooping under load.

In the more typical case where the chassis battery has some charge but not enough to turn the engine over, it's still going to provide a reasonable amount of current to the starter when both are combined.

[blueh20]

mchero, thats what I was told, if the starter battery is dead, turn the charging relay to the other position and let it send juice to the starter battery for 15 minutes or so, but assume before I new the starter battery was dead I would blow one of my 150 amp fuses. so larger fuses are needed,,,,correct?

[red31]

What purpose do you plan for the ml-acr?

The ML-Series ACR automatically combines batteries during charging, and isolates batteries when there is no charging sensed on either battery bank.

Will solar charging cause the backward wiring to combine the batts?
Or do you plan to manually combine?

[mchero]

Also, lets say your starting battery is FLAT DEAD. Don't connect the house battery and immediately try and start the engine. Give the house battery a couple minutes to get some juice to the starting battery.

[blueh20]

ok great info,, protecting wiring and to stop a catastrophe in case of an accident is why I put the fuses into the system, I will check on the 2/0 cable rating and buy new fuses, thanks

[pauldub]

Fuses are generally used to protect wiring so you want a fuse that is appropriate for ampacity of the wire you are using. It has nothing to do with the alternator.

[blueh20]

are you saying I should put in like 350amp fuses, someone mentioned I should only fuse it for 10% over the alternator output,but he didnt have all the info of my setup, he may have been speaking "in general". Im a newbie to this 12v stuff so I appreciate any help you can give.. I went to that link you sent and and it only went up to "00", I didnt see a rating for 2/0 wire,