Blue Sea 7622 wiring

J.Spicoli · 12-16-2016, 11:21 AM

Sorry if this has been covered, I tried searching and there's a ton and while I'd love to read them all I have a battery box to build and wire out.

So quick question is that I've got a Lifeline 4D for the house battery and pretty sure a stock 2014 E-250 starting battery as well as the Blue Sea 7622 that will combine them.

I was going to do a basic setup for now by just running a positive off the starting battery to the Blue Sea and the same off the Lifeline to the Blue Sea and then ground it via the black wire from the Blue Sea. Tech support said this would work fine.

Question is about charging and protection and longevity. If my alternator puts out about 225 amps is this going to hurt the Lifeline house battery after a while. Thinking long drive to the mountains with sustained high alternator output.

And along those lines with the constant charging from the 300 watts solar hurt the starting battery?

1der · 12-16-2016, 11:36 AM

re: Charging -

Solar controller (Which one do you have?) should regulate voltage going in from the panels. Your alternator regulator should regulate what the house and starter batteries are looking for in terms of charging.

Did you replace your alternator or you have dual alternators? Trying to figure out where 225 amps is coming from. Also, keep in mind your alternator is supplying the needs of the engine and numerous other systems while you are driving so the first 40 to 60 or more amps are just to keep up with those demands.

scalff77 or other s can explain in more detail.

J.Spicoli · 12-16-2016, 12:27 PM

Ray...you are a wealth of info man.

I have just the one stock alternator and looking at specs online and according to auto parts store it's a 225 amp unit.

I have the Renogy Commander 40A MPPT Charge Controller and know it will take care of the house battery, I just didn't know how having the 7622 hooked in there would change things.

I forgot that the alternator should regulate things as well. I just want to make sure that it's not going to do more harm than good over time since a wet cell starting battery is totally different from a slow discharge AGM.

J.Spicoli · 12-16-2016, 12:30 PM

So much for working outside today. Went out and started to get set up as a slight drizzle was seemingly ending and blue sky was opening....or so I thought.

It's now snowing and starting to stick. Grrrrr.

I looked at my weather app and it updated from rain ending at 10:30 to snow starting 11:00....WTF weatherman?!?!

boywonder · 12-16-2016, 12:42 PM

Your connection is fine.......tie the house battery to one side of the separator and the van battery to the other side of the separator.

The current flowing to each battery is determined by the internal resistance of each battery.....which is determined by each battery's state of charge......ie the load (batteries in this case) determines the current that's flowing......the batteries don't care what the rated output of your alternator is.

Just because your alternator is rated at 225 amps does not mean it put's out 225 amps all the time. It means that as the resistance of a connected load is decreased, the alternator can put out current at it's rated voltage all the way up to 225 amps; draw more than this and the voltage will start to sag and the alternator may begin to overheat.

**daveb** · 12-16-2016, 12:45 PM

I'd suggest you're OK as far as overcharging goes. Batteries take what they need amp wise. I think it partially depends on how well the voltage is regulated at and what the battery manufacture specs the charge voltages at. Most alternator regulators never charge the battery fully to the float level. I actually relied on my solar to top off the batteries.

I've ran a few different alternators with mixed results. They all had different set voltages. I think the stock alternator I had early on put out about 14.2 volts but lacked enough amperage (as 1der mentioned) to run the vehicle's load plus the Starcool A/C. So I purchased a 200a model but the max voltage was only 13.8v. I then upgraded to a XP-270. That alternator put out plenty of amps but also a higher voltage. I was seeing voltages of 14.8 to 15.2 at the house battery bank and a Lifeline tech said I would fry the batteries. I didn't like that so I had a smart regulator installed in the XP-270.

J.Spicoli · 12-16-2016, 12:53 PM

Quote:

Originally Posted by boywonder

Your connection is fine.......tie the house battery to one side of the separator and the van battery to the other side of the separator.

The current flowing to each battery is determined by the internal resistance of each battery.....which is determined by each battery's state of charge......ie the load (batteries in this case) determines the current that's flowing......the batteries don't care what the rated output of your alternator is.

Just because your alternator is rated at 225 amps does not mean it put's out 225 amps all the time. It means that as the resistance of a connected load is decreased, the alternator can put out current at it's rated voltage all the way up to 225 amps; draw more than this and the voltage will start to sag and the alternator may begin to overheat.

Ah yes. That's what I was looking to hear. Makes sense.

I knew the alternator wouldn't put out a constant 225 due to the variable engine RPM's just didn't quiet get how the voltage regulation would happen at the batteries.

Awesome, thanks for your help guys.

Guess I'll go xmas shopping since the van is on another weather hold.

boywonder · 12-16-2016, 01:18 PM

For further clarification......

The alternator has a VOLTAGE regulator, not a CURRENT regulator....

As Daveb mentioned above, most typical OEM auto alternators may not provide sufficient voltage to fully charge an AGM battery. (Compare the alternator's rated output voltage to the battery's required float voltage..) So using just an alternator over time may result in an undercharged house battery.

The alternator's VOLTAGE charging profile is also rather "dumb" compared to a quality shore power charger or solar controller. These devices typically have 3 stage charging, bulk, absorb, and float. These stages (depending on battery state of charge) typically require different VOLTAGES from the charging device, whether it's shore power, solar or an alternator.

Note that the word CURRENT does not appear anywhere in the above paragraph.......

Also, as Daveb mentioned above, some alternators with a higher than normal voltage setting may overcharge an AGM battery, specifically when the alternator voltage (as determined by the voltage regulator) exceeds the float voltage rating of the battery. Exceeding the rated bulk voltage rating may also harm a battery, although I'm no expert on this.

Most of us here with Solar rely on the solar controller to fully top-up our house batteries since these controllers are smart multistage and can typically be set to charge AGM batteries correctly voltage-wise.

J.Spicoli · 12-16-2016, 05:07 PM

Thanks for the clarification boywonder. I totally get it. I guess that is what I was trying to get at without knowing it if that makes sense. I knew there was a difference between the batteries and therefore thought the charging profiles might be different and didn't know that both the alternator and the battery itself play a roll. What you said really ties it all together.

So yeah, I have the Renogy 300W kit with the controller stated above so that should take care of the battery pretty good. I just wanted to be able to take advantage of the alternator since it was already there.

Thanks again you guys. At this point I've been trying to get a quick battery box in the van but between learning what I need, 100 trips to Home Depot, then ordering what I forgot in the first place I'm still in the getting started phase, lol. This project is taking waaaaaaaay way way waaayyyy longer than I anticipated.

Scalf77 · 12-17-2016, 06:12 AM

All good info here, but I would recommend installing the switch that comes along with 7622. It gives you manual control when needed, indicator as to status if open or closed and some diagnostic features, such as low voltage lock out, etc.

A couple of areas to to watch since you have a flooded starting battery and a AGM house would be charging both from your solar or shore power charger. While it is great to top your "starter" to full capacity, leaving the starting battery on extended "float" charging will reduce water in your flooded starter. This will take some time, but it is a usual culprit of early starting battery death. More so if you plug in all the time or live in a area with excellent solar capabilities. Moving to a AGM starter will limit this issue. I still usually run one charge cycle , then manually disconnect the ACR when parked and the house is in float long periods.

The second area is the one that Daveb pointed out, many of the higher amp alternators also tend to put out to high of a voltage, even especially for your fully charged house battery, being able to disconnect while on a long drive alleviates that issue, even on the lower voltage alternators.

-greg