Its just not that simple.
You can have over 11 volts but if the ratio of depleted reserves in amp/hours is large enough combined with the continued stereo draw that is large enough the voltage will drop like a rock and the Blue Sea will open again. This isn't a problem for minor systems but is a real world challenge with BIG systems when you cross a threshold in stereo size and stereo battery bank reserves.
Having 200 amp/hours at 80 percent (11.5 volts) depletion is far more challenging than having 65 amp/hours at 100 percent (10.5 volts) depletion. Its more an issue of current versus voltage. Voltage is just the consequence.
Seriously depleted batteries can be a real liability to the charging system and the ACR/VSR operation.
Like I said its complex and a moving target as systems become larger.
Thanks David. I think my system is more in the moderate category but I did send you an e-mail with the details of my system and look forward to hearing your thoughts on improving my set up, if necessary.
Originally Posted by EarmarkMarine
At a minimum, it sounds like I need to install a digital voltage gauge at the helm to keep an eye on the stereo bank battery voltage.
I spoke to David and he shared with me a slightly different wiring scheme that eliminates the need for a resettable breaker between the ACR and the battery. In my set up, I have the ACR wired directly to the battery with an inline resettable breaker on each leg. This allows me to open the breakers and isolate the ACR when I have the onboard smart charger hooked up.
With Davidís scheme, the ACR is wired to the output posts on the switch instead of directly to the battery. So when itís time to charge the batteries, you can put the switch in the OFF position and the ACR will be isolated. This accomplishes the same thing as opening the breakers in my scheme. Itís a more elegant solution that mine since it does not require additional components (the resettable breakers).
Hope that makes sense. This is only relevant if you are going to charge your batteries with a smart charger.
Below is a revise schematic showing Davidís scheme in red.
Thanks David for sharing this with me.
Great write up & sketches are definitely worth a thousand words, etc. I'd been scratching my head on how to incorporate a dual bank charger with a battery switch/VSR combo. Thanks.
I only have 90 rated amps of stereo, one Optima blue primary battery, one Optima blue stereo only battery, a Blue Sea Dual Circuit Plus Switch, and a SurePower 1314-200 VSR. I picked up a 140A alternator (more than I need, but the price was too good to pass up). Rather than upgrading the wiring in the old harness, I'm thinking of running an additional wire to help carry the load. If I wanted to land a second feed (properly sized & fused, of course) directly off of the alternator output, where should it tie into the last diagram?
It should land on the pos terminal of the starting battery. Newty upgraded his alternator so you might ask him what he did.
Actually, the power feed from the alternator goes to the starter and is connected to the 2/0 cable that connects the starter to the starting battery. This is how the alternator current goes back to the starting battery. So if you want to add an additional cable, I would run it back to the starter.
Originally Posted by cab13367
Thanks, Cab. Forgot to mention this is on an old Supra Saltare. While I love my Supra forum brothers, I found your diagram & ya'll seem to be bit more electrically inclined over here.
I traced the alternator feed wire (looks to be 10 or 12 ga) back to the engine loom. From there, it wye's into one wire headed up to the helm and one to the 50 amp breaker. It jumps from the breaker to the starter solenoid & then to the starter where it would tie into the same terminal as the battery cable back to the primary battery. Should I bypass the breaker and solenoid & go directly to the starter? Just upgrade the wiring along the same path (won't I risk popping the 50A breaker with a 140A alternator)? Or land directly to the primary battery, or battery switch, or VSR? Now I've gotten myself totally confused??
I'm really not qualified to advise you on this. We are getting a little over my head now. All I know is that if you want to run a feed back to the battery, you definitely want to land it on the battery, not the switch or vsr. The vsr will sense the charge and combine your batteries when appropriate so both batts will get charged.
Thanks cab for the diagram... did my set-up last night. Made things a lot easier and quicker than trying to understand all the lines without a diagram. Only difference was I went with the ProMariner 20 3 Bank charger than your set-up. Everything worked so far in the garage, I guess I'll find out tomorrow if I get any feedback with my amps and such as some people get. Thanks again!
Great! Glad to know it helped you out.
Originally Posted by bbuhtz