Adding an onboard charger

[Broke Pilot]

Hey guys, now that I'm all moved into the new house I can get back to messing with the boat.
I'm looking at putting an onboard charger on it. I've got 2 batteries with the factory VSR and switch ('06 24SSV GG)
I've searched and read everything I can find but I can't figure out if it's ok to run a 2 bank charger and charge both batts at the same time with the VSR. I know I can charge through one battery and that's what the VSR is for, but I don't like the thought of relying on that when the charge/float/maintenance voltages are so low. Seems like it might be switching a lot. Also, on a side note, anyone know if the factory one is a dual or single sense?

I know this is the wrong forum, but the Supra forum doesn't seem to be the happening place to be anymore. Hopefully one of you guys running a VSR will have the answer.
Thanks y'all!

[dusty2221]

You can run a dual bank and run each bank directly to its own battery. Charge with the switch in the off position (at least I would).

Make sure your charger is rated somewhere within 10% in outout amps as your total battery amp hour capacity.

[MLA]

Broke

In the most ideal setup, the dual bank charger will be wired directly to the batteries and the VSR will not be closed during shore charging. However, this can be effected by the brand of VSR, style of switch used and how they are all wired.

[Broke Pilot]

It's a BEP VSR, they came factory on the supra with the dual batts.
So if I turn the batt switch to off, does that completely cut the VSR outta the loop?

[zd215]

I have a ProSport 12, dual bank charger with the factory BEP VSR and switch.
I ended up wiring a relay inline on the VSR sense wire where it is only able to sense battery voltage when the switch is on.
The logic is, if my battery switch isn't in the off position, I'm more than likely far away from shore power. The VSR will never bridge the batteries if it cannot sense voltage on the starting battery, this maintains positive battery separation when the switch is in the OFF position.

Notes from my relay wiring schematic.
30 - Starting Battery Sense (-) ground to relay
86 - 12v Switched Engine Wire (+) Energizes coil on 12v when switch is on 1, 2, 1+2
85 - Battery Sense Jumper from 30 (-) Provides ground for relay coil
87 - Relay Sense (-) To VSR sense input

[gregski]

It's a BEP VSR, they came factory on the supra with the dual batts.
So if I turn the batt switch to off, does that completely cut the VSR outta the loop?

Like MLA said it depends on how it's wired... maybe someone on here will know the specifics of how the factory did it but you might need to dig in a little to figure it out. Here are a few ideas:

The BEP VSR doesn't have an enable/disable switch. So whenever the sense voltage is above 13.7, it closes the relay. I would expect most chargers to output something around 14.5V so this would close the relay unless you have some other isolation switch and it sounds like you might.

Where is your battery switch (electrically not physically) with respect to the BEP? Take a look at the BEP VSR manual and compare to your setup. http://www.jgtech.com/pdf/VSR_instructions.pdf Notice that they have two examples, the left one shows the VSR on the "isolated" side of the engine switch (the load side, not the battery side); while the right drawing shows the VSR on the non-isolated/battery side of the switch. Figuring this out will be key to answering your questions.

Is it critical to charge each battery independently / Do you need to care if the VSR connects both batteries and charges them in parallel? Notice the recommended layout in the BEP VSR manual on the right. They show one charger connected to the house battery, using the VSR to connect to the starting battery (once the voltage is above 13.7V). This seems like a reasonable setup to me. You could get a bit of relay chatter if the charger has only enough power to hold 13.7V for the house battery but not both together. If you used a single output charger sized to handle both batteries, I don't think this would be an issue. You said that you don't want to rely on that method because the charge/float/maintenance voltages are so low. I don't think that "so low" is a fair description. Take a look at the pro sport manual: http://promariner.com/wp-content/upl...n-3-Manual.pdf page 7. The charge voltage is 14.6V which is plenty to close the relay and charge both batteries. The maintenance voltage is 13.4 so this will open the relay and only keep a maintenance voltage on one battery but the reconditioning charge would go to 14.6V again and apply to both batteries.

[MLA]

Yes, the type of battery switch and how the switch and VSR are wired, make a difference. Two things to consider when using a single bank charger to charge 2 banks through a VSR 1) This may be ok is both batteries are same size, type, age and and used the same as in alternating between 1 and 2 from one outing to the next. If the batteries are different and used different, as in one is a dedicated cranking battery and the other is a dedicated house battery, then they will need to be conditioned and charged differently from each other. Passing through a VSR wont allow for this. 2nd, The VSR starts out open most likely, so the charger begins its bulk charge on the main cranking, which is likely not low at all. As the voltage rises, the VSR closes and brings in parallel a house battery which is certain to be low. Now the charger is finally charging the low battery, but through the cranking battery and through the VSR. After awhile then batteries are going to get close to their full charge, so the charger is going to taper off to its float mode. At some point, the VSR could open back up, isolating the house bank before it was fully charged. This is a generic scenario depending on the specs of a VSR/ACR.

So the most ideal route, is to go with a dual bank charger connected to each each bank and take the VSR out of the equation.