What’s the best 2-bank charger/maintainer?

[Fisherdv]

Looking for a dual bank charger/maintainer. I could either mount it on the boat or just use in the garage so either kind is fine. Looking at the Guest Pro 4A/4A, the Pro Mariner, NOCO genius 4A/4A, or a non-on board Deltran battery tender 1.25A/1.25A. I'm not looking for a high amp rate charge as I would like to leave it plugged in while the boat is in the garage. Also my garage in the summer can get hot, close to 100 degrees so I would like a cool running charger and one that won't fry my batteries?

[Fishgriller]

I've been using a Battery Tender marine model for last several years, works great. Their website shows how to connect to dual batteries, either parallel or series.

[neild]

When I went looking for one everything said Noco. I don't know if it's just that good or they write their own reviews. I bought the 4A/4A and just keep it plugged in.

[Chief of the Boat]

I have been running this one for a few years and leave plugged in all the time.
https://www.amazon.com/Marinco-2-Bank-Board-Battery-Charger/dp/B01B22616Q/ref=sr_1_9?ie=UTF8&qid=1526307890&sr=8-9&keywords=marinco+battery+charger

[Hunter]

I have the NOCO Gen 2 Genius for my maintenance / charging system when the boat is in the shop.   Also installed the plug port for super ease of use.  Both the plug port cap and the entire solid state smart charger / maintenance unit are 100% waterproof and there is no "thinking" involved other than to unplug it before I pull out of the shop.   Also really nice to be able run the Espar heater and stereo, etc..... when working on the boat in the driveway or in the shop with the doors open without worry of running down the batts.       PS....   Made in USA

https://www.amazon.com/NOCO-GEN2-Waterproof-Battery-Charger/dp/B003JSJS5I

[Mooch]

ProMariner ProSport 12 2 bank has worked well for me:
https://www.westmarine.com/buy/promariner--prosport-12-heavy-duty-marine-battery-charger--14152151?recordNum=1

I think the Marinco, Guest, Noco and PM are all pretty equal.  Think fearures, size, form factor and output will play big part in decision.  Price can often be a factor too, since on board chargers are often be found on sale.

Key features for me were:
Waterproof
Distributed on demand charging
Storage reconditioning and energy saving modes, since mine is always connected in storage.

I also use a portable Minn Kota charger too that works great for additional batteries.

[J Chaser]

I just use 2 Battery Tender Juniors.

I've never had any problems.

J.

[GregE]

With a good battery manager you don't need to worry about leaving it plugged in.

My Guest 5 5 goes from analyze to charge to maintain - cycling automatically

[Threeweight]

Marinco/Guest are the same company now... when I was researching mine, they were one of the better options and they stick to the same mounting pattern (so you don't have to drill new holes if you ever have to replace one). 

You want to look for units that are fully epoxy potted, IP 68 waterproof rated, and marine-grade wire and connectors.  The physically larger units are heavier (more vibration resistant) and often have finned aluminum housing for dissipating heat, with the trade-off of taking up more room in the boat.  All of the "smart" chargers sold now will have run in a float mode and not harm your batteries.  The best ones also do a battery test and will run a charge pattern to "restore" (de-sulfate) the plates of an old battery.

Battery tenders/Noco Genius, etc... all work, but some are not designed for marine use.  I have a Genius maintainer I installed on my Duramax, and I had to cut the cables to install lugs that worked with the truck's hardware.  Cable wire was not tinned... mine is a cheap little 1.1 amp maintainer, so maybe the nicer units get better wire.  That little guy did recover a 3 year old battery I thought was toast with it's restore function.

I believe the Cabelas house brands are also plain copper wire.

[Fisherdv]

I also have a little 1.1A NOCO now that's works great, but I had to modify the ring terminals. The ones they come with won't even fit a 5/16 battery post. If I get the dual bank NOCO I'm afraid I'd have to modify it too. However for $11.99 ea they do sell an XL 3/8 ring terminal wires  :hoboy: I'm leaning towards the Guest 4/4 but not sure if the cables are long enough (I have one battery on the starboard, and the other battery on the port side)

[DevMah]

Guest/Marinco, NOCO, Pro Mariner , and Master Volt all good brands.

I would recommend to buy a automatic multi stage charger with float and equalization stage.



Dev

[jamaica]

With two batteries and an ACR setup do you need a dual bank charger? Putting a charger on one battery should charge both with the ACR functioning correctly? Help!

[Threeweight]

The ACR will split the charge once one of the batteries exceeds it's threshold (13 volts for 2 minutes, I believe).   

So if you have a single bank, 5 amp charger, with the ACR you can split the charge and send 2.5 amps to each battery.  That is a basically a trickle charge (maybe a tad better).  When the batteries are bridged, for charging purposes it's basically one big 12 volt system and the "smart charging" of the newer units that tailor their charging output to each battery doesn't really work.

I preferred to go with a dual bank Marinco on by tin can, and wire the ACR off the main battery switch vs. the batteries themselves (so it is only engaged when the switch is "on".)  Mine is a 10 amp unit (up to 5 amps to each bank), with the full smart charging technology.

I think either works, but going with a single bank and relying on the ACR to split the charge doesn't take advantage of some of the features of the newer chargers (but it is quite a bit cheaper).

[Fisherdv]

I like the idea of controlling the ACR with the main switch to make sure it's off when not in use and for charging directly with a dual bank charger. Would this diagram be the correct way to hook it up so the ACR is OFF when the switch is set to the off position?

[Fisherdv]

Or should the wires from the ACR go to the bottom posts on the switch (same as batteries are connected to) in that diagram?

[Threeweight]

Mine is wired to the top posts, which only receive power when the switch is "on".

The lower posts are hot all the time, and essentially the same as connecting directly to the battery.

I'd defer to Dev Mah on the most correct way to do it.  My local marine electrical guru gave me a thumbs up to my wiring job, but that isn't the same as hearing it directly from Blue Sea!

[SB Steve]

The other option is to put a switch on the negative ground from the ACR.  It will de-activate the ACR.  You just have to remember to turn it on when you start your motor.

[DevMah]

The other option is to put a switch on the negative ground from the ACR.  It will de-activate the ACR.  You just have to remember to turn it on when you start your motor.

Blue seas is concerned of voltage drop... if your ACR and batteries have a fair distance between then they recommend not to have them on the switched side rateher the hot battery side.

You can add a switch to the negative or run a relay to make it the ACR automatic.
Use a standard 12v relay, wire the B- of the ACR to the NO (normally open side when off) the other side of the NO common contact to the B- with a 10A fuse.
Then simply add a 5A fuse to the house battery B+ System to one side of the relay coil and connect the other side of the relay coil to the B- bus.

Every time you turn the battery switch on you power the relay and it will close the contacts Turing on the ACR.

Dev

[jamaica]

Is it ok to connect my new Marinco dual bank charger to the hot side of my battery switch and the nearby neg. buss? The runs from the switch and buss to the batteries are short. It would greatly simplify the cable runs and keep things around my batteries neat.

[DevMah]

Is it ok to connect my new Marinco dual bank charger to the hot side of my battery switch and the nearby neg. buss? The runs from the switch and buss to the batteries are short. It would greatly simplify the cable runs and keep things around my batteries neat.

Yes

[jamaica]

Thanks Dev, trying to get everything just right.

[DevMah]

Thanks Dev, trying to get everything just right.

My 2 bank 10 A guest is wired in the same manner.

Dev

[Fisherdv]

For those of you wanting to turn "off" or bypass your ACR to charge with a dual bank charger at home another alternative may be instead of putting fuses on the ACR leads put a blue seas circuit breaker with a push button to trip it. Same thing as a switch right? Just reset the breaker when your done charging.