battery charger wiring

moetuna

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Hello , Putting a charger in the boat . I have dual batteries with a guest switch . I'm thinking one wire to the BOTH on the guest switch and one wire to ground from either battery . This will charge both batteries at the same time OR independent by choosing 1 or 2 on the selector switch . Sound correct ?
 

Cool Boat

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If it is a dual bank charger I believe you would normally run one wire to each battery. The way it is noted above, if you turned the Guest switch to off, you would not have battery charging, correct? For a slightly different application: On our trawler, the inverter charger (100A) went right to the house bank and we used an echo charge unit (Balmar) to charge the 8D starting battery. Works fine going on 20 years. What brand and model is the charger?
 

Silverheels

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There are numerous marine grade chargers designed with connections for multiple batteries and also have provisions for type of battery such as AGM or wet. Keeping multiple batteries healthy with one connection is difficult.
 

Cool Boat

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Good point on the multiple battery types. Both the house battery charger and the alternator's voltage regulator were programmable for the type of battery. We went with all wet lead and liked to replace on a 3 year cycle for safety considerations. Never had an issue.
 

moetuna

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I have two group 31 AGM batteries . I'm looking at gis charger : Powermax PM3-60LK 12 Volts DC 60 AMP
 

Cool Boat

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First a disclaimer, I am not an electrical engineer but highly recommend you either speak to one or the manufacturer of the units you are considering. The website details on the noted Powerrmax do not show any manual switching or programming for the different battery types (wet/AGM/lead calcium/gel). It may be internal or automatic, but they are not clear on it. They also do not show multiple outputs for separate batteries. You might want to check on the metal case and if it is suitable for marine use and your proposed mounting location. If its a gas boat maybe if it is explosion proof. I looked up the Xantrex units for comparison. Their manual notes that charging an AGM31 (105A typical) at 60 A would be considered a little above specification. Charging at 40A was their suggestion. Their unit also indicates 3 DC outputs rather than just one. I am not recommending one unit over the other but would research it more. The bass boaters around here also use inexpensive small sealed chargers with multiple battery outputs to their trolling batteries so this might be an option depending on the boat's use. Good luck with it.

http://www.xantrex.com/documents/Ba...Truecharge2 Battery Charger Owners Guide).pdf
http://www.xantrex.com/documents/Battery-Chargers/TRUECharge-2/DS20190411_TrueCharge2-20-40-60.pdf
 

moetuna

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First a disclaimer, I am not an electrical engineer but highly recommend you either speak to one or the manufacturer of the units you are considering. The website details on the noted Powerrmax do not show any manual switching or programming for the different battery types (wet/AGM/lead calcium/gel). It may be internal or automatic, but they are not clear on it. They also do not show multiple outputs for separate batteries. You might want to check on the metal case and if it is suitable for marine use and your proposed mounting location. If its a gas boat maybe if it is explosion proof. I looked up the Xantrex units for comparison. Their manual notes that charging an AGM31 (105A typical) at 60 A would be considered a little above specification. Charging at 40A was their suggestion. Their unit also indicates 3 DC outputs rather than just one. I am not recommending one unit over the other but would research it more. The bass boaters around here also use inexpensive small sealed chargers with multiple battery outputs to their trolling batteries so this might be an option depending on the boat's use. Good luck with it.

http://www.xantrex.com/documents/Battery-Chargers/TRUECharge-2/975-0526-01-02_Rev-D(Truecharge2 Battery Charger Owners Guide).pdf
http://www.xantrex.com/documents/Battery-Chargers/TRUECharge-2/DS20190411_TrueCharge2-20-40-60.pdf
Ya, an electrical tech at work recommended the 60 amp model because of the bang for the buck thing . He has no experience with this sort of thing however .Was wondering if it was too much .....thanks for your input
 

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moetuna

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I just went through this. Negative leads to a common ground. Hot leads to the Batt 1 and Batt 2 posts on the battery switch. It is not the textbook installation, but according to some DEBF experts, perfectly acceptable. It's working fine.

The only reason I didn't go directly to the batteries was because I couldn't secure the wiring properly in the bilge/below deck.

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What make/ model charger did you use and at what amps ? Thank you
 

Silverheels

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As far as the charging goes when cruising, I have a single engine with dual group 27 batteries and the system uses a
Blue Sea Systems SI-ACR Automatic Charging Relay that combines the batteries when the alternator is putting out and isolates the batteries automatically when not running. It's a clean, relatively inexpensive way to accomplish the task and I have always been pleased with Blue Seas components.
 

moetuna

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Please ignore the question of how does it know what type battery its charging . Did the research
 

Cool Boat

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Looks good from the owners manual I found on another site.
https://www.defender.com/pdf/NOCOGeniusGEN.pdf
Was ten amps per battery enough?
The only thing I would consider, I would highly recommend wiring it directly to the battery rather than the Guest switch. Removing the extra contacts and cable from the direct route charging circuit will probably pay dividends in the long run, and eliminate the chance that the unit would not work if a problem with the battery selector switch. It may work fine though and never be an issue for your application.
On my trawler, in conjunction with best practices, and likely the ABYC requirements, we fused the battery to load on the house batteries, and the starting battery to starter. For that application a 400 amp slow blow Little Fuse and bolt-in holder (DD 671) isn't too expensive and may save an electrical fire if something should go drastically wrong. In case of a lower amperage situation where the fuse did not blow we also used locomotive quick disconnects should we need to quickly disconnect the house bank or starting battery for service or electrical fire. In the large, dry engine room they worked great for 20 years, only requiring cleaning once around year 18. I will not use them in the 23' boat that we are building due to exposure concerns and excellent access to batteries.

NOCO goes back to 1914 according to their website.
I like the water resistant and ignition protection too. It will recharge from as low as 2 volts too, better than some of my shop units that want much more than that. It's nice too if you did change battery types later, it already knows what to do without reprogramming.
If you get one let us know how you make out, might put one on my next boat which I should be working on right now.
 

moetuna

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Looks good from the owners manual I found on another site.
https://www.defender.com/pdf/NOCOGeniusGEN.pdf
Was ten amps per battery enough?
The only thing I would consider, I would highly recommend wiring it directly to the battery rather than the Guest switch. Removing the extra contacts and cable from the direct route charging circuit will probably pay dividends in the long run, and eliminate the chance that the unit would not work if a problem with the battery selector switch. It may work fine though and never be an issue for your application.
On my trawler, in conjunction with best practices, and likely the ABYC requirements, we fused the battery to load on the house batteries, and the starting battery to starter. For that application a 400 amp slow blow Little Fuse and bolt-in holder (DD 671) isn't too expensive and may save an electrical fire if something should go drastically wrong. In case of a lower amperage situation where the fuse did not blow we also used locomotive quick disconnects should we need to quickly disconnect the house bank or starting battery for service or electrical fire. In the large, dry engine room they worked great for 20 years, only requiring cleaning once around year 18. I will not use them in the 23' boat that we are building due to exposure concerns and excellent access to batteries.

NOCO goes back to 1914 according to their website.
I like the water resistant and ignition protection too. It will recharge from as low as 2 volts too, better than some of my shop units that want much more than that. It's nice too if you did change battery types later, it already knows what to do without reprogramming.
If you get one let us know how you make out, might put one on my next boat which I should be working on right now.
Thanks for your input
 

moetuna

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Pretty sure Xantrex are considered one of the best out there.
Yes, I believe your correct . It was the first one I considered . I had some issues with them however . They are three bank systems . I need two . So your dividing the overall amps by three if my thought process is correct . So by only using 2 banks of there 20 amp charger I'm getting 6.6 amps of charge to each battery . Also , I would need to acquire all the wiring for there units . I like to keep it simple because I'm doing this myself and me and electricity don't get along to well .
 

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Yes, I believe your correct . It was the first one I considered . I had some issues with them however . They are three bank systems . I need two . So your dividing the overall amps by three if my thought process is correct . So by only using 2 banks of there 20 amp charger I'm getting 6.6 amps of charge to each battery . Also , I would need to acquire all the wiring for there units . I like to keep it simple because I'm doing this myself and me and electricity don't get along to well .
'
Three Bank' chargers only mean they are capable of charging three separate battery banks with their own grounds. We've used 3 bank chargers for single (maybe twice) and mostly for 2 banks. And yes, 10A per battery is ideal for a pair of group 31s, although you could argue they don't NEED that output. Industry "rule of thumb" is literally 15% of the total amp hour rating of the bank. So with a bank of 2 group 31s which range from 90 to 110ah depending on the type, that would mean a 30A charger if let's say they were 100aH each.. which is bullshit! You don't need that unless you're running super high DC draws which would make it almost like a AC/DC power supply. Yes, the charger will bring those batteries up quicker, but we have 30A chargers on boats with 4 31s..A lot of it depends on how often the charger is used.. Some boats on a mooring I would recommend going with a higher output, as you really should have the charger on and 'floating' a the right voltage to maintain them. Just make sure you get a 'multi-stage' charger with at least three stages that include Bulk, Absorption, and Float. as the absorption phase actually takes more(getting the battery up and over than last 10% to a full state of charge than anything else and is what makes a charger dangerous to the life cycle of a battery vs a battery saver.

You want to have your charger plugged in at all times whenever possible, and most chargers these days don't have that issue I mentioned earlier (although some do a better job), as it was really a problem with out 'Constavolt' style chargers that would output the same voltage and amperage until it was turned off, and would gas (hydrogen gets released from those little vent when overcharged) and can't exactly be put back. As the other guys have mentioned earlier in the thread, do not connect the battery charger leads to a battery switch. Fuse them accordingly and I highly recommend these fuse holders Blue Sea MRBF Terminal Fuse Holder that go right on the terminal with the cable. Go right to the terminals with those DC cables and keep those terminals CLEAN and TIGHT!

I'm as into chargers as much as I am into chartplotters, so I firstly if possible, I'd recommend a charger that has a temperature sensor (preferably one that connects to the battery terminal, as some just use an internal sensor in the charger which only accounts for ambient). Also, not sure how you plan on wiring the charger to to AC; the panel, an extension cord, but to clarify, 'On-Board' chargers are technically designed for boats that have no AC panel, hence the actual 110VAC plug. Not that they can't be used, as most are IP65 or even IP68 waterproof, so if you're having to mount in a wet spot, just cut off the 110 plug and wire the hot/neutral and grounding.

We have used a few Noco chargers last year for the first time, no issues which is great, but I have no idea on their customer service. Xantrex makes a great product, and if you're looking for something like the NOCO take a look at the Victron BluePower series of chargers, as those have been bulletproof and I've not been shy about how Victron's product line is, from their 10A charger to their 100A units. Worth a look as I think they have 5 stages including a pre-float which I love and a 'storage' mode. They also can be connected to via Bluetooth to check stats, but IMO 99% could give a shit! Good luck in the search and I'll be checking back!
 

moetuna

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'
Three Bank' chargers only mean they are capable of charging three separate battery banks with their own grounds. We've used 3 bank chargers for single (maybe twice) and mostly for 2 banks. And yes, 10A per battery is ideal for a pair of group 31s, although you could argue they don't NEED that output. Industry "rule of thumb" is literally 15% of the total amp hour rating of the bank. So with a bank of 2 group 31s which range from 90 to 110ah depending on the type, that would mean a 30A charger if let's say they were 100aH each.. which is bullshit! You don't need that unless you're running super high DC draws which would make it almost like a AC/DC power supply. Yes, the charger will bring those batteries up quicker, but we have 30A chargers on boats with 4 31s..A lot of it depends on how often the charger is used.. Some boats on a mooring I would recommend going with a higher output, as you really should have the charger on and 'floating' a the right voltage to maintain them. Just make sure you get a 'multi-stage' charger with at least three stages that include Bulk, Absorption, and Float. as the absorption phase actually takes more(getting the battery up and over than last 10% to a full state of charge than anything else and is what makes a charger dangerous to the life cycle of a battery vs a battery saver.

You want to have your charger plugged in at all times whenever possible, and most chargers these days don't have that issue I mentioned earlier (although some do a better job), as it was really a problem with out 'Constavolt' style chargers that would output the same voltage and amperage until it was turned off, and would gas (hydrogen gets released from those little vent when overcharged) and can't exactly be put back. As the other guys have mentioned earlier in the thread, do not connect the battery charger leads to a battery switch. Fuse them accordingly and I highly recommend these fuse holders Blue Sea MRBF Terminal Fuse Holder that go right on the terminal with the cable. Go right to the terminals with those DC cables and keep those terminals CLEAN and TIGHT!

I'm as into chargers as much as I am into chartplotters, so I firstly if possible, I'd recommend a charger that has a temperature sensor (preferably one that connects to the battery terminal, as some just use an internal sensor in the charger which only accounts for ambient). Also, not sure how you plan on wiring the charger to to AC; the panel, an extension cord, but to clarify, 'On-Board' chargers are technically designed for boats that have no AC panel, hence the actual 110VAC plug. Not that they can't be used, as most are IP65 or even IP68 waterproof, so if you're having to mount in a wet spot, just cut off the 110 plug and wire the hot/neutral and grounding.

We have used a few Noco chargers last year for the first time, no issues which is great, but I have no idea on their customer service. Xantrex makes a great product, and if you're looking for something like the NOCO take a look at the Victron BluePower series of chargers, as those have been bulletproof and I've not been shy about how Victron's product line is, from their 10A charger to their 100A units. Worth a look as I think they have 5 stages including a pre-float which I love and a 'storage' mode. They also can be connected to via Bluetooth to check stats, but IMO 99% could give a shit! Good luck in the search and I'll be checking back!
Thank you for the detailed response . Haven't made my mind up completely yet so I will check a few things out .
 
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