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Old 04-02-2016, 04:34 PM   #1
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What amp charger for 4 6v batteries

Heres what I know. Solaire 317bhsk with 8 gauge wire from the wfco 8955 to the batteries.

Doing my battery research is showing that the WFCO, while it is a 3 stage charger, rarely to never gets into the bulk charge stage. So I want to upgrade the converter/charger to something like the PD or Boondocker with the nod going to the PD unit for the ability to manually initiate bulk charging.

Will a 60amp unit be a good compromise between charging the 4 batteries while not needing to upgrade the 8 gauge wires or should I tear into the bottom of our new trailer and upgrade the wires and get a larger charger? We haven't gotten a chance to use the trailer yet so I do not have an answer as to how much boondocking we will be doing compared to having electrical hookups. We do have a EU3000is when we need it. I am jumping the gun and outfitting the trailer for ALL possibilities before we put it on the road.

I know that in general it would be a good idea to upgrade the wires regardless... But with the trailer being new to us, I am hesitant to pull the bottom of the trailer apart since I don't know whats going to be buried where.
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Old 04-02-2016, 04:48 PM   #2
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I found this on PD's website...

Quote:
11. How long will it take to re-charge my RV battery?
Battery recharge time is controlled by many factors, such as battery size, converter output rating the number of 12-volt lights and appliances that are “ON” during the re-charge cycle and how far the battery has been discharged. In our testing a 125-AH (Amp Hour) battery was fully discharged to 10.5-volts and then connected to a PD9160 (60-Amp) Converter/Charger set to our standard output voltage of 13.6-volts. The battery reached full charge in 70-hours.
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Old 04-02-2016, 05:07 PM   #3
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And from 12 volt side of life..

Quote:
OK, for you techie types, here are the specs for charging deep cycle flooded cell batteries: Most flooded batteries should be charged at no more than the "C/10" rate for any sustained period. "C/10" is the battery capacity in amp/hours divided by 10. For a 220 AH battery, this would equal 22 Amps. Charging at 15.5 volts will give you a 100% charge on Lead-Acid batteries. Note that flooded batteries MUST bubble (gas) somewhat to ensure a full charge, and to mix the electrolyte. Float voltage for Lead-Acid batteries should be about 2.15 to 2.23 volts per cell, or about 12.9-13.4 volts for a 12 volt battery. Flooded battery life can be extended if an equalizing charge is applied every 10 to 40 days. This is a charge that is about 10% higher than normal full charge voltage, and is applied for about 2 to 16 hours. This makes sure that all the cells are equally charged, and the gas bubbles mix the electrolyte. If the liquid in standard wet cells is not mixed, the electrolyte becomes "stratified". You can have very strong solution at the top, and very weak at the bottom of the cell.
So it sounds like a 60 amp converter/charger would be more than enough for 440 ah battery bank.

Right?
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Old 04-02-2016, 07:50 PM   #4
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Originally Posted by opie View Post
And from 12 volt side of life..



So it sounds like a 60 amp converter/charger would be more than enough for 440 ah battery bank.

Right?
Opie, I have a 440 AH bank as well and a PD 9270 with a charge wizard. I also have about 22 feet of #8 between my converter and the battery bank. With this setup the most I ever get on the batteries is about 14.2 volts and it works fine. I doubt if the 60 to 70 makes a lot of difference since I have never seen 70 amps anyway. This wizard is nice since I can force it into boost mode. I am planning on eliminating the negative #8 lead and grounding the negative to the chassis.

You should be fine.
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Old 04-02-2016, 08:05 PM   #5
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Originally Posted by ScottBrownstein View Post
Opie, I have a 440 AH bank as well and a PD 9270 with a charge wizard. I also have about 22 feet of #8 between my converter and the battery bank. With this setup the most I ever get on the batteries is about 14.2 volts and it works fine. I doubt if the 60 to 70 makes a lot of difference since I have never seen 70 amps anyway. This wizard is nice since I can force it into boost mode. I am planning on eliminating the negative #8 lead and grounding the negative to the chassis.

You should be fine.
Thanks for that. My negative lead is grounded to the A frame about 3' away from the batteries.

I have also been reading about leaving the stock converter charger in and locating a better unit closer to the batteries. I like this option but wiring the additional unit in has me puzzled.
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Old 04-03-2016, 12:32 AM   #6
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Maybe this will help.
INTELI-POWER PD9260 for Better RV Battery Charging
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Old 04-03-2016, 03:45 AM   #7
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You will not find better info on rv battery charging than here:
https://handybobsolar.wordpress.com/...ging-puzzle-2/

It is a long article, but he knows what he's talking about as he has lived in his rv for many years.
Although he uses solar for his battery charging, all the tech aspects apply to any type of battery charging system.

Using much of his advice, my system has been working/charging flawlessly for 2 1/2 years now. (I live in my W&P)
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Old 04-03-2016, 07:28 AM   #8
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Originally Posted by Silverado2500HD View Post
So perhaps I have been misunderstanding.... Folks that purchase a charger and locate it closer to the batteries are not relying on it to convert 120 to 12 to run the 12v in their trailer while plugged in?

Thats what is stumping me... Is a "closer to the batteries" converter charger replacing an OE unit or is it being run as a standalone. Seems like there would be some wiring to be done to relocate the OE unit and still have it function as a converter charger for the TT.

Admittedly, though, I don't have a full grasp of TT wiring yet.
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Old 04-03-2016, 08:15 AM   #9
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Originally Posted by Snuff Gear View Post
You will not find better info on rv battery charging than here:
https://handybobsolar.wordpress.com/...ging-puzzle-2/

It is a long article, but he knows what he's talking about as he has lived in his rv for many years.
Although he uses solar for his battery charging, all the tech aspects apply to any type of battery charging system.

Using much of his advice, my system has been working/charging flawlessly for 2 1/2 years now. (I live in my W&P)
Thanks for the link. Ive seen it but never read through its entirety.

What I am taking away from what he wrote is there isn't a converter/charger on the market that will properly charge a battery. The majority of what he wrote, 2/3 or so, is specific to solar units and solar charging. Perhaps its because it has not been updated in regards to currently available converter/chargers on the market that say they put out 14.4-14.8 volts in bulk mode.
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Old 04-03-2016, 08:18 AM   #10
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I have a converter that came with the camper and I recently purchased a PD 70amp converter. I have just installed a bank of four six volt batteries separate from the camper battery bank, I have a 40amp battery charger. Would it be better to hook the PD 70amp converter up to the new bank of batteries or use the 40amp battery charger. I have a 3,000 watt inverter hooked up to the new bank of batteries, I plan to use the new bank for dry camping


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Old 04-03-2016, 08:33 AM   #11
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I believe folks are wanting to take wire size out of the equation by placing a larger converter/charger closer to the battery. My last rig had a 100 amp charger and although when the batteries (2x Trojan T105's) were low charging would start off at 70+ amps but drop down to 40+ amps in less than a minute. The batteries will only take what they can and a larger charger won't do anything. My Trojan info sheet said to use a charger rated at 25% on the amp hr rating of the battery bank. (220x25%=55amps)
My only reason for switching out the Wfco charger to my PD9145A was because I found out quickly that the OEM unit never reached float charge so I was going to be adding water to the batteries and replacing them every two years. My previous experience with the PD's has been very good. The T105's had been in the MH for 7 years and during 6 of those we spent at least 90% of the summers dry camping out west for 4-6 months at a time. I put the PD in the MH to run in the garage at home and so I could charge with the Honda 1000 while dry camping. I knew the stock Xantrex unit would destroy the batteries in storage because its float was 13.5 to 13.8 volts.
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Old 04-03-2016, 08:50 AM   #12
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Another of my dumb questions.............

Why can't you simply install one of these:
Minn Kota MK-440D 4 Bank On-Board Battery Charger -
directly to 4 batteries (or get the 2 Bank model if you have two batteries), regardless of what else the batteries are connected to?

This is what I have on my boat. I leave it on anytime the boat is parked. It charges fully, then maintains.........

Why wouldn't it do the same to a trailer battery bank? Why replace what is there? I admit I am unsure......but that seems the simplest to my simple mind.
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Old 04-03-2016, 09:50 AM   #13
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Originally Posted by dontay View Post
I believe folks are wanting to take wire size out of the equation by placing a larger converter/charger closer to the battery.
Yes, I believe that is the driving factor as well.

But how do you wire it back into the power center? Is it as simple as the existing 8 gauge wires carrying what it needs back and giving the remainder to the batteries? How would one wire in their battery meter? Again, is it simple and I am overlooking it because "it cant possibly be that simple?"

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Originally Posted by dontay View Post
My last rig had a 100 amp charger and although when the batteries (2x Trojan T105's) were low charging would start off at 70+ amps but drop down to 40+ amps in less than a minute. The batteries will only take what they can and a larger charger won't do anything. My Trojan info sheet said to use a charger rated at 25% on the amp hr rating of the battery bank. (220x25%=55amps)
IIRC, in the "12v side of life" the equation was 10% of total amp hours. That and another one I read said volts are more important than amps. 6v batteries should be charged around 14.4-15 volts.

Right now I have 2 Duracell EGC2 batts from Sams. Haven't put them into service yet but I am making provisions for 2 more. I purchased a Blue Sea disconnect that will allow me to set them up as 2 separate banks on the switch but be able to combine them through the switch.



At this point I am leaning towards upgrading the existing wiring from the batteries to the charger. My ground hooks to the frame 3 feet from the batts so I only need to carry positive back.

BUT.... If I move the charger closer to the batts I can get this this
which will charge in bulk at 14.8, it just wont fit in the existing opening. I know I could always leave the OE unit and simply run the PD unit as a standalone charger.... But at that point I could also simply buy a 3-4 stage battery charger...
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Old 04-03-2016, 10:00 AM   #14
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Quote:
Originally Posted by BandJCarm View Post
Another of my dumb questions.............

Why can't you simply install one of these:
Minn Kota MK-440D 4 Bank On-Board Battery Charger -
directly to 4 batteries (or get the 2 Bank model if you have two batteries), regardless of what else the batteries are connected to?

This is what I have on my boat. I leave it on anytime the boat is parked. It charges fully, then maintains.........

Why wouldn't it do the same to a trailer battery bank? Why replace what is there? I admit I am unsure......but that seems the simplest to my simple mind.
That looks like a nifty little unit. And being that is for a boat, one could probably mount it next to the batteries.

This is what Im using as a battery box...


I found this after looking around on the web. There is one caveat (issue) that I ran into. The individual that found this and used it stated it would work for 6v batts but showed it with 1 group 24 sized battery in it. It wont work with 6v batts without adding a piece of 1/4" something to the bottom. Otherwise the batteries, if you are using 4, will sit on whatever is used to attach the box to the frame. Height wise there isn't enough room in the box to do that so the channel that runs along the lid needs to be trimmed and modified to make clearance. The picture isn't exactly representative of the unit they sell at the stores. If it was, than no modification would need to be made.

EDIT: In composing this post is when I noticed the difference on the interior configuration of the lid. I may return this box and purchase one off amazon that wont need the lid modified.
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Old 04-03-2016, 10:16 AM   #15
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Originally Posted by ScottBrownstein View Post
Opie, I have a 440 AH bank as well and a PD 9270 with a charge wizard. I also have about 22 feet of #8 between my converter and the battery bank. With this setup the most I ever get on the batteries is about 14.2 volts and it works fine. I doubt if the 60 to 70 makes a lot of difference since I have never seen 70 amps anyway. This wizard is nice since I can force it into boost mode. I am planning on eliminating the negative #8 lead and grounding the negative to the chassis.

You should be fine.
Re quoting because Ill probably do this and if I find voltage at the batts lacking, then Ill upgrade the wiring. Seems like the simplest solution.
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Old 04-03-2016, 10:21 AM   #16
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Yes, I believe that is the driving factor as well.

But how do you wire it back into the power center? ...
Opie,

In many units the converter is not part of the power panel but is a separate unit the routes back to the battery bank and does not go through the panel. It seems that Trojan and others (Solar Bob) have now begun to recommend higher boost charge voltages to maintain 100 SOC. We are not talking about equalization here, but simply boost. While most converters seldom are able to put out their rated output for more than a few minutes, the voltage drop in the wire from the converter back to the batteries can be a serious limitation to even getting the 14.5 volt boost mode from most converters. In my RV I lose around .4 volts in the #8 wiring. #6 would have been better. My engine alternator actually gives me more like 14.5.

If you want, get a 14.8 PD and wire it to the batteries (and the frame) with #6 and either turn off your existing converter, or leave them both on. The lower voltage converter will back off when it senses the higher voltage from the new unit but it won't harm anything but I agree it doesn't seem that clean.

Put in a Trimetric and if you like put in 150 watts of solar on a Bogart SC-2030 charge controller. It will support the higher boost voltages when required and can be set to any number of top end voltages depending on the make of battery that you have. It also will compensate for the drop in the wiring from the controller to the battery since it gets is voltage data (and SOC, and current, etc) from the Trimetric over a digital interface. That way you get a nice boost and "mini-equalization" every day the sun shines...and always have 100% SOC. In fact, since it knows how much you took out when you discharged, it is able to provide that +10 or 15 percent overcharge that battery manufacturers recommend,since the Trimetric has that data.

Solar Bob loves it! https://handybobsolar.wordpress.com/...-2030-perfect/
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Old 04-03-2016, 10:33 AM   #17
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Originally Posted by opie View Post
Thanks for the link. Ive seen it but never read through its entirety.

What I am taking away from what he wrote is there isn't a converter/charger on the market that will properly charge a battery. The majority of what he wrote, 2/3 or so, is specific to solar units and solar charging. Perhaps its because it has not been updated in regards to currently available converter/chargers on the market that say they put out 14.4-14.8 volts in bulk mode.
Take what he says about converters with a grain of salt, the information is not all that accurate.
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Old 04-03-2016, 10:55 AM   #18
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Originally Posted by ScottBrownstein View Post
Opie,

In many units the converter is not part of the power panel but is a separate unit the routes back to the battery bank and does not go through the panel. It seems that Trojan and others (Solar Bob) have now begun to recommend higher boost charge voltages to maintain 100 SOC. We are not talking about equalization here, but simply boost. While most converters seldom are able to put out their rated output for more than a few minutes, the voltage drop in the wire from the converter back to the batteries can be a serious limitation to even getting the 14.5 volt boost mode from most converters. In my RV I lose around .4 volts in the #8 wiring. #6 would have been better. My engine alternator actually gives me more like 14.5.
Doesn't the converter/charger send its 12v output through the fuses/12v distribution panel prior to going to the batteries? How it was explained to me is when not connected to shore/generator the 12v system runs off the batteries. When connected to shore/12v all the 12v systems run off the converter and any extra goes to the batteries.

I know its not "part" of the panel, but it generally sits right below it.

I'm not necessarily interested in a 100% SOC 100% of the time, I just don't want to ruin the batteries due to improper charging.

Quote:
Originally Posted by ScottBrownstein View Post
If you want, get a 14.8 PD and wire it to the batteries (and the frame) with #6 and either turn off your existing converter, or leave them both on. The lower voltage converter will back off when it senses the higher voltage from the new unit but it won't harm anything but I agree it doesn't seem that clean.

Put in a Trimetric and if you like put in 150 watts of solar on a Bogart SC-2030 charge controller. It will support the higher boost voltages when required and can be set to any number of top end voltages depending on the make of battery that you have. It also will compensate for the drop in the wiring from the controller to the battery since it gets is voltage data (and SOC, and current, etc) from the Trimetric over a digital interface. That way you get a nice boost and "mini-equalization" every day the sun shines...and always have 100% SOC. In fact, since it knows how much you took out when you discharged, it is able to provide that +10 or 15 percent overcharge that battery manufacturers recommend,since the Trimetric has that data.

Solar Bob loves it! https://handybobsolar.wordpress.com/...-2030-perfect/
I finally decided to stop over analyzing it and ordered the 60amp Boondocker and the TriMetric 2030rv. Once I get everything installed Ill at least know where I stand and what improvements can be made and more importantly, where they need to be made.
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Old 04-03-2016, 11:16 AM   #19
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From my battery charger or the converter to the batteries will be no more than two feet. I just don't know what would be best, the 70amp converter or the 40amp battery charger.


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Old 04-03-2016, 11:59 AM   #20
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The biggest problem we all have is achieving the 15+ volts required for periodic equalizing. Equalizing at 15+ volts would be detrimental to some of the 12v electronics in our campers. If you can apply 15+ volts, you should disconnect (separate) the battery from the load side of the camper and only apply 15+v to the battery(s). The only charger I know of that has an equalizing mode is made by Xantrex. (Of course there may be others that can equalize.) The PI chargers talk about the boost mode for equalizing, but that only achieves 14.4v, not the needed 15+v.
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