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Old 09-27-2022, 02:01 PM   #1
bighamstoy
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Charging 450AH battery bank

Iím looking to buy a battery charger that will charge my 4 battery, 450Ah battery bank. Maybe at least a 50 or 60 amp charger. Something I can plug into my generator to charge my batteries back to full capacity quickly. Chargers Iíve found go to 30 or 40 amps and the higher amps are to jump start (60 second timer). Any suggestions?
 
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Old 09-27-2022, 03:01 PM   #2
Carl n Susan
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You don't mention the year and model of your RV, but if it is less than 10 years (or maybe more) older, the onboard converter is more than adequate to charge non-lithium battery banks. MY 2012 keeps my 600 amps of GC batteries charged nicely from the generator.
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Old 09-27-2022, 03:31 PM   #3
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Sorry forgot. I have a 2017 3610RL. Ran the generator for 4 hours and batteries still weren’t fully charged. Don’t have any solar (yet) but research says I need around 80 amps charge rate (20% of battery amp hours). Have a 15 amp charger and took about 30+ hours to fully charge batteries.
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Old 09-27-2022, 04:09 PM   #4
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Sorry forgot. I have a 2017 3610RL. Ran the generator for 4 hours and batteries still werenít fully charged. Donít have any solar (yet) but research says I need around 80 amps charge rate (20% of battery amp hours). Have a 15 amp charger and took about 30+ hours to fully charge batteries.
How much load is on the batteries during the "30 hours to fully charge batteries"? What is type and size of each battery in the bank?
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Old 09-27-2022, 04:13 PM   #5
Carl n Susan
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AFAIK, the generator and stock converter will get you to 90+% of charge in a couple of hours. That last 10% takes time regardless of the charging amp rating.
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Old 09-28-2022, 07:56 AM   #6
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More info. I have 4 Everstart 29D deep cycle batteries (yes, Walmart specials, but work great) each having 112AH. I was reading about "balanced" and "unbalanced" battery banks, and mine were unbalanced. The article showed how unbalanced systems would use some of the batteries (depending how it was connected) more than others. So, I followed the diagram and connected them balanced. Sure enough, it takes much more use before they drain down. It also takes much longer to charge them, now that everything is balanced. When charging at home (battery disconnect off, so no load) is when it takes 24-30 hours to charge them @15 amps. By the way, had 2 Interstate batteries (when my battery bank was only 2) and they failed after 2 years. These Everstarts are 2 years old and still working great!
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Old 09-28-2022, 07:58 AM   #7
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AFAIK, the generator and stock converter will get you to 90+% of charge in a couple of hours. That last 10% takes time regardless of the charging amp rating.

Maybe that last 10% is why I can't get the "full" light to come on. Never goes above the 2/3 light while dry camping.
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Old 09-28-2022, 09:57 AM   #8
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Quite frankly I'd load test the batteries. I can get a full charge in 30 minuets using my Onan 3600. One bad battery will kill um all.
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Old 09-28-2022, 09:59 AM   #9
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More info. I have 4 Everstart 29D deep cycle batteries (yes, Walmart specials, but work great) each having 112AH. I was reading about "balanced" and "unbalanced" battery banks, and mine were unbalanced. The article showed how unbalanced systems would use some of the batteries (depending how it was connected) more than others. So, I followed the diagram and connected them balanced. Sure enough, it takes much more use before they drain down. It also takes much longer to charge them, now that everything is balanced. When charging at home (battery disconnect off, so no load) is when it takes 24-30 hours to charge them @15 amps. By the way, had 2 Interstate batteries (when my battery bank was only 2) and they failed after 2 years. These Everstarts are 2 years old and still working great!
Having used 12V batteries for years on boats I've owned and had as many as 3 battery banks containing as many as 6 batteries to a bank I am very familiar with charging the battery correctly. If your batteries are all the same brand, group size and have same specifications then connecting them in parallel is all that is required. All connecting cables need to be the same size cable and length as well. You do not need to balance batteries in parallel. Am I missing something in your application? I have 3 Interstate SRM24 deep cycle batteries on my Monty all connected in parallel and they are charged by the onboard Keystone charger installed in 2005 and have no issues whatsoever.
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Old 09-28-2022, 10:06 AM   #10
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AFAIK, the generator and stock converter will get you to 90+% of charge in a couple of hours. That last 10% takes time regardless of the charging amp rating.
Your statement is 100% correct for what my generator and stock OEM charger/converter do.
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Old 09-28-2022, 07:04 PM   #11
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Iím looking to buy a battery charger that will charge my 4 battery, 450Ah battery bank. Maybe at least a 50 or 60 amp charger. Something I can plug into my generator to charge my batteries back to full capacity quickly. Chargers Iíve found go to 30 or 40 amps and the higher amps are to jump start (60 second timer). Any suggestions?

My suggestion is to purchase a separate progressive dynamic deck mount converter/charger. Something like the 9260, 9270 or even the 9280.
Keep your existing converter/charger as is. Don't mess with it at all.
Mount the new one as close to the batteries as you can to keep wire length short. Use the supplied pendant to use the boost mode,14.6 volts and much higher amps, to quickly get your battery bank back up to 90%. The last 10% will still take a while but you'll reduce your over-all charge time significantly.
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Old 09-28-2022, 07:32 PM   #12
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You cannot charge lead acid that fast. That is the problem. Look at the charge algorithm for bulk, absorb and float for those batteries. That is the big advantage of lithium batteries, they’ll take 100 amps. But, lead acids charge more in the 10\15 amp per hour range. You will shorten the life significantly doing it faster. https://www.upsbatterycenter.com/blo...20expiration).
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Old 09-28-2022, 08:43 PM   #13
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But, lead acids charge more in the 10\15 amp per hour range. You will shorten the life significantly doing it faster. https://www.upsbatterycenter.com/blo...20expiration).

Deka, one of the worlds largest lead acid battery manufacturers, says 30% of C20 for their true deep cycle batteries. That's double what you are stating above and what I've been doing for 30 years. I average 5 to 7 years out of 6 volt GC2 batteries. I've ran them for decades in my scissor lifts with daily charge/discharges. Always charged at a much higher rate than you state above.

You do not "push" amps into a lead acid battery. They "pull" amps as needed per depth of discharge and quickly reduce their draw as you begin charging. I've run 470 amp hours of 6 volt GC2 in campers for many years. I have 120 charging amps available if needed but rarely see them pull more than 80 for a brief time before they start dropping. True deep cycle lead acids are absolutely capable and recommended to be charged at 30% C20.
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Old 09-29-2022, 06:10 AM   #14
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While that may be true, keep in mind that the lead plates in a GC2 6 volt battery are more than twice the thickness of the plates of a normal 12 volt deep cycle. They are workhorse batteries meant to be charged/discharged a great deal.
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Old 09-29-2022, 08:27 AM   #15
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As Bob mentioned, the OP has standard deep cycle batteries. They are not the same thing as the deep cycle that Creeker mentioned. Rather than putting money into charge system, I would recommend spending $100 on a smart shunt (Victron) monitor and also looking at lithium batteries if you are boondocking a lot. Also, lead acid drops voltage at a much quicker rate than lithium. With my last rig, I used a Bogartbattery meter and 4 6v batteries. I usually was under 12v before I got to 50% discharge.
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Old 09-29-2022, 09:45 AM   #16
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One word solar is the answer. Ok four words..... As long as there is sun my batteries stay charged all day. Firing up the gen for any heavy loads. Best investment unlike my home solar which we wont talk about...
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