I am planning on upgrading my batteries to 4 6v batteries wired in series and parallel to have a 12v system with plenty of Amp Hours. There is a ton of information on how to wire things up but nothing on how to charge them both to top them off while boondocking and long term during the winter month's. Do I have to disconnect the parallel connection and charge them as 2 separate 12v banks (2 banks of 2 6v in series) or unhook everything and charge as 4 independent batteries or is there a charger that can charge all 4 batteries without disconnecting any of the battery connections? Also, what would be a good battery charger to get to accomplish the charging? I have an inverter generator and I'm looking at portable solar panels in the future to use while camping and will be storing the batteries in my basement during the winter month's. Thanks for your input.

I am currently working on the same battery bank layout with two groups of two 6VDC GC2 batteries wired in series.It will look something similar to this layout...Roy's imageI will be using the PD9260C Converter/charger unit to charge the whole battery bank using 12VDC with the capacity of around 60AMPS DC current.I have never played with the 6VDC GC2 batteries in series before so I do not know how many AMPs DC current each of the two groups of two 6VDC batteries will be demanding when first hit with 14.4VDC Boost charge voltage.I suspect they will demand around 20AMPS per group of the two 6VDC Batteries in series.This will relate to around 40AMPS Total DC Current demand for the two groups of 6VDC batteries in series the first 15 minutes or so before they start tapering back.I am looking to be able to return my 50% depleted battery bank from its 50% charge state up to its 90% charge in around three hours time using the PD9260C Converter/charger unit. I will be using my 2KW Generator to power up the PD9260C converter/charger unit during this time period.My planned Trojan T-105 Batteries really want to see around 14.8VDC for the initial charge sequence but I will only be using 14.4VDC... I am hoping this will work just fine but perhaps taking alittle longer than the three hour charge routine...I have been asking the battery bunch here for a month or so now how many DC Amps demand two groups of two 6VDC GC2 batteries will want to see when first hit with 14.4VDC charging voltage.. Not getting a good answer I am planning now to just measure this for myself when I finally get to purchase the 4EA 6VDC GC2 T-105 batteries... Hoping I won't have to purchase a 80A DC current PD9280 converter/charger unit...My current three 12VDC batteries in parallel want to demand around 17AMPS for each of the three 12V batteries wired up in parallel for a total of around 53AMPS when first hit with 14.4VDC.My game plan at any rate haha...Roy Ken

1 battery or 10 is not that different. I recommend you verify that you have a good three stage converter and just leave the RV plugged in. Charge 48 hours and use a disconnect switch if you cannot stay plugged in. No need to remove any parallel connections.

Leave them all wired up and just charge them with the rig's converter, using either shore power or generator power. No need to take them inside for the winter unless you have no shore power over the winter. the converter will look after them.How many watts is the inverter-generator you bought after the previous thread of yours on that? That will be your limiter on how big in amps of a charger/converter you can run with it.If you do take the batts inside for the winter, you will need a "maintenance charger"--usually about 2 amps that holds a steady voltage like 13.4v the whole time it is plugged in. (DO NOT get a "manual" "trickle charger" for that job! It will let the voltage climb way high, and overcharge the batteries.)EDIT--Roy, to repeat myself here on your question, a 50-90 on 440AH with a 55 amp charger will take about 106 minutes for the bulk stage. At about 72% SOC, amps will taper for the absorption stage, that will take about 172 minutes. So total time will be about 4.6 hours.If you want to do it in 3 hours you will need to do just 50-80s instead of 50-90s, or try 40-80s if you need the AHs. If you had more generator, you could go to higher amps charging to get a faster recharge.The four batts will not "demand" a limited amount of amps in bulk. Forget that notion, please :( The 440AH bank will "accept" at least 160 amps at 50% no sweat, so don't worry about that.

Leave the batteries hooked together in their 12V series-parallel connection for charging.For winter storage, there's generally little need to remove the batteries to your basement. The cold will not hurt the batteries in the least so long as they aren't discharged. If you charge them fully and disconnect them (so there are no parasitic loads), they will not self-discharge too much over a New York winter as self-dischrage rates are quite temperature dependent and much lower at cold temperatures. If you have solar or power available, so much the better to keep them charged up in the RV.What charger or converter to use depends somewhat on how big a generator you have. For boondocking, the general goal would be to get as much charge into the batteries as quickly as possible, which boils down to having a charger or converter with a sufficiently high voltage output that maximizes the (apparent) power the generator can produce. Many converters have rather poor power factors, so the apparent power is somewhat higher than the actual power consumption.(If you aren't familiar with apparent power vs. real power, here's a quick rundown. "Apparent power" is the product of the RMS current and RMS voltage of an AC load, the two measured independently. "Real power" is the actual rate of energy consumption, computed by integrating the instantaneous power over time. Apparent power will be higher than real power if the current waveform is not a sine wave in phase with the voltage waveform. The ratio of real power to apparent power is the power factor, which is always less than 1 and often expressed as a percentage.)

BFL13 - Thanks for the info... I tried to PM you earlier but that wasn't allowed on your end...I guess the word demanding is the issue. I do know on my 12V batteries if I am using 14.4VDC as charge voltage it will show 53AMPS DC current being drawn from my 60A source of power... If I had 200AMPS capacity in my battery charger it will still only show around 53AMPs which is determined by the batteries internal resistance I suspect. The only way for me to show more DC Current would be to raise the DC charge voltage... This is where I was coming from on using the word 'demanding'...I will only have 14.4-13.6-13.2 DC voltages available using my 60AMPS PD9260C charger unit... My fear was it would want to draw more than 60AMPS when I was using the 14.4VDC mode for the two groups of 6VDC GC2 batteries connected in series. I don't really want to purchase a larger current capacity Battery charger at this time. Stretching funds now living off retirement checks hehe... The 4.6 hours will fit into my daily routine of charging the batteries when camping off grid at my normal camping spots. We have generator run time restriction big time around where I live here in Virginia. As soon as the batteries taper back to around 6-8AMPS for each battery then I will be able to switch to solar panels once I get those installed if I have good sun for the rest of the day. Hoping this will cut back on my generator use to just over an hour a day required. The solar panel DC Current output looks like is going to be around 20AMPS total DC current for the three panels in high sun I will be installing on my POPUP roof...Think I will be in good shape here doing this method of charging my batteries each day when camping off-grid...Hopefully in a couple of months I can purchase the four T-105 batteries and will be able to see for myself what the DC Current status is going to be for my setup...Thanks again for the rerun of answering my earlier question about this.Roy KenKing George, VA

Charging a Battery Bank | Good Sam Community

275 Replies

time2roll
Nomad
Jan 20, 2017
BFL13 wrote:
I pity the poor guy who wants AGMs with just a converter that does whatever it does, and he is stuck with that.
The right converter is available for any battery.
At 14.1 to 14.4 an IOTA or PD-14.4 would be fine.
Float on the PD is a bit below specs so my choice on this battery would be IOTA.
landyacht318
Explorer
Jan 20, 2017
The Deka Intimidator and its relabelled brethern are, in my opinion, a good starting battery for a car whose owner can't ever be bothered to check electrolyte levels, and has had terminal corrosion issues in the past they also could not be bothered with.

It makes an OK battery when cycled lightly and fully recharged promptly.

Perhaps the occassional deeper discharge. but the rest of their marketing.......No.

It cannot compare to a Lifeline AGM in total cycles accumulated in the same treatment, Unless of course both are chronically undercharged.

The best battery is not immune to chronic undercharging.

Manufacturer specs as to charging are general guidelines. Strict adherence is not totally necessary.

What is important is to reach as high a state of charge as possible before the next discharge begins, and to not overheat the battery.

Enter the manufacturer recommendations.

If exceedng manufacurer recommendtions were strictly prohibited, then the first pair of flooded golf cart batteries which received more than 32 amps would have exploded. Yet people here regularly charge them at 2x that rate.

If an 30% limited AGM is used as a starting battery, and say it needed a jumpstart, the alternator would easily double this 30% 'maximum' charge rate for a while anyway.

I am not saying that manufacturer recommendations are dismissable, I am saying they can be massaged.

6v AGMS do not enjoy the same advantage as flooded 6v have over their 12v counterparts, as flooded 6vs are true deep cycle, and 12v batteries, with very few exceptions, are not, and not even close.
BFL13
Explorer II
Jan 20, 2017
time2roll wrote:
Yea I would not press AGM too hard.

This AGM thing is difficult! We have Lifelines that want oodles of amps, but only 14.4v, while many others want 14.8v but only 30% amps.

Now we have this Sam's Deka that only wants 30% amps AND only 14.1-14.4 volts.

One of them? also had a minimum volts or amps spec I forget.

I am good anyway they come with an adjustable voltage charger. I pity the poor guy who wants AGMs with just a converter that does whatever it does, and he is stuck with that.
Joel_T
Explorer
Jan 20, 2017
BFL13 wrote:
Joel_T wrote:
I've got enough solar to handle conservative needs....in the sun....but we're primarily Pacific NW campers, sooo we carry a 2200w genny. I'd rather not use it at all but that's a fantasy. When I do I want it fast. I've got BFL13's pot mod at the top of my list now. I'm intrigued by the adjustable voltage. I'd forgotten about generator limits but I think my genny will push a 75a charger.

If you do get that "15 minute thing" the cure is to snip the wire at the top of R1. Now it will go straight away to the voltage you set.

If you screw that all up, just buy another one :)

The 15 minute thing was to ensure it went to 14.x Boost every time, same as Iota, where before it was like a WFCO, which needs to "see" under 13.2v at start up to go into boost. Usually with WFCOs as installed, when you start them, the battery voltage spikes to over 13.2 so it won't go into boost.

I don't know how anyone could just know this stuff. You really must enjoy it all. You officially qualify as a charger junky. :-)
BFL13
Explorer II
Jan 20, 2017
Joel_T wrote:
I've got enough solar to handle conservative needs....in the sun....but we're primarily Pacific NW campers, sooo we carry a 2200w genny. I'd rather not use it at all but that's a fantasy. When I do I want it fast. I've got BFL13's pot mod at the top of my list now. I'm intrigued by the adjustable voltage. I'd forgotten about generator limits but I think my genny will push a 75a charger.

If you do get that "15 minute thing" the cure is to snip the wire at the top of R1. Now it will go straight away to the voltage you set.

If you screw that all up, just buy another one :)

The 15 minute thing was to ensure it went to 14.x Boost every time, same as Iota, where before it was like a WFCO, which needs to "see" under 13.2v at start up to go into boost. Usually with WFCOs as installed, when you start them, the battery voltage spikes to over 13.2 so it won't go into boost.
time2roll
Nomad
Jan 20, 2017
Yea I would not press AGM too hard.
Joel_T
Explorer
Jan 20, 2017
I've got enough solar to handle conservative needs....in the sun....but we're primarily Pacific NW campers, sooo we carry a 2200w genny. I'd rather not use it at all but that's a fantasy. When I do I want it fast. I've got BFL13's pot mod at the top of my list now...and the warranted version at #2 :-) I'm intrigued by the adjustable voltage to handle different objectives, different batteries or different temperatures. All this may not be that big a deal but if I can't find out I'll never know. I'd forgotten about generator limits but I think my genny will push the 75a charger.
BFL13
Explorer II
Jan 19, 2017
RobWNY wrote:
Based on eveyone's input into this thread, I've made a decision. I've decided to take SoundGuy's advice and buy 2 6V batteries instead of 4. I'm still going to get the AGM batteries though. Since I can't get Trojan's locally and only one brand of AGM battery is sold locally, I've decided I will buy the Duracell's that are sold at Sams Club. My WFCO 8955 converter/charger works fine to convert ac to dc but appears to have issues charging. My fuse is good and from what I can see of my wiring, it looks good as well. Instead of spending more time figuring out what exactly is my issue, I'm going to take the advice of BFL13 and buy a deck charger to accomplish my charging needs. I'm leaning toward the Power Dynamics PD9260 model but I don't know which one to get. There are two. The PD9260C and the PD9260C-14.8 I can't seem to find the voltage specs for the Duracells so I don't know if 14.8 would be too much? I plan on using the remote pendant for those units as well. Any suggestions on which model to buy?

I posted those Deka specs already. Here they are again

http://www.mkbattery.com/documents/9037Renewable%20Energy%20Charging%20Parameters.pdf

The regular 14.4v PD meets the Deka AGM specs, while the 14.8 would be over.
SoundGuy
Explorer
Jan 19, 2017
RobWNY wrote:
Based on eveyone's input into this thread, I've made a decision. I've decided to take SoundGuy's advice and buy 2 6V batteries instead of 4. I'm still going to get the AGM batteries though. Since I can't get Trojan's locally and only one brand of AGM battery is sold locally, I've decided I will buy the Duracell's that are sold at Sams Club. My WFCO 8955 converter/charger works fine to convert ac to dc but appears to have issues charging. My fuse is good and from what I can see of my wiring, it looks good as well. Instead of spending more time figuring out what exactly is my issue, I'm going to take the advice of BFL13 and buy a deck charger to accomplish my charging needs. I'm leaning toward the Power Dynamics PD9260 model but I don't know which one to get. There are two. The PD9260C and the PD9260C-14.8 I can't seem to find the voltage specs for the Duracells so I don't know if 14.8 would be too much? I plan on using the remote pendant for those units as well. Any suggestions on which model to buy?

Go here and you'll see Duracell batteries are actually manufactured by East Penn. These are in fact Deka batteries, sold also here in Canada labelled as RV Care batteries ... ALL the same.

Deka Intimidator AGM Batteries

Here's a pic I took at my local dealer's of an RV Care branded 8A27 AGM and on the left you can see recommended charge voltages, along with the warning that temp compensation must be used.

This same information would apply to the 6 volt 8AGC2, regardless that it may be wearing a Duracell label.

JMO, but regardless of which charger you go with I'd leave the existing WFCO as is, turn it off, mount the new charger in the front pass through cargo compartment close to the batteries, and use it only as a charger, thereby avoiding potential voltage loss issues along too small gauge cable running from the WFCO to the batteries.
RobWNY
Explorer
Jan 19, 2017
Based on eveyone's input into this thread, I've made a decision. I've decided to take SoundGuy's advice and buy 2 6V batteries instead of 4. I'm still going to get the AGM batteries though. Since I can't get Trojan's locally and only one brand of AGM battery is sold locally, I've decided I will buy the Duracell's that are sold at Sams Club. My WFCO 8955 converter/charger works fine to convert ac to dc but appears to have issues charging. My fuse is good and from what I can see of my wiring, it looks good as well. Instead of spending more time figuring out what exactly is my issue, I'm going to take the advice of BFL13 and buy a deck charger to accomplish my charging needs. I'm leaning toward the Power Dynamics PD9260 model but I don't know which one to get. There are two. The PD9260C and the PD9260C-14.8 I can't seem to find the voltage specs for the Duracells so I don't know if 14.8 would be too much? I plan on using the remote pendant for those units as well. Any suggestions on which model to buy?

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Charging a Battery Bank

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