What charger should I use?

BFL13 wrote:
I was sort of hinting that you could get a deck mount and use it as a portable now, and still have that handy as a portable when you get your new rig. No reason to give it away to the guy that buys your old rig.

It is always good to have a spare charger along in case your converter dies while on shore power somewhere. Means no need to panic and buy the replacement converter at some outrageous price at the nearest RV store.

This is exactly my M.O. Use it as portable. I've no idea how long I'll be keeping the 21 footer, or will I want to upgrade... hence the portable solar panel set and the PD9245C with 8 gauge wire and ring terminals. Works fine, so far, for my applications. A 150 amp hour battery can only take so much charging rate. 45 ah as max is fine, more than enough, for my uses. If I get a different rig, these items will come with me, not go with the unit to the new owner.

I was sort of hinting that you could get a deck mount and use it as a portable now, and still have that handy as a portable when you get your new rig. No reason to give it away to the guy that buys your old rig.

It is always good to have a spare charger along in case your converter dies while on shore power somewhere. Means no need to panic and buy the replacement converter at some outrageous price at the nearest RV store.

trikepilot wrote:
Because you use yours as a portable unit I like the idea of the strain relief on the cables. In a permanent installation replacing my 6345, I could get by without it. I wonder if I were to solder the exposed wires together into a tinned strip and insert that into lugs. Would the solder melt with enough amperage flowing through the wires? I have used a propane torch before to solder brass lugs onto a jumper cable wire when I was using the eyelets instead of clamps at one end. They never failed but I could have just been lucky. Last thing I want to do is burn the MH to the ground.
The cables I have are pretty beefy. Designed to jump start a diesel from a vehicle parked behind it. 30 ft long and probably 12 to 15 lbs of copper, brass, and insulation. Thanks for the pictures BFL13.

I have seen stranded cables with the ends tinned like that to go in set-screw terminals. Not sure you need to do that for a better grip, but can't hurt I guess. would keep stray strands poking out and touching the other terminal--I used the tape for that.

Terminal and wire will only get hot if the connection is loose. No idea how hot it has to get to melt any solder. The other end of the set screw terminals is bolted to the circuit board and solder is on that to hold the wires that run through those reverse polarity fuses.

The chassis ground lug should be used with the deck mount when actually installed as shown in the second photo in the OP here back when I had it that way.

http://forums.trailerlife.com/Index.cfm/fuseaction/thread/tid/26237237.cfm


You don't need that with a lower portion replacement because its metal case touches the main power centre metal case and that is grounded to the frame already with the 120v bare copper wire to the 30a main breaker and also with some 12v grounds to the frame.

Those blue wires in the photo were store bought #1 gauge--I got 106 amps as what the 100amper did.

http://www.canadiantire.ca/en/pdp/switch-to-starter-battery-cable-1-gauge-0111088p.html#.Uz2wRGdOVjo

trikepilot wrote:
OK here is a question for those who are showing the math in their responses. The math that I do not understand. Since I am going from a 6345 charger powering one group 24 battery with 75AH capacity, to now having three group 24s with 225AH capacity, will I gain any advantages from using a higher amp charger?

Short answer: You will cut perhaps 15-20 minutes off the recharge time, All of this in the BULK section of charging.

Long answer: At the cost of slightly more freequent battery replacement (Very slight, perhaps 9.5 instead of 10 years).

I would still consider a pair of GC-2's. each pair of those is as good as your 3 Group 24's. and other than being slightly taller, fit in much the same tray.. I just put a new pair of them in my coach. The "OUCH" part was the injury I got from the old ones when I dropped it on me. The OUCH! Well... Good batteries hurt the wallet and I got good ones. I figure to be in my 70s when I next have them replaced.

Because you use yours as a portable unit I like the idea of the strain relief on the cables. In a permanent installation replacing my 6345, I could get by without it. I wonder if I were to solder the exposed wires together into a tinned strip and insert that into lugs. Would the solder melt with enough amperage flowing through the wires? I have used a propane torch before to solder brass lugs onto a jumper cable wire when I was using the eyelets instead of clamps at one end. They never failed but I could have just been lucky. Last thing I want to do is burn the MH to the ground.
The cables I have are pretty beefy. Designed to jump start a diesel from a vehicle parked behind it. 30 ft long and probably 12 to 15 lbs of copper, brass, and insulation. Thanks for the pictures BFL13.

Any old wire will do as long as it is fat/short enough for the job. Jumper cables come in all gauges, most kind of thin but they look fat with the insulation on them #4 copper is the thinnest I would go to still get full amps.

Attachment depends on the terminal type of the converter or charger you choose. Many use the set screw type with a limited gauge of wire you can get in there.

If your wire is too fat you have three methods, all work and you don't lose any amps:

- shave off some strands until it goes in, or
- use a short piece of wire that will fit and attach the fatter wire to that.
-use one of those wire terminals that have a little spike on the end so it will fit in (can't remember what those are called--step-down?)

If the wire you use has a million thin silky strands instead of a few fat strands, the silky end is hard to keep in the set screw. In my case, using cut off jumper cables for my portable, I added a sort of strain relief as shown in the photo (just an idea, might not be needed with an installed charger)

(I have a modified PowerMax 100amper I use as a portable for on Honda 3000 gen, and I kept the trailer's original converter for when on shore power) I cut off the end of a heavy set of jumper cables so it has clamps like a portable.

Any deck mount converter can be used this way



Here is how I rigged up a strain relief for the heavy cables I used (probably overdid it there, but I had a set of heavy jumper cables doing nothing so I cut off one end and used that. I used the chassis ground lug as the support as shown. I also put some red tape by the pos terminal to help me keep things straight :(

Another thing is the two wires are close together at the terminals and it is hard to keep a few strands from poking out and touching the other, so some tape there helps keep them apart.

Thank you BFL13 For the chart. I don't need to know why that line is curved. Or why the higher current steps down at a lower percentage of state of charge. I just need to know what will work best. It looks like I can upgrade to a 55, 60, or 75 amp charger converter and keep my run time down to a reasonable rate. I am sure that I will have to upgrade the wires between the charger and battery bank.

One more question. Can I use the wire from an old set of jumper cables that I have laying around? I am sure that it will take the amperage, but I am unsure about the thick insulation around the wires. Is there a spec that I should concern myself with for this type of wiring?

Here are the recharge times for a 220AH bank using 35,55, and 70. You can eyeball other sizes between those.

Note how going higher has diminishing returns for saving time, so at some point it is not worth the money for a more expensive, higher amper.

You can't do these times with the 13.8v 6345, you must go to 14.4 or so, whichever brand you choose. Generally 33% is the highest charging rate you should go (75 on 225) and you are right to choose fast charging over battery life. Your batteries work for you, you are not working for them :)

OK here is a question for those who are showing the math in their responses. The math that I do not understand. Since I am going from a 6345 charger powering one group 24 battery with 75AH capacity, to now having three group 24s with 225AH capacity, will I gain any advantages from using a higher amp charger? If I choose a PM-4B converter charger I have the choice of a 45, 55, 75, or 100 amp model. What do I gain with a higher model except higher out of pocket costs? Maybe reduced generator run time? Maybe longer battery life? If I was to balance the longer battery life achieved through a slow charge rate with the extra gas burned in the generator to perform this task I might come out even in the end. If that is the case then I would opt for the faster charge rate and replacing the batteries more often. More convenient for me. Can you math guys explain why a 45 is better than a 100 or vice versa?

Thanks for all your help. I am really trying to understand this stuff. My regular weekend routine with the old setup was to run the generator for an hour and a half every morning and an hour every night before retiring.Some mornings the generator would not start and I had to start the engine for a few minutes to charge the coach battery enough to get the genny to roar to life. There were other pilots at our meetups who never ran their generator all weekend. None of them had solar. Just larger battery banks.

Looking at the thread again, Support the folks who say DO NOT BUY WFFCO made in china with typical china quality (Very high failure rate).

As to "Do I need a bigger converter"

NO. you do not.

However here is some math..

As i said a group 24 is 75 AH roughly (74-76 depending) so 30% of that (For most batteries 30% is the recommended MAXIMUM recharge rate) is 22.2 amps. So a 45 amp converter (About the smallest you can get) is max speed for a pair of Group 24's..

HOWEVER: Trojan says for best battery life use 10% of c/20, not 30. So that woudl be 15 amps for a pair of G-24's

(Lifeline AGM and only LIFELINE, says minimum 30% so if you go LIFELINE AGM, upgrade the converter)

Why the differences: Why Lifeline recommends such a fast charge I do not know.

But Trojan knows that for most Lead Acid batteries, the slower the re-charge the longer the battery lasts (In terms of years) so they sugest the slower rate.

Thus a smaller converter, provided it is a good 3-stage like a Progressive Dynamics 9245, will make the batteries last longer than a faster converter.

The 30% figure comes from Xantrex, they make chargers and inverters.