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Old 04-12-2018
Randy Dupree's Avatar
Randy Dupree Randy Dupree is offline
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Join Date: Dec 2007
Location: Port St Joe,Fl
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Originally Posted by yesmar View Post
FMCA is working on a deal that could enable us to buy Lit/ion batteries for half the price. At least that is what they said at one of the seminars I attended.

If it happens—great. If it doesn’t, then ????. I believe prices may go down in the future. But that does not help today.

Buy a Honda 2000 for $1000.00 to charge your batteries and burn 1 gallon of fuel every 8 hours.

I have friends who never dry camp and have 8 house batteries. WHY???
I bet the battery vendors at the FMCA conventions are excited to hear that FMCA is getting into the battery business!

If i never dry camped i would have maybe 2 house batteries,just enough to make the relays and stuff work.

What am i thinking? i only have one house battery now!
email me at randy@randydupree.com only.

Randy Dupree
2000 LXI 43
Port St Joe Fl.

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Old 04-12-2018
mahansm mahansm is offline
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Location: Lynn Haven
Posts: 367

Charging/Discharging rates:

Battery manufacturers use ratios involving C to describe charge/discharge rates. C is simply the nominal (rated) capacity of the battery in amp-hours. If I'm charging a 200 AH battery at C/10, my charge current will be 200/10, or 20 Amps. For a 1200 AH bank being charged at C/5, my charge current will be 240 Amps.

It's done this way so that you can compare discharge rates normalized for capacity and see immediately from the number whether it's a high or low discharge rate. A 10 amp discharge rate doesn't tell me how heavily the battery is being loaded until I know the size of the battery. For my house bank of 1200 AH, 10 amps is not much. For a single "D" cell alkaline battery, 10 A is quite high (C is around 14 AH for that battery). As a rule of thumb, C/10 is a conservative charge/discharge rate for common type cells (lead-acid, NMH, most Lithiums, Ni-Cad, etc...). Specialty type cells may have much lower discharge rates (Zinc-air, as hearing aid batteries). Engine start batteries may have to sustain a short burst of 10C to crank a cold Diesel.
Stephen & Kathy Mahan
Bubba & Mattie (malti-poos)

Lynn Haven, Florida
1999 LXi 43 dual slide
Honda CR-V toad

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Old 04-12-2018
badandy badandy is offline
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C/10 for a lithium is like driving 15mph on a 70mph freeway. You can charge them at 1C every time and discharge them at 1C every time. Conservative for a lifepo is C/2. The automotive cells are rated *way* higher. GM rates the Volt cells at 7.8C for discharge for example.

Also, you can discharge a lifepo a few degrees below 0F without any damage at all. The capacity at that temp is quite a bit lower, however. Charging for typical lifepo lithiums still must take place over 32F, but other chemistries are able to be charged into the 20's. If you're charging in the cold then you should have enough extra power to warm up the batteries, too.

Lithiums are very efficient to charge compared to lead-acids, too. I think they are generally around 98%. If you run solar panels then the lithiums will take every drop of power they can put out. There's no float charge, no equalization, none of that with a lithium.
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Old 04-12-2018
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MRPutz MRPutz is offline
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Location: Mesa
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Originally Posted by 1derer View Post
Am I drowning in battery land? Mr. Putz, please throw me a life preserver, quick !

I’m still learning about batteries and hope I haven’t made mistakes: In the ’75 Bird which started life with one battery bank, some years ago a mechanic made that bank dedicated to the house and set up another bank for starting batteries. Early this year I replaced the starting batteries with two 12v Everstart maintenance free (but not agm) lead acids, and this week I replaced the house bank with 4 Trojan T-105 GC2 wets. Somewhere I read it’s bad to charge different batteries or different aged batteries at the same time from the same source. I’m pretty sure my pto-driven generator only charges the house batteries, and I presume the alternator is charging the starting batteries (though for all I know it’s charging the house batteries at the same time). The banks and pto genny were all done by people in the business of doing these kinds of things, so I presume they did what made sense. Would there be anything bad about the alternator charging both banks (that have different aged and different types batteries) simultaneiously ?

At the moment I’m trying to get things going on a SOB (Safari Trek) that was born into this world with two separate banks. About 6 months ago I replaced the starting batteries with Duracel 12 v maintenance free. I’d be inclined to replace the house bank with a maintenance free version of the Trojan T-105 GC2 wets if such a thing exists, except the wets are too wide, which is why I guess I’m stuck just replacing the current 12 v wets with 12 v again, except I want to go maintenance free. One merchant said the way to go maintenance free there is with agm, which is why I asked about agm, but I’m open to just plain maintenance free (which is cheaper) if that isn’t making a mistake. (It seems all the non-agm maintenance free quote cca which you counsel against in a house battery (though I have to report even some of the agm batteries quote ccm, some up to 1000.) In the Trek, the alternator charges both banks, shore power just charges the house bank, and I think maybe the generator just charges the house bank. My immediate problem is knowing what to replace the house batteries with. Please point the way: They’re dead as doornails. The total space available is 27 inches long, just under 7 wide, 11.5 high.

I’ve been searching for agm today and it seems Trojan group 31 agm is available, though even this brand/model quotes cca as at http://www.trojanbattery.com/pdf/dat...ata_Sheets.pdf

Googling Rolls Surrette Premium Deep Cycle brings up a slew of Rolls Premium batteries, none actually called Rolls Surrette (unless maybe they’re all that? since they’re made by Surrette)
Rolls 4 ks is too big & quite expensive, and 4volt anyway
What does Battery Charge C/4 AGM mean?
4d, 8d, GC2, and L16 are all too big
John, Rolls are a premium top of the line battery and are very costly $$$. They make batteries in several flavors of volts. Trojan T105's are a good bang for buck brand to buy, I've run them the last 3+ years and noticed a big performance over the Costco's they replaced.

You should look at AGM and not maintenance free wet cells. Maintenance free wet cells fall under the "gel" battery and you want to stay away from those. It's "ok" to combine the battery banks to charge under the alternator but only while driving. After that they should be separated (solenoid or diodes) with the house having it's own smart charger. Just note when all connected not all batteries will be charged 100%. Typically the start batteries will charge up first due to their lower internal resistances and keep the deep cycles from reaching a full charge, but better than no charge at all. This is where my solar typically fixes the gap.

The "C" rating is a standard used to rate the best (longer life) charge/discharge rate of a particular battery. Most deep cycles like to see about a C/10 charge rate Trojan recommends 10-13% charge so for my 660ah T105 battery bank that would mean I can charge them at 66-85 amps. I actually charge mine at 100a so I'm just a little over the recommended rate. They'd last longer if I would turn that down a bit, so it's a compromise between life and faster charge. I hear many people charging at 100 amps for only 4 batteries (use to be me) and that is a bit much and lowers the life of the batteries.

ALWAYS have two battery banks, one for starting and one for house. The current draws needed for start & deep cycle are two completely different needs from two completely different designed batteries. If you watch the evolution of Wanderlodge you'll see them do this in later years.

Feel free to email/phone me directly if you have a quick question or concern. Michael
Michael & Tami Putz
78FC35SB & 83FC35SB Wanderlodge - "Putz'n Around"
'90 GL1500 Goldwing | '67 VW Rail | '82 CJ5 Jeep
eMail=Mike.Putz@cox.net | Web=http://mikeputz.com/
Solar = https://www.solarpenny.com/SearchResults.asp?Cat=257

FMCA #236459, Good Sam #17270530, Vintage Birds #1509
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Old 09-11-2019
DW SD DW SD is offline
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Join Date: Jul 2010
Location: Encinitas
Posts: 1,578

From Andy:
You bring up a good point - you need to figure out what your 12v DC loads are so you can size the DC-DC converter(s) correctly. The older the coach the fewer of these loads, I suspect. But there are a couple of ways to skin this cat.

My newer M380 seems to have less parasitic draws than the ‘83 PT. I attribute that to 1. Less continuous duty solenoids to isolate circuits. (in both I hard wired some or all of these to disable on off functionality so as to reduce base consumption of the solenoids)

2. I turn the inverter off when not in use.

Thus steady state for each coach settled at about 3 to 4 amps. The dual fuel refrigerators’ control circuit and propane safety the lion’s share of that consumption. With the slide computer consuming some small amount.

I will do some lithium conversion when my lifelines show signs of age. But with 900W of solar a nicely integrate MPPT controller (PT100 by Magnum) and light consumption (down -50Ah to 100Ah) in the morning before the sun starts recharging, I think they will last a very very long time.

I COMMEND the early adopters and innovators in Andy, Jack, Van, Randy And Juan with his public ally documented custom build. Great to learn from you all.
Doug W.
Encinitas CA
2004 M380
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Old 09-11-2019
ChrisRasman ChrisRasman is online now
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Join Date: Jun 2019
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Posts: 671

If your getting battries that have a built in BMS , it will take care of itself in regards to low and high voltage. It will disconnect itself if either of those things occur. If not, you might need a few things. I have solar (yet to be installed) so I am looking at it a different way. People do charge them with alternators. They just have to be set up a different way. It be better to charge them the proper way, but I am no expert. I have yet to build the Leaf battery up to something that can fit in the bus. That will be this winter. That will need a lot of off board management. It will also save hundreds of pounds on the coach and make more power then the AGM lead cells we have now.




Just to confuse. The Sterling charger looks like a good idea. Takes juice from the start batteries (and alternator) and properly charges the LiPo battery bank. Should work on any LiPo as long a it has a built in BMS. I am not sure if the Trace can be set right to charge the LiPos. Someone else might know.
Christopher Rasmussen
Fort Myers, FLORIDA
2003 Wanderlodge 40LX
Body# F133835
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