Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 


Reply
 
Thread Tools Display Modes
 
Old 07-09-2015, 06:12 AM   #1
Senior Member
 
E350's Avatar
 
Join Date: Oct 2010
Location: Sacramento Delta, CA
Posts: 1,024
Basics: RV/RE "House" Batteries

A reference for the solarpaneltalk forum was recently posted by someone here and I have to say that this sticky is simply outstanding:

http://www.solarpaneltalk.com/showthrea ... s-Tutorial

__________________
2002 E350 ext.; 160K; 7.3L; 4R100 (w/4x4 deep pan & filter); 4x4 conv. w/2007 F250/F350 coil frnt axle (oppos. dual Bilstein press. shocks cured DW) diff chg from 3.55 to 3.73 (bad!); BW1356 t.c. (bad!); LT265/70R17/E Michelin LTX M/S2; Engel MT60 Combi Fridge-Freezer; 4 BP 380J pv panels; Auragen 5kw AC gen. in top alt. position; Webasto Dual-Top; Voyager top. 1995 5.8L EB Bronco, bone stock.
E350 is offline   Reply With Quote
Old 07-09-2015, 07:07 AM   #2
Senior Member
 
LenS's Avatar
 
Join Date: Jan 2009
Posts: 1,220
Re: Basics: RV/RE "House" Batteries

Golf cart batteries are excellent for house battery use. They are designed as true deep cycle batteries, repeatedly delivering loads for extended periods of time and repeated recharging. As with other use flooded wet cell batteries, the fluid level will need to be checked regularly and topped up with distilled water when needed.

The price of a battery is heavily driven by the manufacturing cost and that is very sensitive to production volumes. Golf cart batteries are a high volume battery so can be very cost affective. They are a 6v volt product so two are required for a 12 volt system.
__________________
Len & Joanne

The Green TARDIS
LenS is offline   Reply With Quote
Old 07-09-2015, 07:13 AM   #3
Senior Member
 
LenS's Avatar
 
Join Date: Jan 2009
Posts: 1,220
Re: Basics: RV/RE "House" Batteries

A very good article on house batteries (also factoring in there cost) was written by R.V. Roamer for the RVForum and is in that user groups library. You would need to join to get access to it. The title is: "Choosing a Battery for Your RV". It is a good general RV group to join although I think 60% of the posts are on the bigger class A rigs.

On second thought try going here w/o joining.....might take you directly to Gary's great simple article.

http://www.rvforum.net/joomla/index.php ... Itemid=132
__________________
Len & Joanne

The Green TARDIS
LenS is offline   Reply With Quote
Old 07-09-2015, 10:44 AM   #4
Senior Member
 
E350's Avatar
 
Join Date: Oct 2010
Location: Sacramento Delta, CA
Posts: 1,024
Re: Basics: RV/RE "House" Batteries

LenS link is certainly worth reading. However, it does not discuss rate of charge and rate of discharge when the charging device is solar.

From what I have gathered from the solarpaneltalk link:

1. Starting batteries discharge amps quickly to power the starter to turn over the engine quickly to start it. Starting batteries also can be recharged quickly. The engine's alternator is paired to work with the starting battery's quick recharge rate. But starting batteries have the shortest lifespan in terms of the numbers of discharge/charge cycles.

2. The type of AGM batteries which are "deeper cycle" batteries than regular starting batteries can discharge a little slower than starting batteries and can recharge not as quickly as starting batteries but quicker than true deep cycle batteries. And they can cycle more times (i.e., last longer) than starting batteries.

3. True deep cycle batteries (like Trojan golf cart batteries) can cycle more times (lasting longest) and discharge slowly but can only be recharged slowly. Which is not a problem if they are plugged into a power outlet at the golf course over night, but what about trying to recharge them with solar -- is usable daylight too short to recharge them in our rigs?

So, if we have a limited solar array and live in North America, which at least in the Winter has limited sunlight available with short days and cloudy skis, do we need a faster charging battery (i.e., AGM) to recharge our house batteries from solar?

Or if we only do weekend trips in the Winter can we get by with true deep cycle (e.g., golf cart) batteries, charge them with our alternator or second alternator when driving, use solar when parked and then recharge them at home with a real battery charger (but a smart charger) to top them off and then use a BatteryMinder to desulfate them?*

If so, what do you guys and gals recommend for batteries for our mini-rv's with our necessarily limited roof top area for solar panels and our limited carrying space/weight for batteries?

And what do you recommend for a bulk smart charger to charge a big Amp Hour house battery while at home or with "shore" power at an rv park?

* See BatteryMinder 1500 review re Trojan deep cycle desulfation:

http://www.amazon.com/gp/cdp/member-rev ... 72FUQN9XYS
__________________
2002 E350 ext.; 160K; 7.3L; 4R100 (w/4x4 deep pan & filter); 4x4 conv. w/2007 F250/F350 coil frnt axle (oppos. dual Bilstein press. shocks cured DW) diff chg from 3.55 to 3.73 (bad!); BW1356 t.c. (bad!); LT265/70R17/E Michelin LTX M/S2; Engel MT60 Combi Fridge-Freezer; 4 BP 380J pv panels; Auragen 5kw AC gen. in top alt. position; Webasto Dual-Top; Voyager top. 1995 5.8L EB Bronco, bone stock.
E350 is offline   Reply With Quote
Old 07-19-2015, 04:33 PM   #5
Senior Member
 
E350's Avatar
 
Join Date: Oct 2010
Location: Sacramento Delta, CA
Posts: 1,024
Re: Basics: RV/RE "House" Batteries

daveb's recent post in the following thread is touching upon some thoughts I have been having recently about how big and what type of house batteries I should buy as I get closer to redesigning my system.

Read any post by Sunking and SunEagle here:

http://www.solarpaneltalk.com/forumdisp ... amping-etc

Both posters are brutally honest about the inadequacies of solar for recharging a house battery in an rv setup. Basically the idea is that the truck alternator has much more recharging capacity than solar when compared to an rv's limited real estate for panel installation. See quote from thread below.

"Those are a UPS batteries. However they are not made to be cycled. If cycled you get 100 cycles and they are pretty much done. You do not want them, they are chit.

A 12 volt 9 AH battery if discharged at a very slow 20 hour rate of 5 watts have 50 watt hours usable. Discharged at the 10 hour rate of 10 watts only 30 watt hours usable. However any USB charger you buy today is a Serial device meaning if it uses 2 amps or 10 watts @ 5 volts, it draws 24 watts or more from the battery. Or about 2 hours till dead on a 12 volt 9 AH battery. That is one or two cell phones. Good luck with your plan.

Your whole idea is badly flawed based on bad information and assumptions. If your truck has a two heavy duty batteries and electrical system like you claim, you do not need anything. If anything just a simple 20 to 100 watt panel connected directly the truck battery so you fell better by spending money. Or run the truck engine for 10 minutes which will do more will do more than a 100 watt panel in a week. Your truck battery and alternator has more than what you need to do what you want by a magnitude of 10.

But if money is burning a hole in your pocket at least do it right. A 100 Watt Panel panel, 10 amp Controller, and an Optima Blue Top D31M, or Odyssey 31-800. Should not cost you a penny more than $500. That ought to cool your pockets off.

If it were me just use the truck."


http://www.solarpaneltalk.com/showthrea ... -do-I-need

Granted he was talking about small uninterruptable power supply batteries in the quote above, but the concept applies. Solar vs running the truck to recharge our house batteries.

Peeling the onion even further. There is a discussion in the offgrid subforum of solarpaneltalk.com that smart controllers are going from bulk to absorb to float mode too quickly and undercharging and thus killing batteries prematurely and not because the battery is at a state of charge that it only needs to be topped off, but because the solar array doesn't have enough voltage output as the sun moves so that it can only power the controller to do float when the battery really needs bulk. In other words, just because your solar charge controller is in float mode, doesn't mean that your battery is fully or nearly fully charged. So some of the newer advice is to program the MPPT controller that bulk=absorb=float so that it never leaves the bulk mode. These same posts say that amps-out / amps-in State of Charge counters like my BMV are worthless and misleading. That has been my experience, because the additional variables are way too much for the counter to monitor. In my case, when I reset it and I had to reset mine frequently, it was never reset on a fully charged battery - try as I might to recharge the battery fully at home with a 10 amp battery charger. I just bought this battery charger:

http://www.napaonline.com/Catalog/Catal ... 0006389653

I like it because it is a smart charger with desulfation but a big amp charger too. Unlike the BatteryMinders which cannot charge or desulfate until the battery has been brought up to at least 10 or so amps by a bulk charger. But I may try to take it back and get the next size up.

Peeling the onion even further, there was a discussion of whether it is better to have a faster recharging type of deep cycle battery paired with a bulk output solar controller to maximize the few hours of usable sunlight available. Concept is that if you only have ___ hours of usable sunlight a day, you better not expect that a slow recharging type of deep cycle battery will be recharged by a solar controller. (I received my beta test "Kid" (PWA) controller from MIdnite but I haven't installed it yet.) But apparently faster recharging types of deep cycle batteries don't have as many cycles before failure as slower types of charging deep cycle batteries.

But what daveb is talking about is becoming to be the key for me in house battery discharge and recharging design. I don't know what to design into my system yet, but these design concepts are floating to the top in my mind:

1. Battery AHr size/capacity should be based on expected usage/loads WITH expected mean(s), speed, volt output, and frequency of recharge in mind. (I.e., running the engine at idle or fast idle every morning to recharge or nearly recharge the battery. In my case, normally only a weekend, two nights of furnace, constant power to the Engel refrigerator/freezer. Depending on how fast the battery recharges from the alternator, a smaller AHr house battery may be all that's needed, thereby reducing weight and initial purchase expense and expense from burning vehicle fuel to haul around a heavier larger AHr house battery;

2. Battery recharge profile paired with alternator output (or in my case battery charger output - this applies to you inverter/charger guys in spades - in my case the 5kW AC producing Auragen on the second alternator position on the diesel). A fast recharging 14.8v accepting Odessy battery like those mentioned by daveb has a use for the military and likely for us;

3. Balance quick recharging from alternator with the amount of cycles one gets from a quick recharging battery type. Apparently there is a trade off to be aware of.

4. Hook up after the weekend at home (or whenever possible) to shore power with a smart charger of sufficient amperage output which does true Bulk, Absorb, Float, Desulfation with an output profile paired to the battery's recharge profile to recharge but not destroy the house battery.

My first solar/house battery design was flawed from the beginning. Too much money and not enough thought expended.

Now, I believe that daveb has pointed us to the starting point. The speed and max volts recharge profile of the batteries sized to our expected loads with the expected mean(s), speed, volt output, and frequency of recharge in mind.
__________________
2002 E350 ext.; 160K; 7.3L; 4R100 (w/4x4 deep pan & filter); 4x4 conv. w/2007 F250/F350 coil frnt axle (oppos. dual Bilstein press. shocks cured DW) diff chg from 3.55 to 3.73 (bad!); BW1356 t.c. (bad!); LT265/70R17/E Michelin LTX M/S2; Engel MT60 Combi Fridge-Freezer; 4 BP 380J pv panels; Auragen 5kw AC gen. in top alt. position; Webasto Dual-Top; Voyager top. 1995 5.8L EB Bronco, bone stock.
E350 is offline   Reply With Quote
Old 07-19-2015, 07:14 PM   #6
Site Team
 
daveb's Avatar
 
Join Date: May 2007
Location: Turlock Ca
Posts: 10,407
Garage
Re: Basics: RV/RE "House" Batteries

Remember like I posted, there are several views on this. A lot depends on the size of the battery bank and the RV. Big RV's typically have much larger battery banks as well as loads. I'm not too sure I agree with your other post links especially when comparing our systems to UPS systems.
One point I'd like to make is I've sized my system to the battery bank and have yet to have any issues. My alternator might be a bit too much for what I have from what I've read. Being I've seen so many SMB's with light solar and a 130w panel system work well, how can you (edit-we) dispute the design? In the end it just depends on your load demands and the size of the array+ battery bank. Over and under charging is something to factor in but so far I'm not having problems. That is just with MY system. Everybody's setup is going to be different.
__________________
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer

Sportsmobile 4X4 Adventures..........On and off road adventures
daveb is offline   Reply With Quote
Old 07-19-2015, 07:19 PM   #7
Senior Member
 
Viva's Avatar
 
Join Date: Feb 2012
Posts: 879
Re: Basics: RV/RE "House" Batteries

One note on the comment that alternators are better (stronger) than limited capacity solar panels: That's great, but the alternator only works if you are running the engine. So if you want to park or camp for a week, and don't want to run your engine, you need another way. I like solar because it's quiet and doesn't need maintenance (like an engine does). Also it doesn't negate the alternator when I do drive.

When I researched I found that each solar controller had things I liked and things I didn't like. None of them had my ultimate combo so I had to weigh and choose.
Viva is offline   Reply With Quote
Old 07-19-2015, 09:21 PM   #8
Site Team
 
daveb's Avatar
 
Join Date: May 2007
Location: Turlock Ca
Posts: 10,407
Garage
Re: Basics: RV/RE "House" Batteries

I agree but also want to point out that each solar and alternator systems have different factors to add to the equation. I'm far from being an expert in the field. And just because it's "on the internet" doesn't mean it's true. Everybody needs to research this on their own. All I know is what has worked for me. Every battery manufacture has their own parameters. Like insurance companies, I've never been able to get a solid answer, only a round about set of parameters. Just look at the difference between Concorde and Rolls. But I do agree there is a melding point. Many manufactures take a particular stance. It doesn't mean it's right or wrong but generally addresses what their warranty covers. That's huge! They have an obligation to the public. I guess I push the limits from time to time...so be it.

An example of manufactures disagreeing with operations is that I take current readings with a standard Fluke amp meter on 12Kv voltages. Does Fluke agree with this? Hell no. Does it work, yes. Some of this is a safety issue and them being sued. I understand this.

Each system is different.
__________________
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer

Sportsmobile 4X4 Adventures..........On and off road adventures
daveb is offline   Reply With Quote
Old 07-19-2015, 09:45 PM   #9
Senior Member
 
E350's Avatar
 
Join Date: Oct 2010
Location: Sacramento Delta, CA
Posts: 1,024
Re: Basics: RV/RE "House" Batteries

My Universal Power Group UB-8DL AGM single battery 12v 250 Ah 24.70" x 10.55" x 9.65" 160.94 lbs cost $475 from Wholesale Solar in Mt. Shasta City in July 2009 (before climb and ski on Lassen).

And I killed it by overusing it and undercharging it. It is heavy and takes up way too much space on the frame rail.

What I am suggesting is a smaller battery, paired with a recharge profile matched to the alternator and using the alternator to assist during peak loads (like running the microwave) and having the battery do all the work during the night when we are sleeping and during the day when we are away.

Here is a discussion regarding the design of such a system. It is contrary to established battery sizing thinking that you should have a large AHr heavy battery so that your depth of discharge (DOD) is never more than 50%:



"Thanks for providing a "typical" battery cycle life graph that we can look at.
The first thing that you see is that at 20% DOD, the number of cycles is about ~2500.
At 80% DOD, the number of cycles drops drastically to only ~500.
The first reaction to that is "Oh my, the life in cycles is only one fifth of what it would be with the lower discharge level."

And that would be perfectly correct if what you are looking at is a system that is designed to draw the batteries down to 80% DOD every day.

There are two other ways to look at the lesson that this graph is teaching us:

1. If you plan for 20% DOD and accept four days of no sun before being forced to start the generator or conserve drastically, then you are at 80% DOD and find that you have used up the battery life equivalent to five single day 20% cycles. But that battery life increment has carried you through four days without running the generator.

No longer the simple factor of five loss of battery life that we took from the first look.

2. If instead of designing for 20% DOD and getting ~2500 daily cycles, we design for 80% daily DOD, we will be replacing out batteries five times as often. But we are only buying a battery bank that is one fourth the size. Still not a good deal and probably a bad way to design if you want reserve capacity and autonomy, but not the factor of five misjudgement that we thought we saw at first glance."

"It's all about cost/kWh. You can cycle a battery shallow and get more more years from it. But that doesn't mean you got more kWh into and out of that battery. Or you can buy less batteries and work the snot out of them and replace them more often, getting better charging efficiency and more kWh into and out of them over their life. I prefer the latter method. Getting 7-8 years down the road and dealing with batteries that only have 50% original capacity left and trying to squeeze another couple years out of them when they're half dead doesn't save you any money because their charging efficiency at that age is going up in smoke. You're throwing your energy you put into them right out the window."

http://www.solarpaneltalk.com/showthrea ... en-Support
__________________
2002 E350 ext.; 160K; 7.3L; 4R100 (w/4x4 deep pan & filter); 4x4 conv. w/2007 F250/F350 coil frnt axle (oppos. dual Bilstein press. shocks cured DW) diff chg from 3.55 to 3.73 (bad!); BW1356 t.c. (bad!); LT265/70R17/E Michelin LTX M/S2; Engel MT60 Combi Fridge-Freezer; 4 BP 380J pv panels; Auragen 5kw AC gen. in top alt. position; Webasto Dual-Top; Voyager top. 1995 5.8L EB Bronco, bone stock.
E350 is offline   Reply With Quote
Old 07-19-2015, 10:17 PM   #10
Site Team
 
daveb's Avatar
 
Join Date: May 2007
Location: Turlock Ca
Posts: 10,407
Garage
Re: Basics: RV/RE "House" Batteries

Well while I agree with much of it, I still need to point out that each system is unique.
__________________
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer

Sportsmobile 4X4 Adventures..........On and off road adventures
daveb is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Sportsmobile Registry

Beatrice

Drizzt

Moby

new2tx
Add your Sportsmobile
» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Sportsmobile SIP or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 05:39 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.