I broke my RV house batteries, now I need new ones...

[d2reid]

Once again I am going to ask the very knowledgeable folks here to help me with my ignorance. Just talking about watts and amps makes my head swim, but I must delve into this area once again, I am just hoping you will have pity on me and help along.

2017 Momentum 376TH. The first time I tried to boondock with my type 27 deep cycle 12v battery I discharged it too much, and it kept getting worse. In November of 2018 I did my research and determined that the Battle Born batteries would be best, except, there was this little thing about not being able to charge them when it's cold. Since I spend the winters at ski resorts I figured that they wouldn't work for me. Plus they were pretty pricey, around $1000 a battery.

So I purchased two Lead Acid US Battery 2000 XC2, 6 volt batteries. I even managed to get them wired without burning anything down or blowing anything up. And they have been holding up pretty good. But, I neglected to take them to a battery shop for a deep discharge when my Victron thingy said I should. And then I didn't add more water when I should. And then I didn't clean the green gunk off the posts the last time I looked at them. And now it's 93f outside.

How do I know my batteries are broken? I was going to change the oil in the generator. Pretty good indicator I had bad batteries right? It get's better, I like to warm my oil up a bit before changing it. So I figured it was a good time to run some non-ethanol gas through the generator, get the oil all stirred up and do the oil change. I always shut off my shore power when starting the generator, I know I don't have to, it just scares me to have two big power sources coursing through my RV at the same time. You just don't ever know what you are to cook. So I shut off the shore power, go to start the generator and the one control box is blank, won't boot. Hmm' I go to my Victron thingy and push some buttons, no response, hmmm! So I grab my trusty multi-meter and head to the batteries to see what's what. I open the covers and there is this green stuff all over the place. After going back inside and searching on instructions on how to read DC on the multi-meter I go back outside and put the black wire on the black post and the red wire on the red post of the left battery, -6.5V. How do you get minus V, is it like sucking electricity out of the air or something? Oh, yea, there's this reverse polarity thing that can happen. If I remember what I read it's not good.

The other battery was reading 3V. I kind of think I may want to hurry up and get these batteries replaced.

I read that they solved the lithium cold weather charging problem by making heated batteries.

So I am asking for advice from you folks that live and breathe this stuff. I think lithium battery prices have come down some. There are also other manufacturers out there now. Our wintering days may be done, another story for another day. About Wednesday or so I am going to pull those batteries out and head into town for replacements. I will call around to see what the local stores recommend. I am pretty sure I would like to have Lithium batteries, mostly because they take less maintenance and I can run them down more without damaging them. I don't mind spending and extra buck or two.

Option one; replace the golf cart batteries with similar. Cheapest easiest, not optimal, short lived.

Option Two; go with an AGM battery. Less maintenance, I think I can still use my OEM converter, even though it tends to cook batteries.

Option three; go lithium, heated batteries. Oh boy my bookeeper isn't going to like this, but if I pony up now I am pretty sure the battery system will last longer than I keep the Momentum, maybe another 5 years. I bet I will have to get a new converter/charger also.

A couple of key deciding points. I only boondock maybe 5 days a year. I have a Onan generator built in. While I don't particularly like annoying the neighbors with it to charge my batteries I will do it the few times I have to instead of installing a solar system. I don't have a residential refrigerator. I won't be trying to run the A/C units off the batteries, nor the refrigerator, or any other 12v appliance, I will run the generator for that. Occasionally I will need to run the furnace while boondocking, but turn the thermostat to pretty chilly before going to bed. Then use the generator to warm things up in the morning.

Any thoughts or advice?

[Cate&Rob]

Hi Dallas,

It is interesting that there are at least three similar, flooded vs AGM vs lithium, battery discussions going on in parallel on this forum, at the moment.

Similar to you, I have been considering an upgrade to LiFePO4 (lithium) batteries to carry more reserve in the same space. I don't have any intention of going down the solar/boondocking rabbit hole . . . just not our RVing lifestyle. I am concerned about A) the price, B) cold weather performance and C) the need for a new converter to properly charge the lithium batteries.

As mentioned in previous threads, I like redundancy in a battery system. (a holdover from my boating days). In the same space that you have two 6V deep cycle batteries, I have two 12V deep cycle batteries. I run on one or the other, but not both (unless I am running the inverter which is a rare occurrence) Thus, if I run a battery flat with whatever I am doing, I know that I can switch over to the other one and have that same amount of time to sort out a recharging solution.

The more I think about this, I am leaning towards staying with my two 12V lead/acid battery installation. Back to your question about a "recommendation" . . . I would suggest that you do the same. Two 12V AGM sealed lead/acid batteries (since you do seem to be rather "battery maintenance" challenged . . .LOL) with a 1/2/both/off four way high amperage marine switch. Run on one battery or the other but not both. All you have to remember is to switch from one battery to the other, every month or so to even out charging/discharging. Then, when "things go quiet", you can switch to the other battery while you figure out why . . . and have lots of battery power to run the furnace for the rest of the night, or to start that generator.

Just my 2 cents worth . . .

Rob

[TucsonJim]

Dang Dallas. That's quite a write up. LOL.

Here's my take:

Option one Pros:
These are the lowest price initial outlay.
No converter change needed

Option one Cons:
The batteries don't last as long, so your long term cost may be more.
The flooded batteries require maintenance such as frequent charging, cleaning, and watering.
They are heavy
Should only be discharged to 50% of their capacity

Option two Pros:
Maintenance free
Less pricey than lithium
No converter change needed.
Can be discharged a little more than flooded.
Will typically last longer than a flooded battery

Option two Cons:
Batteries are more costly than flooded.
Batteries are heavier.
Will not last as long as a lithium battery

Option three Pros:
Maintenance free
Longest life span
Can deeply discharge with no adverse effects
Very light weight
Lowest overall price when compared to long term usage.
Good warranties

Option three Cons:
Very high initial price.
Would recommend a lithium dedicated converter.

If it were me and I was using the batteries as you describe, I'd go with Option two. You're not deeply discharging the batteries when you use them. And with only 5-6 days of boondocking, the generator will easily recharge you when needed.

JIm

[howson]

d2reid (Dallas), assuming you're still in SD and willing to drive to Rapid City, talk to the guys at Dakota Battery on Deadwood Ave to see what they have available. When my friend and I had the DC-DC Charger SNAFU that's where we stopped to get a new relay. They should be able to hook you up. https://dakotabattery.com/

Take your bride to the Firehouse Brewery while you're in town for a Buffalo burger and beer. You'll be a hero.

[Country Campers]

I am concerned about the converter cooking your batteries, if this is indeed what is happening a converter replacement may be in order. I also think that sealed batteries would be a good fit for what you do plus if there is a battery issue they are easier to find a replacement.

Brian

[Cate&Rob]

Country Campers Brian . . . good catch on figuring out what is cooking the batteries before replacing them.

Rob

[d2reid]

Thanks, I knew I could count on you for good sound advice and direction.

Hi Dallas,
It is interesting that there are at least three similar, flooded vs AGM vs lithium, battery discussions going on in parallel on this forum, at the moment.

I thought I did a pretty good search before I posted, but apparently I didn't.

As mentioned in previous threads, I like redundancy in a battery system. (a holdover from my boating days).

I had boating days also, two batteries separated by a 1-2-All-Off switch. Ran 1 on odd days and 2 on even days. All while running back in the afternoon to charge both. When the boat hit the trailer the switch got put to Off so that system worked well. More bother than I want in the RV. However, my brother in law recently bought a boat with starter and house battery banks. His mechanic highly recommended a fancy doo dad, hmmm, An Automatic Charging Relay (ACR). Apparently it sensed the charge state of the battery and would send juice to the battery that needed charging but would not draw off the starter batteries to feed the house batteries.

Looks like I have to go do some reading to figure out how the thing works and if it can be used in an RV setting, kind of like auto switching from 1 to 2. Hopefully it would cut power is V drops below xV. More research needed.

Back to your question about a "recommendation" . . . I would suggest that you do the same. Two 12V AGM sealed lead/acid batteries (since you do seem to be rather "battery maintenance" challenged . . .LOL)
Just my 2 cents worth . . .
Rob

As always Rob your 2 cents worth have a much higher value.

Dang Dallas. That's quite a write up. LOL.

Yes I know, in my career I was often chastised in being over verbose in my technical explanations. The art of communication has many facets. I have always had a drive to provide enough informaton for my audience to understand the problem completely, but yes, I talk too much. It's part of who I am and I am comfortable with it annoying folks, but you have to enjoy a good yarn...

Here's my take:
If it were me and I was using the batteries as you describe, I'd go with Option two.
JIm

Jim that was an excellent, succinct response. I could turn that into four pages, but I thank you for your recommendation, that's two for AGM... and I am just messing with you about the succinct part...

Dallas, assuming you're still in SD and willing to drive to Rapid City, talk to the guys at Dakota Battery on Deadwood Ave to see what they have available. ...Take your bride to the Firehouse Brewery while you're in town for a Buffalo burger and beer. You'll be a hero.

Howard thank you for the recommendation. We are still at Custer State Park. I did a search for battery sales in Rapid City, didn't get much of a response. When I was researching my last battery purchase there was a really excellent battery shop in Salt Lake that I went to, those guys new their stuff. I have had poor dealings with Interstate Battery stores, they know only one thing, and it aint RV battery situations, of course there will be exceptions to my previous experiences, but I wasn't looking forward to going through the drawn out conversation to find out if they knew what I needed. I saw Dakota Battery, and like what I read on their website, but closed till Monday so couldn't follow up. Batteries Plus Bulbs? Ok enough said there.


We enjoyed the Firehouse Brewery, especially so because my wifes brother is a retired Fire Fighter. And the food was good. When/if you guys come back through we will have to try the Alpine Inn Resteraunt in Hill City, only two things on the menu, cash only, you have to make a reservation in person before 3pm for that evenings meal. We are told it is an exceptional experience.

I am concerned about the converter cooking your batteries, if this is indeed what is happening
Brian

Good point Brian... do I really have cooked batteries or just worn out ones. I don't recall the specific model of converter that I have, but it is my understanding that it has 3 stages and no smart monitoring at all. As long as I never drew that batteries down too far (11.7V?) and kept adding distilled water to them they should be fine, right? Or maybe if I can of ran them down to like 10.9V and maybe I kind of didn't have any distilled water around for a month or two it may not have been a converter cooking the batteries, but the user abusing said batteries, and then they got cooked.

I am actually a little surprised my converter has lasted 5 years. On my old 5^th wheel I was replacing the converter every other year, it got so bad I always kept a spare in the closet. Where it was located was pretty tight, a nicer model would not fit in the location, so I kept replacing it with the cheap one.

So maybe it's time for me to improve my converter. LOL, first step is to find out exactly what my OEM converter is, maybe I already have a smart converter, don't thinks so, but could be. Next I have to find a smart converter, one that monitors the battery condition and charges appropriately without overcharging (cooking) the batteries.

As much as I think Lithium is the best thing in batteries I am inclined to go with the less expensive Option 2, AGM batteries. Series/parallel? If I have it correct my 6volts are rigged parallel to provide 12v, so I can't use the same wiring diagram with two 12V batteries, I will have to link them in a series.

I am debating putting them on a rotating schedule, I am battery maintenance challenged and know that I will probably forget to switch them over, which means when one quits and I switch it over the second one will not be charged. I am inclined to run them in the All position. I can kind of tell when I am having battery troubles . The lights don't come on. I am going to read more about that ACR thingy. You may have noticed I have decided on two batteries. The one battery I had before would not stand up to my boondocking routine. 232AH is what I have targeted.

Thank you guys for your in-light-ed and informed suggestions. If you have any knowledge or feedback on the ACR it would be appreciated, if you have a recommendation for a better converter that also would be appreciated. Monday I will call Dakota Battery and talk with them. We will be driving into town on Tuesday, so maybe I can have my battery problems solved by Wednesday.

[TucsonJim]

Series/parallel? If I have it correct my 6volts are rigged parallel to provide 12v, so I can't use the same wiring diagram with two 12V batteries, I will have to link them in a series.

Dallas - That's backwards.

If you have two 6V batteries, they are in series to give you 12V.

Series - Two 6V batteries and 225 amp hours each will result in 12V, and 225 amp hours (Voltage adds, current capacity is the same)
Parallel - two 12V batteries with 120 amp hour capacity will give you 12V and 240 amp hours (Voltage is the same, current adds).

Jim

[d2reid]

Dallas - That's backwards.

If you have two 6V batteries, they are in series to give you 12V.

Series - Two 6V batteries and 225 amp hours each will result in 12V, and 225 amp hours (Voltage adds, current capacity is the same)
Parallel - two 12V batteries with 120 amp hour capacity will give you 12V and 240 amp hours (Voltage is the same, current adds).

Jim

Got it. Up late trying to remember what my needs are. Average use hours are an estimate of boondocking for 24 hours when the temps are near 50F. I sure goofed when I though my 2 6v 232ah batteries in series would result in 464AH. Still only 232AH. But did I figure my AH needs correctly? Load amps being the number of amps I need to run each device the average number of hours I expect to use it. Looking at my old chart I built, if I need 122AH per day of boondockiing, and I only have 232AH, I will be running my batteries down 52%, or down to around 6V, which would ruin them. No, that can't be right, I am missing something.

	Amps	Watts	Avg usage hrs	Load Amps	Watt usage
Cutoff Switch Off
Base One control/monitor	0.5	6	1	0.5	3
One Control System	0.5	6	24	12	72
Refrigerator	2.8	15	24	67.2	1008
Gas Water Heater	1	12	6	6	72
Gas Heater	2.5	30	4	10	300
Awning	1.5	17	0.25	0.375	6.375
Overhead Fan	0.5	6	3	1.5	9
				0	0
Lights				0	0
Awning	0.2	5	1	0.2	1
Flood	0.8	10		0	0
Front LED	0.3	4		0	0
Hutch	0.2	3		0	0
Kitchen Ceiling	1	12	12	12	144
Chandalier	0.1	2		0	0
Living Room Ceiling	1	12	12	12	144
Porch	0.5	6		0	0
Step	0.5	6		0	0
Kitchen Accent	0.2	3		0	0
Bedroom	0.5	6	1	0.5	3
Bathroom	0.2	3	1	0.2	0.6
Hall Light	0.1	2		0	0
				122.475	1762.975
		Battery AH	232
		Battery AH	232
			464
		%used	26.29%
		Hours to recharge @ 200watts	8.814875

[Scott'n'Wendy]

Agree with checking the charger in your buggy. At this point it may just be your connections and not over charging. That green stuff is a pretty decent insulator and it's possible the charger was doing it's job as best it could but the voltage drop at the post connection prevented the batteries getting charged. With what you describe...IMO, most likely what happened. Same thing can happen with your car. Leave the posts corroded/corroding long enough, it won't start.

As for your battery options...

The added capability/expense of LiFePO4 isn't needed the way you RV. So between #1 and #2....I'd stick with #1. Two golf cart batteries likely have more available power than two 12v agm batteries and while as C&R says, having backup is nice, but....you only boondock for less than a week a year - so I wouldn't be too concerned about having a backup battery.

AND...if you let that green gunk buildup...even after you have seen it, it doesn't matter what battery you choose...they won't work. So keep your connections clean and tight.

[TucsonJim]

The added capability/expense of LiFePO4 isn't needed the way you RV. So between #1 and #2....I'd stick with #1. Two golf cart batteries likely have more available power than two 12v agm batteries and while as C&R says, having backup is nice, but....you only boondock for less than a week a year - so I wouldn't be too concerned about having a backup battery.

There are lots of 6V golf cart style batteries that use AGM technology and provide 225 amp hours. They don't have to be flooded to provide that kind of power. For example, this battery is 6V, AGM, 225 Ah for $330.

https://www.amazon.com/VMAXTANKS-Vol...8077801&sr=8-6

Jim

[d2reid]

Ok, logic check. Trying to compare batteries. My old 6v batteries are rated at 232, the one Jim posted 225. The Dakota Battery web site they are advertising Intimidator AGM batteries. When I pull the chart up it doesn't show a relative AH rating, but they do show minutes at 25amp and 20 cap ratings. My old 6v chart shows 20 hour rating of 232 and minutes at 25 amp as 474.

Old battery chart:


Looking up the Vmax, they added another nomenclature I am not familiar with, 25A @ 1.75/Cell 500Min. Had it just said 25A 500Min I would have been impressed, but what's @1.75/cell mean, 1.75 amps per battery cell?

Looking at the Dakota Battery Intimidator chart it shows the type 27 having 185 minutes at 25 amp. If I get two of them parallel will give me 370 AH, correct? I was looking at the 8D battery, 517 minutes on one battery. But then I noticed the weight and size. Getting that thing into my battery space would be challenging. I really don't want my wife to hurt her back when she loads that thing in. Plus I'll bet the 8D is pretty pricey.



Jim's Amazon recommendation is excellent for setting price point. 225AH for $660.

Amazon prices for Deka batteries.

Deka Type 27 x 2 $700
Deka 8D $800
Deka Type 31 x 2 $825,

Ok, I know I am all over the place with this. But if I have this figured correctly two type 27 parallel will last longer than 2 6v in series.

[TucsonJim]

d2reid

Looking at the chart above, use the 20 HR CAP column to determine amp hours. In this case, the group 27 battery would have a 20 hour rate of 92 amp hours, or 184 ah with two in parallel. Battery amp hour ratings are typically given in 20 hour capacity in order to standardize the draw down time between batteries. Most group 27 batteries I've used in the past had between 85 to 95 amp hour capacity at a 20 hour rate.

The column marked "Mins at 25 amps" shows that if you were pulling a constant 25 amps out of the battery, it would take 185 minutes to deplete the battery. If you had two batteries in parallel, it would take twice as long, or 370 minutes to deplete the two batteries at a draw rate of 25 amps.

Jim

[Yoda]

d2reid You mentioned "I though my 2 6v 232ah batteries in series would result in 464AH. Still only 232AH" Just a reminder. Battery's in parallel the voltage is the same and the AH add. Battery's in series the voltage doubles, but AH stays the same. However both batterys or all batterys in a group should really be identical. An example I have 4 - Crown CR260 batterys in a series/parallel combination. First is series to go from 6V to 12V. AH is still 260AH. The the series banks are tied in parallel to my Lynx power in bar resulting is still having 12v but 520AH . As I can only used 50% I really only have 260AH available for use..

AGM sounds like the way to go for you right now, but the AH ratings are usually slightly less for the same size battery in a flooded version. MY next upgrade a few years down the road will be to to go with two 206 AH versions of these https://www.us.sokbattery.com/products?ref=m-cvbsdfgtk, That wold give me 412 AH total and most of that is usable. But technology is changing the the prices keep dropping. Not sure where you are at, but if you can take a look at the Crown line if there is a dealer near you. They also sell and ship from the factory.

[RoyB]

I had boating days also, two batteries separated by a 1-2-All-Off switch.

This is what I had on my last camper and had the dealer do on my current one. Although I keep it to both all the time. If one goes bad, I can switch to the good battery.

The Lion are cool, but they are they expensive. I think they really shine when you use them with solar and use them with an inverter to run 110V stuff. For 5 days of boondocking, I think that's overkill.

I looked into the 6V stuff before, but decided to stay with a 12V setup. If one battery goes down, I have the 2nd to use. If I need to replace it, 12V is more readily available.