Additional 12v battery for Roo 21 RS...

[Jimsue]

I've purchased an additional 12v Battery and carry box for mounting on the AFrame on the front of my trailer, next to my existing battery. Two questions:

1. Where can I get "jumper" cables to connect the terminals to configure the two batteries to run in parrallel. They have to be approximately 24" in order for me to route them thru the side portals of the battery boxes...see attached drawing:


2. When camping and plugged in to an AC power source,

[Jimsue]

Originally Posted by Jim Coolyard

I've purchased an additional 12v Battery and carry box for mounting on the AFrame on the front of my trailer, next to my existing battery. Two questions:

1. Where can I get "jumper" cables to connect the terminals to configure the two batteries to run in parrallel. They have to be approximately 24" in order for me to route them thru the side portals of the battery boxes...see attached drawing:
Attachment 50930

2. When camping and plugged in to an AC power source,

Do I need to disconnect the batteries to avoid "overcharging" .... We typically camp for one or two weeks in one spot...

[lswartz]

Originally Posted by Jim Coolyard

1. Where can I get "jumper" cables to connect the terminals to configure the two batteries to run in parrallel. They have to be approximately 24" in order for me to route them thru the side portals of the battery boxes

I got mine at Walmart.

[bikendan]

i have a two 12v setup also and i also got the connecting cables at Walmart i think.

and no, you shouldn't have to disconnect the batteries when hooked to shore power.
that's what your 3 stage converter is supposed to do, recharge the batteries.
UNLESS your converter is going bad.

i hope you bought a matching 12v battery and the other one is still almost new.

[Jimsue]

Yes...both are brand new batteries...thanks..i'll check Wallys.

[Jimsue]

Its not recharging I'm concerned about...it is overcharging. My battery salesman said that unless the system shut down the charging sfeature automatically, i would run the risk of overcharging and burning out my new batteries.

[bikendan]

Originally Posted by Jim Coolyard

My battery salesman said that unless the system shut down the charging sfeature automatically, i would run the risk of overcharging and burning out my new batteries.

that's what i meant, when i said a 3-stage converter. that's what modern RV converters do.

and your salesman obviously doesn't know anything about modern RV converters.
he's a battery salesman, not a RV tech.

[Jimsue]

Good point. That's why I do my due diligence here with pros such as yourself. As I understand it, then, it is ok to leave my trailer plugged in to shore power indefinitely with this type of setup, assuming my converter is functioning properly. How would I know, then, if it is not functioning as it should?

[RPAspey]

Problems you may run into with a dual 12v setup are as follows:

1-your charger is not a true 3-4 stage, it may not properly charge the batteries as it will look at output voltage. You'll need to hold that bulk charge longer, them go into a proper float mode with a lower voltage/current. This will reduce their lifespan.

2-Boiled of water. most likely a lower grade charger will overcharge as it won't go into float mode. It will hold the higher voltage too long and boil off the fluids. If you get sealed batteries, you have no way of adding distilled water. With all battery sets, you must check your fluid levels often.

2000 Cherokee 31BH, "flipped axles and raised",LEDs, solar, inverter, etc..aka "boondock ready". '07 Tundra 5.7L DC-LB, modded as well.

[Jimsue]

RP
Thanks very much for your explaination, though I must confess that I am a bit overwhelmed by how much I don't know about this subject. At risk of taxing your already generous giving of time and expertise, perhaps you could either direct me to a good source or try to explain in simple terms the following:

your charger is not a true 3-4 stage, ( How can I tell? Are chargers normally located in accessible areas? )it may not properly charge the batteries as it will look at output voltage.

You'll need to hold that bulk charge longer, (Bulk Charge...what is it? ) them go into a proper float mode (Float Mode? )with a lower voltage/current. This will reduce their lifespan.
(This might be a good point for me to be referred to electronics 101, a class I missed)


2-Boiled of water. most likely a lower grade charger (is there a way to tell if my charger, wherever it may be, is "lower grade"?)will overcharge as it won't go into float mode. It will hold the higher voltage too long and boil off the fluids. If you get sealed batteries, you have no way of adding distilled water. With all battery sets, you must check your fluid levels often. (Fortunately, my new batteries (24 Marine DC 12s) are not sealed, so I can periodically check them).

Sorry to be so clueless; your patience is valued.

[Jimsue]

Researching, I discovered I have a WFCO Power Center Model WF-8955PEC three stage switch mode power converter that is fully automatic.
The three modes are: Absorbtion, Bulk and Float.
No mention of a fourth mode.

[Triguy]

1) Cables
You will want those two new cables to be the same length. This diagram below also recommends you make the cables going to ground and to your converter the same length but you won't be able to do that with your trailer. Don't worry about it, just make sure the two "internal" wires connecting the batteries (+ to + and - to -) are the same.



2) Disconnecting
As said previously, you don't need to disconnect and don't want to. Your converter will look at your two-battery bank as just one big battery.

3) Converter stages
Your WFCO 8955PEC is fine for your need. Although the WFCO's are not the best, they are not terrible converters and it can charge your two 12-volt battery bank.

Here's the manual (WFCO 8900 Converter).

The WFCO's three stages are:

• Absorption Mode at 13.6 Vdc range
• Bulk Mode for when the converter thinks the batteries are less than 50% charged will give 14.4 Vdc for a maximum of four hours.
• Float Mode is a trickle voltage of 13.2 Vdc if the RV is not being used for approximately 48 hours.

4) Extra information
WFCO is a less-than-desirable convertible with certain deep cycle batteries, though.

One is that its well known to almost never go into bulk mode. Two - it drops its amps quickly to a trickle in order to protect the batteries (I think it does this because many campers like to leave their trailers plugged in all the time, even in storage, so its not a bad thing). Three - many deep cycle batteries need a higher voltage than the converter can provide (e.g., my Trojan batteries need 14.8 volts).

I recommend the use of a good portable three or four stage charger as a supplement to your converter to extend the life of your batteries. Its not absolutely necessary, though, but I believe it helps to extend battery life.

In my case (I have the same converter) I use a portable 40amp 3-stage charger from Stanley that hits the voltage requirements for my batteries. I charge through the converter for convenience and when I am using the trailer, but use the charger when I am at home.

Its important to note that sulfation occurs when a lead acid battery is deprived of a full charge, which will happen if the converter cannot charge to its recommended volts as explained above. Crystals form within the battery and eventually larger crystals reduce the batteries active capacity. See Sulfation and How to Prevent it.

The WFCO 8900 series does not have the ability to de-sulfate the batteries so periodic reconditioning is recommended to maintain a battery's optimum performance and prolong its life.

On a healthy battery bank, reconditioning mode on my charger sends a series of electrical pulses to break up the crystalline form of lead sulfate and turn these chemicals into useful battery electrolytes.

[Triguy]

Jim, you might also find some of these resources handy to learn more about 12-volt systems.

Our library has a number of interesting resources Forest River Forums - Downloads - Power and Electrical

The 12-Volt Side of Life is a good primer.

Consider buying this book on managing 12-volt systems in RVs and boats. It does a phenomenal job helping to diagnose issues that will almost certainly crop up in your ownership of your trailer:

Managing 12 Volts: How to Upgrade, Operate, and Troubleshoot 12 Volt Electrical Systems by Harold Barre.

Finally, invest in a decent multimeter and bring it with you when you camp.

[RPAspey]

Originally Posted by Jim Coolyard

Researching, I discovered I have a WFCO Power Center Model WF-8955PEC three stage switch mode power converter that is fully automatic.
The three modes are: Absorbtion, Bulk and Float.
No mention of a fourth mode.

Well Jim, your charger should be ok. It's a three stage charger.

You'll have to keep close tabs on the water level. At first you should check it weekly until you can determine how much the batteries use. As a battery is charging, it bubbles, this is a normal part of the charging process. often referred to as boiling. As the battery nears full charge, a 3 stage charger should reduce the voltage (which reduces the current going into the battery). If the voltage isn't reduced, the boiling continues, and the battery will lose fluid. AKA, boiling off.

BTW, 3 stages are BULK - as much current as can be put into the battery based on battery voltage(state of charge)/internal resistance/charger capabilities. After reaching a predetermined voltage usually 80-90% of full charge, the charger will switch to ABSORPTION- which is a slightly lower voltage level until the battery reaches full charge. The lower voltage reduces charge current to prevent overheating and boiling off of the fluid. Once charged, the charger will switch to FLOAT - basically a charge voltage to keep the battery at 100%.

2000 Cherokee 31BH, "flipped axles and raised",LEDs, solar, inverter, etc..aka "boondock ready". '07 Tundra 5.7L DC-LB, modded as well.

[Batts-toy]

Originally Posted by Jim Coolyard

Yes...both are brand new batteries...thanks..i'll check Wallys.

If you haven't been out to get your cables yet most auto parts stores have them and probably a better selection than Wally's. I got everything I needed to install 4 six volt batteries in my TT at O'Reilly Auto Parts. They had a very large selection but I ordered the ones with the small holes to fit the battery post better than the standard automotive style, got them the same day.

[f5moab]

My dealer used 12 gauge wire between the dual batteries; I have a 30 or 35 amp system. So for that short of a run 12 gauge is ok. (For 36 amps, up to 10 feet is ok for 12 gauge wire, 12 volt system.)

I have the 8900, and this past week, I have verified, via a Trimeter 2025RV battery system monitor, that the converter will go into a 14.4 bulk mode, if batteries drop below 50 percent, and then drop down to the 13.2 float mode. (I purposely drained the batteries to about 40 percent (11.8 volts) with the fridge, then plugged it in, and watched the meter shoot up to 14.4 volts. Did not time the length of time it remained at 14.4, I left, came back a few hours later and it was charging at 13.2 volts. So it might have been at 14.4 volts for four hours or five minutes....not sure.)

[Jimsue]

Thanks to everyone for the links, tips and solutions. I purchased and installed the 4 gauge "jumper" cables and they seem to be working fine thus far. Now I'm going to the local Library or Amazon to begin my education with the resources recommended. Your support has been outstanding. I hope I can "pay it forward" when I gain some experience.

[KMP44]

Originally Posted by Jim Coolyard

Thanks to everyone for the links, tips and solutions. I purchased and installed the 4 gauge "jumper" cables and they seem to be working fine thus far

Sounds like you are all set with cables, but I came across these at McMaster Carr. They are pre-made cables designed to connect 2 or 3 batteries.


McMaster-Carr

Automotive battery cables from Walmart or Autozone seem to be fine too. I made up mine (before I found the pre-made ones) but its a pain to find a proper crimping tool when you only want to make a couple cables.

We have (2) 12 volts on our Roo and the facory converter seems to do OK at charging them even though its not the best setup. Over the winter I used a Diehard 4 stage charger (less than $100 at K-mart). It's pretty slick - it monitors the battery and determines the best settings. Revived my Dad's car battery after it sat dead all winter - I was amazed! So I use that for winter maintenance on the deep cycles.

[Jimsue]

Originally Posted by KMP44

Sounds like you are all set with cables, but I came across these at McMaster Carr. They are pre-made cables designed to connect 2 or 3 batteries.


McMaster-Carr

Automotive battery cables from Walmart or Autozone seem to be fine too. I made up mine (before I found the pre-made ones) but its a pain to find a proper crimping tool when you only want to make a couple cables.

We have (2) 12 volts on our Roo and the facory converter seems to do OK at charging them even though its not the best setup. Over the winter I used a Diehard 4 stage charger (less than $100 at K-mart). It's pretty slick - it monitors the battery and determines the best settings. Revived my Dad's car battery after it sat dead all winter - I was amazed! So I use that for winter maintenance on the deep cycles.

KMP
I wonder if I could use a charger like the Diehard to charge TWO batteries at once? Like when I'm storing them for extended periods in my garage or basement...by using the aforementioned jumpers ?

[Triguy]

Originally Posted by Jim Coolyard

KMP
I wonder if I could use a charger like the Diehard to charge TWO batteries at once? Like when I'm storing them for extended periods in my garage or basement...by using the aforementioned jumpers ?

Yes, you can. The charger just sees one large battery. With two 12-volt batteries, the parallel connection will increase your current rating, but the voltage will stay the same. So, two 12-volt 100Ah (@ the 20-hr rate) batteries in parallel give you a battery bank equal to 12-volts and 200Ah.

Generally, the recommendation for deep cycle batteries is that the maximum constant current rate of the charger in amps should be approximately 20% of the amp hour rating of the battery. At least that is what Trojan and interstate advise.

The following below is a guideline from Trojan batteries...

What size charger should I buy?
A properly sized charger takes into account battery capacity and the time interval between charges. In applications where cycling is infrequent, such as weekend RV users, or infrequent or seasonal trolling motor usage, a charger with an output current rating between 10 and 13% of the battery's rated 20-hour capacity will suffice. In applications where battery recharge must be accomplished within 8 to 10 hours, a three stage, automatic charger, rated at 20% of the battery capacity, may be required.

Example: A good charging rate for a battery with a 20-hr capacity of 225 amp-hr is about 22 to 29 amps. You can of course go slightly higher or lower depending on what is available on the market.