quick question on battery charging

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

endeavor

New member
Joined
Jul 9, 2018
Posts
3
Hi
I'm in the process of setting up my RV to run on batteries as we dont have shore power at our new camping spot.
Right now I am running a generator during the day, and 12v battery for the lights after 11pm

In the long term, I am going to install solar but we'll leave that for another day's discussion.

So I currently have 4 x 12v batteries wired in parallel, as below:

The batteries are connected to an inverter, which in turn goes to a transfer switch to alternate between generator and battery power for the trailer

My question is, how do I go about charging the batteries in this configuration, I dont want to be re-wiring them just to recharge every couple of days. Will I degrade the performance of one or more batteries if I just connect the pos/neg leads directly to an external battery charger? The inverter will be remote switched off during charging phase

hope someone can offer some advice

Thanks
Simon
 

Attachments

  • 12-volt-parallel-4.jpg
    12-volt-parallel-4.jpg
    28.9 KB · Views: 13

AStravelers

Well-known member
Joined
Nov 14, 2016
Posts
1,591
Location
San Antonio, TX
Simple answer is: Yes, you can just connect the leads from the external battery charger to the battery bank in your RV.

However there should be some method of charging the batteries already built into your RV.  Is there some reason why you are not using the built in charger to charge the batteries?

More complete answers about charging the batteries would be possible with more details about your RV, i.e. make, model & year. 
 

endeavor

New member
Joined
Jul 9, 2018
Posts
3
Thanks for the reply

I was under the impression that the inbuilt charger is a trickle charger and not quite up to the job of replenishing a larger battery bank?

I have a 1980's Prowler Travel Trailer which is kept on site. it's our first season with it, so we're new to all this.
We got it for an offer we couldn't refuse and trying to work out if it's viable for us for every other weekend.
 

endeavor

New member
Joined
Jul 9, 2018
Posts
3
I should add, the single 12v battery to power the lights currently is able to be charged by the onboard converter

the bank of 4 batteries is to power 110v appliances and outlets.
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
73,542
Location
At our Silver Springs FL home
If the old Prowler still has the original converter/charger, then yeah, it's a minimal sort of charger.  I would vote to replace it with a modern unit. which will charge faster, keep the batteries more healthy, and handle larger battery banks. That won't cost any more than a good quality and fairly large automotive type charger and give you 45-60 charging amps.  I gather you already have an inverter - too bad you did not get a combo converter/inverter that would do the entire 12v power management job.
The Prowler probably has a Magnetek 63xx power center. There are several upgrades for that, either replacing part of it (lower section), replacing all of it with a WFCO or similar unit, or adding a deck mount converter/charger to it.
 

John From Detroit

Well-known member
Joined
Apr 12, 2005
Posts
24,807
Location
Davison Michigan
The simplest answer is: You have ONE BIG 12 volt battery. SO it's in 4 pieces. it is still ONE battery.
So number them 1.2.3.4 I'd hook the Positive lead to either 1 or 4 and the negative to 4 or 1 (The other end)

Unless those are some BIG 12 volts. like 4D DEEP CYCLE.. I'd suggest upon replacement going to GC-2 six volts arranged as below

-6v+-6v_= 12 volt
-6v+-6v_= 12 volt

(the two 12 volt ends are joined as are the left side)

Again you have one BIG(ger) 12 volt battery in 4 pieces for ease of lugging. ROughly the equal to two 4D and they are DEEP CYCLE.. Plus less cost per amp-hour.
 

grashley

Well-known member
Joined
May 7, 2015
Posts
6,566
Location
Western Kentucky
You can connect all 5  12V batteries together in a single battery bank and use it for both 12V needs and feeding the inverter.  There is no need to keep the two separate.
 

nodnod

New member
Joined
Dec 23, 2018
Posts
1
You can connect a charger to your battery bank and charge them as if they are one large battery. You can verify that they are being charged equally by checking the voltage across each battery while charging. Voltage should read the same across each battery. To check the condition of an individual battery, it must be disconnected from the others. It can then be checked for voltage. I bought a cheap load tester ($40.00 CAD) that puts a load on the battery and gives an indication of its performance. All of the batteries should perform about the same. If one performs significantly worse than the others, and all the connections  are good, then that battery should probably be replaced. Having said that, the age and general condition of the other batteries should be looked at. It is always best to have all the batteries in a bank the same size, type, age and condition.
 

Larry N.

Well-known member
Joined
May 26, 2010
Posts
7,740
Location
Westminster, Colorado
grashley said:
You can connect all 5  12V batteries together in a single battery bank and use it for both 12V needs and feeding the inverter.  There is no need to keep the two separate.
Be sure the batteries are at least the same capacity when you do this, and preferably the same age as well. Battery differences can affect how well the charging goes.
 
Top Bottom