Charging 6v batteries on rv

[texaspete1]

I replaced the 2 12v batteries on my fifth wheel with 2 6v. I have an onboard 5500 Onan generator. It will have to run for quite sometime to just get to 2/3 (three red lights) it will then run down rapidly to one light and will not have enough power to turn the generator over. I then have to jump the generator with my truck. I even have a separate battery charger plugged into an outlet on the outside of the rv and attached to the battery. I have it set to charge at 45 amps. I thought this would be a way to get extra power to the batteries but still they drain rapidly. (15-20 minutes) The batteries are not even a year old. Please help. Electrics are so frustrating to me.

[007matman]

How did you wire up those batteries? They should be wired together.

Positive on one battery is connected to the camper.
Negative on the other battery is connected to the camper
The remaining two terminals (a positive and a negative on each) should be connected together.

Also, use a similar or lower (larger) guage wire to connect the two.

[bikendan]

Originally Posted by texaspete1

I replaced the 2 12v batteries on my fifth wheel with 2 6v. I have an onboard 5500 Onan generator. It will have to run for quite sometime to just get to 2/3 (three red lights) it will then run down rapidly to one light and will not have enough power to turn the generator over. I then have to jump the generator with my truck. I even have a separate battery charger plugged into an outlet on the outside of the rv and attached to the battery. I have it set to charge at 45 amps. I thought this would be a way to get extra power to the batteries but still they drain rapidly. (15-20 minutes) The batteries are not even a year old. Please help. Electrics are so frustrating to me.

Did you wire them in series(correct way)or in parallel(wrong way)?
Suggest that you check out this website:

http://www.marxrv.com/12volt/12volt.htm

[flyflotrtim]

If the batteries are wired correctly (see posts above) there is a chance one or both of the batteries is bad. There have been some recent posts of Costco batteries failing within the first year.

[tomkatb]

Without a battery monitor it is difficult to figure battery stuff out.

Those red led’s on the wall somewhere are best used for entertainment.

A full battery takes days on shore power. Don’t know your situation.

Full voltage is 12.6. Higher readings indicate it is charging. Nothing else. 13.5 indicates the converter is running full tilt.

[TitanMike]

Originally Posted by texaspete1

I replaced the 2 12v batteries on my fifth wheel with 2 6v. I have an onboard 5500 Onan generator. It will have to run for quite sometime to just get to 2/3 (three red lights) it will then run down rapidly to one light and will not have enough power to turn the generator over. I then have to jump the generator with my truck. I even have a separate battery charger plugged into an outlet on the outside of the rv and attached to the battery. I have it set to charge at 45 amps. I thought this would be a way to get extra power to the batteries but still they drain rapidly. (15-20 minutes) The batteries are not even a year old. Please help. Electrics are so frustrating to me.

Assuming the "new" batteries were installed correctly they most likely were either discharged more than 50% regularly, not fully recharged, or both.

When batteries indicate full charge but go flat in less than an hour, they no longer have any capacity left.

When installing new batteries also install a GOOD battery monitor like the Victron Smart Shunt and put some black tape over the LED's that pretend to be monitoring the battery state of charge. They are more battery killers because of the faulty information.

A good battery monitor can save you hours of generator time too.

[texaspete1]

Originally Posted by 007matman

How did you wire up those batteries? They should be wired together.

Positive on one battery is connected to the camper.
Negative on the other battery is connected to the camper
The remaining two terminals (a positive and a negative on each) should be connected together.

Also, use a similar or lower (larger) guage wire to connect the two.

The local rv service wired them in. I do believe they are installed correctly.

[texaspete1]

Originally Posted by TitanMike

Assuming the "new" batteries were installed correctly they most likely were either discharged more than 50% regularly, not fully recharged, or both.

When batteries indicate full charge but go flat in less than an hour, they no longer have any capacity left.

When installing new batteries also install a GOOD battery monitor like the Victron Smart Shunt and put some black tape over the LED's that pretend to be monitoring the battery state of charge. They are more battery killers because of the faulty information.

A good battery monitor can save you hours of generator time too.

Can you recommend a good battery monitor?

[camaraderie]

OK...first..you have a CONVERTER built in that charges your batteries from ANY 120V source....the campground pedestal OR your generator. It will likely be rated for 55amps or more of current WHICH IS THE MOST your batteries can absorb anyway.
You NEVER want to go below 50% charged before recharging. Your current batteries are likely toast no matter how new.
IT WILL TAKE A MINIMUM of 6 hours of plugged in or generator time to CHARGE TO 100%, You need to know when to START charging AND when to stop charging your BRAND NEW BATTERIES. So get a real monitor installed. Victron bmv700 will do all the basics you NEED for about $150... BMV712 adds more at $200 and is popular here so check that out as well.
FINALLY...when you put away the RV for some time...fully charge the battery THEN disconnect the black negative wire. This will insure a good battery when you come back to it. Check that voltage on your monitor reads above 12.4 every couple of months and then recharge as needed.

[texaspete1]

Originally Posted by camaraderie

OK...first..you have a CONVERTER built in that charges your batteries from ANY 120V source....the campground pedestal OR your generator. It will likely be rated for 55amps or more of current WHICH IS THE MOST your batteries can absorb anyway.
You NEVER want to go below 50% charged before recharging. Your current batteries are likely toast no matter how new.
IT WILL TAKE A MINIMUM of 6 hours of plugged in or generator time to CHARGE TO 100%, You need to know when to START charging AND when to stop charging your BRAND NEW BATTERIES. So get a real monitor installed. Victron bmv700 will do all the basics you NEED for about $150... BMV712 adds more at $200 and is popular here so check that out as well.
FINALLY...when you put away the RV for some time...fully charge the battery THEN disconnect the black negative wire. This will insure a good battery when you come back to it. Check that voltage on your monitor reads above 12.4 every couple of months and then recharge as needed.

Thank you for your response. We will definitely get the monitor installed.

[RVGo2]

I could be wrong but it sounds like you may be trying to charge the batteries from two seperate sources at the same time - directly from the generator with a seperate charger and directly through your onboard 120vAC converter to 12vDC system. If this is the case then the two seperate systems are telling each other that the end user (the batteries) are fully charged and signaling to each other to stop charging. If so try without the seperate charger connectted to the generator. I hope this helps - I've been there too!!

[ScottBrownstein]

Something is wrong here. It should not take a long time for the charger(s) to get up to 13.3 or so. Another symptom is that the auxiliary charger needs to be set at 45 amps to do anything. Now, the two charging sources could the confusing each other as another post warns. Love to know what the actual battery voltage is when only the converter is running. Could be a shorted cell that is pulling down the chargers. Voltage reading from each of the two 6 volt batteries with the chargers off would be nice. LEDs are good to verifying that charging is taking place and they don't give us a lot of confidence that is actually happening. SOC reading is way beyond the scope of this problem....

[Flybob]

It is a long shot, but if this is a very recent problem, check to insure that the breakaway brake switch is not pulled. This could cause the issue you are seeing.

[ScottBrownstein]

Originally Posted by Flybob

It is a long shot, but if this is a very recent problem, check to insure that the breakaway brake switch is not pulled. This could cause the issue you are seeing.

Brakes engaged...interesting thought, but I didn't know that 5th wheels had breakaways....but I guess they might!

[NJKris]

Originally Posted by camaraderie

OK...first..you have a CONVERTER built in that charges your batteries from ANY 120V source....the campground pedestal OR your generator. It will likely be rated for 55amps or more of current WHICH IS THE MOST your batteries can absorb anyway.
You NEVER want to go below 50% charged before recharging. Your current batteries are likely toast no matter how new.
IT WILL TAKE A MINIMUM of 6 hours of plugged in or generator time to CHARGE TO 100%, You need to know when to START charging AND when to stop charging your BRAND NEW BATTERIES. So get a real monitor installed. Victron bmv700 will do all the basics you NEED for about $150... BMV712 adds more at $200 and is popular here so check that out as well.
FINALLY...when you put away the RV for some time...fully charge the battery THEN disconnect the black negative wire. This will insure a good battery when you come back to it. Check that voltage on your monitor reads above 12.4 every couple of months and then recharge as needed.

This is actually a bit of a misconception on this forum. True deep cycle batteries like golf cart batts can be discharged as low as 20% without damaging them. Best practice is to not go below 50%, as it is a good compromise number to get the maximum number of charge cycles out of the batteries. You can get even more cycles by going even shallower with discharge. More important is quickly recharging after discharged and not leaving in a discharged state.

[rsdata]

texaspete1...

read this short article for some background info...

https://www.victronenergy.com/blog/2...ectrical-life/

[OYO]

I and many here have learned a lot from this site: The 12volt Side of Life (Part 1)

I'm not sure it's totally up-to-date, but it explains things nicely.

Sorry if it's already been mentioned, I didn't see it.

[CHICKDOE]

Originally Posted by ScottBrownstein

Brakes engaged...interesting thought, but I didn't know that 5th wheels had breakaways....but I guess they might!

yes, at least our fifth wheel came with a factory installed break away switch and cable. i thought they were standard on all trailers, both bumper pull and 5th wheel.

[Rolland]

Originally Posted by CHICKDOE

yes, at least our fifth wheel came with a factory installed break away switch and cable. i thought they were standard on all trailers, both bumper pull and 5th wheel.

I believe breakaways are required by DOT on all travel trailers and fifth wheels. I’ve seen my share of damaged beds from fifth wheels coming loose due to improperly connecting the.

[Chuck_S]

Break away switch is required for trailers.

Forget you have two (2) 6v batteries. Once wired in series you have one (1) 12v battery. Treat it as such.

All a 6v battery is is three 2v cells in series in the same case; a 12v battery is six 2v cells in series in the same case. Putting a pair of 6v batteries in series gives you the same six 2v cells in series only they're in multiple cases.

-- Chuck