6 volt batteries in travel trailer

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bobdog
bobdog Solar Expert Posts: 192 ✭✭
in Off Grid Solar & Battery Systems #1
Hi guys. It's been awhile. Been busy per us all. Anyway, my cousin just bought 2 x 6 volt golf cart batteries for his travel trailer. The thinking is that one set of those in series is better than 2 lousy 12 volt "marine deep cycle" batteries. I have to say I concur. The typical marine-style battery is just a starter battery with a little umph. And he has more amp/hours to boot. Given this, he used it over the weekend and it barely made a dent in the batteries. I guess from 1.0 to .75 over the course of 5 days. Not bad. Here's the problem though. He hooked them back up to his truck to drive home and when he got there ( a trip of 600+ miles) he found that they hadn't charged at all. At least the battery meter on the travel trailer didn't register that they had charged. So, any thoughts as to why they didn't charge up? I'll leave it at that. Thanks in advance.

Tim
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #2
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    Re: 6 volt batteries in travel trailer

    Trying to charge a pair of GC-2 batteries from a alternator in a truck is a waste of time and effort with standard output. You need 25-30 amps of charging amperage and as soon as the truck battery fills up the regulator will cut it back.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
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    Re: 6 volt batteries in travel trailer

    try checking the specific gravity of the batteries to see if they are fully charged. it's possible they didn't need much to charge up.

    as to this,
    "1.0 to .75 over the course of 5 days"
    1.0 what to .75 what?
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #4
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    Re: 6 volt batteries in travel trailer

    I run a camper forum and this question comes up often. First thing to check is the wiring from the front to the back of the truck where the Bargeman (7 pin) connector is. The +12 charge/power line needs to be at least 10 gauge, 8 is better. Pre-wired factory wiring and most after market wiring by places like U-haul is usually 12 gauge. If the camper battery is low and you have the fridge on in 12 volt mode (which pulls about 10 amps by itself) you'll have such a severe voltage drop on the +12 line that nothing will get charged and the fridge will be warm. I almost always just use propane mode on the road now.

    Then look at the ground line. Most of the time it is a short line to the chassis, so increasing the gauge of that line won't do much, but can't hurt. However, if it is run all the way to the front of the truck its gauge is even more critical than the +12 line. That line handles all of the loads - brakes, brake lights, running lights, fridge, charging.

    Next you need to make sure your connection at the Bargeman is good. Those contacts are exposed to the worst conditions and corrode easily. Usually a squirt of WD-40 on all the contacts and then inserting & removing it a half-dozen times works for me. Also open up the plug and socket to look for loose wires where the screw terminals are. Lots of vibration loosens them up all the time.

    Finally look at the wiring from the Bargeman back to the converter, and the ground connection to the frame of the camper. At each step in this process take voltage measurements at the camper battery while the truck is running to see if you have something in the 13-something range. Also look at your truck's manual, many of the modern trucks have computer-controlled alternators, and when tow-haul mode is on (or the headlights are on) it forces the alternator to a higher voltage specifically to help with this problem.
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  • bobdog
    bobdog Solar Expert Posts: 192 ✭✭
    #5
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    Re: 6 volt batteries in travel trailer
    niel wrote: »
    try checking the specific gravity of the batteries to see if they are fully charged. it's possible they didn't need much to charge up.

    as to this,
    "1.0 to .75 over the course of 5 days"
    1.0 what to .75 what?


    Sorry Niel. That was the soc based on the little meter that most RVs have to show you how much battery power you have left. Basically an idiot light, and I'm an idiot for using such a thing on our site. However, given I don't have the trailer at hand (it's in Calif., I'm in NM) it's all my cousin can give me as far as information. 1.0 is fully charged, 0.75 is 3/4 charged and so on.
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  • bobdog
    bobdog Solar Expert Posts: 192 ✭✭
    #6
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    Re: 6 volt batteries in travel trailer
    techntrek wrote: »
    I run a camper forum and this question comes up often. First thing to check is the wiring from the front to the back of the truck where the Bargeman (7 pin) connector is. The +12 charge/power line needs to be at least 10 gauge, 8 is better. Pre-wired factory wiring and most after market wiring by places like U-haul is usually 12 gauge. If the camper battery is low and you have the fridge on in 12 volt mode (which pulls about 10 amps by itself) you'll have such a severe voltage drop on the +12 line that nothing will get charged and the fridge will be warm. I almost always just use propane mode on the road now.

    Then look at the ground line. Most of the time it is a short line to the chassis, so increasing the gauge of that line won't do much, but can't hurt. However, if it is run all the way to the front of the truck its gauge is even more critical than the +12 line. That line handles all of the loads - brakes, brake lights, running lights, fridge, charging.

    Next you need to make sure your connection at the Bargeman is good. Those contacts are exposed to the worst conditions and corrode easily. Usually a squirt of WD-40 on all the contacts and then inserting & removing it a half-dozen times works for me. Also open up the plug and socket to look for loose wires where the screw terminals are. Lots of vibration loosens them up all the time.

    Finally look at the wiring from the Bargeman back to the converter, and the ground connection to the frame of the camper. At each step in this process take voltage measurements at the camper battery while the truck is running to see if you have something in the 13-something range. Also look at your truck's manual, many of the modern trucks have computer-controlled alternators, and when tow-haul mode is on (or the headlights are on) it forces the alternator to a higher voltage specifically to help with this problem.


    Thanks techntrek for the through response. Very helpful. I'm working from afar here so I'll have to spoon feed him everything. I won't be seeing him or his truck/RV for quite sometime. I will tell him to check the gauge of the wire, which we went over with the battery cable(s), but he still won't know what that means. So, without tipping his hand he will need to go to an RV dealer and find out what gauge they are. I'll have him get all lines checked AND see how they are running including those to the Bargeman.

    Tim
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  • bobdog
    bobdog Solar Expert Posts: 192 ✭✭
    #7
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    Re: 6 volt batteries in travel trailer
    Blackcherry04 wrote: »
    Trying to charge a pair of GC-2 batteries from a alternator in a truck is a waste of time and effort with standard output. You need 25-30 amps of charging amperage and as soon as the truck battery fills up the regulator will cut it back.

    This seems like a no brainer, but do you mean that the voltage regulator will curt off/down the amps going to the trailer batteries as well as the starting battery when the starting battery is full? If that is indeed the case then how can one even charge up cheap "marine" batteries with this method? Confused also how more amps from an alternator would change this as it would only charge the starting battery up that much faster, thus cutting the excess amps back down. I'm sorry but I guess I'm missing something here.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #8
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    Re: 6 volt batteries in travel trailer
    bobdog wrote: »
    This seems like a no brainer, but do you mean that the voltage regulator will curt off/down the amps going to the trailer batteries as well as the starting battery when the starting battery is full? If that is indeed the case then how can one even charge up cheap "marine" batteries with this method? Confused also how more amps from an alternator would change this as it would only charge the starting battery up that much faster, thus cutting the excess amps back down. I'm sorry but I guess I'm missing something here.
    It's about resistance. The Truck battery is a couple feet from the Alternator / Regulator. The regulator senses the closest battery voltage. They make a Isolator / Relay that will take the Starting Battery out while charging your house batteries. There is still no guarantee that the wiring is sufficient to give you the amperage and voltage back to the trailer batteries especially if your using the truck frame as the ground path.
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  • bobdog
    bobdog Solar Expert Posts: 192 ✭✭
    #9
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    Re: 6 volt batteries in travel trailer
    Blackcherry04 wrote: »
    It's about resistance. The Truck battery is a couple feet from the Alternator / Regulator. The regulator senses the closest battery voltage. They make a Isolator / Relay that will take the Starting Battery out while charging your house batteries. There is still no guarantee that the wiring is sufficient to give you the amperage and voltage back to the trailer batteries especially if your using the truck frame as the ground path.

    So, not to be a numbskull here, what you are saying is that with the conventional set-up, the V-regulator takes out the batteries, including the house batteries when the closest one (the starting battery) gets full. However, there is a relay (or an isolator) that I can install (or he can) that when the starting battery is full it becomes isolated, then most of the power from the alternator goes back to the house batteries to charge them. I hope I have that right. If so, where would I start to find such a relay/isolator? and how about directions on wiring it up? Obviously he will need to run a dedicated ground from the (engine ground?) to the Bargeman? Thanks for your help and patience.

    Tim
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #10
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    Re: 6 volt batteries in travel trailer
    bobdog wrote: »
    So, not to be a numbskull here, what you are saying is that with the conventional set-up, the V-regulator takes out the batteries, including the house batteries when the closest one (the starting battery) gets full. However, there is a relay (or an isolator) that I can install (or he can) that when the starting battery is full it becomes isolated, then most of the power from the alternator goes back to the house batteries to charge them. I hope I have that right. If so, where would I start to find such a relay/isolator? and how about directions on wiring it up? Obviously he will need to run a dedicated ground from the (engine ground?) to the Bargeman? Thanks for your help and patience.

    Tim
    Here you go, I am sure they have a wiring diagram somewhere. This company makes all kinds of battery accessories. Alternators ( especially OEM ) always have a shaky output, at best, very few ever put out their rated output. This relay is rated for a input of 80 amps, there bigger ones 240 amps. These are based on output. A good DVM and amp meter would help you find where the problems are. You may have several to run down.

    This just one, there 100's different ones on the market. Lot's of them cheaper.


    http://sterling-power-usa.com/ProConnect-VSR80amp12vor24v.aspx

    Manual

    http://www.sterling-power-usa.com/library/ProConnect%20Relay%20Installation%20and%20Owners%20Manual.pdf

    Another type

    http://shop.pkys.com/Blue-Sea-Systems-7601-Mini-Automatic-Charge-Relay-_p_1520.html

    Manual

    http://assets.bluesea.com/files/resources/instructions/980014350.pdf


    .
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #11
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    Re: 6 volt batteries in travel trailer

    Like I said in my first post, most modern trucks have a solution to this problem, built-in...
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  • bobdog
    bobdog Solar Expert Posts: 192 ✭✭
    #12
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    Re: 6 volt batteries in travel trailer
    Blackcherry04 wrote: »
    Here you go, I am sure they have a wiring diagram somewhere. This company makes all kinds of battery accessories. Alternators ( especially OEM ) always have a shaky output, at best, very few ever put out their rated output. This relay is rated for a input of 80 amps, there bigger ones 240 amps. These are based on output. A good DVM and amp meter would help you find where the problems are. You may have several to run down.

    This just one, there 100's different ones on the market. Lot's of them cheaper.


    http://sterling-power-usa.com/ProConnect-VSR80amp12vor24v.aspx

    Manual

    http://www.sterling-power-usa.com/library/ProConnect%20Relay%20Installation%20and%20Owners%20Manual.pdf

    Another type

    http://shop.pkys.com/Blue-Sea-Systems-7601-Mini-Automatic-Charge-Relay-_p_1520.html

    Manual

    http://assets.bluesea.com/files/resources/instructions/980014350.pdf


    .

    First off, thanks for the leads Blackcherry04. That helps a lot as a road to go down. I wasn't aware of such systems and I can think of many places that they could be useful... However, I have to ask right off the bat, and this goes to techntrek, too, trucks have been charging 12 volt set-ups for a long time, even cars have. So, why is this situation so different that a truck (Ram 2500 with tow package) wouldn't have been set up to do this w/o all the extra stuff? I mean the trailer had 2 12 volt "marine" batteries to begin with and they apparently never seemed to be "not charged". ( I certainly can't say they were never undercharged though) but you get my point. As a matter of fact I have a trailer that has a dual battery set-up and my Chevy truck charges the batteries just fine between stops. So, with that being said, why is it different here? I can only think that having GC batteries and their needs as the only reason that this set-up is not working. What do you all think? I can't believe it, but it seems to be the only explanation. Or at least the most parsimonious explanation. If that is the case, then changing wire and possibly charging components is in order.

    Tim
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #13
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    Re: 6 volt batteries in travel trailer

    Based on my own experience with RV batteries and the 5 or so I inadvertently 'murdered', there is a BIG difference between an 'OK' charge and a real good full 3 stage charge.
    Once I found this forum I learned that my 3 stage intelligent charger from a big automotive chain store is ok for boosting my PV batteries if I am stuck, but it does not give a good quality charge. Car manufacturers are not in the business of doing anymore than keeping your rig running, the rest is your thing... now that winter is here, car batteries start to fail.

    PS you may be partly right about the GC-2's being a different beast to charge, best to give them a good charge before putting them to bed for the winter.
     
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #14
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    Re: 6 volt batteries in travel trailer

    I guarantee the problem here is the wiring size and/or bad connection. And... check if his truck has the ability to boost the alternator voltage via tow/haul or the headlight switch and then use that option if it is available.
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