Issues converting to 6v golf cart batteries.

[shortbus]

I had been having the feeling that my house batts were kinda on the weak side. They were just a mismatched set of marine batteries that were there when I bought it. They worked fine, but if I were to park up for a more extended period I kinda felt they might not hold up. I was only using them for a night or two before another day of driving. I hadn't worried about it much because I mainly travel with my rig and didn't need to stay parked for very long. The other month I came across an ad on CL by a local golf cart place that was selling brand new blemishes for $50 a piece. I figured I should jump on that. So now I have two matching 6v golf cart batteries. Boy they were hot, I could turn on a bunch of lights and you couldn't see the battery meter or lights dim when running the water pump. Big improvement, but not that I have traveled for a bit with them they don't really seem too much better than what I had. I am assuming you just can't get enough juice in these things with the alternator, or do I have some kinda issue. I can tell they are charging for sure, they just don't seem to get as hot as when I got them at the store. My onboard charger is the original 1987 charger, hums like a Bugger and warns to check the water levels on a weekly basis while in use, I take that as it sucks and will just dry out by batteries and not really charge them properly so I haven't use it at all. I have a modern 45amp converter charger,3 stage I'm pretty sure, I plan on installing as it should charge and maintain the batteries much better. I do lots of traveling and pretty much relying on the alternator charging everything up while I drive and then boondocking over night. Having to plug in to get these batteries up to charge would really be a bummer for most of what I do.

[Rickf1985]

Are you making sure the batteries are full of water? And especially are you using distilled water to fill them? Batteries generally get better for about 6 months and then level off for several years if taken care of. 2 6 volt batteries is not much for a camper unless you are not running much at all. Most RV's have at least 2 12 volt batteries which would be 4 6 volt batteries. I would get a hydrometer and check the specific gravity of the batteries to assess the actual condition of them.

[shortbus]

I haven't really checked the water yet. These things are like 2 weeks old so I didn't think I would need to be checking them this soon.


I'm still learning about batteries, but I know electricity pretty well. Saying two 6v batteries isn't much for a camper just doesn't make any sense. 12v is 12v no matter how you add up batteries to get it. These golf cart batteries have very high amp hour ratings. I should have a bit more backing these two 6v batteries than I would get 2 standard 12v batteries. I probably should invest in a hydrometer, but again, these things are only 2 weeks off the shelf, and they were very strong when I 1st installed them. My suspicion is that the alternator may not be getting up to the required voltage to get these things as charged up as they could be.

[legomybago]

Yes, the better battery set-up is the two 6v in series vs the two 12v parallel. People been using this combo for years in RV's.
You need to get a meter and start checking out-put voltages on your charging systems.

[ClydesdaleKevin]

If you are trying to charge them from your alternator, its not going to work unless you go on long drives.  Those batteries hold a lot of energy, so it takes a lot of input to fill them back up.  If your converter isn't charging them while you are plugged into shore power, invest in a decent battery charger for now...even the cheap Shumacher ones work pretty well from Walmart.  When you can afford to, replace your converter with one that charges in 3 stages, called smart charging.  They aren't too expensive from Bestcoverter.com.  I love our Powermax Boondocker converter, although there are other very good brands out there and available on their website.  A more expensive option is to add an inverter/charger to your system.  They charge your batteries when you are plugged into shore power, and then turns your 12 volts DC of battery power to 120 volts AC when you aren't plugged in.

Kev

[Rickf1985]

I missed the part about charging from your alternator. The problem there is that the alternator is sensing the charge from the chassis battery. Are these batteries in the chassis battery position or are you using a regular 12 volt for the starting battery? If so then the only charge going to the house batteries is overflow from the chassis battery, not a full charge. If you have a switch on the dash to change the charging over to the house batteries then that is different. And you will get just about them same amount of reserve power from two 6 volt batteries as you will from one 12 volt. Doubling the voltage does not double the reserve time.

[shortbus]

Often 8 to 10 hours of driving, I thought that would be enough for a little use for a night or two, but that was also a pure assumption. It seems you missed the part where I said I had a modern converter charger, I just haven't gotten around to installing it yet. I just checked it out, it's a progressive dynamics 45amp 4 stage. I'm sure this will help, but I guess I'll be relying on the generator because I am often without hookups.


These batts are hooked up as the house batteries and there is a separate 12v automobile battery for the chassis. I have no switch but I kinda like where that idea is going if it can get me some more juice in the house batteries while I'm driving. I don't think you are understanding these 6volt golf cart batteries. These 2 batteries take up more space than the two 12v marine batteries I use to have. I imagine I will get about the reserve power that they are rated at when I have them fully charged, which is a good bit because like I said these things have a fairly high amp hour rating. Much more than two smaller 12v batts. There is no way you are really trying to say that one 12v battery would give me more power than two big 6v batteries hooked up for 12v is there? I'm not doubling the voltage, like I said 12v is 12v.

[Rickf1985]

What I am saying is you are taking two 6 volt batteries at say, 1000 amp hour each. You hook these up in series to get 12 volts and you will still have 1000 amp hours but at 12 volts, not 6. I understand what you are saying about the 6 volts batteries being bigger. I am talking about comparable size batteries. If you have two 1,000 amp 6's and are comparing them to a 800 amp 12 then yes, they will last longer. But if they are equal size then they will last pretty close to the same amount of time. NOW, One big advantage of the 6's is that they are true deep cycle batteries and will live a much longer life if taken care of than the 12 volt SLI battery. They will also tolerate lower discharge rates and more charge cycles so yes, buying them is a good choice. My original comment was based on replacing each 12 volt battery with two 6 volt batteries to get the same amount of reserve capacity, therefor if you had two 12's get four 6's.

[PwrWgnWalt]

Hi there, shortbus!


Having redone my entire 12vdc system, a couple of possibilities come to mind if I understand your posts correctly. 


Short answer is, with reasonable 12vac draw, those 6volt golf cart batteries should last quite a while. There are mathematical equations elsewhere on this site that provide the answer to "how much for how long" (amp-hour based, so you'll need to know the parameters of the batteries)


First, have you verified you are getting charging voltage to your 6v battery bank when the engine is running?   
(since there are various methods of splitting the alternator output to charge the 12v 'chassis' battery and the 'coach' battery bank, how does yours accomplish this?)


Second, have you verified charging voltage to your 6v battery bank from your modern converter/charger?


Basically, map out exactly "when" your 6v battery bank is getting charge current (under what conditions); and exactly "how much" charge it's getting in each case.
From that info, you should be able to figure out if there's an issue, and where it stems from.


Walt

[shortbus]

Oh yea, even if it's just by the onboard poor-fair-good meter, you can tell they are charging. The lights get much brighter when the engine is running. It's obvious the voltage is increasing. I am using the original battery isolator that she came with. I have noticed that when starting the engine the house lights will dim a bit. Is this normal? The battery isolator does seem to be working, the two batter banks are at two different voltages and don't try to equalize or anything.


Ok, all and all they may not really be doing that bad. To give an example I have been parked up at my parents house since Sunday evening. It's been cold here and I have been using the furnace now for 3 nights and a bit through so of the days, but not really set too high. The fridge has been running, but on propane so just the circuit board and igniter, a few hours of light, the water pump just enough to flush a few times and brush my teeth and charging my phone. When I checked the bank a few hours ago I was at 11.9ish volts. I might would be using them more if I was out in the woods, more lights, lots more water pump, some music or video games. Might would be a wash if it wasn't cold and I was't using the furnace though, some LED lights will probably be soon enough too. All the lights had good bulbs when I got it and I just haven't messed with them yet. So say I will need to run the gen for a few hours every 2ish days if I was trying to do an extended off grid stay somewhere.

[Rickf1985]

Charging through a battery isolator is not the optimum way to charge the batteries. If you have the new charger you mentioned hooked up to the generator then that would be the best way short of installing solar on the roof. The use you mention is actually pretty good for one set of batteries. That type of use would normally call for a larger battery bank, hence why I mentioned the two 12's or 4 6's. If you are going to be doing a lot of boondocking then you should convert all of the lighting over to LED, that will save a lot of power. That and dig up the power charts on here and sit down with them and figure out your exact power use and battery power availability. Then you will know how long you can go and whether you are getting what you think you should be getting. A lot of people do not realize just how much power they actually use. A heater blower fan is pretty power hungry, as are some older water pumps.

[DaveVA78Chieftain]

The 87 Southwind opeators manual indicates you have electronic (diode based) dual battery isolator.  Most likely located on the firewall up under the front engine access hood.  Maybe located inside of a battery control center (BCC) on fleetwood products.  The manual also indicates the AUX battery side of the isolator is also fused.  You need to use a volt meter to verify that charging voltage is reaching the AUX battery when the engine running.  Should be up around 13.1VDC when the engine is running.  Typically these type of isolators only sense "engine" battery charge level so, the "AUX" battery may not be getting recharged properly.  However, that 13.1VDC value can be misleading in this sort of setup.  Because it is referenced to "engine" battery charge level the regulator adjusts the output current such that it maintains that 13.1VDC level.  If, the "engine" battery charge level is near full, the amperage rate needed to maintain that 13.1VDC level will be very small  even though the "Aux" battery may still need a lot of charge.
A better design for the "alternator" based charging system is to use a Bi-Directional Isolator Relay (BIRD).  This system deletes the diode based isolator and uses your "AUX" start solenoid as the battery cross connect.  It monitors both battery systems (engine and aux) and energizes/de-energizes the AUX start relay as required to redistribute charging current across both systems.

An one more plus of the BIRD, it works in both directions!  Engine running while driving and DC converter/charger while hooked to shorepower/generator.