Battery Maintainer

[msmith1199]

I used to leave my motorhome plugged in all the time and let the onboard charger keep the batteries charged. But I found myself having to replace the house batteries every couple of years as I think the onboard system was supplying too much charge to them. I keep my motorhome in indoor storage and I have a 15 amp outlet inside. I've found I can disconnect the house batteries with the switch up front and they keep their charge for several months. But the chassis batteries get a little draw from the engine computer and they will be dead in a couple of weeks.

I had bought a battery maintainer for a 12 volt system and I attach it to the chassis batteries while the RV is in storage, but I think it's too small to keep up with both batteries as after a few days it starts giving an error signal. What I'd like to find is a decent battery maintainer that I can hook straight to the chassis batteries to keep both charged without having to power the onboard inverter at all. Anybody got any suggestions for one that will work to keep two 12 volt batteries charged?

[msmith1199]

I have the onboard inverter/charger to fully charge them.

[Gjac]

msmith1199 wrote:

Gjac wrote:

msmith1199 wrote:

stevenicol wrote:
I keep my two 6-volt AGM batteries charged and maintained with a battery tender. You can keep 2 12 volt batteries charged and maintained the same way; connect the batteries in tandem so that the battery's amp hours are added and the voltage stays 12 volts: a 12-volt charger will keep them "full."

I have a 12 volt Battery Tender charger and it doesn't keep them full. That was the reason for the post.

I would disconnect your neg cable and check to see what your parasitic amp draw is. Mine is about .4 amps if yours is over an amp you may have something left on. A 1.5 amp maintainer should maintain your 12v battery. Like I said in my first post just disconnect the neg cable on your chassis battery after it is fully charged, If it draws down in a week or so you may have a bad cell or sulfated battery. A good battery that is disconnected should last a month in between camping trips even in Ca.

I notice you kept saying "battery" as in singular. The post is about "batteries" as in two 12 volt batteries connected together. I would agree that the 1.5 amp should keep one charged, but based on the research I've done, it isn't enough for two. The only question is what is enough for two? And the biggest problem with the one I have is it will stay in charge mode "red light on" for several days, and then it starts flashing an error code and I assume shuts down. So that is why I'm sure it just isn't big enough. I've never seen it with just the steady green light on which is what it is supposed to switch too when the battery is fully charged and is just being maintained.

Have you checked to see what your parasitic draw is? It sounds to me if your batteries are being draw down in 2 weeks and your getting an error signal that something may be failing in your batteries or your batteries were not fully charged before you put the maintainer on. Do you have a portable charger to fully charge your chassis battery?

[DSDP_Don]

Check this brand out..Noco Genius. You can charge multiple banks with the level of charge you need.

[msmith1199]

Gjac wrote:

msmith1199 wrote:

stevenicol wrote:
I keep my two 6-volt AGM batteries charged and maintained with a battery tender. You can keep 2 12 volt batteries charged and maintained the same way; connect the batteries in tandem so that the battery's amp hours are added and the voltage stays 12 volts: a 12-volt charger will keep them "full."

I have a 12 volt Battery Tender charger and it doesn't keep them full. That was the reason for the post.

I would disconnect your neg cable and check to see what your parasitic amp draw is. Mine is about .4 amps if yours is over an amp you may have something left on. A 1.5 amp maintainer should maintain your 12v battery. Like I said in my first post just disconnect the neg cable on your chassis battery after it is fully charged, If it draws down in a week or so you may have a bad cell or sulfated battery. A good battery that is disconnected should last a month in between camping trips even in Ca.

I notice you kept saying "battery" as in singular. The post is about "batteries" as in two 12 volt batteries connected together. I would agree that the 1.5 amp should keep one charged, but based on the research I've done, it isn't enough for two. The only question is what is enough for two? And the biggest problem with the one I have is it will stay in charge mode "red light on" for several days, and then it starts flashing an error code and I assume shuts down. So that is why I'm sure it just isn't big enough. I've never seen it with just the steady green light on which is what it is supposed to switch too when the battery is fully charged and is just being maintained.

[Gjac]

msmith1199 wrote:

stevenicol wrote:
I keep my two 6-volt AGM batteries charged and maintained with a battery tender. You can keep 2 12 volt batteries charged and maintained the same way; connect the batteries in tandem so that the battery's amp hours are added and the voltage stays 12 volts: a 12-volt charger will keep them "full."

I have a 12 volt Battery Tender charger and it doesn't keep them full. That was the reason for the post.

I would disconnect your neg cable and check to see what your parasitic amp draw is. Mine is about .4 amps if yours is over an amp you may have something left on. A 1.5 amp maintainer should maintain your 12v battery. Like I said in my first post just disconnect the neg cable on your chassis battery after it is fully charged, If it draws down in a week or so you may have a bad cell or sulfated battery. A good battery that is disconnected should last a month in between camping trips even in Ca.

[Blaster_Man]

Be careful when you buy a battery "maintainer." Some of the trickle maintainers will maintain your battery, but will not recharge it if it needs to be recharged. It will tell you on the box.

[wa8yxm]

Battery tender makes models that do one battery bank, 2, 4, 8, and I think 16 (Used in battery stores)

However ... You said "I used to have...." Years ago the most common Converter in RV's was a pile of junk by today's standards.. Anyting made this century should not do that. Specifically the Magnetek 6300 was well known for destroying batteries.. But I'm sure there were others that were nearly as bad.

[msmith1199]

The main ones I'm concerned about are the chassis batteries. Since the house batteries can be disconnected with a switch they tend to stay charged between uses, but the chassis batteries die even with the battery tender I use. The one I use isn't the cheapest, but it isn't the biggest either. The one I have is the Battery Tender Plus and it is 12 volts at 1.5 amps. So clearly it's too small to maintain the two chassis batteries. Sounds like the ones that connect to multiple batteries are out since I'd have to disconnect batteries to use them.

This one is a 5 amp model so you think it will keep the two big batteries charged? 12 volt 5 amp Battery Tender

[msmith1199]

stevenicol wrote:
I keep my two 6-volt AGM batteries charged and maintained with a battery tender. You can keep 2 12 volt batteries charged and maintained the same way; connect the batteries in tandem so that the battery's amp hours are added and the voltage stays 12 volts: a 12-volt charger will keep them "full."

I have a 12 volt Battery Tender charger and it doesn't keep them full. That was the reason for the post.

[msmith1199]

Gjac wrote:
There are several ways to maintain batteries, but what I do is fully charge both house and chassis batteries then disconnect them. They set for 3 months over the winter that way. During the camping season I do the same until I plan on going camping, then will plug MH into my 50 amp plug and charge several days with my old Mangntec converter charger and the refer cools at the same time. The HF maintainer charger will charge the chassis battery. I also have a B&D 40 amp charger that can equalize and desufate. I equalize every 3 mos or so and desulfate maybe twice a year. Batteries will be 10 years old this year and I dry camp 95 persent of the time. I think leaving the charger on continuously eats away at the lead plates quicker, you just don't want to let them sit too long in a discharged state or they will begin to sulfate.

We don't have a winter in California. Camping season is year round so I want to keep the motorhome ready to go whenever I am.

[time2roll]

msmith1199 wrote:
I'm looking at the Battery Tender and I see they have one that has four separate charging units. I think the problem I have with my current one (which is a Battery Tender Model) is it's a single 12 volt charger and I'm hooking it to one battery, but both batteries are connected to each other. So I'm wondering if with their four batter unit, can I hook one to each of the chassis batteries and will it work even with leaving the batteries hooked to each other? I'm trying to avoid having to disconnect batteries. I take fairly good care of my motorhome and I go to it at least once a month and make sure it gets started and driven around. I don't want to be messing with connecting and disconnecting batteries. I just want to unplug it an go.

Not to mention I used a battery tender on my Harley Davidson and I got 9 years out of the original battery. So I want to use a battery tender on it.

You are doing it right with the existing BT. A single battery can go bad. You need to separate and test individually.

The four battery charger is made to charge batteries that are separated from each other. Avoid this unless you want to remove cables to separate. Possibly get a dual charger with one on the chassis and one on the house. Still your MH may connect the batteries when it senses charging voltage depending on how yours is equipped. Regardless of this you can still have a battery go bad.

[stevenicol]

I keep my two 6-volt AGM batteries charged and maintained with a battery tender. You can keep 2 12 volt batteries charged and maintained the same way; connect the batteries in tandem so that the battery's amp hours are added and the voltage stays 12 volts: a 12-volt charger will keep them "full."

[Gjac]

There are several ways to maintain batteries, but what I do is fully charge both house and chassis batteries then disconnect them. They set for 3 months over the winter that way. During the camping season I do the same until I plan on going camping, then will plug MH into my 50 amp plug and charge several days with my old Mangntec converter charger and the refer cools at the same time. The HF maintainer charger will charge the chassis battery. I also have a B&D 40 amp charger that can equalize and desufate. I equalize every 3 mos or so and desulfate maybe twice a year. Batteries will be 10 years old this year and I dry camp 95 persent of the time. I think leaving the charger on continuously eats away at the lead plates quicker, you just don't want to let them sit too long in a discharged state or they will begin to sulfate.

[crasster]

Go with a Battery Minder with desulphator. You'll love it.