12V Battery - Connect a dual purpose with a deep cycle?

[d-mac1]

One of my 12V dual purpose batteries has a bad cell and the other is fine. I've read on here that the dual purpose aren't preferred cuz we don't need the CCA for a genny so I'd like to replace the bad one with a pure deep cycle battery, but I don't know if there is a downside to having 2 slightly different batteries hooked up in parallel?

I've currently got two of these Deka DP27 (dual purpose) batteries:

http://www.easternmarine.com/deka-12v-marine-master-dp27-dual-purpose-battery

Walmart has the following Everstart Grp 27 deep cycle batteries which per the Q&A has a 109 amp hour rating:

http://www.walmart.com/ip/EverStart-27DC-6-Marine-Battery/16795212#Specifications

I can't find the amp hour rating of the Deka's but it says 150 min at 25 amps.

What do you think? Can I hook a regular deep cycle with the remaining dual purpose?

Thanks!

[d-mac1]

Coach-man wrote:

d-mac1 wrote:
Appreciate everyone's help. We belong to sams so thats where I went first. Was gonna go check on price of trojans but there was a big road. construction jam up so I opted out.

Does anyone know if I can use a Battery Tender (thats the brand) to keep em topped up or do I need to use a regular charger set to 6 volts? Also, I'll check the water level, but wonder if I shouldn't charge them before my trip? I've got 2 days.

Thanks again.

I had a similar setup using the Battery Tender in my class A, worked great no problems, still working well when I traded it!

I thought my Battery Tender was adequate until my most recent trip. I used it to keep my two 12v batteries in good shape, or so I thought. I went to turn on the furnace when we got a cold blast recently and not enough juice to fire it up. I thought I had a furnace problem. I learned otherwise via this forum. Even after a week of use and charging via generator each day in addition to 2 solid days of towing it wouldn't hold a 'full' charge for more than a day.

I may be to blame as one of the batteries was low in electrolyte, but I couldn't see the top of the plates when I refilled it with distilled water. I now know to check fluid level regularly, so I'm gonna go check a couple other batteries that I've been neglecting.

I think I'm going to read the Battery Tender's website to see what they say as far as what types of batteries their tenders are designed for. It would take days to charge my 12v...and probably never fully charged em.

[d-mac1]

Me Again wrote:
I good strong charge is good for a battery, it stirs the aid up. Never run your trailer on just batteries unit the lights are getting dim, as you are way below 50% charge and damaging the batteries. While you have 220 AH, only 110 are really usable without damage to the batteries.

Here is a good start in learn more about batteries. There is a part two also.

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

Chris

That is some GREAT info Chris! I can't thank you enough!!

I haven't read part 2 yet, but I did check em with a good volt ohm meter when I got them home and based on his open circuit charge chart, I now know that my brand new batteries are between 50 and 75% charged....even though I thought they were nearly fully charged at 6.17 and 6.22 v.

For a few hours last night I had one of em on my 35 year old 6 amp battery charger and made some progress but now that I've read this, I may hafta look into getting a better charger. I dunno about integrating one into the trailer...yet...but a stand alone one could work for my other vehicles if needed.

Thanks again!
Dave

[Coach-man]

d-mac1 wrote:
Appreciate everyone's help. We belong to sams so thats where I went first. Was gonna go check on price of trojans but there was a big road. construction jam up so I opted out.

Does anyone know if I can use a Battery Tender (thats the brand) to keep em topped up or do I need to use a regular charger set to 6 volts? Also, I'll check the water level, but wonder if I shouldn't charge them before my trip? I've got 2 days.

Thanks again.

I had a similar setup using the Battery Tender in my class A, worked great no problems, still working well when I traded it!

[Me_Again]

I good strong charge is good for a battery, it stirs the aid up. Never run your trailer on just batteries unit the lights are getting dim, as you are way below 50% charge and damaging the batteries. While you have 220 AH, only 110 are really usable without damage to the batteries.

Here is a good start in learn more about batteries. There is a part two also.

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

Chris

[d-mac1]

Got it. Thanks.

Anyone know if I can you a tender on them or do I need to use a charger? I wonder if the tender never got my 12v batteries fully charged and that contributed to failure...plus me letting fluid get low in the one that got a bad cell.

[time2roll]

Just plug in the RV to charge the battery.
One amp Tender could easily take more than two days to charge.

[Ductape]

"So for charging, connect charger red lead to positive of battery who's positive is 12v lead to trailer and connect black charger lead to trailer ground where 2nd battery's negative lead connects to trailer. Thereby its one big battery. Is this right?"

Exactly right. If you charge with the converter in the trailer it's no change at all.

Just be sure you get the 6V hooked up properly. Every now and then someone switches from parallel to series batteries or vice versa and gets the wiring wrong.

Trailer positive lead +[battery]- +[battery]- trailer ground lead. That's what you want for 6v. I'm sure you know this already, just chipping in in case.

[d-mac1]

Me Again wrote:

d-mac1 wrote:
Appreciate everyone's help. We belong to sams so thats where I went first. Was gonna go check on price of trojans but there was a big road. construction jam up so I opted out.

Does anyone know if I can use a Battery Tender (thats the brand) to keep em topped up or do I need to use a regular charger set to 6 volts? Also, I'll check the water level, but wonder if I shouldn't charge them before my trip? I've got 2 days.

Thanks again.

When you hook them up in series you treat/charge them like any other 12V.

Ground/Chassis - Neg (Batt 1 6v) Pos -jumper- Neg (Batt 2 6v) Pos - To camper loads.

Ground on one battery get the same ground as the 12vers. The Pos of that battery is jumper to the neg of the second battery, the Pos of the second battery is your 12V lead for the camper.

Chris

Thanks Chris...So for charging, connect charger red lead to positive of battery who's positive is 12v lead to trailer and connect black charger lead to trailer ground where 2nd battery's negative lead connects to trailer. Thereby its one big battery. Is this right?

Thanks again.
Dave

[d-mac1]

Me Again wrote:

d-mac1 wrote:
Appreciate everyone's help. We belong to sams so thats where I went first. Was gonna go check on price of trojans but there was a big road. construction jam up so I opted out.

Does anyone know if I can use a Battery Tender (thats the brand) to keep em topped up or do I need to use a regular charger set to 6 volts? Also, I'll check the water level, but wonder if I shouldn't charge them before my trip? I've got 2 days.

Thanks again.

When you hook them up in series you treat/charge them like any other 12V.

Ground/Chassis - Neg (Batt 1 6v) Pos -jumper- Neg (Batt 2 6v) Pos - To camper loads.

Ground on one battery get the same ground as the 12vers. The Pos of that battery is jumper to the neg of the second battery, the Pos of the second battery is your 12V lead for the camper.

Chris

Thanks Chris...So for charging, connect charger red lead to positive of battery who's positive is 12v lead to trailer and connect black charger lead to trailer ground where 2nd battery's negative lead connects to trailer. Thereby its one big battery. Is this right?

Thanks again.
Dave

[Me_Again]

d-mac1 wrote:
Appreciate everyone's help. We belong to sams so thats where I went first. Was gonna go check on price of trojans but there was a big road. construction jam up so I opted out.

Does anyone know if I can use a Battery Tender (thats the brand) to keep em topped up or do I need to use a regular charger set to 6 volts? Also, I'll check the water level, but wonder if I shouldn't charge them before my trip? I've got 2 days.

Thanks again.

When you hook them up in series you treat/charge them like any other 12V.

Ground/Chassis - Neg (Batt 1 6v) Pos -jumper- Neg (Batt 2 6v) Pos - To camper loads.

Ground on one battery get the same ground as the 12vers. The Pos of that battery is jumper to the neg of the second battery, the Pos of the second battery is your 12V lead for the camper.

Chris

[laknox]

Me Again wrote:

laknox wrote:
My 2 6v batteries are about 110 a/h each, so I have about 220 a/h capacity. My old 12v batteries only gave me about 150 a/h, total. The real off-gridders use 2v batteries, and can last for days and days without charging.

Lyle

Lyle, two 110 ah 6v battery when place in series are a 12V battery with 110 ah.

I believe you maybe have 220 or 225 ah 6Vers that you series to product 12V. Parallel increase ah's, series increase voltage, just so everyone understands!

Chris

Dammit! I always get that bass-ackwards. Thanks for the correction. Still, my 2 6v batteries give me more a/h than my 2 12v batteries did.

Lyle

[d-mac1]

Appreciate everyone's help. We belong to sams so thats where I went first. Was gonna go check on price of trojans but there was a big road. construction jam up so I opted out.

Does anyone know if I can use a Battery Tender (thats the brand) to keep em topped up or do I need to use a regular charger set to 6 volts? Also, I'll check the water level, but wonder if I shouldn't charge them before my trip? I've got 2 days.

Thanks again.

[Me_Again]

laknox wrote:
My 2 6v batteries are about 110 a/h each, so I have about 220 a/h capacity. My old 12v batteries only gave me about 150 a/h, total. The real off-gridders use 2v batteries, and can last for days and days without charging.

Lyle

Lyle, two 110 ah 6v battery when place in series are a 12V battery with 110 ah.

I believe you maybe have 220 or 225 ah 6Vers that you series to produce 12V. Parallel increase ah's, series increase voltage, just so everyone understands!

Chris

[GoPackGo]

Remember - If you combine two 6-volt batteries in series, each having 200 amps, you do not get 400 amps at 12 volts. You get 200 amps.

- If you double the voltage (by combining them in series) you must halve the total additive amps.

Tim