Community Forums

618AMR44III · 03-19-2010, 05:11 PM

Realizing that a similar thread was discussed a year ago, I still wanted to get some opinions on a possible option.

Any experience using the Optima Blue Top, AGM Spiralcell, 12V Deep Cycle D34M? This a dual purpose battery indicated for RV house use, made by Johnson Controls. It is the same size as the 6V Lifeline GPL-4CT and Deka 8AGC2M AGM batteries, so four of any of them would fit where my four failing Interstates are now. Costco price for the Optima is $154 vs $275 for the Lifeline and Deka so the cost savings is considerable. Also an 80 pound weight savings.

Since we know that in parallel, amps add together, and voltage is unchanged. In series, voltage adds together and amps are unchanged. Wouldn't performance be enhanced by all the 12V wired in parallel, vs two 6V in series, then each pair in parallel?

Enlighten me!!

TandW · 03-19-2010, 06:00 PM

That's what I have done. It allows for simpler cabling. I have 12 batteries paralleled. They run my oxygen machines when I don't have shore power. Good luck!!

UFO Pilot · 03-19-2010, 07:34 PM

I was using 2 of the Optima Blue Top D34M batteries in my RV before I replaced them with 2 of the 300 amp Lifetime 6 volt batteries. I only have room for 2 house batteries so I changed to the 6 volts to get more amp hours. I was very happy with the Optima Blue Tops while I had them.

RV Wizard · 03-20-2010, 03:09 AM

Here are some additional links of information about batteries that for those serious about them will find useful. Be aware that when you "equalize" that the inverters are using a high voltage for a long period of time and you may want to disconnect your appliance controls from this circuit during this time; I do. It is a good time to defrost the refrigerator and do other maintanance.
U.S.Battery/Leader in Deep Cycle Batteries
Frequently Asked Questions (FAQ) - DC Battery Specialists
Deep Cycle Battery FAQ
Sources
http://www.batteryfaq.org

hamguy · 03-20-2010, 10:21 AM

In theory, it makes no difference how they are wired (assuming you do maintain 12V). That is because the system consists of 2.1V cells. Each 6VDC nominal battery is made up of 3-2.1VDC cells and every 12DC nominal battery is made up of 6-2.1VDC cells. IOW, a 12V Battery is nothing more than 2-6V batteries in series.

You can mix/match these combinations all you want without altering the outcome. In reality, the only differences are in the construction of the batteries. That is, the amount of lead and the amount of acid.

wa8yxm · 03-20-2010, 10:28 AM

I recommend against Optima batteries for one very simple reason.

First: Optima batteries are very good AGM type batteries, they are rugged as all get out and if you are going to go slamming across waves, be they water or dirt, in an off road or water craft such as a 4-runner or wave runner.. They are fantastic

They also have peak current ratings that are among the best in the business.

BUT... This is why I recommend against them for RV use.. they are only 3/4 battery.. Yes, 3/4 battery... Now I can easily prove this.. LOOK AT IT, what do you see, you see 3/4 battery and 1/4 air, wasted space, air

If you look at the amp-hours capacity and compare to a traditional battery of the same size, be it AGM or wet cell (maintenance free or not) you will see the Optima has only 3/4 (Well I think it's 73% but 3/4 is easier to type) the capacity of the traditional retangular battery

And it's 4/3 the price.. usually

Gary RVRoamer · 03-21-2010, 10:37 AM

The Optima is an AGM battery and AGMs have their advantages - essentially no maintenance and no gassing. But if I were going to buy an AGM (and I have), it wouldn't be an Optima. Lifeline is my favorite brand but I now have Trojan Group 31 AGMs cause I got an excellent deal on them from a dealer who wanted to move them. In my opinion, the Optima is overhyped and under-performing.

For example, an Optima D34M has an RC rating (deep cycle capacity) of 120 minutes, while a Trojan 31AGM is 190 minutes - more than 50% greater capacity.

wa8yxm · 03-21-2010, 03:29 PM

Gary:.... Thanks for the support.

As I too said.. Optima is only 3/4 battery at 4/3 the price.. Avoid it for this application (NOTE: the price figure is punned, I've seen them from same to 2x)

It is not a good battery for RV house use.

Great where it's needed though

618AMR44III · 03-24-2010, 11:29 PM

Many thanks for all the input. This is a fantastic group. A 6v AGM (Lifeline, Trojan, Deka, US Battery or Rolls) will likely be the choice. I maybe can get 3 big 12v in the battery tray which is large and rolls out. That could total 600+ Amp hours at 20degree. But I have a nice 7500W Onan diesel generator which can recharge readily, so a huge amount of amp hours may not be needed. Cost may be deciding factor.

EngineerMike · 03-24-2010, 11:45 PM

You should be able to recharge AGMs at a higher charge rate than comparable amp-hour flooded cell batteries. That would be less generator time for those worried about that. My 4-300AH 6V AGMs (600AH @ 12V) charge at 120amps in bulk charge from the Xantrex RS2000 inverter/charger, where the flooded cell batt's @ 660AH I took out were set for about 80amps max charge rate.