Battery Question

How many batteries would you recommened?

Battery will be the Odyssesy 2150 rated at 100 Ah

My system will be running between 2000-2500 RMS.

I will have an onboard charger.

I am planning on at least 2 but leaning towards 3. Is 2 going to be enough for the day or will I need 3? Any help would be great.

2000 watts all day??? Probably requires ten 100ah batteries. I sent you a spreadsheet, but you can probably figure on 0.5 to 1 hour per battery between charging if you don't push things too hard. What are you running for an alternator.

I will not be running 2000 W all day. My guess I will be running between 500-1000 most of the day. The alt is a 90 amp

(Message edited by oaf on November 15, 2006)

Like Mike said, if plan on cranking the tunes that loud all day without the engine running then you will need a LOT of battery.

2000 watts at ~12 volts is 166 amps. If the battery provided full rated amp-hours it would still only last 0.6 hours, or 36 minutes. Unfortunately, the amp-hour rating is usually based on a a 20 hour rate, and the capacity drops considerably as the current goes up. At that kind of draw you would be lucky to get half the amp-hours, or only ~ 15 minutes per 100 amp-hour battery.


Now, the good news is that you are very unlikely to draw 2000 watts continuously unless you enjoy the sweet sound of an air raid siren. Assuming that your music actually has some range to it I would guess that your average power is about 25% of the max, so you might get an hour out of a 100 amp-hour battery.

So this has just been a long winded way of saying I agree with Mike.

If you plan on going for a ride or two during the day then you can factor in the size of your alternator, how long your rides are, etc.

Bottom line: You would be better off keeping a battery for starting purposes only and running the amps off a separate battery bank. I would recommend a pair of golf cart batteries.

I have done the 6V before, but they take a lot of room. I would rather do 2 Group 8D with over 250 Ah , I still may. I always have a starting battery and a bank for the stereo. I don't wnat to get stuck and have the wife down my throat. I am just looking at how many Amp Hours I will need to play my tunes all day (5-6 Hours). My guess is that I will need about 300 Ah for what I do and hook up the charger at night. My other option is doing a High Output Alt with a Balamar charging system hooked up, but I want to try out the onboard charger first to see how it goes (the High Output is $$$$). I guess I am still going round and round about how many Ah I will need and the most cost effective way to achieve it is.

Based on Rod and other's input I went with two golf cart batteries, I am quite happy with thier performance.

Here is a little chart that compares 4 of the standard smaller blue tops, 3 of the larger blue tops, and 2 golf cart batteries.

4D34M 3D31M 2T105
Ah 220 225 225
weight 176 180 124
cu.in. 2148 2342 1608
cost $676 $600 $138

Ah/$ 0.33 0.38 1.63
Ah/lb. 1.25 1.25 1.81
Ah/cu.in. 0.10 0.10 0.14

Thanks for the help Mike.

Here is another comparison chart for ya all.

http://www.carlsonspeed.com/~tombrown/QuickLink/Battery%20analysis.pdf

Next question is where are you putting your batteries in your boat?

I would go with three blue tops they should last all day from what I have read on here before .

Coach...here' a real wordl example, nothgin scientific about.
This summer I had my boat beached listening at I would say an average volume all day, about 18-25 out of 35 max on HU (if that means anything). My two Trojan t-105’s were fully charged at the start of the day. I ran for about 6 hours straight. I had a few times where I would turn down the music at 10 min intervals to keep the lake patrol happy. I have a mix between flea market amps and higher end JL amps. I have rough 2k watts RMS. After the 6 hours my boat started with no problems (started using the gold cart batteries), but the golf cart batteries were low. It was idle back with radio off, then plug into charger. My 7 amp trickle charger was not able to recharge them overnight. But a bigger charger probably could. Listing to alto of hip hop/rap

(Message edited by acurtis_Ttu on November 16, 2006)

I liked my Trojan T-105's but I found where I boat (Colorado River in AZ) matainance of the batteries is very difficult. I am going to run a AGM battery of some type. I am looking at the Odyessy, Trojan 6V AGM, or a Group 8D battery. One of the biggest concerns is where I can put the batteries.

Thanks for all of your help.

Coach-
I have a couple comments that might help. My intent was similar to yours when building my system. I was hoping to get 6-7 hours playing the stereo at say 5/8 volume without worrying about dead batteries (system is somewhere between 2 and 3k RMS). I opted for 6 optima blue tops in my boat. In hindsight I wish I would have opted for the Balmar system (per Grant's post) or something similar. I am lucky to get 3 hours or so when the batteries are fully charged. There is also the problem of re-charging them by the next day (think separating them and multiple 20-30 amp chargers to get them even close by the next morning.) My batteries are mounted on a 3/4 plexi base with back lit plexi-glass covers. I have been very happy with this install area as it helps to weight the front of the boat some(which is empty unless the kids are with us). I am at work but can post some pictures once I get home. Hope this helps some

8tens you are correct.