Battery System Design

I know this gets asked a lot and trust me I did a lot of searching to try and figure out the best way to design the battery system in my new RZR. The total amplifier RMS power is 3950 watts.

We will primarily use the stereo with the boat running but there will be several times throughout the season where we will park and jam the stereo for a couple hours.

I plan on just using the factory battery locations which should give me enough room to install a total of 4 batteries (1 starting, 3 stereo) without taking up any usable locker space. I have a 40A Xantrex TrueCharge 2 that will charge and maintain the batteries, usually after each weekend of use.

Here's what I am thinking:

Starting Battery
Factory Installed Interstate 24M-XHD. I'm not sure if if makes any sense at all to replace this battery. The factory system comes with the SRM-24 for the stereo bank if I remember. It has less CCA than the 24M-XHD but is deep cycle, would this be a better main starting battery or does it really matter that much?

Stereo Batteries
3) US Battery US-145XC wired in parallel.

Battery Isolation/Switching
Blue Sea Systems SI-ACR automatic charging relay.
Blue Sea Systems 3003 HD Series Switch

Wire
All power and ground wire, including the factory charging cable from the alternator and main ground will be 1/0 all the way up to the amp distro's where it will be reduced to 2 AWG.


Since I am just wanting to have a total of 4 batteries, I think it makes sense to get a nice battery like the US-145XC for the stereo bank. Is there any issue doing 3 of the 6V batteries instead of multiples of 2?

I want to do an automatic charging relay so that the alternator will keep the stereo bank maintained while the batteries are at a good voltage. The way I understand it is that the ACR will disengage if the stereo bank falls below a certain voltage, correct? Is there a better ACR I should use or is the SI-ACR even compatible with the US145XC?

First is that 6v batteries have to be wired in series in order to increase the voltage. Wiring them in parallel will keep the voltage the same. I assume that you want to use the US 145XC's for you stereo so you would have to buy two of them and wire them in series. To wire in series you take the positive of one battery and connect to the negative of the other battery. The remaining unused positive and negative terminals will be used power and ground. Nothing else get's connected to that jumper wire that combines the batteries. So a pair of 145's wired in series will appear as one 12v battery with 252 amp hours.

If you wanted to increase that stereo bank you would have to add 6 volt batteries in increments of two. Same deal here, you would put a jumper between the positive and negative as we did above. To add them to the other two, you would run a wire from the non jumpered positive on the first set to the non jumpered positive on the second set and do the same thing wil the negative.

I do not know that much about ACR's - I use a manual switch only.

Thanks Murphy, that makes sense. Not sure what I was thinking when I said parallel.

Can you run 2) 6V batteries in parallel and then series them to a 3rd or will it not work like that? I think a total of 4 batteries is what will fit best in the factory locations. Maybe I should just stick to regular 12V batteries.

Has to be even numbers. Here is a link with how you would wire up 4. Pay attention to the part that mentions 6volts.

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

Not sure you really need to increase the stock battery cables from the alternator/block since you aren't going to increase the output of the alternator. That being said increasing it isn't going to hurt. I think I would either do 4 golf carts or 3 group 31/29's for the house bank. If you want all the batteries to match add a 4th group 31 for starting. One battery company I would look at is Deka. They are made in the US as all of their batteries are(except a few motorcycle batteries or some other small batteries like them), they have multiple different battery options in the same group size. For example in group 31(standard Class 8 truck battery size) they make 3 or 4 different starting versions, a dual purpose starting/deep cycle version, a deep cycle version, a gel version and an AGM version. Hell they even make the Duracell branded batteries which have a 2 year free replacement warranty. If you have the room you could also do something like a 4D or 8D which are friggen huge and not to expensive for the standard flooded version.

As for the auto charging relay just make sure that the relay stays off and/or the 2 battery banks are kept separate when your xantrex charger is plugged in. You want to charge up the 2 seperate banks completely independent of each other if possible.

Now if you want to get really fancy you could look into adding a Balmar series 6 150 amp alternator. Problem is they are expensive. I think we sell them for around $750 or so.

I know batteries have been beaten to death on here lately but while researching batteries for my boat I ran across the US Battery US12V XC:

http://www.usbattery.com/usb_us12vxc_marine.html

155Ah seems really strong for the size. I haven't seen anyone mention this battery or the Interstate version: 12VGC. Both are around $200ea. Are these not a good option or is there something that's just much better for the money?

Originally Posted by Houstonshark

I know batteries have been beaten to death on here lately but while researching batteries for my boat I ran across the US Battery US12V XC:

http://www.usbattery.com/usb_us12vxc_marine.html

155Ah seems really strong for the size. I haven't seen anyone mention this battery or the Interstate version: 12VGC. Both are around $200ea. Are these not a good option or is there something that's just much better for the money?

Looks like a 12v version of a Golf cart battery. That would be a pretty slick setup because you could use odd numbers of batteries instead of only being able to use pairs like with the 6v GC's. Deka makes those as well. The part number is GC12V and the AH rating is 155 like those. 2 of those give you quite a bit higher AH rating then 2 6V golf cart batteries.

regular GC 6V battery like T105(trojan) or GC15(Deka) have an AH rating of around 230 so a pair would get you 230 AH at 12V.

The 12V GC's with an AH of 155 and a pair in parallel would get you 310 AHs at 12V. That would be a great setup. They aren't all that cheap though. we would sell for somewhere around $240/ea where the standard 6V GC is somewhere around $130-140.

I started researching 12V golf cart batteries and ran across the 150Ah Trojan T 1275:

http://www.trojanbattery.com/Products/T-127512V.aspx

Most of the people on the golf cart forums prefer the Trojan batteries over any other brand, at least from my limited scanning.

There is a Continental Battery location right down the road from my office so I stopped by this morning to check pricing and availability of the T 1275. They had them but for less money they also had the same battery in their Continental brand.

I was blown away when they said the price was $120 with a core and has a 1 year warranty. I'm pretty sure my battery search is over unless someone strongly objects or has had a really bad experience with these batteries. It looks like I may only be able to fit 2 of these where I want to put them.

Originally Posted by Houstonshark

I started researching 12V golf cart batteries and ran across the 150Ah Trojan T 1275:

http://www.trojanbattery.com/Products/T-127512V.aspx

Most of the people on the golf cart forums prefer the Trojan batteries over any other brand, at least from my limited scanning.

There is a Continental Battery location right down the road from my office so I stopped by this morning to check pricing and availability of the T 1275. They had them but for less money they also had the same battery in their Continental brand.

I was blown away when they said the price was $120 with a core and has a 1 year warranty. I'm pretty sure my battery search is over unless someone strongly objects or has had a really bad experience with these batteries. It looks like I may only be able to fit 2 of these where I want to put them.

Trojan's are good batteries and almost seem to have had the GC market locked up for a long time. Not sure if it was because they wre the only one to make them or just they were/are the best. If you can get a 12V golf cart battery for $120 with similar specs then there is something not right. How can they be 75-$100 less then everybody else? Just make sure they aren't pulling some BS with them. Might be worth a shot though for that price.

There has always been a strong correlation between the weight of the battery and the performance. It can be difficult to compare specs from brand to brand. Its easy to cheat on specs but its a little harder to cheat on weight. So check the two dollar values against the two pound for pound. I would question any major difference in that ratio.

David
Earmark Marine

It is all about LEAD....more lead more amp hours....more lead more weight.....more lead more cost.

They had both batteries there but I didn't look at them. I didn't have my cores with me and I want to wait until my boat gets here late next week to double check all the measurements.

The Trojan weighs 82lbs which is pretty much the same as the US Battery and Interstate versions although they are rated at 155Ah.

Continental had the Trojan for $160 which is still cheap. If the Continental version is the same I may have to find some space for a few more @ $120ea!