battery setup question

hi there, few questions and a little history

last year my wife and i bought our first boat. i took it to car toys and had them install a new kenwood head unit, 4-channel 160-watt soundstream amp and a 10" jl sub in a custom box. i left the stock jbl 6.5" speakers in the rear. i also had them install an optima blue top and a battery switch. the way they hooked it up was, they put the optima on position 2 and the main stock battery on position 1. the stock battery is running everything and the optima is there only as a backup starting battery. so now, i'm getting ready to take it back in and replace the jbl's with polk momo mmc650's, add two polk db1000 tweeters and add a second amp, either another 4-channel, or a jl mono sub amp, probably just the 250:1. so here's my question, is the current setup going to be okay for that? or do i need to have them reconfigure the batteries somehow? i don't have room for anymore batteries and currently, there's no way to charge both batteries at the same time that is safe for the alternator. i have to manually switch to position 2 while underway to charge the optima. which really isn't a big deal. as long as i keep it charged, i can rest easy that if i drain my stock battery the optima will start the boat. i guess what i'm asking is that too much for one battery and my alternator to handle? any advice? thanks in advance-

how big is the alternator? My batteris are setup identical to yours and my sytem is alot bigger. (i use golf cart batteries vs traditional 12v). The math is sasy your batteries have an amp hour rating. take that into how ever many amps your amplifiers pull and there's your run time with the motor off.

My guess is you should be fine. your stereo time with the boat off may decrease, but b/c yoru baot is new ( and hopefully a v-8) your alt should be around 60-80 amps.

You need a battery combiner http://www.hellroaring.com/
or west marine also sells a couple
http://www.westmarine.com/webapp/wcs/stores/servlet/product/10001/-1/10001/5461/10001/12106/544/9
Note: the 150 amp westmarine one is NOT ignition protected so it needs to be mounted appropriately

Bruce:

The size or number of batteries will have minor (if any) impact on the alternator.

It is a really bad idea to mix battery technologies, ie, a standard lead acid with a Optima AGM battery. If you do have both types then you really should keep them separate, only connect them together if you need the other battery for emegency starting.

You can use a "Battery isolator" so that you can charge both batteries. Unfortunately, the design of an isolator seriously degrades the performance of the alternator so if it was marginal before it will be even worse on an isolator.

You would be better off to use the same type of battery for both starting and reserve, then add a "battery combiner".

Rod, what would you suggest to charge two different types? Two alternators? I've got Optimas and golf cart 6Vs. almost finished installing two 6V batts (in series) for my sound system. I was planning to keep them entirely separate and not charge the golf cart batts. I also have optima blue tops for starting and half the sound system. My alternator says "180A" on the side. I would assume this is 180 amps, although from what I've read, that is ridiculously large. Sounds like I have spare "juice" so how do I safely charge the old golf cart batts?

okay, i'm a little confused

this is what i have. is this an isolator?

http://www.westmarine.com/webapp/wcs/stores/servlet/product/10001/-1/10001/91533/10001/297/207/9

(also, this IS ignition safe right? i have this in my engine compartment)

i'm not sure i understand what you mean by an isolator will degrade the performance of an alternator. forgive me, i'm not smart that way and that's why i'm posting.

also how does a combiner work exactly? if i ran out both batteries, isn't it just like i had one and i'm dead in the water? or are there failsafes like alarms or something? i'll search, but can you reply back rod? my setup worked good last year, but i never really ran the sound system more than an hour or so and now i'm about to add another amp. i like the idea of having a fully charged battery for cranking in reserve, but if my setup isn't going to handle a couple amps and 5 speakers, then i should probably tend to it.

thanks again for your help

okay, so i think i get it. what i have is NOT an isolator, it's a simple switch. 1 or 2 or both, or off. never run in both i was told because they are different batteries. that part i get. and i get that ideally a second blue top is ideal along with a combiner. my problem more than anything at this point is real estate. car toys really surprised me that they were even able to get a second battery in my boat and i doubt we could find room for the combiner. so i guess what i'm wondering rod is do you think my current setup will work as is? would i be doing myself any favors by replacing the current stock battery with a second blue top or should i just wait until it's dying. i'll take another look, but i just don't think i have the room for one of those. they look about the footprint as a blue top, is that about right? maybe half...

i just want to get this right the first time because it's a real pain to bring it to the installer and i want to get it right the first time

thanks again!


(Message edited by brucemac on January 30, 2006)

hey, also, i remember when i was at west marine asking the sales person about it, they told me that this type of switch when in either position 1 or postion 2, it prevented the batteries from discharging to each other. does that make sense? is that correct?

Bruce,

Just use a Yandina C100 battery combiner, they are tiny and they will supply enough current to charge the blue top. They are also ignition protected so they can be mounted inside the motor compartment.

okay, so i read that yandina c100 faq

couple questions

do i still connect all accessories, etc to one battery and leave the second as a backup only? how does that work? if i drain one listensing to music, and then i go to start what happens?

Leave your switch in position 1 (battery 1)for everything and switch to 2 or "BOTH" only if you do not have enough charge to crank battery 1. Once started and running you can switch back to battery 1. The combiner will not go into the combine mode until battery 1 is up to approx. 13.4 v.

jtw, forgive me, but i thought the whole idea of the combiner is not to have to have a switch.

You do not need a switch but does offer you as Rod says "the best of both worlds". You now have manual function as well as the automatic function the combiner offers.

Bruce--
See the Mikeski diagram below .

Mikeski battery diagram Boat_Battery_Diagram-276814[2].pdf (17.6 k)

okay, i see. just downloaded the manual. so really all this gets me is i don't have to worry about switching to "2" to charge the backup battery. right? it isn't going to help me with runtime or anything with the motor off. it just guarantees the backup battery is always charged. which i guess is a good thing. so i could use this with my current switch, i'd just need a second optima blue top. the thing that concerns me is, how would you ever know if this was overheating and turning off. it says IF this happens a lot it's a problem, but how would you ever know if it's tucked away by the batteries? it looks like a cool product. i just wish there was some sort of interface you could have at the helm to monitor.

okay, making more sense

thanks so much for the replies guys

how long are those postive leads btw?

my batteries are litterally right next to each other. just hoping i don't have a bunch of extra wire strung all over. is this the "best" smallest solution out there? the one that everybody here is using?

Yes, you can use with your current setup . I have the same setup as the Mikeski diagam above less the 2 6 volt golf batteries. He wired those in series to get his 12 volt . I have a D34m blue top for starting battery and a D34m for my stereo battery . Not sure about the monitoring for the overload condition .

how about the leads? are they pretty long? got any pictures?! you think someone like a car toys (local chain audio installation services) would be able to handle this? or would they shy away?

(Message edited by brucemac on January 30, 2006)

Tie wrap up nice and neat . DO NOT CUT THE 2 RED LEADS.

Check the Yandina site but as I recall the leads are probably 3 feet long. Car toys could and should handle this install . The combiner itself is a very simple 5 minute install you can do yourself. NO pics of my installation.

hey thanks jtw, one last question

what else do i need other than the combiner? would car toys have the rest of the stuff? or are there fuses and stuff, what about the zap-stop thing?

Bruce-
Here is a pic of my battery,combiner and perko switch. You will notice how small the combiner is on the lower right . Please note that the cables have not been routed properly yet and still need to be dressed up . You will also notice my on board battery charger cables on the terminals. This pic has the combiner negative wire just hanging and not hooked up yet as well as the negative cable between the 2 terminal not hooked up yet . I just installed this stuff a few weeks ago .

cool, thanks for the pic jtw.

so do you float charge them then during the winter? what do you use? does it only have to connect to one battery? or does it go throught combiner somehow?

I purchased a XL dual pro 6 amp 2 bank on board charger. For the winter I disconnect the ground to the combiner and the ground between ea. battery. The smart charger charges ea. battery independent of each other. You could put the charge to battery # 1 and leave the combiner connected and would work just fine but I prefered to not have the combiner connected for the winter months and keep the batteries monitored independent of each other. Below is the charger I purchased which sits in the same compartment.

http://www.batterystuff.com/battery-chargers/12-volt/marine-chargers/DP6-2.html

You can control the combiners at the helm. Just add a switch and one direction (+12V) or the other (ground) will cause the combiner to stay connected or stay disconnected. I think the hellroaring one does have an led option so you can see whats going on all the time. Best way to hook up the combiner is run the alternator output straight to your stereo or house bank and thru the combiner to your start bank as this draws way less current to charge back up (all according to hellroaring site, which makes common sense). Im still not convinced connecting different banks together is really that bad especially if you do charge your batteries when you get in for the day. Best bet if you have the money is to run same model and date code batteries but who has all their batteries dead at the same time and for stereo batteries and start batteries usually they are different. I did some major research and my plan is for a couple golf cart batts for the stereo.