Mixing deep cycle and standard batteries

I recently bought a Rienell boat with a 135hp outboard and duel batteries. The former owner told me the batteries were bad and needed to be replaced. After inspection I find that they are hooked up paralell and one is a deep cycle and one isn't! Even though I'm new at this it doesn't seem right to hook these two together!<br /><br />Any comments or suggestions? BTW, the batteries do seem to be weak even after Deep Cycle charging of the one and regular drip charge for the other. They always get me started, even though sometimes they have a bit of a hard time with the initial start. Is it bad to run weak batteries?<br /><br />Thank you guys. I'll set back and learn from the experts.<br /><br />Ted

Re: Mixing deep cycle and standard batteries

P.S. Is my Deep Cycle already toast because of this setup?

Re: Mixing deep cycle and standard batteries

Hi Ted. It sounds from your post that you don't have your batteries hooked together anymore. Unless it is a dual purpose battery, your deep cycle should not be used for starting, and just because it turns your engine over slowly doesn't mean it's toast. Deep cycles have lower cranking amps than starting batteries do. It may still be fine for running electronics and trolling motors or whatever. I would try fully charging both batteries separately, make sure they're disconnected and then use them. Use the deep cycle only for electronics and use the starting battery for the engine. If the starting battery is turning the engine over slowly, it probably is toast. If you want to hook your batteries together, get two new dual purpose deep cycles. Batteries that are hooked together need to be the same type and same age. Hope this helps.

Re: Mixing deep cycle and standard batteries

Thanks. Yes, they are still set up in parallel although they are temporarily disconnected.<br /><br />You know of a chart or explination of how to set them up as you described?

Re: Mixing deep cycle and standard batteries

Hi Ted. If you want to keep the two batteries that you have, it's simple. Just disconnect them and run your engine starter cables to the starter battery and your electronics to the deep cycle. If you want to get two new dual purpose batteries, I would get a 1/2/both/off switch from your local marine supply store. This switch will come with directions for hooking it up. You don't need the switch, but it's nice to have because you can isolate one battery to use for emergencies or you can use them both at the same time for extra power. You can always hook the two new batteries up in parallel and continue the way you have been. That would work good too. It just depends on your application. Size boat, size motor, lots of trolling time, etc... Good luck, I hope this answered your question. Keep posting.

Re: Mixing deep cycle and standard batteries

With most other things electrical we have circuit breakers or fuses. Cars have fuses, breakers, or fuseable links. In older boats at least, why do we so seldom have any way to control a short circuit? Toasting your boat is bad whether in your driveway, marina, or on the water. And on the water if there should ever be a short how would you prevent a fire or keep it out once you got it extinguished in the first place? (Like you can just get out and run home?!!!) At the very least there should be a battery switch of some sort, even if for only one battery. Much easier than trying to remove very hot cables directly from the battery. I tried it, didn't like it. <br /><br />I prefer two deep cycle batteries; I keep one on the outboard and the other for trolling motor- not connected together. The latter gets charged as soon as it gets home. The outboard's gets charged if not used within two or three weeks. I'd probably have the same arrangement for a smaller inboard also so long as I could fit in an adequate deep cycle for starting and could get to it for easy maintenance. The dual purpose batteries are OK, though I think for me the advantages of the true deep cycle outweigh whatever benefit the compromise battery would offer. Properly maintained, a quality deep cycle will outlast a dual purpose battery every time. Aside from Optima and the really high end batteries, maintenance free/low maintenance are only better when you won't be able to keep your battery supplied with distilled water religiously. Comes down to choosing which hassle you prefer, really.

Re: Mixing deep cycle and standard batteries

The item "distilled water" brings about a question when dealing with batteries.When I run low on water in a battery ,I just add tap water,but then I'm adding chemicals.How bad is this?.An electrical engineer once told me .....if you remove all the metals out of water you can put two conductors of opposite polarity in water and no short circuit will occur.Does battery acid ring a bell.......back to basics I guess.

Re: Mixing deep cycle and standard batteries

It is true. Distilled water does not conduct electricity. The more turbid water is the better is conducts electricity. If you want to quickly destroy a battery, add tap water to it.

Re: Mixing deep cycle and standard batteries

Hi all,<br />Those rotary 1/2/Both/Off style master switches need some caution when in use.<br /><br />If you change the position of the switch when your engine is running you run the risk of blowing your alternator regulator or worse the EFI ECM. Most of those switches "break" the electrical circuit completely as the control is rotated.<br /><br />They can only be safely switched when the engine is stopped.<br /><br />The safest method is to use 3 separate master switches correctly linked together to parallel the start and house batteries.<br /><br />A split feed charging (diodes or similar) system keeps everything topped up.<br /><br />Regards<br />Peter

Re: Mixing deep cycle and standard batteries

I wondered about that. So it is possible to charge both batteries at the same time, but only have starting power coming from one, and running power coming from the other?

Re: Mixing deep cycle and standard batteries

What I'm really looking for is something I don't have to think about very much! I don't have a troller either. Do you guys think I should just run one battery and be done with it? Maybe I don't even need the extra power of two batteries? However, I do like the idea of spare power just in case . . .

Re: Mixing deep cycle and standard batteries

ted this is a good set up for two<br />

Re: Mixing deep cycle and standard batteries

Hi Ted,<br />I am off to our beach house tonight which is where my boat is sitting while I am doing my refit. I can take a couple of pix of my setup and email to you if you wish.<br /><br />Let me know

Re: Mixing deep cycle and standard batteries

Thank you for the diagram Bubba. That's great.

Re: Mixing deep cycle and standard batteries

I may have missed the boat on getting pix of your setup Pete, but if not I would love to have them. My e-mail is paperdesk@yahoo.com<br /><br />Would really help me visualize this! I'm not very familiar with working with these kinds of things.<br /><br />Ted