wiring batteries

[svdk]

The boat I bought currently has two, 12 V standard auto batteries wired for 24 V. To keep from draining these to often, I was contemplating putting in two more and setting up all four for 24 V service (two parrallel sets in series).<br /><br />Anyone ever wire four, 12 V batteries for a 24 V system?<br /><br />Any pitfalls in doing this?<br /><br />Thanks,<br />svdk

 

[briannh1234]

Re: wiring batteries

What are you going to run with it?<br /><br />Assuming a trolling motor - sure it will work and give you double the runtime. But auto batteries? They should be at least deep cycle batteries - preferablly marine ones.<br /><br />If you allready have a 24 volt charger it will work with the four battery setup - It will just take longer to charge completly.

 

[18rabbit]

Re: wiring batteries

No pit falls. As soon as Aldo wakes up (he's on the other side of the world) he can fill you in on something similar that he did with his renovated houseboat.

 

[svdk]

Re: wiring batteries

Thanks for the replies. I'm running a trolling motor. My main issue is that the boat came with two new high amp automotoive batteries. I'm trying to make these last as long as possible before buying two deep cycle marine batteries. So I thought, since I have access to two additional 12 V auto batteries, I'd setup all four to minimize the discharge rate.

 

[18rabbit]

Re: wiring batteries

It is wise to kick up the capacity of the battery bank if you can. Often, the cost of doubling its size will more than doubling the useful life of the battery bank. The deeper you discharge a battery per cycle, the faster it decays. Some common bats have a life of 20-years if you don’t discharge them more than 10%, but only 300 to 400 cycles if taken down to 50% discharge. Most recreational boats aren’t designed for the space and weight distribution of a bunch of batteries, but then for occasional use a bunch of bats is overkill.<br /><br />When I read “high amp” I think starting battery. If you have starting bats in there for your tm, they will give up the ghost very quickly, and that leads to a huge strain on any other bats you added in the bank. This is why it is recommended you use bats of the same age, size, manf, type, model number, etc when connecting them in series. It’s a good idea but not as important if connected in parallel. In most cases, when connecting multiple bats folks will be using NEW batteries or bats purchased within a few months of each other. Can’t stress enough how important it is to use identical bats in a bank when in series.

 

[svdk]

Re: wiring batteries

18rabbit, thanks again. I am concerned about mixing batteries of different types/sizes/age.<br /><br />My plan was for each parrallel set to have one original battery (that came with boat)and one newer battery (with similar rating). I'm guessing this could still cause problems since both sets will be in series. I'm guessing that over time not all batteries will charge or dischare at the same rate.<br /><br />These are "starting battteries" as you stated. My grandfather who sold me the boat also owned an autoparts store. His eyesight is bad (one glass eye and only 10% sight in the other) and he had pulled the wrong type of batteries from inventory.<br /><br />Right now I'm getting about 6 to 8 hrs of good use from these batteries before recharging(only used for two trips).<br /><br />Any concerns for damage to the other batteries or equipment if one battery fails before the others?

 

[Silvertip]

Re: wiring batteries

Since you are mixing batteries sizes, types, and ages, you must understand that no matter where you put the new batteries, the weaker parallel bank will tend to draw down the stronger bank until both are equal.

 

[Dunaruna]

Re: wiring batteries

SV, I have 6 x 6v batts wired in series (2 x 2) to produce 12v and then paralleled (3 banks). The principle is the same for 24v. All are deeps, all are identical. They are feed by a VSR (voltage sensitive relay) which doesn't allow them to drop below 10.5v, this is important to extend the life of the deeps. I also have a seperate and isolated batt for the outboard only.<br /><br />Upinsmoke is correct, the weakest batt will dominate the system and prematurely kill the others. Ideally, you need all batts to be the same type, age and rating but thats not always practical (let's face it, you don't want to throw away any good batteries if you don't need to). It's your call but be aware that the life of your system will be reduced.<br /><br />Marine rated batts are built way better than auto, they handle vibration better and infrequent charge/discharge cycles better.<br /><br />Good luck. Bring Out Another Thousand <br /><br />Aldo

 

[briannh1234]

Re: wiring batteries

svdk -<br /><br />I'm assuming that you also have a starting battery that is seperate from these 2 batteries?<br /><br />Keep running the system the way you have it now until the 2 existing batteries finally give up the ghost. (won't be long)<br /><br />Then rewire yourself a new system with new batteries of the correct type.

 

[LubeDude]

Re: wiring batteries

When your present batteries fail, (it will likly be sooner than later), And it will happen at an inopertune moment, Bite the bullet and buy a set of the larger Trogans, you will be able to go for two days in the wind with them and will swear by them and not at them. Think about the wieght of the four batteries right where you dont want extra wieght, (Assuming you will be installing them in the stern of the boat. That could cause boat handling problems such as porpoising.