Deep-Cycle Flooded/wet lead-acid batteries used as STARTER batteries? (Trojan T-105)

[ErikFinn]

Howdy folks,

is anyone using deep-cycle batteries as starter batteries? You think it makes sense or not?

I believe it is generally not recommended, but rather to use the thinner plated more oomphed designated starter batteries instead. But..

One of my projects is to replace the batteries and I was thinking if it would make sense to use the old still good deep-cycle batteries from the house bank as a starter battery? I want to replace the whole domestic bank at one time, and don't want to combine old and new batteries, and thus I kinda don't feel so good about just throwing the ok ones away (one has apparently dropped a cell, so that goes). And because I need a new starter battery then its not too difficult to get this idea about transferring the old Trojan T-105 batteries to the starter side, replacing the old bad starter battery...

Another advantage I could see, doing the above is that, if needed, I could add 50% to the existing domestic bank by using the starter bank to domestic needs also.

I use the boat here in the tropics and get a lot of sun. I have 8x85W solar and my domestic bank currently is 4 x Trojan T105. New solar charge controller(s) is on the list, as is a new fridge compressor and evaporator; oh boy these list just accumulate dont they..?

Does this make any sense? What say you guys? Am I thinking about something that would simply only cause more problems than solve ones...

PS my engine is a Perkins M50 2 liter 4 cylinder diesel, 50HP

[Uncle Bob]

Originally Posted by ErikFinn

Howdy folks,

is anyone using deep-cycle batteries as starter batteries? You think it makes sense or not?

I believe it is generally not recommended, but rather to use the thinner plated more oomphed designated starter batteries instead. But..

One of my projects is to replace the batteries and I was thinking if it would make sense to use the old still good deep-cycle batteries from the house bank as a starter battery? I want to replace the whole domestic bank at one time, and don't want to combine old and new batteries, and thus I kinda don't feel so good about just throwing the ok ones away (one has apparently dropped a cell, so that goes). And because I need a new starter battery then its not too difficult to get this idea about transferring the old Trojan T-105 batteries to the starter side, replacing the old bad starter battery...

Another advantage I could see, doing the above is that, if needed, I could add 50% to the existing domestic bank by using the starter bank to domestic needs also.

I use the boat here in the tropics and get a lot of sun. I have 8x85W solar and my domestic bank currently is 4 x Trojan T105. New solar charge controller(s) is on the list, as is a new fridge compressor and evaporator; oh boy these list just accumulate dont they..?

Does this make any sense? What say you guys? Am I thinking about something that would simply only cause more problems than solve ones...

PS my engine is a Perkins M50 2 liter 4 cylinder diesel, 50HP

Hi what you are suggesting is exactly what I have just done.
The start batteries have been deep cycle as long as I have owned the boat, 2 x 200 ah 6 volt and are only used as start and to run the windlass.
I purchased six new batteries and then realised that the two used for the engine start were not nearly as bad as the four used in the house bank, so decided to expand the house and retain the existing start. So far so good.

[cal40john]

Use as house supplement as needed? Parallel charged start bank to dead house bank just discharges the full batteries. Or switch house loads from dead house bank to full start bank, then chance not being able to start the engine.

With all that solar power you might as well just leave it all as one bank all the time then.

[ErikFinn]

Originally Posted by Uncle Bob

Hi what you are suggesting is exactly what I have just done.
The start batteries have been deep cycle as long as I have owned the boat, 2 x 200 ah 6 volt and are only used as start and to run the windlass.
I purchased six new batteries and then realised that the two used for the engine start were not nearly as bad as the four used in the house bank, so decided to expand the house and retain the existing start. So far so good.

Thanks Uncle Bob, glad to hear the idea is not too bad..

[ErikFinn]

Originally Posted by cal40john

Use as house supplement as needed? Parallel charged start bank to dead house bank just discharges the full batteries. Or switch house loads from dead house bank to full start bank, then chance not being able to start the engine.

With all that solar power you might as well just leave it all as one bank all the time then.

Thanks cal40john, the idea has crossed my mind..
At the moment, 2 out of my 4 T-105 batteries are still quite ok, and I need to buy SOME batteries obviously. I do not want to combine old and new batteries (these are about 6 years old). Trojan T-105 is priced at USD 200 over here, which is not cheap. In Langkawi (just north of here, a popular sailing destination) they are an incredible USD 500. Yes five hundred USD. Each. So im kinda trying to think ways to save a few bucks here, and hope I only need to buy 4 of them at a cost of USD800...
If I was in the US I would just get all new batteries.

[snotter]

Until you get up to 6 cylinders and more, stick with the deep cycles--they are more than sufficient. Heck, in the winter, I need almost 45 seconds of glow-plug use before I even can hit the starter button. In all my years of owning sailboats (stink-pots are another issue), I've always used deep cycles. It is always nice having having identical batteries on board. Occassionly, I do switch them into the house bank. I want the battery plates to be as thick as possible on the batteries I buy. Also, the deep-cycles usually have more room between the bottom of the plates and the bottom of the cases, making them more resistant to shorting out--they last longer than thin plated, automotive style batteries. The surface charge issue associated with thick plates just hasn't been an issue for me in the past.

[sparrowhawk1]

Eric sounds like a good plan. Under normal situation starting batteries have an easy life that's why you don't need the heavy plates. So long as you have the amperage to crank your engine I don't see how it could be a problem. I also have a large solar array and my boat came with a large deep cycle starting battery bank so I just combined the bank into one huge bank whenever my batteries got low I would start my engine to charge both banks which didn't happen very often. you just always need to be aware of your state of charge so you're not left with a flat battery.( which you want to do anyway for the life of your batteries) worst case scenario just have to wait for a sunny day and then start my engine. But when it comes time to replace either my house or my starter batterys I'm going to do what you're doing. Having the new batteries as my house and have it separate

[valhalla360]

There is absolutely no harm in using deep cycle batteries to start a motor. Make sure the battery bank is rated for the cranking amps your starter calls for but otherwise...

The reason it's not typically done on big power boats is deep cycle batteries put out fewer peak cranking amps, so they would need a massive battery bank just to start the motor.

For a small sailboat engine, it should be fine. The one catch is if the house bank is far from the engine and your existing starting battery is right next to the engine. Long cable runs can result in voltage drop which might give you some issues.

[onestepcsy37]

Been doing that for ten years now. Four golf cart batteries to start my perkins 4-108.

[Ex-Calif]

Originally Posted by ErikFinn

Thanks cal40john, the idea has crossed my mind..
At the moment, 2 out of my 4 T-105 batteries are still quite ok, and I need to buy SOME batteries obviously. I do not want to combine old and new batteries (these are about 6 years old). Trojan T-105 is priced at USD 200 over here, which is not cheap. In Langkawi (just north of here, a popular sailing destination) they are an incredible USD 500. Yes five hundred USD. Each. So im kinda trying to think ways to save a few bucks here, and hope I only need to buy 4 of them at a cost of USD800...
If I was in the US I would just get all new batteries.

As others have said the deep cycles will work for engine starting. They won't put out as many continuous amps as a deep cycle but it should not be a practical issue.

You don't say how your start batteries are charged but you mention you want to use the relocated batteries to augment the house.

I had the same idea and am installing the Blue Seas 7611 ACR. This ACR leaves the start and house batteries paralleled longer (down to 12.25v vs. 12.75v) What this does is allow access to more start battery amps automatically.

12.25V will be plenty to start my engine and I am a "set and forget" kind of person so I am hopeful of this setup.

http://assets.bluesea.com/files/reso.../ChooseACR.pdf