Alternator/Battery/Electrical Problem

[rustydust]

Been having trouble with my 2000 21V. Had to get a new alternator a few months ago (got the DB 70Amp). Lately even with charged batteries the motor is slow to turn over for a while then speeds up and starts. When I am idling my voltage meter on the dash reads at the level of the batteries then when I give some gas it will go up to ~13.2. After a little while the batteries will go down. I just have a 1000W amp for my 4 tower speakers. The batteries are new but just standard cheaper marine batteries. Have them on a selector switch. Should I get a larger 90 amp alternator? Any suggestions on where to get one? Guess I need a deep cycle battery as well. Appreciate any suggestions.

Thanks,

[boatwakes]

A few possible causes for the starting issue: first and foremost, K.I.S.S. keep it simple, stupid... 99 out of 100 it's the simplist thing. When did the slow turn over start occuring? Check for loose connection where the ground bolts to the block as well as the positive to the starter. Double check tightness of the connections on the batteries as well as the selector switch. Have you ever shut off the battery switch with the engine running? If you did, the alternator is shorting out when the engine isn't running and killing your batteries.
If your engine is a Mercruiser, the alternator doesn't excite until it sees about 1000 engine rpm, then it begins to charge according to where it reads the state of the battery system. I switched over to Optima gel cells about 8 years ago and if you also decide to go gel, you MUST put an external voltage regulator on the alternator that will charge at no more than 14.1 volts with 13.7volts being the preffered voltage for those batteries. We just got back from our week long houseboat trip and those batteries are 8 years old and we've never had a problem.
Anyway, I guess I need some more information on what the problem(s) are with your boat. Under what conditions are you having low battery problems? Does the boat ever start "easy"? How long did your last batteries last? Let's start with that info and go from there because I don't want to see you throwing money at a problem that may easily be fixed.

[rustydust]

Thanks for the input. I have checked most connections but I need to check the ground for sure. I want to go to the gell cell batteries, do you have a suggestion on what voltage regulator to use? Where does this connect into?

Also I want to add a shore battery charge to mount in the boat and just plug in when the boat is out of the water. Any suggestions on which one? Is there one that can connect to both batteries?

[chpthril]

Thanks for the input. I have checked most connections but I need to check the ground for sure. I want to go to the gell cell batteries, do you have a suggestion on what voltage regulator to use? Where does this connect into?

Also I want to add a shore battery charge to mount in the boat and just plug in when the boat is out of the water. Any suggestions on which one? Is there one that can connect to both batteries?

(see in bold text) Why?

[rustydust]

Well deep cycle. Thinking the cheap walmarts need some help.

[chpthril]

Well deep cycle. Thinking the cheap walmarts need some help.

From an Ah v's $$$ standpoint, you cant beat a plain old wet-cell lead acid marine deep-cycle battery, so yes, swapping out one of you "Starting" batteries for a deep-cycle for the stereo bank will benefit in both play time as well as battery longevity (providing proper battery maintenance is observed).

Gel-cells typically require a high charge voltage, and therefore are often times left undercharged by the alternator. For this reason, I dont like to mix battery types, unless the banks are isolated.

What is the static (at rest) battery voltage of each of your current batteries?

Does the engine spin up any faster with the switch on "Both"?

Battery charger: You can get a single, dual or 3-bank chargers. Most can be set to charge different types of batteries, but a mix. What you set it to, is for all banks. I like to go with a charger that will deliver an amp rating of about 10% of the Ah's of the bank. A really drained deep-cycle needs a kick in the but to get it to start taking a charge and a small trickle charger will not do it.

Some setups can get away with a single-bank charger, and just run it on the stereo bank, as the main starting battery never really gets depleted if the loads, such as stereo, lights, etc, are on the stereo bank.

How long you want to play the system with the engine off will dictate what size or how many batteries you will need, then the charger can be decided on.

[boatwakes]

Guest makes an excellent all around battery charger for single or multiple banks of flooded lead acid and they're inexpensive and fully automatic. The West Marine model numbers are: 1903467 for the single battery (single bank) at $99 and 307530 for the dual battery (dual bank)for $150. If you do go to gel, they are more cost effective in the long run but have a relatively high initial cost. I would suggest you remove the alternator and take it to a respected shop for the external regulator fitting instead of doing it on your own. Expect to pay around $150. Also, their onboard battery charging must be done by a charger designed to be used with gel batteries. ProMariner makes an inexpensive and extremely durable unit compatible with all battery types using a selectable charge profile designed to meet a specific battery chemistry needs. Their prosport 12A is designed for a dual battery system, runs about $160 and is west marine model number 9368606. Both manufacturers units have a regular male cord end to plug your extension cord into and because they're fully automatic, you're covered for the off season. Even if you don't go to gel adding a FULLY AUTOMATIC battery charger will greatly extend the life of your batteries. Hope this helped.

[Ewok]

See page 6 from the thread below, I installed the guest dual bank, isolated battery charger. I have an optima AGM battery on the house side and standard marine starting battery on the engine. It works very well.

http://www.tigeowners.com/forum/show...t=11909&page=6

[laserfish]

I have the same boat, and had the same problem for a couple of summers. Finally, it just gave up and wouldn't start. Discovered it was the starter getting weaker. Installed a new starter, and it turned over like it never had before. Seems thats what it was all the time, and I was thinking like you that it was the charging system or batteries. Good luck.

[rustydust]

Thanks for the input. The starter does sound like a likely culprit.

^^Nice job on the thread above. I really like the battery setup. I need some help on my battery set up. Right now I just have two batteries on a perko selector switch and just use whichever battery has a good charge. How do I seperate which is the starting battery and which is the house? Should I purchase an isolator relay? Not too familiar with how this should work.

[chpthril]

Thanks for the input. The starter does sound like a likely culprit.

^^Nice job on the thread above. I really like the battery setup. I need some help on my battery set up. Right now I just have two batteries on a perko selector switch and just use whichever battery has a good charge. How do I separate which is the starting battery and which is the house? Should I purchase an isolator relay? Not too familiar with how this should work.

ACR's (Auto-Combining Relay) are easy to install and will basically make your switch a "set it and forget it" setup.

With the main starting on post 1 and the house on post 2 and the ACR combining the 2 batteries, you can leave the switch in "1" and only use "Both" or "2" if needed for an emergency starting battery. With the engine running, the ACR will allow both to get a charge from the alternator and when the engine is off, the ACR opens, isolating the stereo battery from the main starting battery. This will allow you to pull off the stereo until it's drained, and have a fully charged starting battery in the waiting.

I prefer the Blue Sea 7610. Sure Power also makes a couple different ones. I have not used them, but my distributor started carrying them, so I think I will order a couple and try them out.