Starting battery issue

[JHenry]

I had my boat in the shop at the end of May. I put the charger on the night before and all lights were green. Took shop a few days to look at the engine, but when they did my starting battery was dead. They said it was taking a charge but barely. They said I should replace it but it was new in Octoer of 2016,so I used it all summer and it seemed fine. Well I was getting ready to fish a tourney on 9/11 and sure enough the bank on the charger was all red. Put my Minn Kota hand held tester on it and it was at 0%. I went to Sams and bought a Duracell AMG series 34 to replace it and fished the tourney. Plugged the boat in when I got back and shut charger off on Sunday, all lights were green. I go to get the boat ready today and the AMG battery is dead,0%. Put a portable charger on it with clamps and after a few minutes go to check it and the clamps are red hot even through the colored rubber. I unplugged everything and now I am wondering what my issue is? I have a 2004 Ranger and shut off both breakers after fishing so I dont think anything is on but could something be? I am not good with electrical things but want to try and find this issue so I dont have to pay a shop to chase electrical gremlins.

[bdog7198]

Are they AGM approved chargers?

[billnorman1]

We're talking AGM, and size 31 right? If you're disconnecting the battery from the boat circuits with switches that just leaves the motor. You might have a bad voltage regulator and/or a shorted stator.
If so, and you didn't disconnect the big motor leads it could overload the chargers.

[JHenry]

Ok, I will check those motor parts.Sorry it is a AGM. The battery is actually smaller than a size 31, between a 24-27 lead acid size. They call it size 34. Yes on the chargers. I called Dual Pro about the onboard charger before I bought the battery and looked up the portable one online to make sure it was ok.

[Lou r Pitcher]

I called Dual Pro about the onboard charger before I bought the battery

When you called Dual Pro, did you provide them the actual serial number of the charger you are using. If not, what was used to identify the specific charger as being one of their AGM compatible models?

and looked up the portable one online to make sure it was ok.

Who is source of on-line? Hopefully not only the charger manufacturer.

Charger/AGM Battery compatibility is best determined by checking with the battery manufacturer......as charger manufacturers are not necessarily knowledgeable about every AGM type. For some chargers, the battery's marketing group simply assumes "AGM compatibility" as long as their charger is not damaged affecting their warranty costs. They may care little if it damages some AGMs as they do not warranty batteries.

Put a portable charger on it with clamps and after a few minutes go to check it and the clamps are red hot even through the colored rubber.

AGMs and especially dead AGMs can draw higher currents and charge much quicker than flooded lead acids.

No way to know what "red hot" means to you, but have found that somewhat 'hot to touch' wires are not always necessarily a fault condition..... insulation of course should not be allowed to melt. If it is being compromised, it is a good indication the charger is not appropriate for charging a large capacity deeply discharged AGM.

Sometimes a heavily discharged battery can be partly recharged by parallel jumping it with a charged battery for a few minutes and then the Dual Pro charger can detect it and finish charging.

[billnorman1]

My supposition was the motor is drawing current otherwise he would not have two DEAD batteries, on three occasions, one of which was new.

[Lou r Pitcher]

You might have a bad voltage regulator and/or a shorted stator.....
My supposition was the motor is drawing current otherwise he would not have two DEAD batteries, on three occasions, one of which was new.

He has indicated he runs a 2003 E-TEC HO which stator's circuit uses no battery voltages and running E-TECs, including ones having failed voltage regulators have run normally even if no battery is connected. Although not designed, they all (even the big V6s can be rope started.

[billnorman1]

He has indicated he runs a 2003 E-TEC HO which stator's circuit uses no battery voltages and running E-TECs, including ones having failed voltage regulators have run normally even if no battery is connected. Although not designed, they all (even the big V6s can be rope started.

I didn't see where he indicated he had that particular motor. Since there is nothing else connected to the battery except the motor, what do you think is killing them?

[Lou r Pitcher]

Outboard model was indicated in an ops earlier thread. While an unknown engine failure might draw down a battery, the stator's circuit seems unlikely as it is not connected to battery power.

He indicated in above opening post he is unsure what else might be connected as he only switched off the main breakers..... Rangers of that era might have battery direct connected bilge/float pumps or user added accessories that if failed or being left On could explain repeated dead batteries. If not being overly discharged, charging may be inadequate.

[JHenry]

Thanks for the replies guys. I have not had time to bring boat down to see if voltage regulator is bad. I will say that I can't seem to charge this battery, it is dead. Whatever my issue is it totally messed up a new AGM battery. I do have a 2003 Rude 200HO.

[Lou r Pitcher]

I will say that I can't seem to charge this battery, it is dead. Whatever my issue is it totally messed up a new AGM battery. I do have a 2003 Rude 200HO.

Try earlier suggestion...last paragraph of post# 5.

Newer chargers will not apply a charging voltage to battery having a very low voltage. Tto prevent a dangerous spark in a bilge compartment it delays applying voltage until it confirms a battery having a voltage is connected.

[billnorman1]

Try the "other battery in parallel" trick BUT disconnect it from every thing else, or better yet take it out of the boat and charge it on the bench with a good battery and a portable charger. Label the leads you disconnect from it to facilitate reinstallation. This opens another can of worms, the battery was changed and maybe someone got a lead on the wrong post.

[JHenry]

Update. Still have not been able to check what is causing issue. I did however put a 10 amp portable charger on it and when the meter showed 25% charged, I hooked it up to the onboard charger to finish up. It is holding a 100% charge as of now.