Charger overheat problem!

tahoejag

Petty Officer 1st Class
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Jul 4, 2009
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ProMariner Tournament 100 2 bank 10amp 12/24 volt system charger. (2) SRM-29 Interstate Deep cycle bat. Minnkota Terrova 80lb 24 v motor 1 year old. SITUATION - First off, charger checks o.k. bench tested as per ProMariner Service Tech and also batteries check o.k. tested under load (was said to be like new). 2 banks (one on each 12 volt bat that is connected as 24 v system) batteries charge fine and charger does NOT get hot at all (charging cycle takes aprx 10 hours) (note: at this time the batteries are NOT connected to the trolling motor wiring that lead to the bow plug).

When the trolling motor wiring is connected to the batteries (w 50 amp breaker in line), yet the trolling motor itself is unplugged from the bow plug - the charger will get VERY HOT as cannot even hold hand on it. Yet it does go thru the charging cycle and goes into a float mode.

When on the water motor seems to perform ok and drains batteries down as normal. What is not normal is the overheating of the charger once the 24 volt battery system is connected to the motor wiring even though the motor itself is unplugged at the bow while charging. Was recommended just to disconnect the wires that lead to the bow plug from the batteries, but that is not fixing the situation, rather masking it.

I have talked to and took the boat to several shops and they are stumped as to why the charger overheats when the system is connected, and so am I. Could it be the motor itself shorting something out? Any input/suggestions or help is GREATLY appreciated in this matter. Thanks! John.
 

j_martin

Admiral
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Sep 22, 2006
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7,474
Re: Charger overheat problem!

Is the charger mounted where it can't get any ventilation?

Mine's in a storage compartment, and it'll get pretty hot if I don't leave the lid open when it's running. The clue I'm running on is it seems to operate normally except for the temp.

In the boat, try isolating the batteries by disconnecting the jumper between them, or if there's a switch in to bow, put it in the center position. See if it makes any difference. It really shouldn't.
 

Silvertip

Supreme Mariner
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Sep 22, 2003
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28,771
Re: Charger overheat problem!

Do you have a two, three or four wire system running from the batteries to the receptacle at the bow? Are there any other accessories powered from the troller batteries.
 

tahoejag

Petty Officer 1st Class
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229
Re: Charger overheat problem!

Do you have a two, three or four wire system running from the batteries to the receptacle at the bow? Are there any other accessories powered from the troller batteries.

It is a two wire system (one neg/one pos to the receptacle) totally separate system only for the trolling motor.
 

tahoejag

Petty Officer 1st Class
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Re: Charger overheat problem!

Had this system hooked up for over two seasons and just noticed the overheat problem aprx month ago. Plenty of ventalation to charger and batteries. Never had to disconnect jumper or any other wires while charging in the past.
 

Silvertip

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Sep 22, 2003
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28,771
Re: Charger overheat problem!

Heat means high current draw. Something in the wiring is wrong. I wold concentrate on the back of the receptacle. Look for frayed wires that may be touching. Are you absolutely certain you have the correct wiring at the batteries and that you have the POS and NEG pairs from the charger correctly attached. In other words, is the POS and NEG from output #1 on the same battery. Same for output #2.
 

tahoejag

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Messages
229
Re: Charger overheat problem!

Conclusion - All wiring was correct with no frays. Looking at receptacle I have a 3 wire marinco with adapter to allow me to use 6 ga wire, even though i do not use the third wire slot. I have neg to slot#1, pos to slot#2 and slot #3 is empty. I did notice spider webs in slot#3, so cleaned them out (maybe that was the problem?). I measured voltage across #1 and #2 and got 26.8 v (which i believe is good). Measured for voltage from #1 (neg) to #3 (empty slot) and got .08 v. I then measured voltage from slot #2 (pos) to #3 (empty slot) and got .8 v. Is this normal to get a low voltage readinig thru the receptacle even though there is no wire in slot #3? I would assume there would be no voltage reading there and only across the pos and neg of the receptacle??? Or is this an acceptable reading or is the receptacle bad? Thanks!
 

j_martin

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Sep 22, 2006
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7,474
Re: Charger overheat problem!

You're measuring leakage of microamps with a sensitive meter. It's not a problem at all.

The charger circuits (inside the charger) should be completely isolated. It's possible an internal failure in a transformer or heat sink is causing a problem.

Disconnect the trolling motor. Disconnect the jumper between the batteries. Plug in the charger. Touch the jumper to it's connection. There should be no spark. If there is, there's an internal problem in the charger.

hope it helps
John
 

tahoejag

Petty Officer 1st Class
Joined
Jul 4, 2009
Messages
229
Re: Charger overheat problem!

You're measuring leakage of microamps with a sensitive meter. It's not a problem at all.

The charger circuits (inside the charger) should be completely isolated. It's possible an internal failure in a transformer or heat sink is causing a problem.

Disconnect the trolling motor. Disconnect the jumper between the batteries. Plug in the charger. Touch the jumper to it's connection. There should be no spark. If there is, there's an internal problem in the charger.

hope it helps
John

There was no spark at jumper when connecting to terminal with charger plugged in....just got in from the lake after using troller for aprx 2 hrs......plugged in charger...still hot-still same problem...I AM STUMMPED!!! All this just started about month ago......never had issue before.
 

j_martin

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Sep 22, 2006
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7,474
Re: Charger overheat problem!

What kind of batteries in the boat. AGM batteries have an extreme acceptance rate that tend to heat up charging equipment.
 

ac0j

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Apr 26, 2011
Messages
98
Re: Charger overheat problem!

If the only time the charger gets hot is when the trolling motor harness wires are connected to the batteries, and the trolling motor is not plugged in. THERE IS A PROBLEM in the trolling motor wireing or receptical. With the troll motor wires disconnected from the batteries, and the motor unplugged, you should have zero ohms across the trolling motor wires. If you have any resistance on those wires, you need to find the short.
 

tahoejag

Petty Officer 1st Class
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Jul 4, 2009
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229
Re: Charger overheat problem!

Tested resistance on trolling harness and it's 0. Both lead-acid batteries have been off charger for a day and both read 12.8v. It seems that everything is working, holding a charge, motor runs ok. Just can't explain why the chargr gets so hot when charging, but does cool down after it hits float mode. Maybe charger is on its way out??? Had it for about 4 yrs now, but just starting overheating bout a month ago.
 

tahoejag

Petty Officer 1st Class
Joined
Jul 4, 2009
Messages
229
Re: Charger overheat problem!

Tested resistance on trolling harness and it's 0. Both lead-acid batteries have been off charger for a day and both read 12.8v. It seems that everything is working, holding a charge, motor runs ok. Just can't explain why the chargr gets so hot when charging, but does cool down after it hits float mode. Maybe charger is on its way out??? Had it for about 4 yrs now, but just starting overheating bout a month ago.
 
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