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TOPIC: 6v battery charge rate

6v battery charge rate 11 Aug 2019 00:41 #1

  • Mr Vegetable Trousers
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1976 DT250B standard 6v points setup.
New “wet” battery.
I noticed drips of water from the battery overflow tube after a test ride. Slight acid smell as you would expect.
Meter across terminals shows 6.5 at idle going up to 8.6 when revved up to say 7000 rpm. A little less with lights on.
New regulator in the loom.

All bulbs in place.
Are these figures too high? The manual suggests it’s about right.

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6v battery charge rate 11 Aug 2019 05:26 #2

  • RT325
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By new regulator i just want to be sure you not referring to the two wire rectifier under the tank as the single wire regulator if fitted should hold it back to an acceptable level. Just for a minute thinking if the regulator isn't working & someone has tapped the daytime charge off the yellow wire from the mag which will be the highest output as runs the lights--then it could boil the battery in daytime running at revs/speed. Was only a thought & might be miles off. Hope you have a nice long breather pipe off the battery or it'll eat the paint pretty quick then rust the steel.
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6v battery charge rate 11 Aug 2019 05:38 #3

  • Mr Vegetable Trousers
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Yes sorry I mean I fitted a new rectifier.
The bike retains the lighting circuit yellow wire regulator that it came with and there is a “Stanley brand regulator under the tank.
Yes nice long tube emerges under the bike.

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Last Edit: by Mr Vegetable Trousers. Reason: Typo

6v battery charge rate 11 Aug 2019 06:01 #4

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My mistake... there is no regulator in the charging circuit, just a rectifier.
The only regulator I have is in the lighting circuit. My guess is I need to add a regulator in the the charging circuit...

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6v battery charge rate 11 Aug 2019 06:54 #5

  • Gr8uncleal
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In the lighting circuit is the correct place for the retro fitting of the voltage regulator I believe - see link below.

yamaha-enduros.com/index.php/workshop/se...e-voltage-regulators

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6v battery charge rate 11 Aug 2019 22:57 #6

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Any wires been swapped around under the tank or where the loom from the mag meets the main loom. Has someone tried to increase the charge rate to the battery when struggling with an old battery & then now with a new one taking everything you can throw at it--it's boiling the water/acid out.

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6v battery charge rate 12 Aug 2019 00:04 #7

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Gr8uncleal wrote: In the lighting circuit is the correct place for the retro fitting of the voltage regulator I believe - see link below.

yamaha-enduros.com/index.php/workshop/se...e-voltage-regulators


Edit - just to clarify, in the blue wire, not the yellow.

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6v battery charge rate 12 Aug 2019 00:15 #8

  • Mr Vegetable Trousers
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So would that regulate the supply to the battery too?

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6v battery charge rate 12 Aug 2019 05:47 #9

  • MarkT
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A Motobatt will stop the the "leaky acid" problem. The behavior you are seeing is completely normal and expected for a wet cell... and the reason Yamaha pasted warning stickers on the bike showing the proper routing of the battery vent hose. You'll find many bikes with damage from the puking acid. Best (worst!) is when the acid is allowed to drip on the drive chain. Somehow it "crystallizes" the steel and the chain becomes brittle and snaps very easily.

It's probably not what you want to hear but this system with the "wet" battery commonly boiled some of the water out of the battery. You had to check the battery water frequently.

There's no "sensing" that the battery is charged... the charging output is fixed. The battery itself is a very crude "voltage regulator", once it's charged fully, it boils the water out to get rid of the excess energy. To reduce the "boil over", don't fully charge the battery before riding. Let the bike do it during the ride. But you can't let the battery go too low on charge in storage or it will die.

I've never known anyone to install an AC regulator in the battery charging circuit... but you could as long as it was installed immediately before the rectifier. I'm not sure it would help.

Running with the lights on and not "topping off" the battery with a charge before riding will help... adding in a 6 volt bulb or some other load on the battery circuit with a switch could be used as a manual way to burn off some of the excess power.

And yes, make sure someone has not wired in the optional (white) "high output" charging wire... if your bike still has that option.
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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250

6v battery charge rate 12 Aug 2019 06:16 #10

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Wow, whacky stuff but thanks for the info. Luckily I did attach the vent hose and it drips onto the floor. After my test ride it still dripped a bit but not as much as it had when I first ran the bike up.

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