Question for the electrical gurus

[JoeW]

I am working on a beautifully restored military WLA Harley. The bike was finished last year and within the first 150 miles, the battery started to boil and leak acid all over the battery box. I checked the voltage regulator and it's limiting voltage to 6.6 volts. The battery is an odd size and my only choice is a standard flooded lead acid 6 volt 18 Ah battery. I'm thinking of installing two AGM 6 volt 8.2 Ah batteries wired parallel. That would give me 6 volts and a little over 16 Ah. The problem is, these batteries are deep cycle units for use in a house alarm or one of those kiddie cars. Am I asking for trouble attaching these batteries to a primitive DC charging system? Any input or ideas would be greatly appreciated.

[Wayne Orwig]

I am working on a beautifully restored military WLA Harley. The bike was finished last year and within the first 150 miles, the battery started to boil and leak acid all over the battery box. I checked the voltage regulator and it's limiting voltage to 6.6 volts. The battery is an odd size and my only choice is a standard flooded lead acid 6 volt 18 Ah battery. I'm thinking of installing two AGM 6 volt 8.2 Ah batteries wired parallel. That would give me 6 volts and a little over 16 Ah. The problem is, these batteries are deep cycle units for use in a house alarm or one of those kiddie cars. Am I asking for trouble attaching these batteries to a primitive DC charging system? Any input or ideas would be greatly appreciated.

I would first question why your flooded wet cell boiled over. Even 7 volts shouldn't boil the battery.
The AGM battery will just quickly vent and die if there is a serious over voltage problem, which it sounds like there is.
I assume this has a generator, and I can only wonder if the regulator relay is sticking occasionally, or something. Or maybe that wet battery has some type of defect.

[rodekyll]

If it's like my WPL it has a generator.  A generator increases output as rpm increases.  It's capable of much higher voltage than its rated for.  The regulator keeps it in check by fluttering a set of points.  The points shunt from battery + to ground.  If the regulator or the generator isn't properly grounded, the shunt to ground doesn't bleed off voltage and just like having stuck points, you overcharge.  This gets worser as the rpms get higher.  So for no other reason I'd start there -- all the grounds back to the battery.  Next suspect is the regulator.

[JoeW]

I didn't think about a sticking regulator. I may pull the generator and regulator and bring it to my rebuilder for testing.

[Penderic]

I saw a electrical coil refit for a motorcycle's regular cylinders that turned the engine into a hybrid motor.

Neato if it works.

Hummm bzzzz Hummm bzzz (electric potato potato equivalent sound)

Wonder how a Moto Guzzi V twin coil hybrid would look and perform. 

[56Pan]

If the machine is a stock WLA, I believe it'll have a 3 brush DC generator.  Is there a small relay mounted on or adjacent to the generator about 2 1/2 in. long by 1 in. wide?  If so, it's the stock 3 brush. There is no voltage regulator on a 3 brush generator.  Old Farmall tractors had the same system.  You set the base charge rate by moving the 3rd brush which has a slotted mount around the commutator until the charge voltage with the engine running is correct.  When you turn on the lights, the small relay energizes and the lighting field coil is energized to increase the voltage a little more to carry the load of the lights.  Also, if that relay is stuck closed, no lighting load, it will overcharge the battery.  I can try to scan and send the proper service info. if you want for a 3 brush gen. 

[JoeW]

If the machine is a stock WLA, I believe it'll have a 3 brush DC generator.  Is there a small relay mounted on or adjacent to the generator about 2 1/2 in. long by 1 in. wide?  If so, it's the stock 3 brush. There is no voltage regulator on a 3 brush generator.  Old Farmall tractors had the same system.  You set the base charge rate by moving the 3rd brush which has a slotted mount around the commutator until the charge voltage with the engine running is correct.  When you turn on the lights, the small relay energizes and the lighting field coil is energized to increase the voltage a little more to carry the load of the lights.  Also, if that relay is stuck closed, no lighting load, it will overcharge the battery.  I can try to scan and send the proper service info. if you want for a 3 brush gen.

Well, there you go. This is what makes this forum the best on the internet. That is exactly the system on this bike. I had never seen a voltage regulator that small before and you just explained why. I'll do soon searching but, if you could scan that for me, that would be great. Thanks, I'll guess I'll order a the correct battery for it today.

[56Pan]

Well, there you go. This is what makes this forum the best on the internet. That is exactly the system on this bike. I had never seen a voltage regulator that small before and you just explained why. I'll do soon searching but, if you could scan that for me, that would be great. Thanks, I'll guess I'll order a the correct battery for it today.

PM sent.  My info was from memory.  The lighting field is energized through the light switch.  The relay is the "cutout" relay and energizes at ~6.8 volts and turns off the dash gen. light.

[Testarossa]

That's very cool. This has nothing to do with coils or hybrids. It's a pure electric. The blue "cylinders" are battery packs, the "crankcase" is a DC pancake motor. See http://www.evworld.com/news.cfm?rssid=27067

[lrutt]

does that have the 3 brush generator? if so, you need to dial back that 3rd brush. I did find a 6vAGM that fit well in a VLD I had to fix for my BIL. it was a Panasonic.

Anyhow, check that genny and if it's a 3 brush, hopefully you have some documentation on how to dial back the charging rate. I put an ammeter on the bike I worked on and tweaked it in. Maybe you can to.

[Triple Jim]

The points shunt from battery + to ground.

I'm with you except for this part... a regulator does not connect battery+ to ground at any time!  Of course later posts say there is no regulator anyway.

[JoeW]

OK, So I learned a lot. The bike owner is bringing me the shop manual so, I'm going to order the correct flooded battery and test and adjust the system.
Here's a picture of the bike...

[Don G]

You can also use a solid state regulator, basically a diode. bypass the vibrator switch,( can be left on the engine case to look stock). The diode attatchs to the + post of the battery. Ran these for years on the old Flat Heads!.  DonG

[rodekyll]

Yes, I miswrote that part and assumed the two-brush generator with the hi-hat regulator (my WPL's lived on the seat post).  Doesn't apply to the WPA, sorry.

[JoeW]

Thanks for all the input and advice, I picked up the manual today but I'm not sure if I am authorized to red it...

I'm pretty sure that all the secrets about the WLA are public knowledge by now, right?