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Thu Jul 21, 2011 7:17 pm

Hi I have a volkswagen dune buggy with a 1500cc engine in it and was wondering what size battery I should have in it, I had a 450 cold cranking amp battery that I stuck in it but the problem im having is if I drive it short distances after a while the battery goes weak, it goes weak even faster if I drive at night with the headlights on, the question Im wondering is , is all this happening because my battery is maybe just to small and should be bigger, seems to start good when I fully charge it for the first few days then gets weaker over time generator is new and it is working tested it. anyone know what size cold creanking amp battery is the min I should be running in this?

Thu Jul 21, 2011 8:10 pm

Test generator again..... If battery is going weak over short periods of time generator is not up to snuff or you have other problems in electrical system with a parasitic loss.....

Battery capacity should be non issue..... Generator is not performing because it should be able to handle "system" load at its heaviest demand and not have to rely on battery....

IF you are not running huge extra lights or ginormous stereo amp generator should be able to keep system alive almost indefinitely...

Dale

Thu Jul 21, 2011 8:21 pm

Well generator is brand new, tested it and it is charging the battery, dont have no stereo no big lights just stock lights that came on the buggy, did the test with the positive cable took it off and tapped it on the positive post for sparks...no sparks so doesnt look like anything is draining the battery, dont really have nothing extra that would drain the battery...so just figured it would be the battery

Thu Jul 21, 2011 8:22 pm

also read on here a post that someones else put up here that said the min battery that should be run should be nothing less then a 650 cold cranking amp battery....is this correct?

Thu Jul 21, 2011 8:39 pm

squiddley wrote: also read on here a post that someones else put up here that said the min battery that should be run should be nothing less then a 650 cold cranking amp battery....is this correct?

That's the size of battery I had in my 69 Chevy truck, that got me to work in winter when it was -45 outside. A bit overkill for a buggy.

I run a Miata battery in my buggy, I think rated at 420 CCA, it's mounted over the front beam, no problems with starting or charging. I'd look closely at all the wiring in the charging circuit to make sure there is no corrosion.

How old is the battery, and how many months does it sit idle in the winter? The worst thing is for a battery to sit and do nothing. I go once a month and turn on my park lights and the battery charger and run some current through the battery to keep the plates from sulfiding.

The generator will only charge what the battery needs, if half the plates in the battery are sulfided you may be down to 200 CA. Get the battery checked on a load tester.

brad

Thu Jul 21, 2011 10:34 pm

squiddley wrote: Well generator is brand new, tested it and it is charging the battery,

Have you done a load, and cell test on the batter? A bad cell can
do what you describe.
Whats the charge voltage?
Could be a bad regulator.
Grounds, grounds, grounds, check your grounds and I'm not talking about coffee here.

Fri Jul 22, 2011 12:52 am

well battery is new, generator is new, regulator is new, checked negative ground connection the one from the other end of the negative terminal of the battery cleaned it tonight, tried to find ground strap from engine tonight anyone no where that is located couldnt seem to find it, when I take the positive cable off the battery and tap it against the positive post I dont get any spark so I am assuming Im not getting anything draining the battery

Fri Jul 22, 2011 1:04 am

do you have the warning light hooked up?
do you have an amp gauge in line?

well,, that's your homework

Fri Jul 22, 2011 1:40 am

Did you polarize the generator? Must be done very time it is disconnected or serviced. To do that just use a jumper wire from the battery (b or bat) and generator (g or gen) on the cutout relay or voltage regulator.

Do you have the right voltage regulator for the generator, I believe they have to match on amperage output.

Also to fully check the charging system you also need to check amperage.
With and without load. You can use a carbon pile on the battery.
You will also need a amp clamp for your multimeter.

hope that helps

Fri Jul 22, 2011 2:08 am

Low_&_Slow_66 wrote: Did you polarize the generator? Must be done very time it is disconnected or serviced. To do that just use a jumper wire from the battery (b or bat) and generator (g or gen) on the cutout relay or voltage regulator.

I have work on vw's for 20 years and never polarized a generator after disconnecting, no problems so far.

Fri Jul 22, 2011 8:10 am

Low_&_Slow_66 wrote: Did you polarize the generator? Must be done very time it is disconnected or serviced. To do that just use a jumper wire from the battery (b or bat) and generator (g or gen) on the cutout relay or voltage regulator.

Do you have the right voltage regulator for the generator, I believe they have to match on amperage output.

Also to fully check the charging system you also need to check amperage.
With and without load. You can use a carbon pile on the battery.
You will also need a amp clamp for your multimeter.

hope that helps

Generally polarizing a generator is only required when it is installed NEW....

If generator voltage is in the 14+ volt range when engine is running (above at least 1500 rpm) , I would suspect your new battery is bad....

Dale

Fri Jul 22, 2011 9:09 am

I have been running a 275 CCA lawn tractor battery in my buggy with a 1915 cc engine for about 10 years with no problems.

Fri Jul 22, 2011 10:47 am

I'll ask again, what is the charge voltage?
That will answer a few questions

Fri Jul 22, 2011 8:42 pm

I took my tester back to work will have to wait to get it now till monday then I will check the charge voltage and let you know what I come up with...