Battery Boiling Help

Hi there again,

having spent quite a time out on my VFR750 FH over the last few weeks I needed to clean it, service it and replace a few bits such as the headstock bearings and the fork seals.

Anyhoo on doing this i noticed some white marks under the battery on the aluminum frame.

on further investigation the battery had been boiling and leaking acid on the frame, I cleaned this off etc but on looking through the reasons for it, there seems to be too much charge going through the battery, it was visibly boiling on tick over. So after checking the charge it was overvolting to the tune of 18 volts.

So after inspecting things a little the only thing i can think that it is is the r/r however is there anyway of actually confirming that before i fork ou for a new one ? or could it be another reason ?


all help appreciated

 

get a sealed battery maybe loose caps when riding splashing around etc.......cheap batteries suck they just get you on the battery .....www.yuasabatteries.com

 

replace R/R

it's a miracle your CDI didn't fry from excess voltage.....

 

well actually i know why i leaked the bottom was not correctly pushed into the top if you know what i mean so I am going to get a replacement, however its the battery boiling thats the problem i need to get to the route of the reason why its actually boiling.

 

replace R/R cuz it's responsible for any over-voltage condition.

 

thanks a bunch mate, Ill get one ordered and stop riding it till I can get it on.

 

question i have read quite alot today stating that heat could be the reason he R/R goes ? is his true or a myth ? a few things that i have read suggest fitting a small fan near the rectifier to cool it down ? is there any point in this will it help or is it not worth doing ?

 

the heat does seem to be the culprit. its no differnt than voltage regulator on a car alternator in that heat kills it. its all solid state inside, when it gets really hot it fails. everyone gets theirs from different places but the new honda ones are redesigned and seem to run a little cooler. there is also wiring modifications some people have done to help this problem. as far as your battery problem if you get a new one see if it has a nipple on the side for a hose. then you can route the hose down the bike toward the ground instead of your frame.

 

Yes, a small computer fan can keep the regulator cooler and prolong its life......

 

I say this with 200% respect to Squirrel.

Before we go out and start replacing the RR... we should investigate what we mean by boiling the battery.

There are diodes in the wire harness that prohibit over charging... there are indeed diodes in the regulator that prohibit over charging... your rectifier would also need to be failing for a short (closed circuit) in order to put out more than 16.0V.

I question only out of lack of information.

To boil a battery, you need over 16V of sustained power. You would also notice the water level of the battery drop significantly... about an inch of water missing. The Vent tube would also have to either be, disconnected and plugged.

running a battery with constant over charging, would ruin a battery to the point of "non-operation" within 16 hrs of run time. And the electrolytes would be useless, thus you could NEVER recharge a boiled battery.

I would ask;

check your vent tube (should be working well)
be more careful when you refill it next time (spills)
check for double wiring from the RR (home made stuff)
check the battery for proper installation (not tilted, or tightly wedged to crack the housing)
do you lean excessively (spilling over the plates)
how old is the battery? (old batterys tend to allow the plating to build up, from the top of the batterys water level, down... could be going over a semi solid barrier of platelets)

And lastly... I have still yet to see hard data that suggests a fan added to a RR has ANY help. I do have data that shows a 5% loss of life if you DO put on a fan. and I do have data that shows a 7% increase in life if you use an aluminum heat sink, 1 inch tall.

 

I'm using a NON-finned R/R with a Pentium 3 aluminum 1.5" tall heatsink (with heat conductive CPU gel) and CPU fan. The fan is wired to the license plate light I no longer have since I chopped the plate mount down. I also re-wired the charging system (with heavy-duty 15 strand 14 gauge house wiring) from the Stator connector back to the R/R.

Increased impedance (because of poor connections or toasted wires) increases heat. Heat increases the likelyhood of R/R failure.

No charging issues at present.

To the OP - I would check all of your connections and components for scorch marks. Sound to me like you need a new R/R at the very least, probably a new battery, too.

 

thanks for all the help guys, replaced the rectifier with an electrex one, and all is well again, the battery had done less than 500 miles so seems to sill be working ok.


Few other problems have been unearthed with the bike though, it overheated on its first trip out a little as there was dirty water down the side of the bike after about a 20 mile trip out. anyway after cleaning out the coolant, washing it out a number of times and finally getting clean water through, as well as unblocking the expander tank all seems well in that department, however.


recently we changed the head bearings and also replaced the fork seals, on doing so the bike no seems to jerk on braking, its almost like having a warped break disc or something on the car, like a slight judder, which doesn't stop me braking or anything however it is a tad annoying. the brakes are all fine so we are at a loss as to what it could be.

the only thing is we replaced the fork oil with normal oil but before there was some race oil in the forks. would that make this difference ? either that or maybe something with the anti dive mechanism ? anyone got any ideas ?

 

Oil isnt the problem. I really dont feel the need to go in to the chemical mechanics of molecular states for oil... so, its not the oil. you could put vegtible oil in there, and it wouldnt cause any issues to which you are seeing.

There are quite a few things this could be, so I'll just list a few for you to check.

Axle bearings. I didnt think this was the case for me either, but after Squirrel talked me into it, I found he was 100% on the mark.

blown or backwards break cylinder seals. if when you replaced your breaks, you didnt open the resevoir cap, and bleed afterwards, you most likely have inadvertantly pushed your caliper piston seal backwards... sorta like flipping windshield wipers. they still "work" but there is a thump every time you press them.

improperly installed break pads will do this also. check to see that you put the break pads in correctly. no debris, no rolled edge, pin is in correctly, spring is in correctly etc etc.

air bubble in your break lines. probably the most common problem for jerky breaks. remember this air bubble could be anywhere... it sucks to find it cause it takes time, but what else you got to do? laundry?