Bike not charging at idle with headlight on.

[GSJohn]

This is a little off topic but concerning battery power/capacity: My bike came with a battery that will only charge to 12.5 volts even out of the bike. The level is good on this walmart battery...I have not tested the specific gravity though. It was working just fine but for testing my electrical system I put in a small sealed AGM battery (only 4 Ah) I have around that maintains a 12.7V charge. It seems to work just fine but I wonder what the electrical system thinks of a smaller capacity battery. I'm a mechanical engineer so my "electrical intuition" is highly suspect...but I reasoned that the electrical system would just see it as a normal battery until it's reserve capacity is used up. As long as I don't deplete the reserve capacity it should not matter if it is smaller in size, right?

[andrewclaycomb]

Yes, BatteryTender is a brand name. I would suggest you splurge and get the BatteryTender Plus. It's a wonderful little gadget and, over the years, it will save you a number of batteries!\\/ It will keep you battery fully charged but it won't 'fry' it or boil out the electrolyte solution.

I was just using battery tender as a generic term. My "tender" is a Yuasa Smart shot 900. It shows charging and when it's full it goes into storage mode.

[psyguy]

Is a battery tender a trickle charger?

hm, depends where you live :-D
yes it is

[earlfor]

A couple possible problems I see with a small capacity battery are: If your bike takes repeated cranking to get running from a cold start, you could quickly exhaust the battery before getting the engine running. Also, the charging system on a GS is not a load regulated system. Engine rpm controls electrical output. There must be excess output available for the system to be able to charge the battery. Once the battery is charged, any excess electrical production is shunted to ground. A larger capacity battery (I would think) would maintain a more stable electrical system voltage level as opposed to a small battery that may cause the lights to go dim immediately at low engine rpm.

Earl

This is a little off topic but concerning battery power/capacity: My bike came with a battery that will only charge to 12.5 volts even out of the bike. The level is good on this walmart battery...I have not tested the specific gravity though. It was working just fine but for testing my electrical system I put in a small sealed AGM battery (only 4 Ah) I have around that maintains a 12.7V charge. It seems to work just fine but I wonder what the electrical system thinks of a smaller capacity battery. I'm a mechanical engineer so my "electrical intuition" is highly suspect...but I reasoned that the electrical system would just see it as a normal battery until it's reserve capacity is used up. As long as I don't deplete the reserve capacity it should not matter if it is smaller in size, right?

[andrewclaycomb]

unfortunately the only thing I could get in town today was a regular battery and not an AGM one. If the battery was my problem because of the old reg/rec over charging it, I'm getting another sealed one asap. I'm already tired of making sure electrolyte levels are up. I don't even want to think of acid coming out of the vent tube.

This down time has been good for the bike though. I just cleaned the chain and adjusted it (I'm going to try the advice from the chain facts 101 thread and just clean more often with WD40 and no lube. The chain at least looks better. The old lube was really sticky and everywhere)... and I replaced a leaking oil drain plug gasket.

Even though no riding, it's still a good day.

[bakalorz]

unfortunately the only thing I could get in town today was a regular battery and not an AGM one. If the battery was my problem because of the old reg/rec over charging it, I'm getting another sealed one asap. I'm already tired of making sure electrolyte levels are up. I don't even want to think of acid coming out of the vent tube.

This down time has been good for the bike though. I just cleaned the chain and adjusted it (I'm going to try the advice from the chain facts 101 thread and just clean more often with WD40 and no lube. The chain at least looks better. The old lube was really sticky and everywhere)... and I replaced a leaking oil drain plug gasket.

Even though no riding, it's still a good day.

Don't put in the AGM one till the charging issue is straightened out though.
(other than possibly for brief tests to straighten it out)

The AGM batteries are great in a lot of ways, but if you overcharge them enough to cause gas to vent, you can't put it back in.

With the cheap batteries if the overcharge current is low enough that liquid electrolyte isn't really coming out the vent tube (just oxygen and hydrogen gas bubbles are) then you can use distilled water to replace what you lost, with no real damage done.

[andrewclaycomb]

Well, I just got the new charged battery in the bike and of course she starts right up. I take the bike up to 2500 RPM (exactly 13.5) volts and 5000 RPM (14.1 volts) and everything is within the specs on the stator papers.

And then I just now realized that I did the test with the low beam on.

I always ride with the low beam, almost always city. Am I fine for a while until I can go through and replace all of the old connections and properly go through the stator papers?

Can a low volt reading damage my battery?

[earlfor]

Doing the test with the low beam instead of the high beam on will not matter greatly. Low beam is 55watts and high beam consumption is 60 watts and that isnt enough to be concerned about. The voltages you recorded are fine. My 1150 with a fully charged battery always showed a 55/60mph, cruising down the road voltage on the dash volt meter in the 13.1 to 13.5 range depending on speed. You're good to go, enjoy the ride. :-)

Earl

Well, I just got the new charged battery in the bike and of course she starts right up. I take the bike up to 2500 RPM (exactly 13.5) volts and 5000 RPM (14.1 volts) and everything is within the specs on the stator papers.

And then I just now realized that I did the test with the low beam on.

I always ride with the low beam, almost always city. Am I fine for a while until I can go through and replace all of the old connections and properly go through the stator papers?

Can a low volt reading damage my battery?

[andrewclaycomb]

voltage on the dash volt meter

What kind of voltmeter do you have? I'm thinking it wouldn't be a bad thing to monitor more regularly.

[earlfor]

It was a small black digital readout bar that showed voltage, time and temp.
I think it cost me about $25. It wasnt kuriakin (sp) but similiar. I think it was Brian that had posted the link for them. I'll check my bookmarks etc. to see if I still have the addy.

Earl

What kind of voltmeter do you have? I'm thinking it wouldn't be a bad thing to monitor more regularly.

[earlfor]

Ahhh, here ya go. Digital voltmeter, mounts on bike dash.

http://www.casporttouring.com/store/merchant.mvc?page=CST/PROD/cgid/14124

[andrewclaycomb]

Thanks

I just ordered one

[bakalorz]

Is a battery tender a trickle charger?

hm, depends where you live :-D
yes it is

I started to write something up at lunch on this yesterday, but forgot to take home the stick it was on till today, so here it is better late than never

As chuckycheese said an actual "battery tender" is a brandname and a good one (but $$$ )

Also acceptable would be something called a "float charger". There are various models and manufactureres, and they would all be acceptable.

Not really acceptable is something called a "trickle charger"

So whats the difference ?

They are all mainly meant for storage of charged batteries more than charging discharged batteries, although they all can charge discharged batteries back up (although it may take some of them days)

A trickle charger is the simplest, it puts a low fairly constant current into the battery for as long as it is hooked up. It will slowly bring a discharged battery up to full charge. After that (or if hooked up to an already charged battery) it will slowly overcharge it. Done for a short time, not too often, this causes no real harm. If you periodically do it for a specific recomended time, or measure it with a meter, it can be a marginally ok way to maintain your batteries over the winter. Forget to disconnect it for long enough and you WILL damage the battery.
The hassle and potential danger of this method make it not really worth it.

A float charger is similar, except that once it hits a specific voltage (the "float" voltage, usually 12.8 to 13.2 or so volts, up to 13.6 for AGM ones) it will not go over this voltage, and the charging current will taper down to virtually nothing. You can leave a battery connected to one pretty much indefinately without damage. You can also store a battery off the charger, but periodically connect it to the float charger for a bit if that is more convenient, which works about as well. In that case the charge time is not as critical as it would be with a trickle charger.

There are various other types of chargers typically called one of the following: automatic, manual, bulk, taper, 2-stage, 3-stage, smart, and boost. These are for charging discharged batteries more than maintaining them over the winter, and I'm not going to talk about them here with one exception:

The actual "battery tender' is a combination of a 2 stage charger with a float charger. It will first analyse a battery, then charge it at a constant current till it hits something called the absorption voltage (about 14.4 or so volts from memory), maintain that voltage till the current drops to a certain level (or an internal safety timer times out) and then drop to a float voltage of 13.2 volts from then on.

I'll mention one more specific charger, harbor freight sells a cheap $5 float charger. QA on them seems a bit spotty, and they seem to have various voltage settings. But it is a true float charger and will work well if you get one set to the correct voltage. If you want to buy one, bring a voltmeter, take them out of the bin and plug them in and check the voltage. When you find one set to 13.2 volts, get that one and you are set.

[earlfor]

I was pleased with the one I had. Never a problem with it. It did disagree with my multimeters by about 1/10v, but thats not enough to worry about.

Earl

Thanks

I just ordered one

[psyguy]

that's very informative mr bakalorz!

my "trickle charger" is marketed under a full name "trickle charger with automatic overcharge protection" :-D