battery question

[Bill Conquest]

Hi - I have an odysee battery in my '79 R65 that seems to go flat lately if I don't ride for a few days. How can I test the battery? After charging it puts out 12.75 volts for awhile... checked the charging system on the bike & get 13.85 when up to 3500 rpm. I've disconnected the neg on the bike to see if I have a leak of some kind... I put the meter in series from the neg lead to the ground bolt & got .33 volts, does this mean anything?Thanks & sorry for my lack of elec. knowledge!
bill conquest

[Rob Valdez 79 R65]

How old is the battery?

For the current test you are attempting, you want to put the VOM on 'Amperes'.  If it shows current flow with the ignition switch off, you have a drain (short) somewhere.

What is the voltage on the battery when it seems flat but BEFORE you charge it?

How are you charging it?  I use a 10 amp car battery charger on mine, for about 30 minutes or so.
These batteries like a high charge rate.

[Bob_Roller]

The AGM batteries need a high charge rate to bring them back up to a full state of charge after being discharged down to a low level, if you still have the owners manual, they give you the recommended charge rates in there .

You need to fully charge the battery before you do an alternator output test, the engine speed should be around 4500 rpm, as the charging system doesn't really start charging until 3500 rpm.

If you're just taking the bike on short trips in city riding, the battery really isn't getting charged .

[Barry]

AGM batteries are supposed to have very low self discharge rates so if your battery is fully charged it should not go flat quickly.

To test a batteries state of charge with a voltmeter under no load you have to take into account that when a battery has just been charged or the bike ridden the battery will have what is called a "surface charge" which will give give you a higher voltage reading  than normal usually 13  - 14 volts but the figure is meaningless as regards to the batteries condition.

It's best to wait overnight at least to allow the surface charge to dissipate and then the voltage reading will give a better indication. A good fully charged wet cell battery should read 12.6  - 12.65 volts and an AGM 12.75 - 12.8 volts.  Once the voltage has stabilised it should then not fall over a few days if the battery is good.

A reading of 12 volts for either type of battery means it's almost flat and already being damaged by sulfation if stored in this condition.

Measuring 0.33 volts across a connected ground lead suggests a bad connection unless a very high current was flowing. I assume you must have got this figure with the engine running or you should not have found any voltage drop at all.

If you put a meter in series with a disconnected ground lead then you want to be measuring current not voltage. Depending on whether you have a clock or alarm system which continuously draws current then you should read almost nothing a few mA at most or it suggests that there is a fault somewhere which will flatten the battery.

[Bill Conquest]

Thanks for the info everyone - The battery is about 6 yrs. old... I just tested it after 2 days of no riding with the neg battery lead off & got 12.74 volts. Also put the meter on amps( whoops, had it on volts before) and got a zero reading when bridging between the neg. lead & the ground bolt. I have probably not been charging it right... I thought it needed a trickle type charge. My charger is 2 or 6 amps - guess it should be 6 amps, is my charger too weak? I'll reconnect the lead & see if it goes flat & test it again. Most of my rides here are short - it's a small island. Are gel batteries a good replacement?
Thanks again, bill conquest

[Bob_Roller]

The AGM batteries are a good choice over the 'flooded' serviceable type .

No concern about checking the electrolyte levels in the cells, no acid leakage .

Six years is pretty good service life for a battery, here in Phoenix it's a rarity to get a battery to last that long .

[Rob Valdez 79 R65]

Yeah Bill, use the 6 amp setting on your charger.

And I would say 6 years is doing pretty well, and you should start saving for a replacement, if you want another Odyssey.  They are over $100, now.

When you are cruising around, don't be afraid to keep it at 4000 rpm or more.  I consider anything less to be the "dead zone", both for charging and best acceleration.

[Barry]

12.74 volts is a good result after 2 days. Maybe it will last longer yet with a regular top up charge.

When I do my 7.5 mile round trip commute every day during the week I still need a top up charge at weekend unless I'm going to do a decent run. I'm just off out now to do 60 miles so I haven't bothered this weekend.

[Bill Conquest]

Thanks again everyone - I think it's probably time for a new odyssey...any suggestions as to a good place to have one sent in from( not available around here)? I'm definately going to keep the revs up higher & charge on week-ends, too.
thanks, bill conquest

[Bob_Roller]

Do an online search, there are a lot of suppliers that sell them .

I have one of these in my oilhead, and just ordered two more for my '81 and the '82 LS last week, both batteries quit their 'day job' the same  weekend .
 
http://www.staabbattery.com/product/UB12220-V.html

[Rob Valdez 79 R65]

You can't beat Staab's price with an Odyssey any day, I don't think.

I found one place for $105...
and the best on eBay was $120.

I suspect Odyssey of marketing their name, these days.

[Bob_Roller]

I suspect Odyssey of marketing their name, these days.  

I think you're right Rob, my first Odyssey battery was $60US, I can't justify some of the prices that I see these days for one !!!!!!!

I guess it's like Snap-On Tools, at one time they were top of line, now they've got a lot of competition with lower prices with just as good of quality .

[Barry]

I suspect Odyssey of marketing their name, these days.

In the UK they are £85 or about $140. I'm not likely to pay that price when I get get a wet cell for £33 which with care and maintenance should last at least half as long.

It's the with care and maintenance bit which is a disadvantage I suppose.

[Rob Valdez 79 R65]

I grew tired of the constant corrosion & rust on the frame near the battery vent.

That, and I seem to tip over more often than I really should.

An AGM type battery cures all of that - well, except for the tipping over.  

[donbmw]

This summer I needed a battery for my R90/6. Knowing that this battery was a size that you would have to order I got a ETX16L from Orely's Auto It is a sealed AGM battery. It is a little smaller that the orginial battery no cranking issue on the R90. I have since need to replace the battery on my R65 have installed the same battery in this. I have been using the a 16CLB with a little mod to the bottom of the battery tray and add a spacer for the battery to set on. This ETX16L is a smaller and fits in the battery tray.

Don