charging an old battery

Hi all, thanks ahead of time for any information provided.

I recently bought an old 1980 kz550, there are a couple things wrong with it, but i think i got a pretty good deal. I need to charge the old battery, although i have ridden it over 40 miles, i stopped riding it for about 2 weeks and the battery went dead. does that mean i need a new battery?

also if i were to charge the battery by running the engine, do i have to run it at high speeds? or just high rpm? or even at a high rpm?

thanks again!

Battery could be old and weak anyways so unless you know it's history or how old this battery is, may be time for a new one but first.....

You could have a partial short where it was draining the battery slightly over the 2 week time duration... Anopther example, 3rd party clock or some goofy setup that constantly is draining the battery under load conditions... Just examples all, not saying this is the case...

Then there the charging system, get out your service manual (if you don't have one buy one ), get out your volt meter, again buy one if needed, Home Depot, Lowes, ACE hardware.... Hell even radio shack sells them for next to nothing... Or if you have Harbor Freight, get their automotive DVM with tach and dwell included in it....

Then read/research & follow the manual for the charging system... Best advice any of us can give you at this point....

Then there's it could just be a loose or corroded ground connection where it's draining the battery but not charging while running....

OMR

another tip.

but a battery tender its basically a trickle charger i keep the old girl plugged in all the time,
this help because of the short trips and low rpm battery never recovers from start.

second buy some battery top up fluid keep it out of reach of little ppl and check your levels every few mths.

Bike batteries dont last very long. My last one lived for 4 years which by all accounts was excellent. As it neared the end of it's life it would lose charge until eventually after riding and charging then the next day it would hardly have enough power to tunr the engine over.

When charging by riding I dont think it matters anything over about 4,000rpm.

If you think there might be a drain on the battery then I think this is the way - let an electrical expert confirm this first. Disconnect the positive cable from the battery. Connect a multimeter between the cable and the battery terminal and see if you get a reading . Otr if you dont have a meter get a 12 volt bulb and rig some wires to the bulb with crocodile clips on each end - something to protect you from a shock - and connect one to the cable and on to the battery and see if the bulb lights. This should indicate a drain.

Use plain distilled water(the kind used in stem irons) as a replacement fluid. Most if not all batteries need water not more acid to replenish the charging medium.

If you don't know how old the battery is, it probably needs a new one. Can you contact the previous owner to ask when he bought it? They don't last as long as car batteries. Check Sears when you shop around, you might find one on sale. Ed

mine was 50 and is now off the list of problems(churn...churn...churn...nothing)and on to new ones....

it was 70 at one shop and 50 at another 5 miles away....go figure,,,,

makes difference....the po said it was a newer battery ...it lasted me four months...got the 50 dollar one and am into a year and a half 0 troubles.....

best 50 i ever spent.......cours there was that one time in fallon nevada....oh well....