Battery Died

[Ozmadman]

Hi Paul. The following battery spec table might be useful. See what type your bike was originally fitted with and go for something similar. A little bit smaller should be no problem unless you do lots of around town riding at night (probably unlikely for most classic bikes?). A little bit bigger than standard (say a couple of Ah bigger) is good if it will physically fit if you ride at night. However significantly larger than standard batteries should be avoided as the charging system will have a job to keep them fully charged which is bad for the battery's chemistry (unless you hook the battery up to a maintenance charger after every ride).

Alternatively just shove in whatever fits so long as it's the right voltage!

James

thanks Paul

[Les Howard]

I'm pleased that your battery has responded, but be careful with the extended charge make sure you charge it on the lowest setting otherwise it will gas off much of the electrolyte and worse still heat up and distort the plates which will wreck it.. You might find that over a repeated discharge/recharge cycles it might gain a bit more capacity and this might do. If your charger does not register more than 90% full by late tonight, just accept that for now, it is indicative of the plates are somewhat sulphated....(which can be treated.)..Next test is to see if it holds a charge for a few days so see how it goes....Les

[SideValve]

Inspired by this thread I thought I ought to charge my battery (4 year old Yuasa B49-6). So, in the dark, I removed the side panel & connected red to red, black to black and switched on. Check an hour later, dead as a dodo. 0v
I'd forgotten that for reasons lost in time I'd fitted the cables red to - black to +
Swap the clips round and try again, next morning and all is well with the world - started 2nd kick.
Very pleased / surprised it survived my stupidity - I guess it shows how rarely I have to charge it.

1st job when its not freezing outside is swap those cables over.....

[Les Howard]

I bet the reason you confused the polarity is because your bike has a positive earth!

The old wiring method would have had a BLACK cable from the POSITIVE battery terminal going to the earth on the frame and probably a Brown from the NEGATIVE as the live side going away to the ammeter etc. All VERY confusing and I've made the same mistake myself when connecting the charger....I would leave the wiring the same but wrap a good many turns of red plastic tape on the POSITIVE wire at the battery terminal and Black tape on the other wire from the NEGATIVE battery terminal...and stick some red tape on the battery near the + terminal too....this should help in future....Les

[iansoady]

I must admit I've wired a couple of bikes negative earth as everything else I work on is that way round and it just seems more intuitive (yes I know electrons go the other way). Negative earth was common pre- about 1955.

[boyd]

Just wondering...what happens if you put them the wrong way around?

[Les Howard]

Just wondering...what happens if you put them the wrong way around?

I'm assuming you mean connecting the battery the wrong way round?
If you have an alternator system the rectifier would probably burn out in a second or two and also the ammeter with just a chance of frying the alternator too unless you had a line fuse incorporated...... If its a dynamo charged system, probably nothing but it wouldn't charge until you "flashed" the dynamo to re-energise the field coil in the opposite direction to create the negative earth voltage delivery...you would need to swap the ammeter wires over too so it read the correct way....Les