one for the electrical guru's

[MickYork]

Just fitted my second battery on a full dc conversion. The last battery lasted a full season but after not using the scoot for a few months I found the battery flat. On checking the battery there was no volts what-so-ever. I put this down to frost getting into the battery. I fitted my new Exide wet battery 2 weeks ago but last week I inadvertently left the ignition on. I have a GPS with back light wired in and this will have drained the battery. Sure enough the battery was completely flat with no sign of life at all. I disconnected the battery and put it on charge, but the charger couldn't "see" the battery. I checked with my meter and there are no volts at all.....zero.....nothing. it's as if the battery is open circuit.

I'm a sparky by trade so have a decent idea about electrics and the failure of both batteries is puzzling me. Don't think i'm putting too much volts in as I've no lights blowing, but why have both batteries gone open circuit ? Could the vibrations be shaking something loose in the battery ? anyone else had a similar problem.

All ideas and suggestions welcome

[Warkton Tornado No.1]

I am no guru of any kind, but had a similar issue with a dead motorbike battery that wouldn’t take a charge via an Optimate. It lives in a very cold garage so likely to encounter frost, if that can be an issue with sulphuric acid....

Taking the “kill or cure” approach, I connected the most powerful old school charger I had & blitzed it, then put it back on the Optimate.

I then deliberately looked away for a few days. Bizarrely, it took the charge & showed up as being healthy, though I’ve yet to use it to start the bike.

I have no idea why this appears to have been a cure.

[St George]

I had similar issues with my Ninja and Bandit. The modern batteries don't like being stored in freezing conditions. Now I hook up to an Oximiser all year round. Perhaps the new battery was in a cold warehouse. Just a thought. Gell batteries don't seem to have the same issues.

[MickYork]

Yeah I could have killed the first one with frost but the "new" one is the puzzle, only a couple of weeks and it's buggered. It seems draining it completely has killed it. saying that I've took WT1's advice and stuck it on an old charger......it could be flat batteries don't work on the newer, cleverer, chargers.

[Phil D]

I've had exactly the same experience with a few bike batteries in the past.
I put it down to the new type trickle charger doesn't seem to sense that it's even connected if that makes sense .

I have a backup old type charger which sorts them out with a kick up @r23.

(That's just a theory and may have absolutely no basis in electrical facts)

[MickYork]

Looks like it's sorted

As suggested by WT1 and others I connected an old, under a £10, charger to the battery for half an hour............I've just gone back and measured 12v on the battery so tried the all singing all dancing £50 + charger and it's away charging.........just hope it holds the charge.

Thanks to all for input.

[Watfordwhite]

If a battery is really dead, it will require a deep cycle charge to get it going again. Yes cold kills batteries. As will a constant small drain to zero.
New chargers will as you say not even see the battery if it's really low. The best thing to do is trickle charge it for 24 hours. Check the electrolyte levels and let the battery breath (remove any plugs/tops on the battery) while charging. Always charge in a ventilated area. Only use distilled water to top up. (Unless gell type)
Disconnect the battery if the bike / scooter is unused or stored in cold conditions for a while.
Disconnect the battery earth as well as this will promote rust if being stored for a while.

[MK Monty]

Look at what is draining it. I use the burglar alarm ones and have killed one by leaving the ignition switch in parking position. A new battery was cheaper than a new charger. Every load needs to be on the switched side of the ignition switch. Try using the black rear light feed. It's on in all positions once you turn on your lights, most of the others are on in some key positions and off in others. I did a mates who had a cam lam low petrol led and he was concerned if he put it away with low fuel the led would be on all the time. My special was Sorned last year and was only started a few times in that time but the battery was fine. My series one has the EGT and digital speedo wired this way, a blank speedo tells me to turn on my lights that in itself is a good thing.

[grandpa]

Hi Mick york
I always fit a battery isolator switch, plenty of places to put one where you can reach in underneath to switch every thing off.The vibrations dont appear to affect the battery (yuasa standard 12v 5amp motor cycle battery with acid)
Grandpa

[Fast n Furious]

Mick...
As mentioned above it looks as if you have something amiss causing your battery to drain its charge.
When constant voltage leadacid batteries are discharged so there is nothing left, then their internal resistance rises so high that the regular charge voltage struggles to charge it.
You can overcome this by using a variable DC power supply to temporarily force charge with a higher than normal voltage to over come the resistance and get the battery to pull current.
You have to be careful though and monitor the current as it will suddenly start to charge as its internal resistance decreases, then pull the voltage back down to circa 13.5v to control the charge current
Too much voltage can create an explosive situation if your not careful.
PM me if you need a hand.

[MickYork]

Thanks for all the advice but I think i'm ok. I've put a main switch (where the choke is) to switch off all the electrics for the battery. I forgot to turn it off when I last used it and my GPS and fuel gauge drained the battery, causing the battery problem, which is now up and working.

Thanks again for the advice