LCGB Forums

I know that even healthy new batteries will discharge over a period of time if not in use.

My Series 2 with indicators has a 12v SIP battery. The positive terminal has two connectors one for the indicators and the other to the loom. The negative is, of course, just to earth.

I have charged the battery up and I am now getting 12.39 volts showing on a multimeter between the positive and negative. I won’t be using the scooter for the next month, or so. I am planning to just measure the voltage every few days to see how much charge it loses.

Is 12.39 volts acceptable and how much should an unused battery (but one that is wired up on the scooter) lose over the next month?

I usually trickle charge the batteries on my two scooters over alternate weekends.
This is usually sufficient to keep them from dropping too low.

Get a CTEK charger and leave it connected when not using scooter

jonoy wrote:Get a CTEK charger and leave it connected when not using scooter

This one?

https://www.ctek.com/uk/battery-charger ... /xs-0-8-uk

I have been monitoring this battery and the other two Batteries I have on other Lambrettas. This battery was down to 9v in a week, or so, whereas the other two I have have stayed at around 12 or 13v. Given that neither of my other DC battery Lambrettas have indicators, I suspect the indicator system, possibly the flasher unit, is draining it.

I have bought one of the CTEK battery chargers, as recommended by Jonoy. These chargers have a function to analyse the battery itself and whether it is capable of holding charge. It shows that this SIP battery is okay.

So, when this scooter is not in regular use, I’ll continue to keep the CTEK connected.

Storkfoot wrote:I have been monitoring this battery and the other two Batteries I have on other Lambrettas. This battery was down to 9v in a week, or so, whereas the other two I have have stayed at around 12 or 13v. Given that neither of my other DC battery Lambrettas have indicators, I suspect the indicator system, possibly the flasher unit, is draining it.

I have bought one of the CTEK battery chargers, as recommended by Jonoy. These chargers have a function to analyse the battery itself and whether it is capable of holding charge. It shows that this SIP battery is okay.

So, when this scooter is not in regular use, I’ll continue to keep the CTEK connected.

Paul why not wire in an on/off switch for when your not using the scooter I have them on all mine just in case anything causes a drain

I did think of that, Paul. The CTEK has a handy plug in connector which makes it very easy to use. Basically, just take the panel off and plug straight in.

I also think there may be a way of using a multimeter to identify where the drain is actually from

Storkfoot wrote:I did think of that, Paul. The CTEK has a handy plug in connector which makes it very easy to use. Basically, just take the panel off and plug straight in.

I also think there may be a way of using a multimeter to identify where the drain is actually from

The difficulty here is that you'd need to measure very low currents. If you tell me then battery rating in Ah, and the type of battery, agm, lifepo4 etc, I can work out very roughly what the drain current is and whether you could realistically measure with a multimeter.

What sort of meter do you have?

Indicators shouldn't drain the battery unless they've been wired up incorrectly. this can and does happen with some electronic relays.
Suggest putting your multimeter into current measuring mode and connect between your battery earth terminal and chassis. remove your battery earth strap and see what the current draw is with everything switched off.
If you get a reading, then your can start disconnecting things until the current reading drops to zero to determine the cause.

Here is the battery and the setting I used on the Multimeter. I put the red of the multimeter to the negative of the battery (earth cable disconnected) and the black to the earth cable. I kept that connection for a couple of minutes but got no reading. The battery is charged up. Would that affect whether I get a reading, or not?





At some point when I was messing around with the multimeter I did get a reading of “1” between the battery earth and the chassis but when I tried to replicate this later, I got no reading.

Just as a belt and braces excercise...... Move your red lead to the (10Amax) hole and select the 10A scale on the rotary dial.
If you've messed up somehow, then you may have blown the internal fuse inside the multimeter that protects the milliamp/microamp scales (200mA). The 10amp scale has a separate fuse internally.(10A)

The reading of "1" that you got would suggest that you measured a current that exceeded the scale range. When measuring an unknown current always start with the highest scale and then work down from there if necessary to avoid damaging the meter.

OK this is very approximate engineering, but works to explain.

You have 5.5Ah battery that has completely discharged in no more than a week.

A week is 168 hours.
5.5Ah divided by 168hours is 0.0327 or 33mA. If it were losing charge by leakage, then you would see it, especially as the initial current when fully charged would be higher.

Your battery is goosed.

Or your meter is VERY badly calibrated. I've never seen one as bad as that, so I doubt very much if your meter is at fault.

And by the way, F&F is completely correct about fuses. I've been doing this 40 years now and still occasionally blow one.

Posh modern meters warn you, thankfully.

Thanks, both. Much appreciated.

I have blown both fuses (the 10A/250v and the 0.2A/250v ) inside the multimeter I have ordered some more fuses.

The scooter has been off the road whilst I got a fraction more ground off the sliding dog (an ongoing saga ) but it should be back on the road in the next day, or so. Out of curiosity, I’ll then check if the battery charges from a running engine whilst I await the fuses. I suspect it does.

As I clearly shouldn’t be allowed out with a multimeter that confounds me, I’ll then just disconnect the indicator circuit and see if the battery holds its charge then

Before I got new fuses for the Multimeter, I satisfied myself that running the engine does charge the battery. I also disconnected the indicator circuit for a few days and noticed that there was negligible reduction in the voltage from the battery. It stayed around 12.4 volts. This takes me back to suspecting that the flasher unit is the drain, or perhaps the indicator switch (the flasher unit has three connections - earth, switch to activate indicators and battery positive).

Having inserted new fuses, I have today been trying to measure any current drain.

I put the multimeter red to the negative of the battery (using the mA socket) and the multimeter black to the earth connection on the frame, from the battery. I found:

With the flasher unit and indicator switch connected up, I was getting a reading of “2”
If I disconnected the wire that goes to the switch at the flasher unit, the reading was also “2”
At this point, I believe that this is telling me that the drain is not the switch but may be the flasher unit.
If I disconnected the flasher unit entirely, I get no reading.

Am I correct that the flasher unit is the drain please? Also, what does the 2 mA drain tell me?

This is the flasher unit:

https://www.ebay.co.uk/itm/272345319953 ... media=COPY

Surely the relay wouldn’t have any power unless key is on?

L111amo wrote:Surely the relay wouldn’t have any power unless key is on?

Just a cut out switch but, yes, the way I have wired up these “home brew” indicators is to have them as a separate circuit powered by the battery. What I mean is that the battery positive is wired to the flasher unit through a fuse.

Storkfoot wrote:

L111amo wrote:Surely the relay wouldn’t have any power unless key is on?

Just a cut out switch but, yes, the way I have wired up these “home brew” indicators is to have them as a separate circuit powered by the battery. What I mean is that the battery positive is wired to the flasher unit through a fuse.

The way you have it wired, you will have that drain all the time which is why I mentioned that you will need a switch to disconnect auxilary corcuits. Ive had to do it on both of mine as the SIP speedo, Gamma unit take power and would drain the battery if I didnt ride it or a while. 2ma is a very small drain though but 24 hours a day, week on week adds up. you could put an inline switch in the battery feed inside your tool box, gled or even velcro'd to the inside of the door

coaster wrote:

Storkfoot wrote:

L111amo wrote:Surely the relay wouldn’t have any power unless key is on?

Just a cut out switch but, yes, the way I have wired up these “home brew” indicators is to have them as a separate circuit powered by the battery. What I mean is that the battery positive is wired to the flasher unit through a fuse.

The way you have it wired, you will have that drain all the time which is why I mentioned that you will need a switch to disconnect auxilary corcuits. Ive had to do it on both of mine as the SIP speedo, Gamma unit take power and would drain the battery if I didnt ride it or a while. 2ma is a very small drain though but 24 hours a day, week on week adds up. you could put an inline switch in the battery feed inside your tool box, gled or even velcro'd to the inside of the door

Thanks, mate. I know the switch has been mentioned before. I was hoping I wouldn’t have to add any more connections and holes

I’ll see if I can find a small inline switch that’ll fit in the toolbox with some double sided tape.

I fitted one to one of the 4 seat bracket bolt holes, which needed the hole opening up slightly but was hidden yet very accessible.