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Trickle battery charging

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Hi Alan,

Hope you can help with this query!! I own an Atlas which im currently building up and this question may be applicable here also? ,however my question relates to a BSA 650 goldflash ( 1958)

I,m a mechanical not electrical person as you,ll gather!

Question:-, my bike is positive earth, when i attach my trickle charger normally to the battery ie pos to pos neg to neg whilst wired upto the bike the polarity changes? I can tell because the ammeter reads the wrong way round showing charging when the lights are put on etc and not dis-charge, if the battery is taken off the bike and charged normally pos to pos etc then put back on the bike and connected up everything is ok, any ideas????, ( i can,t swop the leads round pos to neg etc as the charger prevents this, probably a daft idea anyway !! lol )

Its a pain to disconnect and take the battery off the bike to charge it thatâs all

Regards

Ian Gibson NOC MEMBER

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How many times have you repeated this Ian? If it just happened once, then there was a good chance that the battery was installed or replaced backwards on one occassion without you realising it. As far as I know your bike has a dynamo? A dynamo's polarity can be changed quite simply by reversing the the static residual magnetism and this cab be accidently done by connecting the battery backwards. Once the dynamo polarity is reversed, it will charge the reversed battery quite normallybut the whole bikes polarity, earth wise, will be reversed too and cause the ammeter to show a reverse delfection, ie: a charge when there is a discharge. I would charge the battery off the bike making sure with a voltmeter set to DCthat the positive terminal from the charger is actually producing a positive voltage. There is just a smallchance that the internal rectifier of the charger has failed and its output is actually AC. Once you have the battery fully chargedcorrectly fit back on the bike. Do not start the engine but check the ammeter discharge movement by switching on the lights. If OK, start the engine a see if the ammeter moves to the right and shows a charge. If it does just leave it alone, all is well. However if the ammeter shows a heavy discharge when the rev rise the dynamo has indeed been reversed polarised. Stop the engine remove the charge control box cover and push down the cutout rocker plate for about 2 seconds. This will correctly repolarise the residual dynamo magnetism to ensure it charges the correct way round.A battery once it has become completely flat can be charged in a reverse direction to create a very small reversed charge but the charge will usually amount to only enough to light a pilot bulb for a few seconds. Overall Ii think it very unlikely you have charged your battery backwards, more likely that you have mistakenly connected it backwards at some time before without realising it as it would have worked that way, as explained earlier.

Les

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Previously wrote:

How many times have you repeated this Ian? If it just happened once, then there was a good chance that the battery was installed or replaced backwards on one occassion without you realising it. As far as I know your bike has a dynamo? A dynamo's polarity can be changed quite simply by reversing the the static residual magnetism and this cab be accidently done by connecting the battery backwards. Once the dynamo polarity is reversed, it will charge the reversed battery quite normallybut the whole bikes polarity, earth wise, will be reversed too and cause the ammeter to show a reverse delfection, ie: a charge when there is a discharge. I would charge the battery off the bike making sure with a voltmeter set to DCthat the positive terminal from the charger is actually producing a positive voltage. There is just a smallchance that the internal rectifier of the charger has failed and its output is actually AC. Once you have the battery fully chargedcorrectly fit back on the bike. Do not start the engine but check the ammeter discharge movement by switching on the lights. If OK, start the engine a see if the ammeter moves to the right and shows a charge. If it does just leave it alone, all is well. However if the ammeter shows a heavy discharge when the rev rise the dynamo has indeed been reversed polarised. Stop the engine remove the charge control box cover and push down the cutout rocker plate for about 2 seconds. This will correctly repolarise the residual dynamo magnetism to ensure it charges the correct way round.A battery once it has become completely flat can be charged in a reverse direction to create a very small reversed charge but the charge will usually amount to only enough to light a pilot bulb for a few seconds. Overall Ii think it very unlikely you have charged your battery backwards, more likely that you have mistakenly connected it backwards at some time before without realising it as it would have worked that way, as explained earlier.

Les

Thanks Les for your reply,

Idont think i worded things very well lol, to cut to the chase and answer the first funamental question, ...if a bike is positive earth and i want to put a permanant connection on the battery for a trickle charger to connect tohow do i wire it up?

Cheers again, Ian

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It should not make any difference - just connect the terminals as you would normally for charging.

I have a Ctek charger with a permanent lead on my commando battery - spares available cheaply from maplin. The charger is superb at keeping the battery in condition without boiling it dry as it switches in and out as the volrage falls and rises.

Ian

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Oh I can see what you were saying now Ian. It depends on what type of connections the charger has. If it's one the modern electronic controlled trickle chargers, they usually come with a lead set that you simply connect permantly to the battery... Always positive (red) to positive you can then leave the flylead in a convenient position for connectionto the reverse sex connector from the charger. They are usually made with a series fuse and holder built in. If you need one you can get them on Ebay.

Otherwiseif you use a conventional charger with crocodile clips you only have to connect the positive crocodile clip to any metal part of the bike (engine or chassis) and the negative to the negative on the battery. By using the bikes earth for the positive connection you cannot get the leads wrong on the battery as it will either charge or not depending if you have the negative lead from the charger on the correct (negative) terminal of the battery, but you will short out the charger (causing a few sparks) if you connect to the wrong battery lead but still better than gettingthem reversed on the battery which will create even bigger sparks and could damage the charger or blow it's fuse.

Of course you could wire up a twin wirelead permantly,connected and colour coded to the battery terminals and have it outside the battery box if that is easier but fit a fuse on it for safety in case of shorts to metalwork on the bike.

What ever way out of the two you choose, you will NOT or SHOULD NOT see any deflection on the ammeter.

Hope this is the answer you wantbut if not fire away again.

Les

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Hi Les thank very much for replying once again, !

The problem was that originally i connected the trickle charger pos to pos ( pos lead off the charger to pos terminal on the battery) neg to neg ( ditto ), but after charging and the leads removed and the bike NOT running the ammeter showed CHARGE with the lights etc switched on, obviously not correct, however when i started the bike everything seemed ok ie the Ammeter read the correct way round showing charge with the lights on when the engine was running?,

With the bike being POS earth i thought i,d maybe connected the charger up the wrong way round , obviously the neg wires on the bike go to the POS side of the battery with it being POS earth so i wondered if i had to connect the charger that way?? I was just concerned i had reversed or damaged something??

The Ammeter appears to be wired up correctly

Sorry if all this sounds double dutch !!

Cheers

Ian

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Hello again Ian. Well if not double dutch, there is one bit I don't understand.

You say: "obviously the neg wires on the bike go to the POS side of the battery with it being POS earth"

So just to make sure here is what you should have:

The POSITIVE TERMINAL on the battery should go straight to the earth frame bolt which is quite nearby.

The NEGATIVE TERMINAL on the battery should have the other wires that come from the regulator or go off to the wiring loom and switch.

When you have it connected this way, you can do a resistance test from the bikes metal work to the battery positive terminal...it should show a dead short.

When you use the charger, it is the same polaries together. That is RED to RED (POS to POS) black to black (NEG to NEG) This stands for ANY charging situation wheteher the battery is ON or OFF the bike.

If you go right back to my first reply, you will see I am saying that you may well have the battery reversedso when the bike is running it overcomes the battery terminal voltage and shows the current flowing correctly as indicated by the ammeter. This would be the ONLY explanation as to why the ammeter is deflecting the wrong way when the engine is not running and the lights are ON. This is now also backed up by the way you have described the manner in which you understand the wiring "should" be which as I have just said is wrong. It would also indicate that your battery is somewhat dodgy and probably has a high internal resistance (not helped by charging incorrectly) It may need replacing quite soon but not to worry at this point in time.

So, Ian make sure you have the battery connected as I have stressed above on lines 4 & 5.

This should get your ammeter to show a normal discharge direction, if not let me know again. We'll get there.

Les

Permalink

Previously wrote:

Hello again Ian. Well if not double dutch, there is one bit I don't understand.

You say: "obviously the neg wires on the bike go to the POS side of the battery with it being POS earth"

So just to make sure here is what you should have:

The POSITIVE TERMINAL on the battery should go straight to the earth frame bolt which is quite nearby.

The NEGATIVE TERMINAL on the battery should have the other wires that come from the regulator or go off to the wiring loom and switch.

When you have it connected this way, you can do a resistance test from the bikes metal work to the battery positive terminal...it should show a dead short.

When you use the charger, it is the same polaries together. That is RED to RED (POS to POS) black to black (NEG to NEG) This stands for ANY charging situation wheteher the battery is ON or OFF the bike.

If you go right back to my first reply, you will see I am saying that you may well have the battery reversedso when the bike is running it overcomes the battery terminal voltage and shows the current flowing correctly as indicated by the ammeter. This would be the ONLY explanation as to why the ammeter is deflecting the wrong way when the engine is not running and the lights are ON. This is now also backed up by the way you have described the manner in which you understand the wiring "should" be which as I have just said is wrong. It would also indicate that your battery is somewhat dodgy and probably has a high internal resistance (not helped by charging incorrectly) It may need replacing quite soon but not to worry at this point in time.

So, Ian make sure you have the battery connected as I have stressed above on lines 4 & 5.

This should get your ammeter to show a normal discharge direction, if not let me know again. We'll get there.

Les

Thanks very much for your time/ pataince and expertise Les, we,re defenetly onto something now !! i did have the bike wired up correctly but some dodgy charging may have gone on in the past lol, i,m going to check everything through, like i said give me something mechanical anyday electrical is all black magic ??!!, many thanks again much appriciated , Ian

 


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