irrotational Posted July 4, 2017 Share Posted July 4, 2017 Hi, feeling a bit naughty as I haven't posted in BC for ages and my question isn't even Caterham related I bought, second-hand, a kids elctric quad bike. We've used it, and importantly charged it, a few times...but the charge never seems to last that long and it always seemed a bit low on power.I've looked at the electrics and they seemed to have been modified along the way.Before launching into the details the basic question is, is the charger connecting up to the batteries properly to charge both of them?So there are 2, 10 volt batteries, each with a live and neutral. There are 4 wires from them, via a keyed-connector block, into the main harness for the bike (which presumably takes the power to the motor(s). The connector block has one sticking out pin and three sockets so it can only be connected up one way. This all makes sense to me so far.The charger only has two wires/pins and is rated as 12V output. As it was supplied, one pin connects to the live of one battery and the neutral of the other battery. There's no other connection between the batteries when charging.I've connected it up as it was, and I get 17V!? across the charging connection. I can only think this is basically the charger, and one battery, acting to charge the other!?So assuming this is wrong - what should I do to fix it? I'm assuming the simplest way is to charge each battery in turn. I.e. connect the two wires from the charger to the two wires from one battery...once charged then disconnect and conect to the other battery?Is there a simple way to alter the charger connection so it can charge both batteries at once? or is this impossible because the charger wont have enough voltage (and amperage!?) to charge both at once.Any advice (or sarcastic mocking) gratefully recieved! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 4, 2017 Member Share Posted July 4, 2017 Welcome back.The charger only has two wires/pins and is rated as 12V output. As it was supplied, one pin connects to the live of one battery and the neutral of the other battery. There's no other connection between the batteries when charging. Do you disconnect the connector block in order to charge the batteries? And how do you then connect the charger? Are you sure that's the right charger? Do you have a manual for the bike? If not what model is it? What voltage do you get at the switch that turns the motor on, with the charger disconnected?Jonathan Link to comment Share on other sites More sharing options...
irrotational Posted July 4, 2017 Author Share Posted July 4, 2017 Hi JK!1. The bike/motor loom has a connector block, as do the batteries, and the charger. To charge the batteries you disconnect the bike half of the connector block and connect the charger half of the connector block.2. Yes - well it was the one supplied with the bike. The connector blocks/plugs are hard black plastic with either 3 sticking out pins, or 3 sockets, and the fourth wire has the opposite (so it's a socket if the other 3 are pins or a pin if the other 3 are sockets). It's an unusual connector (for me) and the only ones we have.3. Good question - i'll quickly google and come back.4. Don't know and not sure i can test easily as all the bike wiring and switching is buried in the bike.The voltages across the batteries are 4.8v and 6v currently - and they stay at this voltage even with the charge connected. They may well be goosed - I'm assuming the weird charging setup has broken at least one of them.If I connect the charger to just one battery, as i would expect, then I get 8.5V across the charging connection, and the same voltage across the battery terminals, as I might expect (although I thought it ought to be 12V but I don't know if the charger does a stepped voltage charge or something). Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 4, 2017 Member Share Posted July 4, 2017 Can you also get a type number or some other ID for the batteries?4. Don't know and not sure i can test easily as all the bike wiring and switching is buried in the bike.As a proxy for that what's the voltage across the connector when connected in bike mode rather than charging mode?...I'm wondering if swapping the connectors allows the batteries to be charged in parallel and drive the motor in series... and something has been incorrectly modified...Jonathan Link to comment Share on other sites More sharing options...
irrotational Posted July 4, 2017 Author Share Posted July 4, 2017 I've made a photo of the wires and tried to annotate it as best i can. The connector blocks are not there any more as I had to take them off and replace them with basic ones. The pins in the connector blocks had broken, which is why I started looking closely at the wiring.https://goo.gl/photos/huV3XQjnujPmsprc7I checked and double checked all the connections before hand. The charger was definitely connecting to the black battery wire, and the white battery wire. The charger wires themselves are both black, so I put green tape around the charger wire and all the white wires. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 4, 2017 Member Share Posted July 4, 2017 But your Google version has a neat zoom facility.Jonathan Link to comment Share on other sites More sharing options...
irrotational Posted July 4, 2017 Author Share Posted July 4, 2017 Thanks for embedding the photo!!Some additional info:-There are two motors with two sets of wires going down to them, so I don't think the batteries are meant to be connected in serial. I think this is why there are 4 wires on the main bike loom.It's the wires to the batteries that look like they have been modified, so i wonder if some kind of parralell connection existed between them originally to facilitate the double charging.I'm quite happy o charge one battery at a time if that is the easiest/safest thing to do.There are a couple of serial numbers on the bike itself but these don't turn up any hits in google unfortunately. Link to comment Share on other sites More sharing options...
irrotational Posted July 4, 2017 Author Share Posted July 4, 2017 Been thinking about it some more. In summary I think the batteries need to be completely separate to drive the wheels (two sets of wiring and two motors are present on the bike) but I would need them to be wired in parralell to charge from one charger (i.e. not doubling the voltage if they were in serial).I can't see any easy way to do this so I think I'll just charge each battery separately in turn.Actually..I think I could put in a bridge between the batteries, i.e. connect positive to positive and negative to negative. I'd then have one battery "bank" driving two motors, and the charger would then be connecting to the positive side of one half of the bank and the negative side on the other half of the bank. Link to comment Share on other sites More sharing options...
Brian27 Posted July 4, 2017 Share Posted July 4, 2017 HiIf you say the batteries are marked up at 10v then you need to check the voltage rating of the motors. With the batteries connected in series (as they appear) you would get 20v total. My guess is that the motors are 10v rated therefore the batteries should be connected in parallel giving 10v output. A 12v charger would be correct for charging both batteries but again connected in parallel.+ on battery 1 to + on battery 2 to + on charger- on battery 1 to - on battery 2 to - on charger.Hope this helps. Link to comment Share on other sites More sharing options...
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