A123 race battery pack Amperage question

[28hodge]

just to lay the scene a little, i am electrically clueless.

so ive managed to buy a couple of A123 battery packs consisting of 4 A123 cells. I've wired these into the battery terminal connections and its starting the bike over starts fine etc, but to be honest the entire arrangement is pretty crude. So now that ive got it all working i m wanting to make it all a bit more user friendly and well neat and tidy really.

So i was thinking i'll get some extra battery cable, anderson connector and wire that in as at the minute ive just got it hooked up by screwing up the battery terminals from the end of the battery pack lead and the battery terminal leads on the existing loom.

Now what amps does the starter motor pull? the main fuse is a 30A fuse so is that all it pulls? if so what thickness battery cable do i want 16mm2 cable wll take 110Amps, can i get away with 10mm2 cable as that will take 85Amps, once i know this then i can get the correct anderson plug to match.

its purely a trackbike so has no ignition which means if i leave the battery all hooked up i think the temp gauge drains the battery so i need to be able to disconnect the battery easily when not in use, i do have all the charging unit in place though so the bike will charge the A123 cells without any issue.

[magg]

You should use the same gauge wire between your the battery pack and the starter motor as the std Honda configuration. Reducing the wire gauge could result in poor cranking and/or damage to the starter motor. The starter motor will draw much more than 30 amps, the 30 amp bike main fuse is not part of the starter motor circuit.

I would not recommend that you leave the std Honda charging circuit connected, from my understanding of A123 batteries, they have a different and quite specific charging requirement. Using the Honda charging system could damage your A123 battery pack. Better to get a charger that matches your A123 batteries and run total loss.

[thunderace]

I assume that this is for your track bike?

You are best running total loss with A123 cells. The bike's charging system is too powerful for LiPo batteries. You'll over-charge and cook them.

[28hodge]

Yeah track bike only, but I thought as long as your charging circuit is working correctly, i.e. your reg/rec is doing its job and its not over charging then the batteries will be fine on the standard charging system. I’m not sure I want to go total loss with it as I don’t really want to buy a charger for these batteries and I’m unsure how to wire them up so that I can connect a charger and a connect to the bike easily.

I’ve had a look at this on loads of RC websites and also the below and they all seem to come back saying that as long as your charging circuit is good then its fine.
http://www.osnpower.com/productID/produ ... 15632.html

I managed to get 2 batteries each with 4 a123 cells in them for £39 from a guy that built them for using in his model aeroplane, they have balancing circuits wired into them they were sent with full charge and fully balanced. They are supposed to be pretty resilient so I’m hoping that they will last better than a ytx7 battery.

I ideally want to just match the existing battery cables but they aint marked with anything to tell me what size they are I’m thinking the 16mm2 cable should be man enough to deal with the amps and I’ll use a 175Amp Anderson connector.

The Anderson plugs that are rated at 175amp seem to be made to be used with 16mm2 cable so that should be ok I think, unless someone knows better, as like I say I’m a bit clueless electrically.

[thunderace]

If they have balance circuits fitted then they should be OK as these will restrict the current flow into the batteries. 16mm cable will be fine

[28hodge]

Nice one, 16mm2 wire and 175amp Anderson plug ordered, got friday off so I'll get it all together and finished off then.

The connection between the individual cells is only done in thin gauge wire, it's got 14awg written on it, should I change that too to some thicker wire, struggling to track down some battery bars!