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Author Topic: Battery advice  (Read 3129 times)

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Offline Theojw71

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Battery advice
« on: 27, June, 2014 - 21:49:38 »
Hi All,

I'm getting some advice and help from Chas around rewiring my C5 to 24v. At the moment I am running on 12v and a single battery connection.

I think my starting point should be the power source. I currently have two 12v small Halfords HCB063 car batteries (46ah and about 12kg each) - looking on eBay I can see stacks of LifePo4 batteries, but no idea from those which are worth the money (there are major price differences) and what the appropriate matching parameters are.

My plan would likely be one 24v battery and circuit for power, and one 12v battery and circuit for accessories.

I've uprated brakes and gearbox already. I'm looking for genuine range from the 24v one, and light weight and value for money from both.

Can anyone recommend a specific battery model for each (24v, 12v), preferably from your own experience or one you are using now in your own C5? Alternatively, anyone recommend where to go to in the North West or online to get trustworthy advice / purchases?

Offline jockywilson11

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Re: Battery advice
« Reply #1 on: 28, June, 2014 - 18:09:56 »
I'd advise a single 24v lipo battery with a 24v - 12v 5a converter to power the accessories ( eBay for about 20quid). Use the 24v with a controller to run the motor. If you want to use two 12v ones just wire up the accessories to one battery at the 12v centre point.

You'll only need about a 40ah lipo battery to give you the same capacity as the 2 lead acid lumps you have now, due to Pukert's law the new batteries are way better than them. They run on a flatter voltage curve than lead acid ones, so the performance of the motor will be better for longer, you won't slow down too quickly the way lead acid ones do.

Well worth it in the long run.

Offline Theojw71

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Re: Battery advice
« Reply #2 on: 28, June, 2014 - 20:52:33 »
Thanks for answering - I'm really struggling to find a 24v LifePo4 with 30ah - 40ah. Do I need this? (trying to match the spec of the current calcium battery and the original lead acid units for the motor.

There are stacks of 10ah and 5ah units at 24v, but higher Ah rating means only 12v available in most cases.

What's the impact and for lower Ah rating and is there a 'tipping point' or lower threshold I should avoid for LifePos, as I can't tell whether this is very meaningful given (a) the weight saving of LifePo4 over standard batteries and (b) I can't quantify the ampage required for all the kit on my C5 (motor, maybe monitor, indicators, lights, horn, etc.)

Offline Theojw71

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Re: Battery advice
« Reply #3 on: 28, June, 2014 - 20:55:47 »
As an example, I was looking at this from Ping.

http://www.pingbattery.com/servlet/the-6/24v-20ah-lifepo4-lithium/Detail

Will this sort of thing do the job?

Offline jockywilson11

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Re: Battery advice
« Reply #4 on: 29, June, 2014 - 11:35:40 »
Yes it would, but you could get these from a UK supplier, and it comes with a charger. You wouldn't need a 24v - 12v converter then.

http://www.ebay.co.uk/itm/2-x-LITHIUM-12V-20Ah-as-17Ah-18Ah-MOBILITY-SCOOTER-WHEELCHAIR-BATTERIES-/121234459035?pt=UK_Health_Beauty_Mobility_Disability_Medical_ET&hash=item1c3a23099b

Cheers John

Offline jockywilson11

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Re: Battery advice
« Reply #5 on: 29, June, 2014 - 12:20:31 »
On mine I have a combined volt/ammeter and led indicators, and led lights. They pull less than 1amp. I also added a motorcycle horn that switches via a 30 amp relay, an it only pulls 1.5 amp for a few seconds as required. I also have a motorcycle radio on mine for my tunes, and it's not hard on it either. So if you budget for say 40w of power for the accessories you will only need 3.5 amps tops, and that will only be when you have lights, hazards and blowing your horn all at the same time. With the Led lights it normally won't even pull 1amp.

Offline Theojw71

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Re: Battery advice
« Reply #6 on: 29, June, 2014 - 21:20:26 »
Hi John, thanks for responding - so you're suggesting you can use two of these 12v batteries together? - with the 12v accessories running off one of them, and get 24v for the motor - sounds ideal for the money! What other kit do I need to regulate the 12v and 24v elements? I was looking to use the Porter5 or Porter10 controller from 4QD, with the twist throttle.

Offline jockywilson11

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Re: Battery advice
« Reply #7 on: 29, June, 2014 - 22:23:57 »
Yes wire them in series and you'll get 24v.  I believe the Porter 10 is the ones folks are going for now, check with Chas for that. Don't forget to fit a fan on the Motor! Just wire the accessories to the first battery across the 12 v of the first battery in series, and the motor controller across the 24 v.