jps
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| posted on 4/12/15 at 11:54 AM |
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DIY battery charger for sons 'electric car'..?
Thought there may be someone on here who can lend some advice, my electrical/electronics knowledge goes only as far as Hornby railways and replacing
the odd domestic plug socket /etc...
My father-in-law dragged an electric toy car out of a skip for my son, He's got it working by taking a battery out of the electric bike he
had.
its like one of these things
Originally it was fitted with 2 x 6v battery cells - wired in series (so that's effectively created 1x 12v battery then?).
It's now working with a 1 x 12v battery from the electric bike.
The bike uses 3 batteries in total - and they are charged in situ in the bike-(i'm assuming the bike runs at 36v and so the charger for the bike
can't be connected straight to the single battery that's now in the car).
So we'd like to figure out what voltage/current to apply to the single cell battery in the car - to charge it in place. Hopefully by hacking the
plug off an existing charger/power supply and just attaching some crocodile clips...
But how do I work out what current/voltage etc I need to be putting into the battery?!
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gremlin1234
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| posted on 4/12/15 at 12:07 PM |
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short answer,
presuming they are lead acid batteries, any standard 12v charger should work
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JAG
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| posted on 4/12/15 at 12:10 PM |
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We need more details of the battery - a picture or a description etc.... but different types of battery require different types of chargers.
IF you get it wrong there's a chance off destroying the battery 
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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nick205
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| posted on 4/12/15 at 12:35 PM |
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Lead acid batteries and Lithium batteries need specific charger types to charge properly and avoid damage.
Some more battery spec would be useful if you have it?
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MikeRJ
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| posted on 4/12/15 at 01:17 PM |
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Electric bikes most often use lithium ion batteries, which require very specific and accurate current limited charging voltage. Overcharging lithium
cobalt cells (the type most commonly found) presents a serious fire risk, so please don't bodge some random power supply onto it.
If it's a sealed lead acid cell (unusual for electric bike) then a small (~3 amp) car charger could get the job done, though ideally a automatic
maintenance type charger would be best.
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BenB
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| posted on 4/12/15 at 03:15 PM |
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Something like an Imax B6 charger would do the job nicely but you'ld still need to know what setting to put it on  As said you really
don't want to get it wrong. Lithium battery fires (particularly chunky ones from electric bikes) can get rapidly out of control.
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Canada EH!
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| posted on 4/12/15 at 03:30 PM |
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Lithium batteries are not to be (toyed) with. I fly electric r/c aircraft which use these batteries.
When I looked into a fire extinguisher for these batteries I was told a small one as would be in a race car was $750.00 Cdn or roughly 480.00 GBP.
They burn and supply there own oxygen so are near impossible to extinguish.
As the local fire Captain told me "think about that the next time you leave your cell phone or laptop on the bed to charge".
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jps
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| posted on 4/12/15 at 03:52 PM |
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I'll get some pics up when I can - from memory there is a bit of info printed on the batteries.. Cheers guys - i was vaguely aware that
batteries should be approached with some care!
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Fatgadget
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| posted on 5/12/15 at 03:00 PM |
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quote:
It's now working with a 1 x 12v battery from the electric bike.
The bike uses 3 batteries in total - and they are charged in situ in the bike-(i'm assuming the bike runs at 36v and so the charger for the bike
can't be connected straight to the single battery that's now in the car
I work on leccy bikes and what you got is an oldie.That is a SLA gel battery.Its not lion.
I recommend you get an iMax B6 charger.Its versatile and charges all common battery chemistries .And its cheap.iMAX B6 Charger
Professional Digital RC Lipo NiMh Battery Balance Charger UK ...They require an external 12V> power supply.Your car battery will do!You can
also get them with a built in psu for more dosh.Beware though,some of them are knock offs!
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jps
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| posted on 5/12/15 at 06:14 PM |
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ok, it's marked up as a 'sealed lead-acid' battery, with the following printed on it:
Constant voltage charge, voltage regulation (20c)
Standby use: 13.5-13.8 volts
Cycle use: 14.5-15.0 volts
Initial current:4.5a MAX
CSB battery EVH 12150 F2
12v 15Ah
[Edited on 5/12/15 by jps]
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