My 2004 Electra Rat Fink ebike conversion

[Rafalicious]

Hi everyone,

Thought I'd finally join this forum after seeing the great community helping each other out, apologies as I am a bit of a newbie to ebike world, but am enjoying it so much when it works, it really suits the cruiser style of bike and has been immense fun to ride.

I have an Electra Rat Fink from 2004, I bought one of those 48V 1000W front wheel electric conversion kits and sourced a small 48V 9AH battery from eBay, this battery used to take me about 8-10 miles on one charge but has since become damaged and only took me 5< miles so I ended up selling it. (The blue battery in the photos is my old battery)

I then bought three Silverfish batteries in one go from a seller on eBay, they are 48V 12AH, these have a funny female style kettle lead connector and a key activated ignition, I assumed that if I cut the XT60 connector going from my controller to the battery and soldered on a male kettle connector, this would provide the vital connection, unfortunately it hasn't. There are connectors on the bottom of the battery, maybe this is where I need to attach my controller to?

I have attached some photos of my bike and batteries, do I need one of these to get it working? https://www.ebay.co.uk/itm/43-E-BIK...771946?hash=item4d762758ea:g:5EsAAOSwzHRbK2Ve

Any help, advice or guidance would be most helpful, I'm in limbo about whether to sell these Silverfish batteries on on eBay and buying another simple XT60 connector battery, I would ideally like to get them working.

Many thanks,
Raphael Daniels

 

[harryS]

I then bought three Silverfish batteries in one go from a seller on eBay, they are 48V 12AH, these have a funny female style kettle lead connector and a key activated ignition, I assumed that if I cut the XT60 connector going from my controller to the battery and soldered on a male kettle connector, this would provide the vital connection, unfortunately it hasn't. There are connectors on the bottom of the battery, maybe this is where I need to attach my controller to?

I have attached some photos of my bike and batteries, do I need one of these to get it working? https://www.ebay.co.uk/itm/43-E-BIK...771946?hash=item4d762758ea:g:5EsAAOSwzHRbK2Ve

Yes. The connector on the side is for charging. Didn't the chargers have that 3 terminal plug? Only two are used to charge the plug. WHile many batteries can power a bike thru the charge connector, apparently yours cannot. In any case, it's not safe to do that since you are bypassing the protection circuits on the discharge.

RIght. The power outlets on a silverfish are on the bottom. I suppose that connector you listed will work. Instead, you can just bring an XT60 out from the battery. connect it to the same points where the two prongs on the bottom are wired to keep the battery safety circuits working.. Verify positive/negative when you wire it up.

 

[Rafalicious]

Hi HarryS,

Thank you so much for getting back to me. There are two connectors on the side of these batteries, one is kettle and one is 3-pin XLR. The 3-pin XLR is for charging, I received some chargers with these batteries which utilise the 3-pin XLR. I don't know what the kettle is for, I assumed it was where you plugged in the controller and where power came out of the battery.

"Instead, you can just bring an XT60 out from the battery. connect it to the same points where the two prongs on the bottom are wired to keep the battery safety circuits working"
I don't fully understand this. So is this suggesting trying something instead of trying that connector I listed? I am not sure about "battery safety circuits" or how to verify positive or negative either.

I must add that I did try connecting one of these batteries to my controller via the home made male kettle connector as shown in the photos. When I plugged it into the middle battery (- +) nothing happened. I tried one of the others (+ -) and nearly melted the plug. The battery itself seems fine though and is displaying a full charge on the LED indicator on the top. It was at this point I gave up and thought I would ask someone who knows what they are doing.

Many thanks again for advising this hapless individual.
Raphael Daniels

 

[harryS]

Raphael, I was wrong then. Those are batteries with side discharge ports, and should run the bike.

Now let me me ask how you got three batteries with different positive and negative assignments?

Your markings or the battery maker's label?

I assume you have a voltmeter? Plug it into the terminals and verify what it really is.

Some of these batteries will simply shut them selves off if they are connected backwards first and you turn the key on. On the other hand, if you turn the key on first and then try to hook them up backwards, you get the big spark and maybe worse things happening. Don't know what you did, but the case where you melted the plug is probably where you had the battery turned on before you made the connections.

I have a little battery that I also keep in a bag and the connector is too big. So I attached an XT plug to the output plug,

 

[sc00ter]

Interesting. I offered to convert my wife's Rat Fink (same as yours, the steel frame model) with a SWYTCH kit. She said no because it would to hard to slow down with just a foot brake.

 

[Rafalicious]

Hi HarryS,

I saw them listed on eBay and thought I'd take a punt, the guy had three for sale so I bit the bullet and bought all three, theory being that if I couldn't get them working I would just sell them on.
Indeed, curious how there's kettle on the side and more ports on the bottom, I assumed the bottom was for a dock charger or something along those lines.

I didn't actually realise the polarities were slightly different until I tried to get them working. They aren't my markings so I'd imagine they are from the battery maker (or whoever has messed around with it?)
Unfortunately I don't have a volt meter or a multi meter, I really need to invest in one!

@sc00ter Hi there,

Good decision on her part, it's a bike capable of about 30mph and with only a coaster brake to slow down, you certainly have to anticipate what's coming and not take risks! I am considering a set of forks with compatibility to carry a disc brake caliper, seeing as the electric wheel can mount a disc.

I've already crashed a couple of times but am being a lot more careful. Picking up another Fink this weekend, a decision made partly due to damage from crashing my old one (bent the frame, it's still solid it sprang back to it's normal geo after my crash, now have a bent metal panel bit and a dent where the frame bent backwards, the "bow" of the top tube actually helped absorb the impact and then spring back into normal shape, my local bike shop told me.)

Many thanks to you both,
Raphael Daniels

 

[harryS]

You're working blind w/o a meter. Get one.

 

[Rafalicious]

I am indeed. Any recommendations on a particular model?

Just came across this build, I'm not a fan of the perspex covering, I do like the welded on disc brake tabs though and would like to do the same myself.

Electra Rat Fink with Mac hub

My latest build is for a friend who has given up smoking two stroke oil after riding my Giant NRS electric bike and seeing the light. http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=17330 This one is going to be based on an older steel cruiser frame by Electra, they now use aluminium...

www.endless-sphere.com