Two batteries?

[Dave_the_B]

Hello there, long time lurker only second time poster here.
I have treated my wife to another battery for her rather lovely 8fun pedelec bike and need some advice as to what is a safe way to use both on a ride please.
The original is a 36v 9Ah and the new one is 36v 15Ah; I have spent rather a lot of time searching this forum and have come to the conclusion that parallel connecting them is not for the thing to do rather using one until it flat then swapping over to the other....cheap, safe and easy..all things I like.
Now here's the bit I really need the advice on: would it be safe to use a DPDT on-off-on toggle switch to switch between the two batteries? I have been looking at using one of these:
http://www.maplin.co.uk/p/10a-toggle-switch-dpdt-f-jk30h
Many thanks Dave

P.S. Silly/how long is a piece of string question: we get 25 to 30 miles from the 9Ah battery so (you know what is coming next) how much farther do you think the 15Ah would go on the same power setting/terrain
Massive post..really sorry, thank you for reading

 

[Nealh]

50 -60 miles ?

 

[Deleted member 4366]

If you want to use two batteries, it would be much better to physically disconnect one before connecting another. The toggle switch is not really rated high enough. You need one of about 20A or more, ideally.

If I were to do it, I'd have the two batteries mounted in different positions. I'd then find the existing wires from the battery to the controller, cut them and extend them out to where I could add a pair of Deans connectors. Put a long enough piece of wire and a Deans on the other battery, then you can swap them easily without having to move anything. The female connector should always be on the battery side. You could also make/buy an optional "M" lead to connect them in parallel when you wanted.

 

[Dave_the_B]

Thanks for the reply d8veh, that solution ticks all the boxes; cheap,safe and easy thank you.

 

[Dave_the_B]

Hello, all done and working
D8veh I did exactly as you said only I used Kettle connectors because that is what is on the new battery.
New battery on top with controller cable plugged in, extended cable with female connector from the old battery on the right at the bottom
Huge thank you for your help
Dave

 

[SteveRuss]

Hello, all done and working
D8veh I did exactly as you said only I used Kettle connectors because that is what is on the new battery.View attachment 11171
New battery on top with controller cable plugged in, extended cable with female connector from the old battery on the right at the bottom
Huge thank you for your help
Dave

If it was me, i'd use an IEC (kettle lead) retainer on an e-bike. All that movement may wiggle it free, or at least to a point where it may start shorting.

Sometimes IECs hold in quite firmly. Others can be quite loose in my experience.

http://www.ebay.co.uk/itm/like/120682972159?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&rlsatarget=&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108

 

[Cyclezee]

Here is an example of a dual battery setup on my old Mk1 eZee Forza. They can be run independently or together.

 

[Deus]

Were those batteries different capacities John?

 

[Cyclezee]

Were those batteries different capacities John?

Hi Deus,

From memory they were both the older 14Ah.

The capacities have changed since then, the VP's are now 11,15, 21 and 28Ah, the FP's are 11 and 15Ah.

Of course any eZee VP battery will fit any eZee bike.

A customer has placed an order for a new eZee bike with dual batteries, 28Ah and 15Ah giving a total capacity of 1,548 Wh.

 

[Deus]

Thanks for that John what happens when the lower capacity battery drains to zero ?

 

[Cyclezee]

Thanks for that John what happens when the lower capacity battery drains to zero ?

The lower capacity battery will shutdown, you will still get power from the larger one.

 

[Dave_the_B]

If it was me, i'd use an IEC (kettle lead) retainer on an e-bike. All that movement may wiggle it free, or at least to a point where it may start shorting.

Sometimes IECs hold in quite firmly. Others can be quite loose in my experience.

http://www.ebay.co.uk/itm/like/120682972159?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&rlsatarget=&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108

Thank you, I didn't even know these existed.
I have followed the link and ordered one
Top work thank you again

 

[SteveRuss]

Hi Deus,

From memory they were both the older 14Ah.

The capacities have changed since then, the VP's are now 11,15, 21 and 28Ah, the FP's are 11 and 15Ah.

Of course any eZee VP battery will fit any eZee bike.

A customer has placed an order for a new eZee bike with dual batteries, 28Ah and 15Ah giving a total capacity of 1,548 Wh.

Sounds like he's trying to make for the border after yesterdays election results That's going to give an amazing range..