Adding a second battery to a Giant Twist Lite.

[Grandad]

Inspired by Flecc and using information garnered from his site I have added another battery to my bike.
Just tested it tonight and it works well.
I have started describing the modification on my site if anyone fancies a peep. At the moment the Salisbury battery is sitting in my saddlebag.

Awaiting your comments.

 

[flecc]

A very neat and efficient arrangement Grandad, well done.

If you intend this page to remain on your site, I'd like to publish the page link to it on my Twist site, credited to you and with your permission of course, providing another source of permanent information on the Twist.

Please let me know if I have your permission and how you'd like it to be credited, with your online, real, or other name, using PMs if necessary.

Thanks.

 

[nigel]

Nigel

Hi grandad well done thats very clever do you know how much extra weight it will be with a second battery NIGEL.

 

[Grandad]

Permission granted.

Yes I will be keeping that site going and will keep the info. on there but I may be adding to it as time goes by.

Keeping my identity anonymous is ok by me at the moment.

Would you like a return link to your site?

 

[flecc]

Thanks Grandad.

Yes, a return link would be welcome, the more widespread the information availability, the better. Here's my Twist site link:

index
.

 

[flecc]

P.S. to the above.

I've made the addition to my site and here's the link to the tips page Grandad.
.

 

[Grandad]

Hi grandad well done thats very clever do you know how much extra weight it will be with a second battery NIGEL.

Nigel
I have just weighed the battery and it shows 4kg but I think it's a bit less than that. It doesn't seem to affect the balance of the bike (I have a load of junk in the other pannier).

I have updated my site again and you can see how I have fitted the battery into the pannier and cable connection.

 

[flecc]

A tip Grandad. Have a look at the brass posts of a 13 amp plug. They're roughly the right dimensions for the Powacycle battery contacts and have screw terminal ends for the wiring. It may be possible to work from a section of the plug, but if the spacing is wrong, you could just insert the posts separately and use some silicone sealant rubber to mould a housing around them to create a flexible plug head.

I think David Henshaw, editor of A to B magazine will be interested in seeing your modification to two batteries, it's an area he's dabbled in as a committed Twist enthusiast. Here's the email address if you don't have it:

atob@onetel.com
.

 

[Grandad]

Flecc
I did try 13A plug pins but they are too thick. (Like me )
This American plug pin is a perfect fit but the two pins need twisting around 90deg.

I was going to smear a release agent around the battery socket, break a plug apart and mould silicone rubber around them whilst they are plugged in.

Anyone else got any ideas?

 

[flecc]

I knew the 13 amp ones were on the thick side but wondered if they could be ground or filed a bit thinner. I'd looked at re-using the empty powacycle case that i have, but like you, couldn't think of any appropriate plug in blades at the time.
.

 

[Grandad]

I knew the 13 amp ones were on the thick side but wondered if they could be ground or filed a bit thinner.

Sorry flecc, I misunderstood your message. might try that.

If someone had a scrap Salisbury bike the connector off that would be ideal.

After a Google I came up with this plug, two of the pins are oriented the right way but haven't found a supplier yet.

NEMA 6-15 Plug


I would prefer something that didn't look too Heath Robinsonish.

 

[Trawlerman]

Q: I know it's late but why bother with the relay? Would it not be better to just add in the second battery and wire it in parallel with the first one?

 

[Baboonking]

Q: Would it not be better to just add in the second battery and wire it in parallel with the first one?

I sometimes use (discharge) my nimh batteries packs in parallel. It has quite a few advantages over pack switching. Such as:

1 a slight increase in speed (maybe 1 or 2 mph) due to lower voltage sag,
2 more than twice the range of 2 separate packs as batteries have more capacity when discharged slowly.
3 Increased cycle life - discharging at a lower rate reduces battery ageing.

The important weaknesses of such a setup is to have a system whereby no battery can be charged with any other in parallel. Charging nimh in parallel can damage them. Perhaps this is why the relay was added?

 

[ITSPETEINIT]

Nema 6-15 plug

Sorry flecc, I misunderstood your message. might try that.

If someone had a scrap Salisbury bike the connector off that would be ideal.

After a Google I came up with this plug, two of the pins are oriented the right way but haven't found a supplier yet.

NEMA 6-15 Plug


I would prefer something that didn't look too Heath Robinsonish.

I looked on the 'net - loaded nema 6-15 plug into google dialogue box got a big choice of suppliers, mostly American.
There was a British supplier:
IDC Plugs - Standards

It looks like the one you want is Japanese.
Good luck
Peter

 

[ITSPETEINIT]

Sorreeeee! Not Japanese!!

I looked on the 'net - loaded nema 6-15 plug into google dialogue box got a big choice of suppliers, mostly American.
There was a British supplier:
IDC Plugs - Standards

It looks like the one you want is Japanese.
Good luck
Peter

Sorry! that should have been
IDC Plugs - Standards
under North American.
pETER

 

[Grandad]

Trawlerman & Baboonking

Thanks for your views. The reason I decided on an isolating, changeover relay is because I am using two very dissimilar batteries.

On the Twist:
NIMH 24V 6.5 Ah, Panasonic 15 months old.

The Salisibury battery:
MIMH 24v 8Ah, Brand new, unknown make.

In my humble opinion it would be dodgy to connect these two batteries in parallel as I feel that the differences would induce a circulating current when off load. On load I would be unsure (unless two ammeters are used) of the current supplied from each battery and therefore the percentages of the remaining power in each battery. Also I do not feel the need for more power and extra current might reduce the motor life

As you use matched batteries and you are not experiencing any problems that is a different kettle of fish.

Peter thanks for that information, I'll follow it up.

 

[Grandad]

I have improved the battery connection, less wobbly, much tighter and the battery requires no alterations.

Your comments are welcome.

 

[flecc]

Neat job Grandad, and obviously a more adequate connection possible. Being raw copper they may need an occasional surface clean of course, though the "bite" of the battery connectors may do that automatically.
.

 

[nigel]

Nigel

Hi grandad
just wondered if you had got round to doing any trial runs yet with 2 batterys in place would like to know what kind of distance you will get and how the twistlite will cope with the extra weight keep up the good work NIGEL

 

[Grandad]

Hi grandad
just wondered if you had got round to doing any trial runs yet with 2 batterys in place would like to know what kind of distance you will get and how the twistlite will cope with the extra weight keep up the good work NIGEL

Nigel
I can't at the moment give any definitive results yet as, when I have been able to use the bike we have had variable weather, high winds, rain hail and sun.

Here are some observations however:

Weight wise, first of all I put the battery in a saddlebag up on end and although when riding no difference was noticed when off the bike and maneuvering it felt a bit awkward and top heavy.

With my new copper strip battery connectors, I was able to lay the battery flat at the bottom of the bag and, as it lowered the centre of gravity, it felt easier to handle.

The new battery seems to give only about 70% of the capacity of the Giant one at the moment but that should improve after a few more charge/discharge cycles. Starting the journeys I use the new battery, returning on the old one.

I have not cut the cable to length yet, it's 2.2M, and so it would be feasible to mount a spare battery in a trailer. I should however get a lower voltage drop when I do shorten it.

I must admit to be pleased with the system, when the batteries are switched over its like switching on the reserve tank on a motorbike.

The next part of the mod is to design, construct and attach a sub rack beneath the saddlebag attached to the pannier rack.

The saga continues.

I’ll bet you wished that you hadn't asked now!