Vectrix Range Extender Battery Ideas

UPDATE May 6, 2008: Due to lack of interest and unability to verify if this is a practical approach, I DO NOT RECOMMEND ANYONE DO ANYTHING DISCUSSED HERE! At a future time if more Vectrix owners are interested in extending their range, then they may find this information at least a starting point. BUT, the diagram below is WRONG per the information provided by Mik in this thread: Vectrix Warranty Voided

Note: I do not own a Vectrix. I have not, nor do I intend to carry out any modifications on one. This is just a very rough idea, and I'm not sure if it will work at all! This thread may be deleted upon scrutiny of Vectrix owners.

WARNING: Carry out any modifications at YOUR OWN RISK! I take no responsibility for personal injury or damage to property. Please understand the conditions of your Vectrix warranty. If they find that you've done any sort of modifications or even adding a battery for extending the range, than this may be grounds for voiding the warranty. It is probably not advisable to post any modifications, as this would be documentation to void your warranty, and anything posted may be saved under google cache! You can of course post any questions or PM me of any modifications done.

Please review these Safety Guidelines for High Voltage and/or Line Powered Equipment

It is advisable to carry a small automotive fire extinguisher with you on the Vectrix after doing this.

I think Vectrix should not be inflating their range specs, AND they should be offering a range extender battery option. This would be trivial for them to do.

An auxiliary pack could be constructed and connected in parallel with the stock battery pack. It could be housed in saddle bags. It would probably need to be fan-cooled during charging. I understand that the main pack has an Anderson SB connector (please let me know if I'm wrong). A 2 to 1 connector can be constructed with 3 SB connector sets to wire an extra 125v battery in parallel with the stock pack. This would result in no modifications to the existing connector, and it could be removed in theory without a trace.

In the drawing, Stock battery -> A1 connector
Aux. battery -> A2
A3 -> battery input

It is highly advisable to measure the stock battery voltage to be sure that you have the main positive and main negative through the right connector.

The stock battery pack is listed as 125v. I believe it may consist of 104 NiMH cells, but I'm not sure on this. In any case, connecting a 104-cell battery pack in parallel may cause a small amount of current to flow. It must not be connected while charging! The aux battery should also be fused for safety with a 125 amp fuse. The auxiliary battery will need to be disconnected and charged separately after a ride.

For the range added calculation, I took the stock battery pack nominal energy: 3744 whrs * .9 (usable energy) divided by 20 miles (worst case range energy usage) = 168.5 whrs. Then I did the above divided by 25 miles (Mik's range) = 134.8. The low number is the additional range calculation based on Erik's reported range. The high number is the additional range calculation based on Mik's reported range. The added battery nominal energy was multiplied by .9 to obtain roughly the usable energy.

Here's some of my potential battery ideas with the required chargers. These can all be drained at a high rate of discharge. I don't recommend the cheap chinese D cells even though they appear to have a lot of capacity for the money because of their high internal resistance. And they are a big expense to waste if the cells are junk.

For 2.53 to 3.17 miles:
18 6-cell 7.2v 3.8ah battery packs from All-battery. 17 of these would be used, and the 18th would be gutted removing just two cells for a total of 104 cells in the pack. This would cost between $500 and $600 including the chargers necessary. 5-pack sections could be charged with 3 of these chargers: 36v smart charger. The last 2 and 1/3 pack could be charged with this charger. This pack would need to be fan cooled during charging. And, it would probably be a good idea to let it cool after riding if it is hot before charging.

For 6 to 7.5 miles:
104 Saft D Cells wired in various sized models that would be charged independently. The cells could be taken to a battery specialist to have tabs welded on, and they could also construct the models (at cost). The smaller the module the batter (or fewer number of cells charged in series), but obviously there is a practical limit because you can only fit so many chargers. It also reduced the potential losses if one charger fails and destroys a portion of the battery pack. It is The cost for the cells would be $2025 with 4 extra cells. Here's a listing of chargers, make sure and select NiMH smart chargers that have both -dV cutoff AND temperature sensing. They all should charge at the same rate. If they can't be, than you will need to wait until each module is fully charged before using it (which is always a good idea anyway). This pack will need to be fan cooled during charging, and it would be a good idea to let it cool after riding.

For 9.3 to 11.7 miles:
104 Saft F Cells again wired in various sized modules that would need to be charged independently. These cells could again be taken to a battery specialist/distributor to have them weld tabs on. The cell cost would be $3,078 with a few spares. Check above for a listing of chargers that can be used, and again make sure the chargers you select have BOTH -dV cutoff and temperature sensing. Again, this pack would need fan cooling.

There are also some chargers listed here: Powerstream, but again remember the criteria I posted above. The smaller the module size for charging the better, and make sure they are special NiMH smart chargers that have both -dV (negative drop in voltage) cutoff, and temperature sensing.

And some more here: All-battery.

The various modules could have modular anderson Powerpole connectors to each. This way, a large connector could be constructed with connectors to each modules + and -. A ride connector could be inserted to wire all of the modules in series and have the main positive and negative come out to connect to the Aux battery connector out. The charge connector could have a connector constructed of each chargers output to mate with each battery module to make it easy. Also, the charge connector may need an extra pin for the temperature sensor to each module.

Another thing: the smaller the module size, the easier it is to find and remove a bad cell. The model with the bad cell could be located by doing a load test on each module. If using the 7.2v RC car packs, than the 7.2v pack with the bad cell can quickly and easily be replaced.

Please help me correct any inaccuracies in this post. If there's a good reason why this idea won't work than this thread will be deleted.