# 90v for Alltrax 7245?



## Stunt Driver (May 14, 2009)

Found at least one EV that uses 7 of 12V battaries for nominal voltage of 84V on 72V Alltrax - http://www.evalbum.com/2712

Anything to fear of here?


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## Coley (Jul 26, 2007)

My 6 X 12v gel batteries show a surface charge of 80+ volts and the 7245 hardly gets warm.

I don't know how well it would perform with 90 volts over time.

That might be pushing it.

You could contact Alltrax and talk to them. They are very helpful on their controllers. They might be able to suggest a programing change.

60volts is getting down there. What are you still having for amps at that voltage? 

I have a hill to climb, when I am just about hiome and I sometimes hit 61 volts and still have 100 amps left just to get up the hill.

At the top, the voltage is 72 and the amps draw is under 50 the last 1/4 mile home. Resting volts before I shut it off is 73.6 to 74.5 (cold weather)


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## blackpanther-st (Apr 4, 2009)

Stuntdriver, the biggest problem I see would be during charging, when your Pac voltage will exceed its max standing voltage by good bit; figure between 14.2-14.6 per 12v battery to reach a good charge rate and that will exceed your 90v limit, so disconnect the controller from the pac during charging; including the precharge resistor. 

Excessive high voltage usually blows the capacitors whether the unit is running or not.


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## EV59RAG (Oct 6, 2008)

Stunt Driver said:


> Found at least one EV that uses 7 of 12V battaries for nominal voltage of 84V on 72V Alltrax - http://www.evalbum.com/2712
> 
> Anything to fear of here?





Let me chime in since 2712 is my car. Yes, I have 7x12 Volts Costco Deep Cycle batteries on my 71 VW. It is being charge by 7xHarbor Freight cheap chargers. It charges up to 14.2-14.5 volts (full charge) then settle down to 12.7 (rested volts) which is 88.9 volts +/-... And it works fine.

Hope this helps.


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## EV59RAG (Oct 6, 2008)

blackpanther-st said:


> Stuntdriver, the biggest problem I see would be during charging, when your Pac voltage will exceed its max standing voltage by good bit; figure between 14.2-14.6 per 12v battery to reach a good charge rate and that will exceed your 90v limit, so disconnect the controller from the pac during charging; including the precharge resistor.
> 
> Excessive high voltage usually blows the capacitors whether the unit is running or not.


In my case... everytime i charge my car, i make sure my keys are off. This means that the contactors are off too... so no voltage on my controller.


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## Renny_D (Apr 21, 2009)

On the ZAP PK it is normal to have a contactor set up that removes one battery from the system so the car can be driven right after it's initial charge. After a mile I kick in the extra battery but the surface charge is gone by then. I am still planning to talking to Alltrax to see if that voltage limit could be changed. I have additional cooling fans to add to the controller. I could post a picture if you are interested.

Thanks
Renny


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## Coley (Jul 26, 2007)

EV59rag, how much does your car weigh?

A friend of mine built a VW like yours and he got 35 mph out of it for over 15 miles with only 48 volts.

It seems to me that you should be hitting 50+ mph with yours.

My Yugo only has an 8 hp motor and it will hit 55 on flat running.

It went 45 with only 48 volts and a 5 hp motor, when I first built it.

A VW is much more aerodynamic than my Yugo.

I thought about adding the seventh as a parallel battery to the pack, but didn't yet.


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## Stunt Driver (May 14, 2009)

Thanks for inputs, I did get to testing myself, adding 3 free starting batteries on top of 4 deep cycle MAXX29. And I use contctor to disconnect those extra 3, as they run out sooner. Ordered mini voltmeters @ $6 each to be installed as a group to monitor individual voltage on batteries.

Controller does shut off and blink red LED if voltage goes above 90v, so if driving right after charge I start off using just 48V core pack, but can connect remaining batts in 1 minute or so. I will keep contoller off when charging, for capacitor's health ofcourse.

Driving does feel much better with 80v under load.  

*Coley* - those are quite impressive numbers you have, which gear would that be in and at what AMPs expense? When I try to push mine to 40 on 48v - I have to shift up and such ALOT of amps. On 60 and below I don't get as many amps, and so as much torgue - accelerating on 2nd at around 20mph will be around 130A. I don't have any hills here, all flat driving, even thou it's called Hillsboro

*Renny_D* - definitely please post pics. As I understand - it is 72 to 12v power supply inside the alltrax that can't handle higher voltage, maybe not even the capacitors. But on mine I don't get any heat during my short 3-4 mile ride.

*EV59RAG* - thanks for jumping in! I am happy my idea is not wild, and people actually do this. Getting those extra 12v really helps from my first experience.


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## Coley (Jul 26, 2007)

Mine will cruise @45 on flat road with less than 90 amps being used.

What I thought about doing is adding the 7th battery and then just use my regular 72volt charger.

It puts 6 batteries up to 84+ volts if you let it go, so what would it charge if 7 were hooked to it?

If they charged to 12.8 or so each, how would that run.

I may try it when I get another battery.


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## poprock (Apr 29, 2010)

Hi, just cruising old posts about controllers and found this. I have set my AXE7245 to 90v and when 7x12v are fully charged it goes to 91-92v. But as soon as the charger is disconnected the settling voltage is approx. 87-88.It will never have over 90v to work with, so it does not exceed the factory setting. The improvement in acceleration with the extra 12v is surprising. But Hey! you probably know all this after three years!


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## epyon (Mar 20, 2008)

What happened to the car ? Does it drive good ?


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## poprock (Apr 29, 2010)

still in progress.see current post..running 72v for licensed electrician inspection 4 rego. see current post


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## epyon (Mar 20, 2008)

EV59RAG , can you have people riding in your car ? does it charge well ? I'm on the fence on a ALLTRAX SPM 72650 an overvolting it too .


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