Why was my SLA pack better then my LiFePo4 on the hills?

[dnmun]

leave it on the charger until every cell measures at least 3.65V while charging, then you can remove it. it is gonna take a long time because they left no headroom in that charger but the headway BMS is very accurate so eventually i think you can get all of them charged.

may take forever. but they don't allow you adjust your own charger.

[e-beach]

may take forever. but they don't allow you adjust your own charger.

If I do ever get to the point that I want to turn up VR2 on my charger, what is a maximum I should over-volt to, providing the board can do it?

[amberwolf]

I wikied a link to this post
http://www.endless-sphere.com/w/index.p ... ns_Listing
but if anyone is willing to create a full article in the wiki on the modification (or any of hte others linked there), it would be appreciated.

Here is an excerpt from our DIY kit guidelines:

"Modifying the charger:

The charger has an automatic shut-off circuit board integrated in the charger itself. During charging, the BMS will shut-off charging if any cell is being overcharged (greater than 3.85V~3.95V), and once the cell voltage falls below the shut-off (aka recovery voltage) voltage, the BMS will allow charging to resume. Without the modification, when the BMS ‘tells’ the charger to turn off, the charger will turn off, but when the BMS ‘tells’ the charger to resume charging, the charger will remain off and will need to be disconnected from the battery and disconnected from the power source in order to reset itself to resume charging.

Modifying the charger will allow the charger and BMS to work together. The charger will charge, the BMS will ‘tell’ the charger to turn off, the charger will turn off, the BMS will allow the charger to resume charging, and the charger will then turn back on without having to reset it by unplugging from the battery or from the wall or other power source. This will also allow the BMS to properly perform the balancing function.

Remove the top two outside corner screws from the end plates of the charger and remove the top lid. There is a small circuit board that is located near the charger output, the fuse and the LED side. It is perpendicular to the main PCB and is connected with a 5 pin connector. This is what needs to be removed for the mod. The pins can be cut (be sure not to damage any of the other components), or, this is the method that I prefer to use, very carefully wiggle the circuit board back and forth being sure not to cut/wear through the existing wire insulation or from damaging other components and it will break off.

Once this is removed, replace the cover, and screws and the charger is ready to go!"

This is the ONLY modification to the chargers that we allow and still honor the warranty, and as long as no other components were damaged while performing the mod, the warranty will be valid. Any adjustments of the pots will void the warranty.

Haven't opened the charger...Might violate some sort of rule, regulation or policy or something. ...Makes me wonder why the charger was shipped set to 220 volts and the PCB thing is still in the way....

We modify the charger and change the switch from 220Vin to 115Vin when we build the battery pack to ensure the charger and battery pack function together and properly before shipping, unless of course it is going to a country that has a 220V grid, then we leave it at the 220Vin. The modification 'procedure' is sent out with our DIY kits, but that is as far as it goes (went). Other than that, we really do not know how the charger is being used so we leave the charger 'as is' just as it was shipped to us.

Due to your post, we are now sending out this modification with all of our chargers that are over 1S, along with a reminder about checking the correct Vin switch depending on the power grid for chargers greater than 600W. All other chargers have automatic detection. So thank-you for letting us know a better way to assist the customers!

As for the smell on the spacer blocks, that is how we received them from Headway China, so not sure what had happened, but we will do a better job in the future.

I apologize about missing your calls yesterday, large shipments came in and we were pretty tied up with inventory. Great talking with you and walking you through this on the phone this morning.

[Holocene]

Your SLA's climb better because they will put out 5C discharge for a few minutes. With a 12Ahr pack, that's 60 Amps available to your 30 amp controller. You'll only get 5 Ahr's out of them used this way, but you're only climbing at 10% for a minute!

Your Headways are only 1.5 C discharge, maybe even only 1.0 C so with a 15 Ahr pack, you've got max 22 Amps and maybe as little as 15 Amps available to the controller. So no oomph to climb vs. the SLAs.

Solutions? First get a Cycle Analyst. Then consider RC Lipo. It'll give you better than 5 C discharge, and is still lite. Want to buy more Headways? You'd need 30 Ahrs to match the short-term power potential of SLAs. So the weight and expense has creeped up again.

Most people here would say 'Go Lipo'. But it's not your charger or low voltage. It's low C rate.

Cheers,
Holocene

[e-beach]

Your SLA's climb better because they will put out 5C discharge for a few minutes.

5c.....Really!!! That explains a lot though.

Your Headways are only 1.5 C discharge, maybe even only 1.0 C....

I went for a run on that hill this morning and got 2/3 the way up. That is as good as I have gotten so far with this pack so 1.5C is probably a good number.

Solutions? First get a Cycle Analyst.

That is moving up on the list, but at the moment it is not in the budget.

Then consider RC Lipo.

I don't like the flame factor.

Want to buy more Headways? You'd need 30 Ahrs to match the short-term power potential of SLAs. So the weight and expense has creeped up again.

OUCH

Thanks for the info. I ride that hill almost every day. But I am into the Headways for the moment so I will just petal a bit more the I used to. I will make-it-up by just not pedaling at all for the other 20+ miles of the ride.

Cheers,

[e-beach]

Your SLA's climb better because they will put out 5C discharge for a few minutes.

5c.....Really!!! That explains a lot though.

Your Headways are only 1.5 C discharge, maybe even only 1.0 C....

I went for a run on that hill this morning and got 2/3 the way up. That is as good as I have gotten so far with this pack so 1.5C is probably a good number. Although I do pull 30 amps WOT so 2C might be a better number. In any case, the wires from my motor are getting really hot now and they never got that hot with my SLA's

Solutions? First get a Cycle Analyst.

That is moving up on the list, but at the moment it is not in the budget.

Then consider RC Lipo.

I don't like the flame factor.

Want to buy more Headways? You'd need 30 Ahrs to match the short-term power potential of SLAs. So the weight and expense has creeped up again.

OUCH

Thanks for the info. I ride that hill almost every day. But I am into the Headways for the moment so I will just petal a bit more the I used to. I will make-it-up by just not pedaling at all for the other 20+ miles of the ride.

Cheers

[dogman]

Glad to hear you at least got the charger sorted. As for the hills, one good way to improve your ability to climb the really steep ones would be to go to a slower winding motor. Or a big motor with real power.

The price you pay though, is a slower top speed, so think about which is more important. I forget at the moment exactly what motor you have, but 10% is pretty tough on any typical hubmotor unless it's in a 20" wheel. 12% can kill a hubmotor, if you keep going long enough.

You're pedaling some up these hills right? If not, start doing it before you cook your hall sensors or windings.

Meanwhile, you might consider a small blob of solder on your shunt, to give your controller about 5 more amps. The headways should be able to do 30-40 amps, even if they don't like it a lot and sag some.

Oh, duh, it's there in your sig. You have the yescom motor. I believe they are wound a bit on the fast side, so they would suffer a bit on hills unless you really amp up. Maybe get a 40 amp controller next? If your battery bms is cool with that, that is.

[e-beach]

You're pedaling some up these hills right? If not, start doing it before you cook your hall sensors or windings.

In real world riding. The non-pedaling stall tests was just to see what the new pack had in it's guts.

Meanwhile, you might consider a small blob of solder on your shunt, to give your controller about 5 more amps.

That sounds intriguing...got any pictures of that trick?

Maybe get a 40 amp controller next? If your battery bms is cool with that, that is.

The bms should be able t take 40 amps.
This from Heasway-headquarters: Continuous Discharging Current 50~60A.

Anyway it is this one: XJI 36V BMS 12 CELLS 50A/100A
http://stores.headway-headquarters.com/-strse-91/36v-50-fdsh-100a-bms%2C-signalab/Detail.bok?category=BMS%2FPCM%2FPCB

And I may be getting one sooner the later....
I went for the Dodger Stadium run today and something stopped working.
I am going to have to ask for help....again....to sort the new problem out.
Opening a new thread as I write this.