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Re: (ET) Junker E15 sort of back in service



NiCD cells. The E15 has 30 BB600 30ah cells, the E20 has up to 120 cells in 4 strings (with the battery box).

The stock charger can get up to 43-44 volts which is a bit less than the 1.5 vpc you should take the Bb600's to. So I perpetually slightly undercharge. And it is kind of recommended to charge them at C rates, so a 30a charger is kind of on the edge.

What I *could* do is dig out a Magnecharger port and controller, and try charging with that. I'm not sure though if they can charge as low as 45 volts, maybe. But it is the ultimate in smart charging: 6.6kw charge rate, 7 stages of constant voltage or constant current charge modes, with cool down times, trickle charging, and 10 temperature sensors you can use to either compensate the charge rate, switch to another mode, or shut down if thermal runaway happens.

I do have 30a 240 volts at the shed so I could use a bigger charger.

Hm.

On 10/29/2023 5:53 PM, Darryl McMahon wrote:
100 amps at 42 volts is 4.2 kW.  Allowing for conversion losses and AC 80% of circuit rating practice (NEC 220-2), you're looking at over 5 kW supply for that charger.  That's getting into the range of a Level 2 EVSE.

So, not for a regular wall plug, but more like a range or electric clothes dryer or central air conditioner circuit.

The OEM Elec-Trak battery boiler charger isn't my favourite for a bunch of reasons, and keeping them operational is well down the list.

Are you charging lead-acid or NiCd in that tractor?

Darryl

On 2023-10-29 5:12 p.m., Chris Zach via Elec-trak wrote:
Well, after a fair amount of work, removing the clunker contactor (which would not close), bypassing 2A to 1a to get me into speed3, and a final push to fix the junk charger the E15 is operational-ish again.

Biggest challenge is the charger: It's just too much of a pain to try and charge the 36 volt pack with a 12 volt smart charger (30a). It takes all day, and is a real pain to hook up. So I needed a 36 volt charger. Which really doesn't exist in the 30a range that the Elec-trak's charger runs. Guess it's the way the world works, but even the Lester chargers are only 20a. To be honest I need 100a or so to properly charge the E20, might just have to build my own charger for this.

But in the meantime I still had that wrecked one I pulled out of the E20: One of the diodes was bad and the whole thing is just an ugly mess. So it sat by the woodpile all summer, I dragged it out of the weeds, cleaned it up, and installed a really nice 4 diode plate from a 12 volt 150 amp manual Sears charger that died. They had wired 4 diodes into the transformer, I'm guessing they were doing a parallel pair of 12 volt center tapped windings to save wire or something. Regardless I put them in parallel pairs of two and hooked them up to the charger core. The center tap is negative, the lug on the diode heat sink is positive.

Wired it into the timer circuit, plugged it in (from a distance) and got the 42 volt DC open circuit voltage. Put it in the E15, and now I have a nice solid little charger. Will check the timer in an hour to make sure it's moving/turns off the charge.

So. The E15 runs. Not well but it does run. Speaking of which if your tractor is ever stuck you *can* make it go by jumpering the left side control lug of the top left contactor (L) to +36 volts. Note that's the little bolts on the front, not the big one on the side. That should get the tractor moving, put it in speed 1 so you have field current, jumper and drive it back to your work shed.

C



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