[QUOTE=timo;15481]Thanks so much for your detailed reply, (which I just found as I went through my email–it was a busy week…). It’s a pleasure–and very reassuring–to have the benefit of your experience and insights!
I’m excited about the new CALBs too…just got them and they’re still sitting in boxes in my garage, so not sure about the fit yet. I hope to find time to pull out the NG1 & the old LAs this week so I’ll keep you posted.[/QUOTE]No problem. I’m excited to have another lithium powered GEM running around somewhere (yours will make a total of three LiFePo4 powerd GEMs that I’m aware of, not including Jack R’s which he only put together temporarily as a test.)
It may take some time to get the NG1 reprogrammed. It took them over 2 weeks to get mine back to me. For a month or so, I left the LA batteries installed and charged them individually with a standard 40 Amp car battery charger.
Just jumper together the two wires that have spade connectors that lead to the NG1 (these wires just hook into the AUX relay on the NG1, and inhibit the GEM from operating while charging). The GEM will then function without the charger being installed.
I do plan to bottom-balance (no BMS), but I’m still exploring exactly how best to do it (in the car, on the workbench…?). It sounds like the process is pretty manual so I’m looking at getting a PowerLab 6 or 8 ( revolectrix . com ) on Jack’s recommendation, as a way to get it done efficiently and this device looks useful for monitoring/documenting/analyzing charge etc as well.
If you are willing to spend the money, why not get a PowerLab! I’m cheap, so I just used big fat 300 Watt 0.05 Ohm resistor to do the bulk discharging manually on each cell. I watched the first one really closely, but after that I knew about how long I had until I needed to disconnect it for the other cells. Good thing I never forgot. IIRC, took me about a day to do each cell. Then went back over all of them again in the final day. Worked well enough for me, but a PowerLab would be neat to own, and certainly makes the job easier.
I particularly appreciate your insights on charge profiles & process with the NG1 & on working with Elcon. The charger algorithm profiles Elcon sent me to choose among look very different than the graphic of what they installed on your NG1. Per your suggestion I will look for an algorithm that tops at 3.5V and then tweak. (btw, I had no idea I could tweak the NG1 post programming.
Elcon originally sent me very different graphics as well. I think what you are probably seeing is Encon profiles. They will then select something from their stock Zivan profiles that is close to what you choose.
The Elcon chargers have a lot more flexibility on what settings they can adjust. With the Zivan profiles, they can only choose the value for I1 and U1. The rest of the values are locked to a ratio of those values, depending on the profile. For example, in the profile in my NG1, I2 is always 32% of whatever I1 is adjusted to, and U2 is always 92.9% of what U1 is set at. Why not just let use choose from all the stock Zivian profiles? I don’t know why, but they don’t like disclosing them. They are much more open to sharing the elcon profiles.
Elcon will give you something close enough to work with, but it will need tweaking to be right, especially if you are bottom balancing (I wouldn’t let Elcon know that, btw.)
Is there a Zivan manual out there that details this process? The manual I found on the Zivan site doesn’t address this feature.) Once I get my NG1 reprogrammed, I’ll need to assess what they’ve actually installed and locate the current/voltage potentiometers. I’ll look forward to comparing notes with you on this.
I am still wondering about max charging current on the NG1: is it actually 14 amps (as your charging profile graphic indicates) or can it go higher? It seems desirable to maximize charging amps in order to minimize charging time, and Jack believes this won’t have a negative impact on the cells.
Btw, How long does it take to fully charge your 160Ah cells from 80% discharge (I expect my 100Ah charging time will likely be a bit less…)? Also, what sort of range are you getting with the 160s? I’m excited to see what I can do with my new CALBs here on the hills of San Francisco…
It’s not in the manual, because you’re not supposed to be in there touching anything.
Yeah, I get 14 Amps out of the NG1 with voltage trimmed to 85 volts (1200 watts-- 20% higher than stock.) I drilled a hole in the case so I could adjust the trim pots without having to remove the charger from the car (but I still have to take off the top half of the dash.) I’ve been running at 14 Amps for a year without a problem, and it gets 100-110 degF out here in the summer, so the charger seems to be fine with it. I have blown the internal fuse inside a Kill-a-watt meter (after using it without issue for some months), so it must be drawing a peak power very close to what a 15 amp 120VAC socket can provide (1800 watts).
While charging, I adjusted the current trim pot until current would not further increase. Don’t keep turning the trim pot past the point where the current stops rising, as the charger seems to act strangely in that case. Also, watch out when you have the NG1 open-- the metal parts are live with 120 VAC! That’s anther good reason to drill the hole for access.
Don’t worry about charging your cells too fast with your NG1. Your cells are rated at 1C quick charge, and C/4 for standard charging. Your puny NG1 is practically a trickle charge! The 35-40 Amps available from the NG3 would be a better charger for someone using most of the pack capacity each day.
Regarding your question on how long it takes to charge: I generally don’t take my batteries down that far, but I do from time to time. From 80% DoD it takes probably around 12 hours. Longer than I would like, but that’s a lot of driving to get the pack that low.
And about my range? IIRC, I’m averaging about 145 watt-hours/mile. So with 11.5KW-h available in my pack down to 90% depth of discharge, I have a range of about 80 miles.
Do you currently drive your GEM on those insane SF hills? Do you have the stock 5HP motor on your GEM? No problem with overheating, or too slow going uphill, or too fast going down? With those hills, you want to max out the pack voltage by using all 25 cells. A 9HP motor upgrade could make sense (unlike most that get them just for extra speed.) Reprogramming the controller might also help with performance and tweaking the regen settings might be a good idea while you’re at it. I can’t think of a more challenging city for any EV.
And thx for the heads-up on the replacement chip. Sounds ideal, if it’ll work. By the time I’m ready to try it, perhaps you’ll have gotten yours to work. (fyi their site says they now only sell in lots of 10 minimum.)
Interesting. Maybe ask them to place you on a waiting list until they get another nine people interested?
Once I get the system up & fine tuned, I’m hoping to include some 12v power for a sound system, seat heat and some LED lighting. Still researching whether to go with a DC/DC step down transformer, or to install a completely separate 12V system, (to prevent parasitic loads from unevenly discharging my main power pack). Any thoughts would be appreciated!
The current 12V DC/DC converter used for the lighting is already sized to handle a stereo. And everything you listed, except perhaps the seat heating.
For the seat heating, I’d probably use the full pack voltage along with
Flexwatt heat tape under the seat/backrest fabric. You could probably use a standard light dimmer switch to control the temp. Might need one of the newer electronic versions, that a compatible with LED and CFL bulbs. Then you need a solid state relay or contactor to turn it on/off.
Here are some other links I have regarding heating (talking about heating battery boxes, but same basic idea.)
Underfloor Heating | Radiant Ceiling Heat | Radiant Heating
Buy Flex Watt Heat Tape for Less
Battery Box Design - DIY Electric Car Forums
Oh yeah, have you thought about what you are going to do about a fuel gauge? The built-in SoC meter will always read full charge with the lithium pack. If you need a suggestion, I’d point you to the high current version of the Cycle Analyst with the 0.5 Ohm shunt. For under $150, you can’t beat the features. I think it could be mounted right on the top of the instrument pod, maybe using the two screws that hold the left/right halves together. Or as you plan on adding a stereo, right above the stereo would be another good location.
Good luck, and we want pictures, or it didn’t happen!