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by T1 Terry
Tue, 04 Feb 2020, 09:59
Forum: Batteries, charging, management and monitoring
Topic: Repurposing hybrid batteries for a full BEV
Replies: 6
Views: 521

Re: Repurposing hybrid batteries for a full BEV

If you can find a Prius traction battery at a wreckers, it isn't difficult to swap the cells around to increase the capacity while dropping the voltage. But you might be better off getting the cells from Matt because he will know what cells are worth the effort and which cells are just paper weights...
by T1 Terry
Tue, 04 Feb 2020, 09:47
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

 "When the charging is disconnected and a few amp load connected across the cell, how long does it remain above 3.6v? Only a few [edit: tens of] seconds. But, as expected, after I disconnect the load (a headlight bulb) the voltage slowly rises above 3.6 V again." Sounds like a high internal resista...
by T1 Terry
Mon, 03 Feb 2020, 15:34
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

@T1 Terry, It's possible that some old models of the EV Power CMUs started bypassing at a higher voltage, but the present-day specification clearly states that it starts bypassing at 3.5 V. But I agree that the present-day EV Power spec of not turning on the alarm until 4.0 V leaves much to be desi...
by T1 Terry
Mon, 03 Feb 2020, 15:19
Forum: Technical and conversion discussion
Topic: VW T3 syncro conversion
Replies: 7
Views: 643

Re: VW T3 syncro conversion

I guess the other upside is the reduced losses through the various transmissions when only requiring 2WD. Can the front axle be fitted with free wheeling hubs? Can you add a planetary gearset between the motors and diff? That would allow a very low ratio to be selected when 4WD crawling was required...
by T1 Terry
Mon, 03 Feb 2020, 08:51
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

The units I linked to are the same as units I purchased some yrs back from one of the WA suppliers, not sure which at the moment. They most definitely don't start bypassing till the cell reaches 3.8v and stop bypassing at 3.6v. These units shift 5 amps with a cell voltage of 3.8v or higher and the h...
by T1 Terry
Sun, 02 Feb 2020, 11:36
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

"I'll be very surprised if you can find any present-day BMS for LFP cells that bypasses at a voltage higher than 3.6 V. Please post a link to its specification. Otherwise, you're just battling straw men." https://www.ev-power.com.au/product/bms-cbm400/ see the heatsink on the negative terminal? Thes...
by T1 Terry
Sun, 02 Feb 2020, 10:58
Forum: Technical and conversion discussion
Topic: VW T3 syncro conversion
Replies: 7
Views: 643

Re: VW T3 syncro conversion

Have you thought about leaving the original gearbox etc intact and just replacing the ICE motor with a suitable electric motor? I seem to remember reading about someone having done something similar, but it might have been an overseas conversion.

T1 Terry
by T1 Terry
Sun, 02 Feb 2020, 09:18
Forum: Batteries, charging, management and monitoring
Topic: Weber & Coulomb's LyteFyba BMS
Replies: 72
Views: 33168

Re: Weber & Coulomb's LyteFyba BMS

The flurocarbon coolants are extremely expensive and have to be kept in an airtight loop. They absorb water which makes them conductive. I was considering to use them for a cooling loop in a 3kv inverter. After funding out about the problems I decided that air cooling was good enough. Do you know i...
by T1 Terry
Sat, 01 Feb 2020, 14:41
Forum: Batteries, charging, management and monitoring
Topic: Weber & Coulomb's LyteFyba BMS
Replies: 72
Views: 33168

Re: Weber & Coulomb's LyteFyba BMS

"Very interesting. I had to go search. I see they are fluorocarbons which are greenhouse gasses with long atmospheric lifetimes and very high global warming potential, e.g. GWP = 9000. I'd think very hard about whether you can't get away with using air as your coolant. Internal resistance of LTO is ...
by T1 Terry
Sat, 01 Feb 2020, 13:28
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

The test is not to prove if your BMS works or not but rather to verify the heating of the cell and resultant damage at a higher voltage. I'm saying that 3.6v is about the limit before the electrolyte starts to heat up, the electrical energy is converted to heat energy and dissipated through the cell...
by T1 Terry
Sat, 01 Feb 2020, 13:06
Forum: Nissan
Topic: Importing Leaf ZE1 (current) model..
Replies: 32
Views: 2132

Re: Importing Leaf ZE1 (current) model..

What I'm saying is that if a grey import 40 kWh Leaf is still too expensive, you might still be able to get a crashed Japanese one for a fraction of the cost and put its battery into a cheap used 2012 Leaf over here. So the total spend might be $20-25k instead of the nearly $40k you'd pay for a gre...
by T1 Terry
Sat, 01 Feb 2020, 12:09
Forum: Hyundai
Topic: KONA EV tailgate story
Replies: 12
Views: 1022

Re: KONA EV tailgate story

With both our Priuses, it depends where you put your hand as to how solidly the boot lid needs to be shut to put the door open light out. On the Prius, it is the Toyota emblem below the rear wing piece. If the wing itself is used more often than not, the lid doesn't shut properly, yet a firm push cl...
by T1 Terry
Sat, 01 Feb 2020, 11:37
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

Thinking more about this test, is it possible to charge the cell to the 3.41v you suggested to start the "bypass" balancing? I believe you were suggesting holding this voltage until all cells reach the same 3.41v and bypassing and then stop the charging ..... have I understodd that correctly? I'm in...
by T1 Terry
Sat, 01 Feb 2020, 10:51
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

Terry, You sound like you're making excuses as to why you haven't done this experiment yourself. ;) I note that your proposed cell opening, to insert a temperature sensor, would not only require a low temperature, but also zero humidity and no oxygen, if you don't want to damage the cell. But measu...
by T1 Terry
Thu, 30 Jan 2020, 10:15
Forum: Batteries, charging, management and monitoring
Topic: Weber & Coulomb's LyteFyba BMS
Replies: 72
Views: 33168

Re: Weber & Coulomb's LyteFyba BMS

Would these use optic fibre links or wire links? Would it require one board per cell group or a board per cell? The reason I'm asking, I'd like to use LTO cylindrical cells in my VW Kombi conversion and liquid cool them by submerging them with one of the battery coolants coming on the market. T1 Terry
by T1 Terry
Thu, 30 Jan 2020, 09:59
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

"I totally agree that one should not design a cell-top management unit to use the cell terminals as heatsinks for its bypass resistors." At least we can agree on something :lol: The first part of the experiment involves temp sensor placement. Useless on either terminal because that is just a block o...
by T1 Terry
Thu, 30 Jan 2020, 07:31
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

Not sure how many cells you have killed testing your theory, but the collection I have here back up my claim that the internal temperature generation is voltage related, the other affects are secondary. As far as loads, as long as the load does not exceed the ion exchange rate, the voltage will rema...
by T1 Terry
Wed, 29 Jan 2020, 15:04
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

No Terry. Even if my batteries die tomorrow, it won't prove anything about our respective BMSs because there are way too many other variables. I never said there was anything harmful about having 5 amp balancing currents, or the idea of inductive charge shuffling. I just wanted to make sure that ot...
by T1 Terry
Wed, 29 Jan 2020, 09:54
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

There will always be different camps when it comes to cell balancing and BMS systems in general. I guess time will tell who has got it right and who hasn't by the cycle life of the battery packs. We are in the 9th yr now with a number of off grid battery packs and at the 8yr point they still tested ...
by T1 Terry
Tue, 28 Jan 2020, 10:38
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

The induction balancers we use switch off once the cells are within 10mV and don't switch back on until the differential is greater than 100mV. That way they are not a constant load on the battery. We tried small current balancers that did the same thing but the balancing was so slow the cells requi...
by T1 Terry
Mon, 27 Jan 2020, 14:52
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

The resistor type balancers work when the cell reaches X voltage and burns what ever value the resistors used can handle. That method relies on the charge current being reduced to less than the resistor burn off rate plus the load at the time ...... that would require accurate cell voltage monitorin...
by T1 Terry
Mon, 27 Jan 2020, 12:04
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63912

Re: Low cost BMS

Just something to keep in mind when using balance boards for house battery packs, voltage has very little to do with actual SOC in any particular cell. I learnt this the hard way, something I already knew from yrs of doing this stuff but unfortunately it didn't trickle through to my system design le...
by T1 Terry
Tue, 21 Jan 2020, 12:17
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 49104

Re: 4Springs' Brumby

So I read Francisco's comment and tested 2000 grit sandpaper. It takes off a bit of the layer, but not the whole lot: IMG_0366.JPG This was very similar to the scourer that I started out with: IMG_0367.JPG So I switched back to the scourer. The things in T1 Terry's link look quite similar, but onna...
by T1 Terry
Tue, 21 Jan 2020, 10:18
Forum: Charging Infrastructure
Topic: If you wanted to convert WA's roads to electric...
Replies: 4
Views: 627

Re: If you wanted to convert WA's roads to electric...

The old argument that crops up every time on other forums, how do you power these additional EV charging stations? Big solar and battery installs that connect into the grid nearby to stabilise the grid? LNG fuelled fuel cells or gensets to provide the energy into a smaller battery bank, that way the...
by T1 Terry
Thu, 16 Jan 2020, 15:10
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 49104

Re: 4Springs' Brumby

A 3M scotchbrite type pad https://www.ebay.com.au/itm/31Pcs-2-Roloc-Surface-Buffing-Sanding-Disc-Polishing-Pad-With-1-4-Tray-Holder/392296880747?hash=item5b56b75a6b:g:-SEAAOSwU1hc20GI and some kero does a great job of cleaning the cell terminals and links. I prefer to use the thin copper links with ...