SLA->Li upgrade options? Celllog 8S on SLA?

Background: I've been running my lashout (600w MAC +rear chain drive) on SLAs for a bit over two months. Two 12v12AH in series came with it; so I don't know their full history.
I use it only uphill, my commute is +300ft and .8 to 1.5 miles depending on the route I take. A few days I run to the local shopping center on the way home, total trip 6miles -- battery never makes that trip LVC cutoff happens before I get home. I also had a problem with my lashout gear (after it came loose while riding.. I just bolted it back on but it was making grinding noises and really ate the battery (I've repacked the gears). The SLAs sit at work uncharged, at at least 5 times I drained them to LVC, including twice when bike was left on and drained them while sitting. I've about 65 charge cycles so far (sometimes 2 a day if I go home midday). I've started feeling the voltage sag compared to when I first got them and its going to start to cool down which will sap the SLA even more. (I'm not bringing them inside, they will stay in the garage at home and outside at school).

Question 1: I was thinking of quantifying the sag.. (I'm a geek).. will a Cell Log 8S work okay for that -- it seems like it can measure pack voltage. I really wanted something that could also measure current draw (but don't want to spend too much on it but happy to consider other solutions.) Also hoping to reuse this if I build a pack as 7 or 8 s will be what I need voltage wise.

Question 2: Would desulfating help extended them enough to justify the expense of the desulfator?

Question 3: Been looking at lithium. I posted about some military batteries before but found out I'm supported to return them to the government and don't really think I can push to 30v base (33 high after charge). The controller is sealed into the motor so I cannot check it out, but I did find some old post saying that the HVC is 30v. So I'll want to design to stay below that.

Question 3: So I'm look at building something of my own now but don't want to do much more that $150 (or my wife will object as I can always just ride a manual the bike was only $250 to start). I know that quality matters to many here, but I see price/quality as a tradeoff and could just stick with SLA which are about $60 to replace but may need more leg energy. My ride is only 2 miles each way but needs a moderate amount of current to get up those hills. I don't want to spend much so been looking at lower end solutions.

I've been looking at three alternatives.
1) LiFEPO4.. self-build.


I've read about the no-name brands and uplabeling, and while I expect that these cells are less than half the spec, I'm thinking they might still be a decent deal.
http://www.ebay.com/itm/High-Quality-LiFePo4-3-2V-4Ah-battery-for-EV-HEV-Scooter-ebike-etc-16pcs-/251603467408?pt=US_Rechargeable_Batteries&hash=item3a94bc3c90
This will allow a 8s2p 25.6v "8ah/5C" pack for $125 (delivered) + BMS + charger (which I'll get separately). My ride draws a max of 600w, which requires about 21A @28.8v. I need that for 1-2 min then maybe 5A intermittent usage for the remainder of the trip. The hills are the first part of the trip so I'll be at charge voltage when I start. With the manufacture's specs, a pack with 8s1p of these cells would be rated at 20A continuous, and I'd have 2P, so I'd be just maxing out the motor using just over half the rating. What do people think? Would I toast these like I did the SLA? Anyone have experience with this company (Just Raw Power..)

2) prepacked LiFEPO4, e.g. putting two ZIPPY Flightmax 4200mAh 4S1P 30C LiFePo4 Pack in series. These are "rated" 30C for 120A, so my usage would be even lower at 5C on these 4Ah pack). These don't have a BMS but I add one or maybe just do balance charging when needed and bulk charging hopefully the majority of the time.

3) Lipo such as ZIPPY Compact 5800mAh 7S 25C Lipo Pack (Not sure if the controller can handle 8s Lipos as that is >33v I'm not even willing to risk testing that high). Given the more touchy safety issues with Lipo its my last choice (even if its a bit cheaper).


Even 1 2 or 3 can provide the current not sure how many Ah I'll actually need (depends on the actual draw at the current levels). Especially the prepacked zippy flightmax at 4.2Ah might be light, but any of them might be a too small given that i can drain the 12ah SLAs to the LVC.

4) Build a 18650 pack from used laptop batteries. Definitely cheap but a lot of work and not sure how many I'll need to get 20A out of it.. If I assume 1A per 8s, I'd need 8s20p which is a big pack and a lot of welds. Despite my budget constraint my time is worth a lot more than that -- I'd do a laptop build mostly for the experience/story to tell students and to appease my wife send of what is "necessary".

Did I miss anything in my budget range that might work?

Given these what do people think, should I go for one the 1-3 approaches, or just wait and collect enough 18650 laptop batteries to build one (which seems like a lot more work but would be lower total cost).

Hmm, drained em to lvc 5 times is enough to cost you 30 cycles each time it happens with lead.

For sure, you need a voltmeter,

http://www.ebay.com/itm/DC-0-30V-Voltmeter-LED-Panel-3-Digital-Display-Volt-Voltage-Meter-for-Motorcycle-/131095052802?pt=LH_DefaultDomain_0&hash=item1e85dfc202

Or better, a watt meter.

http://www.ebay.com/itm/Digital-60V-100A-Balance-Voltage-Battery-Power-Analyzer-RC-Watt-Meter-Checker-/400525712095?pt=Radio_Control_Parts_Accessories&hash=item5d41315adf

I have to wonder if you are ready for a lithium pack with no bms. Particularly a 7s lipo one. Till you learn to turn it off when you park, perhaps back to more lead.


Your usual trip is pretty short, and should go fine with replacement lead if you learn to stop killing it, by using a voltmeter.

Thanks dogman..

Wow..i had no idea riding down to that level was so bad for it. Should I be plugging in at work (would be a real hassle but maybe doable if its needed as it gets cold).


I figured I need a meter/alarm which is why I asked about the Cellog.. I know someday I'll have a Lithum pack.. so though maybe that would be better than a strait pack volt/watt meter.
From the specs it does seem like it would work.. do you see any problems using it on an SLA pack? If I can set my own LVC alarm, at what level should I set it? I used a hand meter after my "killing", and was surprised the LVC is so high. It was 4-5 min after the LVC happened (so some recovery) but the pack was at 23.5v. My guess though is that its a voltage sag on the hills at sent it below LVC and part of why I want a logger not just a meter. I presume its bad to toggle it back on after LVC, which cuts out the motor until its turned off/on again.

Good point about the lack of BMS and turning it off. Not sure I actually left it on.. I park in a rack at school and its quite possible it was someone was playing with it. I know once was my wife, turn it on while moving it out if the garage to paint, and forgot. The other kills were while riding on side trips before heading to work and it dies on the hills. (And riding a 70lb 7 speed up those hills makes one think..) Even now, I recently added a 2 cree LED headlight tided to the power-switch, so I don't think it will be left on again by accident as its quite noticeable. But still since someone could plat with it at school, i will definitely go with a BMS -- so the absent minded professor, or students messing with it, does not destroy the pack.

you meant that the LVC on the controller is 30V i assume. if you buy a lifepo4 battery then it will have a BMS with the LVC built into the BMS so your controller LVC is a no op.

dnmun said:

you meant that the LVC on the controller is 30V i assume. if you buy a lifepo4 battery then it will have a BMS with the LVC built into the BMS so your controller LVC is a no op.

Click to expand...

It is a "24V system". the 30V a possible max I read about somewhere when I was exploring using a 30V battery.. (cannot find a link to it now). The lashout and its childred had a few modes/years. I read that some of them will burned up the controller at 36v. and the newer ones as a 29.6v max cutoff, which is why I 'm not looking to go to above 30V max.

The LVC, low voltage cutoff, is something below 23.5 (which I measured after it died once), but my guess its even lower, maybe like 22 or 21.. and I guess with my load its sagged and by the time I got to measure the battery was back up quite a bit. I know the "green light" on the unit was back on fairly fast after the LVC shutdown. Its 3 color LED red,yellow (says about 1/2 full so I'm guessing about 24v) ,green. Under load on the hills its generally yellow but until it got cold it would return to green right after the steep hills. But now I stays yellow all the way to work, which is part of why I'm worried it won't last much longer and started getting more serious into what I should do next.



I've been reading a bit more and found this thread http://endless-sphere.com/forums/viewtopic.php?f=2&t=49340 in which DrkAngle talks about his experiences with higher volt and currie/Ezip (a cousin of lashout) and said trying 36V never hurt his e-zips but simply did not work on many of them. Maybe I'll do a 30V quick test. If it powers up are there other things to worry about? If its mostly heat then I'm not horribly worried as I might use it only in cooler weather and because my ride is so short it won't be hot for long. Any suggestions on how to test if it will cause a shorter life if it does power up above 30V?

If it will work on 36v go for it. If you can come up with ways to avoid people leaving it on for you, do that too. Some kind of keyed on off switch vs a rocker switch.

One nice thing about switching to a cheap HK lipo pack is you can plug in various types of low voltage warnings. But then, they have to be unplugged while you are in school or work. A better solution would just be carrying enough 7s lithium to not have to worry about it till home no matter what.

I use RC lipo, and that's the trick I use, just carry so much of it you never come close to running out on the usual errands.

As always, with lithium cobalt, store it and charge it in a place you'd build a campfire.

Best. but not so cheap option, have Em3ev build you a 24v 15 ah bms protected pack. Well worth the cost. But the wife is kind of right, your trip is short enough to just pedal it when the weather is perfect. ( so you won't arrive all lathered)

Oh, and btw, is that you hucking the air? Almost time for it again. When I skied and boarded hard, I used to just about die in Oct waiting for the first run.

Thanks .. I did not realize that things like LV alarms/loggers have to be unplugged, e.g. when I part it at school. Os is that just because I may drain them so if I go for larger Ah could I just leave them in there. I gest that is One more reason to go BMS. Are the built in wires on the Lipo packs, which are designed for balance chargers, also usable for direct connections to a BMS or do I need to rewire for that. I found a thread on adding BMS to HK lipo but they seem to disassble the pack (but were also going for an odd size..)

Also 7sLip vs 8s LiFePo.. I was thinking I'd go 8s LiFePo.. just so I don't have to worry quite as much about the charging risks. Its maybe 20 bucks more for 4200ma LiFePo4 vs 5000 Lipo.
and the LiFepO4 has a higher C rating. I'd rather not baby sit it charging I'd prefer a slow overnight charge and a few dollars less. But I guess my next task is getting some testing at higher V first because that might improve the power and also give more choices.


Yep that's me a few years ago at ABasin on the board. Been cutting back on the crazy jumping (after a few concussions).. We aim for 50 days on slope a year

Nice, I know what you mean about the concussions. Always took my worst falls on boards rather than skis. Not that I never rang my bell hucking a cornice on skis. I never fell where it counted, telemarking Taos double blacks, but I sure rang my bell plenty showing off under the lift, overjumping a bump and landing on the flat. Or just eating it going 50-60 mph on 223 DH skis.

I'm waiting for the old pro football player disease to hit me now that I'm old.

Chances are, any bms will require you to rewire to a new plug. Lifepo4 + bms shoud work for you. Make sure anything you order from HK has lots of it in stock.

Just to follow on my own post/comments.. I tested the bike over the weekend. 30.5v worked but at 32v the controller would not respond at all on my lashout. Did do a road test just spinning the wheels on the stand.. but at least I think I can go with 29 or even 29.6v as the max volt on my new batteries. Unfortunately that means the nice BB-2950's i own are out (they carge to 33).. I could try to harvest 18650s from them (I took one apart to see.. its 24 panasonic cells 18650DA cells (2400 mAh )

The SLAs, in the cold, are no longer getting me to work. But oddly after sitting at work and my riding home they are at 26.5v.. so I think its just a problem of LVC from voltage sag with high current draw (steep hills). I'll try to do a test this afternoon to decide for sure. Any lifepo solution is at least a week or two away depending on how fast I can get parts. Riding up the hills with the SLAs is maybe worse than just going back to the regular bike..

As I recall from various threads dogman you built a hybrid pack.. I'll do a bit more reading but just started thinking about quickly adding a some lithum to add capacity/power.. I could add say a 7s3p pack of 18650s to run in parallel with the SLAs (I can find room on the frame for something that small, maybe even 7s4p or even 7s5p) while I develop my longer term solution of either a much larger 18650 or a lifepo4 solution. I'd probably charge the 18650s to 4.0 or 4.1 (not on the bulk charger) so the Li-co are not much above the SLA and with the LVC on the bike at 22 the li-co overall should be at an average of 3.15 under load if it hits LVC (floating back to something like 3.4 3.5). Lower than ideal but still not killer right?

Another alternative for me would be to use my thundersky lipos (from a UAV) for which I have a charger/equalizer.. they are 3S and I could serialize for 6S. But even at full charge that would have backflow from the SLA so I'd need to find a big enough diode or something to separate them.. and for them the LVC would yield an average of 3.6 per cell so safer on the low end but only if If I can find a diode to protect it on the high end. They are, unfortunately, no a great form factor (long and thin) but might make it work.


Any feedback on these stop gap measures?