Why buy exotic batteries? Ways to get more out of SLAs...

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andrew
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Why buy exotic batteries? Ways to get more out of SLAs...

I have some ideas for a few extra miles from SLAs that are worth a try before you spend hundreds on other technologies.

EDIT: 5/3/07 Use this information at your own risk, and please read what other members caution by clicking on the warning links. Also, to help navigate this list type ctrl + [F] into your browser and enter key words of interest.

EDIT: 5/807 More about heat and fast charging

 

1. Pre-heat them before you ride. Installing an electric blanket of some sort will also help cushion them.
CAUTION: At this point I do not know how much this will effect battery life.
CLICK HERE FOR WARNINGS FROM JBIRD
CLICK HERE FOR WARNINGS FROM MF70
Click here for charging voltage vs. temp chart

 

2. Fast charge somewhere along your route. Try multiple Soneils in parallel (no guarantees, try at own risk).
CAUTION: Beware of overcharging. Also fast charging may cause heating which may effect battery life.
CLICK HERE FOR WARNINGS FROM JBIRD
CLICK HERE FOR WARNINGS FROM MF70
Click here for charging voltage vs. temp chart

 

3. Setup a solar/wind charging station if you can't get access to a plug for fast charging.

 

4. Build a hybrid pack. Use lead-acid in parallel with a NiMH or other tech pack of slightly higher voltage. This way you aren't spending as much as if you went entirely NiMH.

 

5. Use a removable lead-acid pack for when you need more range. This also allows for a real quick "charge". Can put in backpack.

 

6. Going slower always helps, but thats no fun :(

 

7. Design a quick change pack. Buy a few extras and you can charge 0-100% in a couple minutes.

 

8. Add a little capacity if you need just a little more range. Batteries of different capacity can be put in parallel, as long as voltage is same. http://www.zbattery.com/sla-12v.html

 

9. Use powerCheqs to improve battery balance, which might help with performance and range.

 

10. Charge really really fast. Hawker has done testing charging to 80% in under 15 min. Can use a large golf cart or forklift charger.
CAUTION: Beware of overcharging. Also fast charging may cause heating which may effect battery life.
CLICK HERE FOR WARNINGS FROM JBIRD
CLICK HERE FOR WARNINGS FROM MF70
Click here for charging voltage vs. temp chart

 

11. Make sure your SLAs are good quality and in good condition before you decide they are not providing enough range. Give them a few cycles if they are new or have been sitting a while.

 

12. Put in a small NiMH/NiCad pack that you can switch on to charge the SLAs in case of those "o sh*t my batteries are dead" situations where you need a mile or two. NiMH AAs have pretty decent capacity for the size.

 

13. A couple controllers can do regenerative braking. Though expensive, this might be just what you need for +10-15% range if you have lots of hills/stops.

 

14. Reduce drag w/bike fairing. More effective the faster you go.

 

15. Check out your EV mechanically, as a tight chain/ brakes that are dragging can waste a lot. Lubricate the chain, and check tire pressure.

 

16. Cut down on weight as much as you can.

 

17. Heat those batteries really hot and insulate them. I wouldn't go past 140 degrees F.
CAUTION: At this point I do not know how much this will effect battery life.
CLICK HERE FOR WARNINGS FROM JBIRD
CLICK HERE FOR WARNINGS FROM MF70
Click here for charging voltage vs. temp chart

 

Consider trying more than one of the listed ideas. The effects might really add up.

jbird
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Re: Why buy exotic batteries? Ways to get more out of SLAs...

There are some caveats to your posts especially about heat and fast charging. Heat in general is bad for SLA batteries as it will age the batteries prematurely. Heat also makes charging more complicated. The voltage of a hot battery pack may not reach the cutoff for many smart chargers. The resulting overcharge will heat the battery even more and lead to cell-venting with resulting loss of electrolyte and water. With careful monitoring and more frequent battery replacements in cyclic applications like EVs, this may not be as much of a problem. Also, fast charging can generate excess internal battery temperatures and also lead to the voltage runaway overcharge phenomenon. If you use a large transformer type charger, the voltage near the end of charge will usually go way above the manufacturer's recommended voltage limit if you don't monitor with a voltmeter and intervene. As you point out it will improve the performance and convience and probably still cost less than other battery chemistries.

http://www.batteryuniversity.com/parttwo-35.htm

I am interested in the technical aspects of how to build a hybrid battery pack with either SLA/NIMH or SLA/NICD. In the past, I have toyed with the idea of initially using a NICD pack until it was depleted then switching to SLA but the hybrid battery pack sound a bit less complex and more convienent to hook up. How many cells of NICD or NIMH would you use per 12V battery and what would be the discharge characteristics of the pack (how would the current be split and voltages behave near the beginning, middle, and end etc.)

andrew
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Re: Why buy exotic batteries? Ways to get more out of SLAs...

Thanks for the comments, I edited the topic post to more easily reference what you posted.

There was someone on the old forum who built hybrid packs. He had the NiMH setup at higher voltage. Because of the low internal resistance of SLAs, you might end up discharging the SLAs first if you use a NiMH pack of the same voltage.

---
Avatar taken from http://www.electricmotorbike.org/
Anyone got one they might want to sell?
My KZ750 Project: here E.T.A. 1 mo

[url=/forum-topic/motorcycles-and-large-scooters/587-my-kz750-electric-motorcycle-project]KZ750 Motorcycle Conversion[/url]
[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
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mf70
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Re: Why buy exotic batteries? Ways to get more out of SLAs...

Hee hee, do you own a Batteries Plus franchise?

The heating idea will help performance, but it will also cook batteries. THe entire process is, after all a chemical reaction, and ALL chemical reactions occur more rapidly with heat, the ones that generate electircity, and the ones that kill batteries.

Also, the commonly used SLA's have very limited capacity to withstand overcharging, and a hot battery is more easily overcharged. (Since Soneils go to the upper limit of float voltage, they can cook a pack if used in summer.)

MF70

andrew
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Re: Why buy exotic batteries? Ways to get more out of SLAs...

Thanks for the comments mf70. There is a good chart of charging voltage vs. temperature here: http://www.powerstream.com/SLA.htm

I added a link to the topic post to your comments for easy reference. It is not my intention to have anyone damage their batteries, so I made a few other changes to the topic post to help better reflect the dangers associated. If you have any more comments or references please add them and I will link to them in the topic post.
---
Avatar taken from http://www.electricmotorbike.org/
Anyone got one they might want to sell?
My KZ750 Project: here E.T.A. 1 mo

[url=/forum-topic/motorcycles-and-large-scooters/587-my-kz750-electric-motorcycle-project]KZ750 Motorcycle Conversion[/url]
[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
Pic from http://www.electri

mf70
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Re: Why buy exotic batteries? Ways to get more out of SLAs...

Your points are a useful compendium of "getting more out" for battery powered units. I don't think you'll cause too many disciples to cook their batteries.

MF

andrew
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Re: Why buy exotic batteries? Ways to get more out of SLAs...

I don't think you'll cause too many disciples to cook their batteries.

Overcharging can kill batteries very quickly. I tried to make that clear by referencing your's and jbird's posts. However, I've seen data from Hawker and others doing very fast charging testing with pulse charging, which certainly heats the batteries up hot. I've also heard from dirt bike riders that charge their batteries very fast to heat them up and get more power.

I don't see any references showing that fast charging, or heating the batteries directly will significantly shorten life. What kills batteries appears to be overcharging which vents off the electrolyte, and can also cause batteries to swell up and crack. Overdischarging is also a big killer, causing weak cells to be reversed.

The key is control. Make sure you are not exceeding the gasification voltage (refer to posted chart). Listen very closely to the batteries during charging for any hissing or bubbling noises. The need for some sort of battery balancing is higher when fast charging! Check the voltage on all the batteries regularly during charging. Make sure your charger is in good condition. Hawkers can take fast charging better than other batteries with less heating due to a lower internal resistance. Finally, some sort of fire protection is a really good idea.

---
Avatar taken from http://www.electricmotorbike.org/
Anyone got one they might want to sell?
My KZ750 Project: here E.T.A. 1 mo

[url=/forum-topic/motorcycles-and-large-scooters/587-my-kz750-electric-motorcycle-project]KZ750 Motorcycle Conversion[/url]
[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
Pic from http://www.electri

mf70
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Re: Why buy exotic batteries? Ways to get more out of SLAs...

Relative to:

I don't see any references showing that fast charging, or heating the batteries directly will significantly shorten life.

Well.... we have the opinion of the folks at PowerSonic:

http://www.power-sonic.com/index.php?doc_id=116

While raising ambient temperature increases capacity, it also
decreases useful service life. It is estimated that battery life is
halved for each 10°C above normal room temperature.

Page 7

That still lets racers do what they want, but racers are crazy anyway.

Mark

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