Can I add a set of batteries to extend range of my scooter?

[Windmaker]

I had someone tell me that I could probably add another set of batteries to my Chinese made, three-wheeled electric mobility scooter in order to double my range, but they didn't tell me how to do it. I'd like to hear some comment on the feasibility of that idea, and if appropriate, how to get it done. I'm presuming it would have to be done with some A/B switching, but I'm an electrical novice and will have to be instructed on those issues. The upshot of this idea is that I'd be able to either charge or use either set of batteries independently by switching back and forth while using the same basic wiring and charging port.

My scooter doesn't have a brand or manufacturer's name, just a model name. It's a Deluxe GT3, has a 48v system powered by a set of (4) 12v/20ah batteries located forward of the motor and rear axle. The hot and ground wires penetrate the storage compartment box under the seat and connect to terminals inside this compartment with a master cut-off switch. The charging port is under the front of the seat on the forward side of the rear cowling (see pic). I suspect I'll eventually have to get a picture of how the hot wire attaches to the electrical system and all it's entities (motor, lights, battery charge indicator on dash, etc.), but I'd first prefer to determine whether this general concept is, or is not, a valid possibility.

The current range is supposed to be near 20 miles, depending on several factors such as weight, terrain, etc., and I'd like to nearly double that figure if possible. The extra set of batteries will fit in the compartment under the seat...barely, but it's workable.

Looking forward to hearing some comments....

 

[amberwolf]

I had someone tell me that I could probably add another set of batteries to my Chinese made, three-wheeled electric mobility scooter in order to double my range, but they didn't tell me how to do it.

As long as you use the same chemistry and number of series cells. you just wire the main + and - of each pack in parallel with the other, when both packs are at the same voltage (full charge, for instance).

Then either charging or discharging will simply see a larger total battery pack, and take longer to discharge, and longer to charge.

You can use a charger with higher A capability to take less time to charge.

Or you can disconnect one pack from the system and charge it separately with it's own charger--but if you do this, you cannot reconnect the two packs until they are both done charging, to be sure they are at the same voltage so you don't get sparks or high currents flowing thru the connection wires from pack to pack.

I'm presuming it would have to be done with some A/B switching,

No switches needed, and it is best not to do that, but just to parallel them, as it means each pack sees less load and wastes less power from voltage sag, etc.


All you need is a Y-cable (made using the same gauge of wire as the original connections) from the output of the first set to the controller, so that the second set can plug right into that.

If your scooter is like others I've worked with, it uses the Anderson SB50 connectors, and probably 10g wire. You can solder the contacts or crimp them, though soldering takes a big iron or a small palm-sized butane torch. Crimpng takes creativity or a special crimper. Powerwerx sells the contacts and housings (and wire). Andersons are genderless, so you just need 4 housings and 8 contacts. (one housing to go on the output of the new pack, and 3 to make the Y). Positives all connect together, and negatives all connect together, using two wires of the same polarity in each contact.



There are other ways to do this that get more complex, but this is a simple way and works fine.



If you use a different chemistry (non-SLA) then you'd be best to just stop, unplug the one pack and connect the other, and then startup again. The A/B switches tend to need to be large for the currents you're going to need, and can get expensive. And they have to be of the Break-Before-Make type, or you could get fireworks as the two packs in different states of charge momentarily connect to each other.

 

[wesnewell]

I'd just replace the sla batteries with a 13s rc lipo pack and bms. 20ah of lipo would would only weigh ~13lbs and take up no more room than a single 12V 20ah sla nattery. That alone would probably double your range. You could probably easily fit 80ah of lipo in there for a range of 150 miles if you wanted to. And lipo would probably last at least 4 times longer than an sla pack will. Or you could just do a straight replacement using lifepo4 12V batteries. But that would probably cost a lot more. But get someone that knows what they're doing to do it.

 

[Windmaker]

I had someone tell me that I could probably add another set of batteries to my Chinese made, three-wheeled electric mobility scooter in order to double my range, but they didn't tell me how to do it.

As long as you use the same chemistry and number of series cells. you just wire the main + and - of each pack in parallel with the other, when both packs are at the same voltage (full charge, for instance).

Then either charging or discharging will simply see a larger total battery pack, and take longer to discharge, and longer to charge.

You can use a charger with higher A capability to take less time to charge.

Or you can disconnect one pack from the system and charge it separately with it's own charger--but if you do this, you cannot reconnect the two packs until they are both done charging, to be sure they are at the same voltage so you don't get sparks or high currents flowing thru the connection wires from pack to pack.

Thank you so much for your truly thorough reply. Nevertheless I'm truly surprised that the battery packs (both SLA's, by the way) can be hooked up in parallel. As previously stated, I'm an electrical novice, but that strikes me as potentially posing an excessive load on a 48v system. I also frankly don't know the specs of my stock charger, but I suspect that is constructed for a 48 volt system and battery load as well. In brief, is there any chance the two sets of batteries configured in parallel could overload any part of the 48 volt system, including the charger?

It also sounds like I'll need to retain someone with electrical knowledge to do this for me. I'm 72, have some health issues, and can't ambulate very well, but the primary concern is competency, or lack thereof, on my part. Your instructions are quite clear and I would print them out for whomever I get to do this.

I'm presuming it would have to be done with some A/B switching,

No switches needed, and it is best not to do that, but just to parallel them, as it means each pack sees less load and wastes less power from voltage sag, etc.


All you need is a Y-cable (made using the same gauge of wire as the original connections) from the output of the first set to the controller, so that the second set can plug right into that.

If your scooter is like others I've worked with, it uses the Anderson SB50 connectors, and probably 10g wire. You can solder the contacts or crimp them, though soldering takes a big iron or a small palm-sized butane torch. Crimpng takes creativity or a special crimper. Powerwerx sells the contacts and housings (and wire). Andersons are genderless, so you just need 4 housings and 8 contacts. (one housing to go on the output of the new pack, and 3 to make the Y). Positives all connect together, and negatives all connect together, using two wires of the same polarity in each contact.



There are other ways to do this that get more complex, but this is a simple way and works fine.



If you use a different chemistry (non-SLA) then you'd be best to just stop, unplug the one pack and connect the other, and then startup again. The A/B switches tend to need to be large for the currents you're going to need, and can get expensive. And they have to be of the Break-Before-Make type, or you could get fireworks as the two packs in different states of charge momentarily connect to each other.

 

[Windmaker]

I'd just replace the sla batteries with a 13s rc lipo pack and bms. 20ah of lipo would would only weigh ~13lbs and take up no more room than a single 12V 20ah sla nattery. That alone would probably double your range. You could probably easily fit 80ah of lipo in there for a range of 150 miles if you wanted to. And lipo would probably last at least 4 times longer than an sla pack will. Or you could just do a straight replacement using lifepo4 12V batteries. But that would probably cost a lot more. But get someone that knows what they're doing to do it.

Thanks, but I already have two sets of SLA batteries that would go to waste.

 

[danielrlee]

Adding batteries in parallel has the effect of increasing capacity, but not power, similarly to having a bigger gas tank on a car. The motor will only draw as much power as it needs, so no need to worry about having "too much".

 

[Windmaker]

Adding batteries in parallel has the effect of increasing capacity, but not power, similarly to having a bigger gas tank on a car. The motor will only draw as much power as it needs, so no need to worry about having "too much".

News to me...sure hope you're right and that it poses no overload of voltage. Thanks again.

 

[Windmaker]

The above comments contain good info. In practice it is better for the batteries to be connected in parallel anyhow; It reduces the load on the batteries overall which leads to a longer life and greater capacity than either set individually-- markedly so for lead-acid. Your charger will take longer to charge and may be a bit undersized for your combined pack. Voltage will only increase if you add them in series, which you never want to do without knowing the limit of your system. Parallel is fine.

1. You should not mix old and new cells.
2. Lead-acid packs benefit from balancing from time to time.
3. Parallel each 12V battery to its mate-- not just the end of each 48V strings. (Build parallel>Series, NOT Series>Parallel)

What wesnewell said is worth noting. Your machine will be much more capable and 'fun' with lithium at half the nameplate capacity as SLA (i.e. a 20AH lead is worse than a 10Ah lithium). While it may seem like a waste of batteries you've already got, IMO it is a larger waste to use and/or purchase lead-acid. Their available energy and lifecycle is pitiful comparatively so they are the more expensive option at this point. 6+ years ago, maybe. With the cost of lithium now, lead is dead.

I'm certainly learning a good deal from you folks, but my ignorance remains stauch. Looking back at wesnewell's remarks I proceeded to do some net searching and of course got a lot of warnings about still present dangers of Lipo batteries, hazardous shipping rates, etc. and some exorbitant prices. On the other hand I found a Lipo that I think matches one of wesnewell's first suggestions at the following site; http://www.batterysupports.com/48v-546v-13s-30a-13x-36v-lithium-ion-lipolymer-battery-bms-pcb-p-271.html ....and that's dirt cheap!....think I might be missing something here.

 

[Windmaker]

I'd just replace the sla batteries with a 13s rc lipo pack and bms. 20ah of lipo would would only weigh ~13lbs and take up no more room than a single 12V 20ah sla nattery. That alone would probably double your range. You could probably easily fit 80ah of lipo in there for a range of 150 miles if you wanted to. And lipo would probably last at least 4 times longer than an sla pack will. Or you could just do a straight replacement using lifepo4 12V batteries. But that would probably cost a lot more. But get someone that knows what they're doing to do it.

This is an excerpt from a reply I just sent to eTrike;

I'm certainly learning a good deal from you folks, but my ignorance remains stauch. Looking back at wesnewell's remarks I proceeded to do some net searching and of course got a lot of warnings about still present dangers of Lipo batteries, hazardous shipping rates, etc. and some exorbitant prices. On the other hand I found a Lipo that I think matches one of wesnewell's first suggestions at the following site; http://www.batterysupports.com/48v-546v ... p-271.html ....and that's dirt cheap!....think I might be missing something here.

No doubt if I go the lipo route I will definitely have to find a knowledgeable technician to do the installation. That may be the biggest difficulty of all in my particular region.

 

[wesnewell]

That's just the BMS. You'd want one of those to charge the pack with. 20ah of 13s lipo will run ~$200 and up, depending on what/where you buy it, but would last a lot longer than the SLA and give you at least double the range.

 

[Windmaker]

I'd just replace the sla batteries with a 13s rc lipo pack and bms. 20ah of lipo would would only weigh ~13lbs and take up no more room than a single 12V 20ah sla nattery. That alone would probably double your range. You could probably easily fit 80ah of lipo in there for a range of 150 miles if you wanted to. And lipo would probably last at least 4 times longer than an sla pack will. Or you could just do a straight replacement using lifepo4 12V batteries. But that would probably cost a lot more. But get someone that knows what they're doing to do it.

Hi Wes ~ I had difficulty finding a 13s rc lipo pack and bms for sale anywhere on the web, let alone a 20ah unit. Could you advise me on some sources to purchase these items? And is it important to match the 20ah rating of my current SLA batteries when switching to LifePo4? I did find a 48v 15ah LiFePO4 Battery 5A Charger BMS Ebike Kits Recharge Power 800W 9 WEEK for sale on ebay for about $317, but I don't know if that would be compatible with my system or not.

http://www.ebay.com/itm/142095995682?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

What's this....$1.00 ? https://www.alibaba.com/product-detail/lipo-13S-battery-pack-48V-10ah_60068377932.html

Supposedly my new(er)/used scooter (same model as my current unit but a bit newer) will be shipped from Garden Grove, CA. in the next couple days. I mention this because because when I talked with the seller today about possible delivery problems with the powerful hurricane Matthew possibly paying us a visit this coming weekend.......to which he replied they had just had a 4.3 earthquake in his area (Andreas fault line) and were warned by Governor's office to possibly expect a much larger (7.0+) earthquake within days.....I said "Well then ship it as soon as you can!"...we'll worry about the hurricane later...What's Murphy's law again?

 

[Windmaker]

Hi. That Sunthing battery has mixed reviews (mostly bad?). It states a very low power level for that type of battery and says it can take ~8 weeks to deliver.

With lithium replacing lead you can use half the rating-- so a 20Ah lead-acid pack can be replaced and be outperformed by 10Ah of lithium. The more Ah you can afford, the greater your range will be in addition to more power and a longer lifespan.

I'll leave the rest for Wes. Cheers.

Thank you eTrike!

 

[wesnewell]

When it comes to rc lipo, you will have to make your own pack using smaller ones. and then if you want to use a bms, you'll have to add that to it.. For a 48V controller with a lvc of 42V 12s will work perfect. You can go up to 14s on any 48V controller without a problem if you want max speed out of your system. Other than diy, I don't know of anyone that sells rc lipo packs pre built. The main reason for that is it only takes minutes to assemble a pack. Personally, I don't use a bms with my 24s packs even though I bought a couple of 24s bms's over a year ago. You connect rc lipo lipo packs the same way you'd put sla batteries in series to get the end voltage you want. I buy mine from hobbyking.com. You can buy bms's from a multitude of places. Those batteries you linked to are garbage. Here's more info on wring lipo.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=39666

 

[Windmaker]

When it comes to rc lipo, you will have to make your own pack using smaller ones. and then if you want to use a bms, you'll have to add that to it.. For a 48V controller with a lvc of 42V 12s will work perfect. You can go up to 14s on any 48V controller without a problem if you want max speed out of your system. Other than diy, I don't know of anyone that sells rc lipo packs pre built. The main reason for that is it only takes minutes to assemble a pack. Personally, I don't use a bms with my 24s packs even though I bought a couple of 24s bms's over a year ago. You connect rc lipo lipo packs the same way you'd put sla batteries in series to get the end voltage you want. I buy mine from hobbyking.com. You can buy bms's from a multitude of places. Those batteries you linked to are garbage. Here's more info on wring lipo.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=39666

While I get the gist of what your telling me Wes, please don't forget that I'm a complete novice in the battery world, especially LiPo's. Taking all your remarks together I gather that 12s, 13s or 14s would work with my system, but I'm still totally lost when it comes to knowing and finding which smaller batteries (when combined) would meet my needs, including ah ratings. I went to the Hobby King site and looked under "Li-Poly (All brands) and couldn't make heads or tails out of the offerings on which combo of units would meet the above criteria.......help! The range of categories listed at the top were 1-8s, 10s & 11.1s, and finally 14.8s.....how do you get 12s, 13s, or 14s out of that? Could you possibly be more specific as to which "smaller" LiPo batteries and with what specific associated properties would be combined in order to be appropriate for my needs?

The other issue I obviously still don't understand is the need, or lack thereof, for a bms. How else can I charge the batteries if I don't have a bms ....wouldn't one of these units help to safeguard from overcharging or other mishaps?

 

[wesnewell]

The link above shows a drawing of a 12s2p pack using 4 6s packs. Here's more info on rc lipo.
http://www.rchelicopterfun.com/rc-lipo-batteries.html
http://scriptasylum.com/rc_speed/lipo.html

 

[Windmaker]

The link above shows a drawing of a 12s2p pack using 4 6s packs. Here's more info on rc lipo.
http://www.rchelicopterfun.com/rc-lipo-batteries.html
http://scriptasylum.com/rc_speed/lipo.html

I'm sorry Wes, but I'm unable to locate "the link above" that you mentioned showing the associated drawing. I also note that you didn't reply to my questions about my needing (or not) a bms for charging, nor did you provide clarification of the other confusing properties of the LiPo batteries needed for my system ("C" ratings, how to combine ah or milliamp ratings, etc.) that I requested. Whatever your reasons I gather that you'd rather not supply that info, so I'm afraid I'm going to have to give up on pursuing the LiPo alternative. I just don't know enough to make the right choices, even though I've read thru your "more info on LiPo" links. Thanks for your time and efforts in any case. I appreciate your trying.

Dick H.

 

[Windmaker]

Hi. I wouldn't recommend LiPo for you, which I why I left that info for Wes. The link he gave is on this site, so it looks a little funny and doesn't have "http://www." at the front.

Here it is: https://endless-sphere.com/forums/viewtopic.php?f=14&t=39666
Here is a similar one: https://endless-sphere.com/forums/viewtopic.php?f=14&t=52240

No worries on C rate for your scenario. More battery info here: https://endless-sphere.com/forums/viewtopic.php?f=14&t=26621#p384360[/quo


Thanks again eTrike.

 

[Windmaker]

I gather you are roughly in my area. I'm watching Mathew, as well.

IMO, recommending RC-Lipo to someone of your age and experience level, is just not right. Lifepo4 would be a much better choice. You might not be clear on the difference, there are numerous chemistries to choose from.

Wes gets better performance, fewer problems, and longer lifetimes from RC-Lipo than almost anyone else I have ever seen. He also recommends them to absolutely everyone who comes along, absent-minded and inexperienced users included. Most folks here would suggest that a minimum of caution, knowledge, and experience is a requirement before such a recommendation.

Lithium in general much better performance, lighter weight, longer lifetime, etc. Higher cost and different charger needed. Far superior to lead.

However, lead is what you have now, and you may already have two full packs? Original in current scooter and second pack in recently purchased unit? Paralleling them may very well make most sense. Shorter lifetime for lead packs may, or may not, be a big concern for you.

Confirm this with an electrician you have confidence in, but connecting two packs will add more amp-hours, or range, but leave the voltage the same and should not affect any systems on your scooter. Higher voltage changes things, higher amps, not really other than range.

Thank you Nelson.....I think your summation is right on target. I am generally familiar with the difference between the chemistries of LiPo and LiPo4 from recent readings only, and I am certainly willing to give lithium power a try. As you astutely pointed out, however, given my age and inexperience I'd be better off to find a good electrician to do the job for me at this point. In the meantime I most probably will give the parallel SLA set-up a try. Both of my sets of batteries are used, one set more than the other, but I don't think it will be like combining a new set with an old one....which apparently isn't advisable. I'll save adventuring into Lithium batteries until after these sets of SLA's expire. Until then.....I truly appreciate your contributing to clarifying this issue in my mind and for the other readers and contributors as well. Lead might be dead, but I've got one foot in the grave and the other one on a banana peel myself.....

 

[wesnewell]

If you want your lead batteries to last as long as possible it's imperative that you charge them asap after use and don't run them down too low to begin with. Lead is fussy when not used. Plug the charger in every possible chance you get. Even if it's just for a short stop. Never let your scooter sit unused off the charger for more than a day. Keep them charged and they will last years, Let them sit for any length of time and they'll die a sure death. LA batteries self discharge quickly. unlike lithium which you don't want to keep fully charged.

 

[Windmaker]

If you want your lead batteries to last as long as possible it's imperative that you charge them asap after use and don't run them down too low to begin with. Lead is fussy when not used. Plug the charger in every possible chance you get. Even if it's just for a short stop. Never let your scooter sit unused off the charger for more than a day. Keep them charged and they will last years, Let them sit for any length of time and they'll die a sure death. LA batteries self discharge quickly. unlike lithium which you don't want to keep fully charged.

Thanks Wes......that's just what I do....whenever I come home the charger goes on. Once these batteries expire we'll talk Lithium again.....

 

[Windmaker]

I wouldn't suggest LiPo without proper knowledge and respect for their care, though the same applies to any battery.

LiFePO4 is extremely tolerant and well suited for lead-replacement. You can find them used cheaply at times.

eTrike.....This question is actually not related to your quote above.......Could you, or anyone reading this, possibly provide a wiring diagram (or a link to a picture of same) of a parallel connection of two sets of 4 x 12v/20ah batteries? I tried looking it up via Google and wasn't too successful. I would hope that I personally could accomplish this task, but in the final analysis I may have to hire someone.

Thanks,

Dick H. (Windmaker)

 

[wesnewell]

First diagram in this post shows how.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=39666

 

[Windmaker]

Hi. Here you go. From this site: http://www.scriptasylum.com/rc_speed/lipo.html

The only change I'd suggest is connecting your main leads to opposite strings so that the resistance equalizes or doing it like Wes' diagram with identical leads.

Thanks eTrike......unfortunately terms like "main leads", "opposite strings", "identical leads" and even resistance equalizing are all Greek to me. I also notice that your link brings up wiring for LiPo batteries. Does it make any difference whether the batteries are Lipo or SLA's when it comes to paralleling? I think I'd better get a good electrician to do my hook up for me...

 

[999zip999]

Before connecting batteries need to be of same voltage or the high voltage battery will super charge the lower battery till equal. Can be dangerous.

 

[Windmaker]

Before connecting batteries need to be of same voltage or the high voltage battery will super charge the lower battery till equal. Can be dangerous.

Thanks, but I seriously doubt I'll be dealing with anything but 12v batteries