Converting a 60v Daymak into a 72v?

[LarryHoova]

Hi everyone!

I have a 60v Daymak Beijing bike.

I want to get more range and accelarion out of the bike and my thought was to add 1 more 12v 20ah battery.

Is it as simple as just adding another battery in series, or do I need to replace the wires with thicker gauge? Do I need a new controller? Do I need a new charger?

Thanks!

 

[dogman dan]

You might need a new controller but likely not. To find out look inside it. If the capacitors inside are marked 100v then you can likely get away with 12 v more with no problems or additional wiring. I bet your controller has the 100v caps. Controllers I have seen have either 63v or 100v inside.

Charging your 72v battery with a 60v charger obviously won't work. You could either get a 72v charger, or charge the battery after separating them again using a second 12v charger for the 12v battery.

 

[LarryHoova]

Thanks for the quick reply.

I bought my bike about 2 weeks ago. It had 40km on it already.

I drove it home from where I bought it which drained the battery in half.

I did a 65km trip the other day and made it there and back no problem barely hitting 2/6 bars by the time I got home - but I tried to be conservative about the power, by coasting down hills etc.

Then I did the same trip again 2 days ago, this time going as fast as possible and never coasting except on giant hills where throttle does nothing because gravity is so strong.

This time, I noticed I used more energy on the way there, so I found a place to stop and charge for maybe 30 mins tops. The last final hill of my trip, the bike could NOT go up, and I had to pedal. Barely made it home. It was at 3 bars at rest and 1 bar when I drove it.

Now after being freshly charged, and going for a 10min ride, it will go from 6 bars at rest to 5 bars when I am driving it, and half way through my short trip I was getting 4 bars when I was accelerating, going back to 6 bars at stopped.

So... I like to do these long journeys and stopping to charge is not really an option, so I am assuming I will get more range from adding another 12v 20ah battery?

More range is my goal.

Also my odometer randomly went from 400km to 30400km sometime in the last few days :/

The left signal light blew after 3 days.

I have removed the wiring harness that leads to the front light and the 2 front signal lights.

I hard wired with a switch, a 12v 55w Halogen light to one of the batteries.

I NEVER had the light on during the 2 long journeys I mentioned above.

I have barely used the light at all yet - maybe 5-10mins of driving tops with it on - I rarely go out at night and I am worried it will draw a lot of power - works great though

 

[dnmun]

what is the voltage output of the charger? when you say 60V is this for 5 SLA batteries in a row? can you post up pictures and a picture of the label on the controller too?

 

[LarryHoova]

Yes the charger is 60v and it is for 5 x 12v in series.

I am going to be buying a single 12v 20ah battery tomorrow.

My plan is to just use a 12v charger and charge it independently by removing it from the series with a switch/connectors.

 

[LarryHoova]

Here is a question though:

What would happen if you took 4 fully charged 12v batteries and a mainly drained 12v battery and connected them to 60v and used a 60v charger?

Would it charge that one empty battery very quickly or would it go slow as hell because they are in series and the other 4 would barely pull any charge because they don't need it?

This is why I was going to charge the 1 battery on it's own - but it would be easier to use my standard charger and just swap them in and out of the series with a switch or something?

 

[dnmun]

if you have 5 SLA in series, your charger is putting out 72V already. i doubt if you really measured and just making up numbers doesn't help us help you. good luck with that.

 

[wesnewell]

If you're looking for more range, just replace those sla batteries with a lithium pack of the same ah. That should at least double the current range. I repaired an old 36V bike that had 3 12ah sla's in it and it was just begging for a 20ah 12s lipo pack with room to spare. I gave the guy 3 old sla batteries I had and he was happy. He picked it up in a dumpster.

 

[999zip999]

Sla batteries are not made to be fully discharged. This will lead to an early death of your sla's. Try and keep them charged fully after they cool from your ride.

 

[LarryHoova]

The charger says 60v on it and I have 5 batteries that are 12v each. Is it possible that my charger puts out more than 60v? Could it charge 72v?

I can not afford to buy 72w worth of new lithium batteries.

I am stuck with my SLA so my only option is to add another SLA to bring it up to 72v.

 

[wesnewell]

First thing you need to do is open the controller and look at the big caps. They need to be 100V caps, as a 72V lead pack can charge to over 80V. Then you need to check the specs on the mosfets it uses, and they need to be rated for more than 80V too. Now you may be able to get by with something close to 80V, as I run 100.8V with my 100V rated caps and fets without a problem in 2 years, but it's a crap shoot. I'm not sure I'd waste more money on another 12v sla battery in any case when you can buy 5ah 4s hardcase lipo packs for under $25 each and 8 of them in a 16s2p config would give more range than you are getting now, and you could fit 16 of them in that battery compartment with room left over if it will hold 5 12ah sla's now.

 

[dnmun]

but a 48V lifepo4 pack is more powerful than the 72V of SLA.

your 60V charger currently puts out 72-73V. but you did not measure it. if you do not have a voltmeter then you should buy that before you buy more batteries.

if you charge 6 SLA packs in series the voltage will be about 6x14.5V=87V DC. most controllers will not handle 87V without upgrades to the parts inside.

 

[wesnewell]

but a 48V lifepo4 pack is more powerful than the 72V of SLA.

Not really.

your 60V charger currently puts out 72-73V. but you did not measure it. if you do not have a voltmeter then you should buy that before you buy more batteries.

Anyone working with electricity needs a VOM.

if you charge 6 SLA packs in series the voltage will be about 6x14.5V=87V DC. most controllers will not handle 87V without upgrades to the parts inside.

Not quite. The charge will never exceed 2.25V per cell, so 2.25*36=81V. That's not to say the charger won't put out more than that. Most 12V chargers will put out ~14.5. If unregulated it will boil the acid in a wet cell till it dries up and ruins the battery or may even explode a sealed battery. That's why newer battery chargers are regulated.

 

[LarryHoova]

First thing you need to do is open the controller and look at the big caps. They need to be 100V caps, as a 72V lead pack can charge to over 80V. Then you need to check the specs on the mosfets it uses, and they need to be rated for more than 80V too. Now you may be able to get by with something close to 80V, as I run 100.8V with my 100V rated caps and fets without a problem in 2 years, but it's a crap shoot. I'm not sure I'd waste more money on another 12v sla battery in any case when you can buy 5ah 4s hardcase lipo packs for under $25 each and 8 of them in a 16s2p config would give more range than you are getting now, and you could fit 16 of them in that battery compartment with room left over if it will hold 5 12ah sla's now.

8 packs of 5ah 4s hardcase lipos... I have been reading about these.

With a 16sp2 config - how many volts total would the system be? What charger would I need to charge it?

Right now I get about 60km range from my 60v 12ah SLA system.

It is going to cost me $85 to add one more SLA or what looks like $200 + shipping for 8 packs of lipo.

Will a lipo pack as described provide me with more acceleration and range? How dramatic would the difference be?

EDIT: My motor is rated for 500w -- what is the most amount of LIPO I could run through it safely to get the most power and range? 36v @ 15sah

How much lipo would I need to match the power and range of my 60v 20ah SLA's right now?

 

[dogman dan]

Ahh, well if more range is your goal, then you don't need more voltage and speed. You need to keep the speed lower, to keep the rate you are discharging lower.

Then get more 60v battery to increase capacity.

You need to add some more capacity in a parallel connection, in 60v. More lead would do it, like 5 more 5 ah sla's. But what would really make your range go far would be to add 60v 10 ah of lifepo4.

Pingbattery.com is a very reputable lifepo4 seller, and he sells 60v packs. You'd charge them separate, then to ride connect the lifepo4 battery to the bike, so that when you ride some power came from lead and some from the lithium.

Adding the lithium will lower the discharge rate coming from the lead, and the way lead is, it will allow more capacity to be actually used from the lead with less damage than before.

If you have enough money though, getting 60v 20 ah of lifepo4 and chucking the lead altogether would be great. You can get 10 ah of lifepo4 now, and add 10 more later when the lead wears out.

 

[LarryHoova]

Ahh, well if more range is your goal, then you don't need more voltage and speed. You need to keep the speed lower, to keep the rate you are discharging lower.

Then get more 60v battery to increase capacity.

You need to add some more capacity in a parallel connection, in 60v. More lead would do it, like 5 more 5 ah sla's. But what would really make your range go far would be to add 60v 10 ah of lifepo4.

Pingbattery.com is a very reputable lifepo4 seller, and he sells 60v packs. You'd charge them separate, then to ride connect the lifepo4 battery to the bike, so that when you ride some power came from lead and some from the lithium.

Adding the lithium will lower the discharge rate coming from the lead, and the way lead is, it will allow more capacity to be actually used from the lead with less damage than before.

If you have enough money though, getting 60v 20 ah of lifepo4 and chucking the lead altogether would be great. You can get 10 ah of lifepo4 now, and add 10 more later when the lead wears out.

Ahhhhhhh I see what you are saying.

I can't afford to drop $500 on a lifepo4 60v 20ah right now.

How much more range WOULD I get if added a " lifepo4 60v 20ah" in parallel?

Is it possible to add "60v of lipo" to my system now in the same manner? Or any amount of lipo?

If I wanted to replace ALL of my SLA's now with a lipo system - how many would I need to match my system now and what would be recommended to DOUBLE the range?

And lastly, IF I do just add another SLA and increase from 60v to 72v -- will I get more range from this?

 

[dnmun]

it is worth a try. if you have a video recorder then you can focus on the controller when you plug in the battery.

after you have converted to 72V then maybe you will decide to buy a voltmeter to figure it out.

 

[LarryHoova]

Someone is bringing over a voltmeter today. We are going to check the output of the charger and I am going to go now and open the controller to try and read the rating on the caps.

this 1 SLA I am adding will be temporary until I replace them with lithium - I want to go LIPO if possible just not sure how many packs I need to buy - someone in this thread said 8 packs of 4s20c

 

[dnmun]

if you live in an apartment building or rent you wanna stick with SLA or lifepo4 until you understand the risks and then when you go to lipo you can get either a BMS and wire up the pack for it or just get a balancing charger and put up with that. if it is your house then it is not as important to worry about the risk of fire from bulk charging or shorts.

 

[LarryHoova]

mmk thanks

It seems my charger only puts out 68 volts so it won't be able to charge six 12v 20ah batteries - I am using a separate charger for the 1 new battery.

Now I have to look at my controller to see if it can handle more than the 65 volts my system has now :/

If not, I need a new controller that can handle what should be around 81v -- guy at the shop told me $129 for something like that but I assume I could find one cheaper? (where?)

 

[wesnewell]

8 packs of 5ah 4s hardcase lipos... I have been reading about these.
With a 16s2p config - how many volts total would the system be? What charger would I need to charge it?

4.2V per cell, so 67.2V. Your 60V sla pack is 67.5V max. More likely under that.

Right now I get about 60km range from my 60v 12ah SLA system.
It is going to cost me $85 to add one more SLA or what looks like $200 + shipping for 8 packs of lipo.
Will a lipo pack as described provide me with more acceleration and range? How dramatic would the difference be?

Speed and acceleration will be about the same. Maybe a little better because the lipo won't sag like lead. 10ah of lipo will get close to double the range of 12ah of lead.

My motor is rated for 500w -- what is the most amount of LIPO I could run through it safely to get the most power and range? 36v @ 15sah

You can put all the lipo you can fit into your battery compartment as long as you don't exceed the voltage your controller is capable of handling. I don't know what that is. Certainly up to 68V though as you have could have that now.

How much lipo would I need to match the power and range of my 60v 20ah SLA's right now?

It's safe to say that the same ah and voltage of lipo will double the range of the same ah of lead. So 10ah of lipo will equal 20ah of lead. Do you have 12ah or 20ah batteries now? You said12ah one place and 20ah in another.

 

[wesnewell]

If not, I need a new controller that can handle what should be around 81v -- guy at the shop told me $129 for something like that but I assume I could find one cheaper? (where?)

Last 72V 1500W controller I bought cost me $33.xx shipped. Price has gone up to a little under $50 since then. Changing controllers on a custom bike presents some problems if your current controller has special features are wiring. You need a controller to support all the features of the one you have if you want all your gauges and crap to work right. So before you buy one, make sure it will do what you want.

 

[LarryHoova]

Thanks for the replies.

I have 60v 20ah not 12ah - sorry that was a typo.

Here is the update. I bought the new 12v 20ah and wired it into series with the other 5.

Previous to doing this, I looked at the controller and it said nothing on the outside as to how many V it could handle - it looked really hard to open so I said f'it and decided to just try it.

So far so good, no heat and it works fine. My guage now says 77.5v.

The new problem I have is that the bike does 39km/h now instead of around 32-33

Can I get a new controller that will limit the speed to 32 again? I was thinking of making a switch that switches it from 5 to 6 batteries. This way I can quickly switch it when needed to be on or off for whatever reason. Also I need to be able to switch it to 5 batteries so I can charge it with my 60v charger because the charger won't charge all 72v - I have to charge the additional battery separately with a 12v charger. At least that is what I believe to be the case. My charger only puts out 68v so that is not enough to charge all 72v right?

Is it possible that once I drive it for 10mins the controller will melt/fail? or would pretty much happen right away once I drive it around the block?

 

[wesnewell]

I like how you think.
When you added the other battery you did 3 things.
1. You increased speed. If you want to go slower, let up on the throttle. That will also increase range.
2. You added more wh so you can go farther on a charge if you keep the speed down to the speed before.
3. You disabled the LVC safety feature that would cut you off when the 5 batteries reached a certain voltage. Usually 10-10.5V per battery. If you now run your battery down to lvc, you will over discharge all 6 batteries, so you need to be careful with this and stop riding at 60-63V. The same 10-10.5V per battery as LVC was set for for 5 batteries.

Don't know why you consider the increased speed a problem. Most people want more speed.
I'd probably just buy a 72V charger so I wouldn't have to hassle with charging ht e separate battery. You may be able to adjust your charger to a higher voltage, depending what you have and how much knowledge you have in that field.
You won't likely have a controller problem unless you ride wot all the time. And even then you may not have a problem. A 12V increase isn't a lot on a 60V system.

 

[LarryHoova]

I like how you think.
When you added the other battery you did 3 things.
1. You increased speed. If you want to go slower, let up on the throttle. That will also increase range.
2. You added more wh so you can go farther on a charge if you keep the speed down to the speed before.
3. You disabled the LVC safety feature that would cut you off when the 5 batteries reached a certain voltage. Usually 10-10.5V per battery. If you now run your battery down to lvc, you will over discharge all 6 batteries, so you need to be careful with this and stop riding at 60-63V. The same 10-10.5V per battery as LVC was set for for 5 batteries.

Don't know why you consider the increased speed a problem. Most people want more speed.
I'd probably just buy a 72V charger so I wouldn't have to hassle with charging ht e separate battery. You may be able to adjust your charger to a higher voltage, depending what you have and how much knowledge you have in that field.
You won't likely have a controller problem unless you ride wot all the time. And even then you may not have a problem. A 12V increase isn't a lot on a 60V system.

thanks for the info

32km/h is the max speed for ebikes here where I live :/

I am thinking about manually adjusting the throttle cable or something to make my own form of limiter?
Would a new controller reduce the speed back to 32?

The other thing is that when I roll downhill now with the throttle off, I used to max out at around 34km/h - now it seems like there is no resistance and I had to hit the brakes once I hit over 40! The bike is a heavy ass tank of a machine and I have no idea how fast gravity can get it to go lol.

I just did a run up and down the hardest longest hill in my area and it went 35km uphill and 39 downhill - unless my speedometer is not accurate.

The charger I have now sucks and is a simple 60v putting out 68v. For now I will make a switch and charge them separately.

This switch will also allow me to go from 60v to 72v on the fly... or switch it from 72v to 60v