48 Volt Lithium Battery Upgrade?

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L0veless

Member
I have built some batteries for my RV and they worked great.
Looking for some guidance on upgrading to Lifepo4 lithium batteries. I will be running 16s series battery with a recommended BMS.
I see 105 Ah batteries with 3c ratings is 100 amp enough power for constant driving?
I have to jump to 130ah for a 6c rating I'm thinking that is over kill ?
For just cruising the golf course ( I know first one there never has a bad lie) how many amps are really needed? running a stock 2006 precedent.
Thank you in advance
 
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Pat911

Cartaholic
Hi L0veless,

This is what I like, someone having a go at making their own.

A stock 2006 Precedent draws about 60A on steady flat ground but between 100A-150A when accelerating hard up a slight incline. I have a 2013 Precedent that is very similar.

Is the 3c rating continuous or peak? If continuous,105Ah with 3c can supply 315A continuous. Why not use a 200A BMS and have a battery that can supply 200A continuous and in the region of 500A peak?

If it’s 3c peak, then continuous is likely 1c. I’d still go with the 200A BMS for added reliability but set it’s parameters to trip if continuous current is greater than 105A for 20 seconds and trip within 1 second at 315A.

The other thing you need to look at is the maximum charge current that both the cells and the BMS can handle. This is not for normal charging but for regen braking where the motor acts as a generator and pushes excess power into the battery, charging it. You don’t want the BMS tripping of under regen, especially down a long steep hill.

Do you have a link to the cells and BMS you’re looking at purchasing, I can advise further after reviewing them better. I build all my own lithium batteries, both LiFePO4 and NMC and believe that making your own is a better solution than the drop-ins. But it’s not for everyone.

Cheers
Pat.
 
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L0veless

Member
WOW Pat Thank you for the information, this is exactly what I'm looking for.
3c is peak with 1c continuous.
I purchased my other from Ali express (280ah) worked great no issues (learned a lot about top balancing)

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Im kind of leaning toward these for what little more they cost. plus the 6000 cycle is impressive.
https://www.aliexpress.com/item/1005002898060619.html?spm=a2g0o.productlist.0.0.598f127bo0EBq8&algo_pvid=9c45ba4a-034b-4d51-a5c8-3274b2da76d6&algo_exp_id=9c45ba4a-034b-4d51-a5c8-3274b2da76d6-0&pdp_ext_f=%7B%22sku_id%22%3A%2212000022672743562%22%7D
And the BMS will most likely be a daly

never thought of regen, can that be turned off?

I'm doing my research now as my batteries are good, but next year it will be time to start looking
 
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Pat911

Cartaholic
Those 150Ah LiitoKala cells are excellent value for the money but I doubt you will get 150Ah from them, more like 135Ah-145Ah, but still great value. The last lot I purchased were LittoKala 200Ah and measured at 188Ah.

Why would you want to disable regen? It helps with braking and recharges your battery when you slow down, win-win. Also stops your cart rolling away if the park brake is forgotten.

I originally liked the Daly BMS’s but have now changed to the JBD ones. They are much more configurable. Their current ratings aren’t as high as the Daly but there are ways around this, especially if you’re using cells which can easily handle the current requirements of your load. The cells you linked to can provide 450A continuous and 900A peak, well under your carts specs. The BMS doesn’t have to provide over current protection, just use it for cell over/under voltage protection and charge protection. Protect your pack with a 450A fuse to be safe.

The cells in my Precedent can provide 550A continuous and I’m using an 80A JBD BMS. Only the charger current flows through the BMS, not discharge or regen current. The BMS protects over discharging by disabling the key switch line to the controller. So if any cell gets too low, the BMS effectively turns off the carts key and the cart stops, preventing damage to the cells. The drop-in solutions are made so that they can be dropped in to any cart, so they protect the cells by cutting off all the power, to do this they must pass discharge current through the BMS. Makes them less flexible.

Cheers
Pat.
 
Diode

Diode

Cartaholic - V.I.P. Sponsor
FYI regen and plug braking are two different things
regen slows you down when you let off the pedal
plug keeps you from rolling away
 
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L0veless

Member
Disconnecting the Regen shows how little I know about these carts. when you mentioned over charging.
I will be looking at the JBD BMS .
their lit, does say150ah to 130ah in the small print I believe.
So you run an 80amp BMS just to charge and 450 amp breaker/fuse on the output?
again thank you Pat I will be researching this out and most likely have alot more questions
 
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Pat911

Cartaholic
Yes, I run an 80A BMS and I charge with a 33A charger. Well within specs.

I didn't see the 130Ah-150Ah fine print but if that's the case then why not advertise them as 130Ah, then they won't get the bad reviews when they don't meet spec. They're still excellent value at 130Ah though.

The BMS passes charge current only, but protects for pack and cell over charging and over discharging as well (high and low voltage). The high voltage cell and pack protection is done by cutting the charge current directly. The low voltage cell and pack protection is done by switching off a 48v relay that is connected to the battery positive and P- connector on the BMS. (P- will go high if the BMS detects a fault condition) The relay then in turn breaks the key switch line to the controller.
 
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L0veless

Member
Diode,
thank you for the input on the braking system, would this set up be enough amp to upgrade to your "speed code 5" down the road if wanted?
 
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