Visit our Popular Forums

kmacdonald · 04-10-2018, 06:08

Quote:

Originally Posted by john61ct

Yes, as long as the noob is trainable, willing to pay attention.

And write big checks.

DIY is easy if you watch everything yourself.

Trying to get foolproof automation becomes a science project.

That's exactly right.

kmacdonald · 04-10-2018, 06:15

It's easy enough to determine charge current and load current. It just takes multiple shunts in different locations or busses and a little subtraction to get the results you want. The system gets more complicated and expensive though.

Sure, there are examples of success but the failures rarely get reported. And the failures are EXPENSIVE. Several companies quit selling LFP. With all the advantages of LFP, everyone would use them if it was easy or viewed to be cost effective.

GaryBode · 04-10-2018, 06:29

Follow the battery manufacture's requirements. A lithium battery manufacturer I was looking at suggested a 40A charger to prevent long-term damage to the batteries. Check the manufacturer's data sheet.

john61ct · 04-10-2018, 08:43

No, with LFP, the battery makers' spec'd recommendations are for much too-high voltages and too-deep cycling.

Following them will only get you their rated cycle lifetimes.

If you want greater longevity, avoiding the voltage shoulders will get much much longer, perhaps decades, we just don't know yet what is possible.

And maximum charge rates are often way too conservative, if you want fast charging, just need robust infrastructure and to monitor for overtemp

GaryBode · 04-10-2018, 09:20

The life cycle is longevity.

GaryBode · 04-10-2018, 09:25

Dude, I don't know why you are posting something like this in a forum with people you can't validate their knowledge of when you can easily check the manufactures website or ask a professional. I've read these posts and either the person knows nothing of which they type or are a frikking expert. People on these forums have quoted wikipedia for crying out loud. These people will get you into trouble. It's fine to ask for someone's preferences on something to get an idea of what you like, but when it comes to technical data go directly to the source.

Fair winds.

CGirvan · 04-10-2018, 12:22

Quote:

Originally Posted by travellerw

Look at the IOTA charger I mentioned earlier. Without the IQ4 option, its just a VERY robust power supply. Its designed to run full bore for days on end. It has a pot inside that allows you to adjust the voltage (between 12V and 15V). For LiFePO4 you set it to 13.8V and watch the current. Manually stop when you see C/100.

For initial balancing don't you need to parallel the cells and charge to 3.5-3.6.
I was looking at:

15V 50A Variable Regulated DC Power Supply HY1550EX for multi-lane Slot Car tracks - Volteq - Reliable Regulated Variable DC Power Supplies

Hoping this would do the job and I could use as a 110v charger for the odd time I need to run the Honda 2000 to charge. I'm thinking the majority of my charging will be via solar.

travellerw · 04-10-2018, 12:44

Quote:

Originally Posted by CGirvan

For initial balancing don't you need to parallel the cells and charge to 3.5-3.6.
I was looking at:

15V 50A Variable Regulated DC Power Supply HY1550EX for multi-lane Slot Car tracks - Volteq - Reliable Regulated Variable DC Power Supplies

Hoping this would do the job and I could use as a 110v charger for the odd time I need to run the Honda 2000 to charge. I'm thinking the majority of my charging will be via solar.

First, let me say there are many ways to do the initial balancing. Yes, Mainsail talks about using a benchtop power supply and doing the pack as a parallel bank. There is nothing wrong with this, and its probably one of the "safest" options. However, it TAKES A VERY LONG TIME.

I didn't have access to a benchtop supply (nor could I ship one here), so I had to come up with a different way. Instead I used my standard onboard charger with the bank hooked up in series. I monitored each cell with my multimeter as the charging progressed. The first 3 hours was pretty boring as the cells pretty much stayed balanced the whole time I was puting in 65A. However, as the individual cells climbed past 3.4V I started to see some imbalance happening. At that point I used a 0.1 OHM 100W resistor ($15 at Digikey) to bleed the high cell. I would then recheck about every 1.5 minutes and bleed again. To push from 3.4V/cell to 3.8V/cell took about 1 hour (so it was a boring hour of repetative work). At that point the cells were within 0.01V of each other and slowly dropping. I reconfigured them in parallel and let them sit for about 18 hours.

In the morning each cell was reading 3.52V. So I reconfigured them back into series and let them sit another 24 hours. At 24 hours they were all still perfectly balanced. I have been using them ever since and they are all still within 0.01V of each other at 3.45V/cell.

P.S. There is no way that power supply you posted could run at its full rated 50A @ 13.8V. I guarntee you will let the smoke out if you do that even a couple of times. It would probably survive 25-30A though. Personally, I think I IOTA chargers are a better deal if you are willing to put in the work like I did.

john61ct · 04-10-2018, 13:06

Quote:

Originally Posted by CGirvan

15V 50A Variable Regulated DC Power Supply HY1550EX for multi-lane Slot Car tracks - Volteq - Reliable Regulated Variable DC Power Supplies

Specs look good but dunno the maker.

Also check out Mean Well (meanwell, mean-well)

john61ct · 04-10-2018, 13:09

Yes overcurrent protection is critical.

But since there's rarely a need for high current doing maintenance / testing, just let it sit around halfway.

Or monitor temperature as you get up past 3/4

john61ct · 04-10-2018, 13:13

iCharger 4010-Duo was recommended to me by an RC group, DCDC can run off PC style PSs, or buffered off an existing bank, usually 18-28V

Can apparently automate load testing too

Saving my pennies or waiting for someone else to pioneer 8-)

GaryBode · 04-10-2018, 15:03

Use a product rated for the use and environment of a boat.

Zil · 04-10-2018, 18:11

If we are still on the subject about chargers, my ProNauticP has temperature sense wiring, but no battery terminal voltage sense wire. My cables are sized for the distance and max amperes for a 1% voltage drop. That solves that problem.

mitiempo · 04-10-2018, 18:33

Quote:

Originally Posted by Zil

If we are still on the subject about chargers, my ProNauticP has temperature sense wiring, but no battery terminal voltage sense wire. My cables are sized for the distance and max amperes for a 1% voltage drop. That solves that problem.

Pronautic P chargers come with a temperature sense cable designed to go on a battery post.