- Thread starter
- #101
Did you adjust the alternator voltage up with caps or a resistor?
LTO Starter Battery
- Thread starter grinchy
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
You may want to regulate the current somehow so you don't burn out your alternator. I was more concerned with the charge voltage profile being designed for LA. I know my vehicle alternator is temperature compensating, so it only puts out ~13.4V when warm and probably wouldn't play nicely with more exotic Li chemistries. I imagine the smart alternators would play even less nicely.
I didn't, as when it was running the SLA, it was charging at 14.5v, which is "ideal" for what I am running. It is interesting that the car now runs at a lower voltage (14.1-ish), so it is something I may consider. If it continues to charge at low 14s, I will def consider modding it to bring it up to 14.5
I have considered this. Short version: As they are 35AH cells, the time taken to charge them to 14.5 volts is fairly low. Even if I didn't drive it for a few days, there would be 0.1AH draw max, so a couple of AH. To recharge 2.5AH would take (at 25amps) 6 minutes. Even if the alt was cooking at 100amps, it would be less than 2 minutes. This is assuming it is putting out the max amps, which it wouldn't, as the voltage difference got smaller. I am pretty sure that a Ford escape 2010 doesn't have a smart alt, but I should double check anyway..... one should never assume!
Would this be suitable for the mod?
I understand that a fuse in series with this is even better...
www.autoelectricalparts.com.au
I understand that a fuse in series with this is even better...
Littelfuse 02400104P Littlefuse 02400104P Mini Blade Diode 1A 400V Keyed
Littlefuse 02400104P Mini Blade Diode 1A 400V Keyed
www.autoelectricalparts.com.au
- Thread starter
- #105
I used a 1A diode. Don’t remember what voltage it was rated at. Got 0.5v increased charge with it In place
Julian73
SILVER Star
ANL fuses while offering a very wide range of rated amperages, don't have great Interrupt Capacities. Class T offers IC of 20kA, Terminal Fuse (aka MRBF) 10kA, ANL 6kA and MIDI 5KA. I uses MRBF's on my system due to fairly high IC, useful rate of 30 to 300 amp sizes and compactness.
HIgh C-rates definitely allow for high current availability in a small capacity package. I can see the desire to use these as a starting battery, and for car manufacturers to eventually go in that direction.
Not as good though for low C-rate long duration draws I would think. That is where LA or LFP excels.
Not as good though for low C-rate long duration draws I would think. That is where LA or LFP excels.
Julian73
SILVER Star
*** edit *** didn't realize I was responding to year old stuff. Sorry.
I think the appeal is:
- extreme longevity and reliability
- extreme temp operational envelope
- very safe
- weight savings over SLA
- Thread starter
- #110
Fully agree on using a class t fuse. I did get one for my LTO project, but when the cells went missing ended up using it instead as a fuse on my winch install:
- Thread starter
- #111
The potential trouble would be driving the alternator at full tilt for an extended period of time, maybe 30 min? I had decided to put a choke on the alternator Input by adding a small series resistance, of 1 ohm or thereabouts. Did some calcs and stainless steel m6 all thread would do it, need around 10cm of it. Could adjust the length to provide the target resistance. Only an idea, as I never built the battery.
Agreed. There are RV and marine folks who have dealt with this for LFP batteries. Check diysolarforum.com
I appreciate the full tilt alternator advice. This will not be an issue. The car is driven daily, the battery is 35ah, the overnight draw did not show a drop in voltage, keeping in mind that these batteires don't lose charge while sitting, only to running my alarm... unlike SLA.
In the event that I add another battery, or go van-lyfe, I will sort it out.
Small update. It is the air con that is causing the voltage sag. When it is on, I get 13.8 - 14.0. When it was off this morning and it was cool(ish) 20C or so, it charged up to 14.3 within 30 seconds. (Which is another factor for me not to worry about the alt catching on fire
)
In the event that I add another battery, or go van-lyfe, I will sort it out.
Small update. It is the air con that is causing the voltage sag. When it is on, I get 13.8 - 14.0. When it was off this morning and it was cool(ish) 20C or so, it charged up to 14.3 within 30 seconds. (Which is another factor for me not to worry about the alt catching on fire
)
- Thread starter
- #114
Yes, I get that you’re not planning to use the battery for house duty. And agree that the only risk is if you drop it down to say, 5ah. Even so, 150/30 is 5, so you should get that 30a in 60/5, 12 min. Probably won’t cook the alt in 12 min. Put the resistor in line to drop the alt down to 120A effective, and it would take 120/30,4 60/4, 15 min to recharge and no worry of cooking the alt. Glad to see an LTO in use and very curious to see what else you learn from living with it for a bit.
Still running well. Next up is adding a balancer (Heltec), with a voltage sensitive switch, so it only balances over 13.8v
In another week or so I will pull it, do some voltage tests on each cell. Probably should lable the cells too
If everything goes to plan, I will make another, do a youtube video of the making of it, get it installed in the wife's car. Or something
In another week or so I will pull it, do some voltage tests on each cell. Probably should lable the cells too
If everything goes to plan, I will make another, do a youtube video of the making of it, get it installed in the wife's car. Or something
Added a balancer as above, ordered 2 new boards as I broke the solder patches and had to "dodgy" the on switch... sigh.
Been going for 3 months or so, still planning on making another, I have the cells, just made the bus bars and will make some design improvements on this next one. The balancer uses SFA power. Once the new one is complete, I will drop that one in the car, take the old one out and capacity test it.
Then, assuming no issues with the "old" battery, I will improve the configuration and put it into the wife's car.
As a side note, Heltec have apparently made custom active balancers that have a voltage detection circuit for LIPO4, so they only run at the very top of the charge cycle.
While that would be cool for my application, it really doesn't make any difference.
Been going for 3 months or so, still planning on making another, I have the cells, just made the bus bars and will make some design improvements on this next one. The balancer uses SFA power. Once the new one is complete, I will drop that one in the car, take the old one out and capacity test it.
Then, assuming no issues with the "old" battery, I will improve the configuration and put it into the wife's car.
As a side note, Heltec have apparently made custom active balancers that have a voltage detection circuit for LIPO4, so they only run at the very top of the charge cycle.
While that would be cool for my application, it really doesn't make any difference.
- Thread starter
- #117
Glad to hear it’s been solid!
I inadvertently stress tested it today. I had it out to find a fault (loose balancing wire) so I did a capacity test. It came back same capacity as when I put it in, which is even better than I thought it would be. Of course after the capacity test, you charge it back up and drop it in, right? Not so much.
I put it back in at 12v. Got in the car, saw it was super low and thought wth? Even with maybe 3-6ah left in it, the car started first pop. (2.5L NA) Drove it 2 minutes to the shops, during which time the voltage showed low 13s. At the shops on accessories only, it had been brought up to a bit over 13v. No problem restarting, 13.5v - 14v on the 2 minute drive home, sagged back on turnoff to 13.5v.
These are the times when watching the alt temp would be a good idea, especially here in QLD where it is 30C and I am running the aircon plus lights. Still, I am super impressed with the setup. Once I get proper lugs for the balancer wires, it will be all go! A Youtube vid will (probably) follow at some point, where I show making up the second battery, missing out all the mistakes I made with the first one!
I put it back in at 12v. Got in the car, saw it was super low and thought wth? Even with maybe 3-6ah left in it, the car started first pop. (2.5L NA) Drove it 2 minutes to the shops, during which time the voltage showed low 13s. At the shops on accessories only, it had been brought up to a bit over 13v. No problem restarting, 13.5v - 14v on the 2 minute drive home, sagged back on turnoff to 13.5v.
These are the times when watching the alt temp would be a good idea, especially here in QLD where it is 30C and I am running the aircon plus lights. Still, I am super impressed with the setup. Once I get proper lugs for the balancer wires, it will be all go! A Youtube vid will (probably) follow at some point, where I show making up the second battery, missing out all the mistakes I made with the first one!
Hi guys, I just registered because I found this thread on Google. I just wanted to let you know that I did the very same thing. My 6s LTO battery is running strong. Here is my thread:
Images:
Images:
Very cool. Thanks for posting!
