LTO bank vs LiFeP04 for daily system

[mat3833 10+ year member]

Alright, small update. From what my VW friends say there is a Regulator for the ECU. Since my car gets grumpy below 15v but above 14.5ish they are suggesting they my ECU Regulator might be going out. A simple modification to make the car accept 15v charging is to add a load resistor with a heat sink to the ECU power line in the harness.

So, I'm going to look into that but the ECU should be happy at anything below 15v. That means I can charge at 14.8v with a harness mod and run 6s LTO and get 75-80% of their capacity. I will need to figure out some kind of balancer that works at that lower voltage threshold, but that's a project for another day.

The alternator shop is trying to figure out what parts they can actually get to build the alt so no more information on that yet.

Matt

 

[winkychevelle 10+ year member]

Alright, small update. From what my VW friends say there is a Regulator for the ECU. Since my car gets grumpy below 15v but above 14.5ish they are suggesting they my ECU Regulator might be going out. A simple modification to make the car accept 15v charging is to add a load resistor with a heat sink to the ECU power line in the harness.

So, I'm going to look into that but the ECU should be happy at anything below 15v. That means I can charge at 14.8v with a harness mod and run 6s LTO and get 75-80% of their capacity. I will need to figure out some kind of balancer that works at that lower voltage threshold, but that's a project for another day.

The alternator shop is trying to figure out what parts they can actually get to build the alt so no more information on that yet.

Matt

Balancers don't really care about the total system voltage they simply balance the cells. I'm assuming you are talking about a bms which can turn the bank on and off due to voltage hi or low, or temp high and low.

Those typically have an amperage rating not really made for high amperage draw.

 

[mat3833 10+ year member]

Balancers don't really care about the total system voltage they simply balance the cells. I'm assuming you are talking about a bms which can turn the bank on and off due to voltage hi or low, or temp high and low.

Those typically have an amperage rating not really made for high amperage draw.

No, from what I understand (could be wrong) balancers have a minimum voltage threshold at which they will start balancing the cells. If Im charging at 15v that's almost .3v per cell below Cutoff for a 6s pack and may not be in range for the balancer to begin its balance process.

Matt

 

[mat3833 10+ year member]

Balancers don't really care about the total system voltage they simply balance the cells. I'm assuming you are talking about a bms which can turn the bank on and off due to voltage hi or low, or temp high and low.

Those typically have an amperage rating not really made for high amperage draw.

Nevermind, the balancer I'm looking at has a start voltage of 2v so it will work at anything above 12v on a 6s pack.

 

[hispls 5,000+ posts]

Nevermind, the balancer I'm looking at has a start voltage of 2v so it will work at anything above 12v on a 6s pack.

I'm not entirely sold on any of the balancing options I''ve seen yet. My guy in China said it really doesn't get terribly important until you get into much higher voltages than we're running in a vehicle. Of course I'm not going to discourage anybody from anything and you might get 5 more years out of your cells than I or whatever, but from where I'm sitting if all my cells crapped out next year I'm already ahead of the game than if I'd have bought AGM so they really don't owe me anything at this point.

I've been buying and dealing with AGM for a long long time so that's sort of the standard with which I measure acceptable cost/space/weight/life of battery systems.

 

[mat3833 10+ year member]

I'm not entirely sold on any of the balancing options I''ve seen yet. My guy in China said it really doesn't get terribly important until you get into much higher voltages than we're running in a vehicle. Of course I'm not going to discourage anybody from anything and you might get 5 more years out of your cells than I or whatever, but from where I'm sitting if all my cells crapped out next year I'm already ahead of the game than if I'd have bought AGM so they really don't owe me anything at this point.

I've been buying and dealing with AGM for a long long time so that's sort of the standard with which I measure acceptable cost/space/weight/life of battery systems.

So out of curiosity, you run a 6s pack correct? When you charge at 14.4 you are basically "charging" at 2.4v per cell. Obviously you can get more power out of them at 2.8v per cell, but in your opinion is a 6s2p pack going to perform well enough "only" charging slightly over resting voltage?

Matt

 

[hispls 5,000+ posts]

So out of curiosity, you run a 6s pack correct? When you charge at 14.4 you are basically "charging" at 2.4v per cell. Obviously you can get more power out of them at 2.8v per cell, but in your opinion is a 6s2p pack going to perform well enough "only" charging slightly over resting voltage?

Yes but really I've been meaning to get my alternator shipped out to be externally regulate so I can do 15 and a bit. Or pending testing with 5S bank of Toshiba cells I may just keep with that. I'd prefer to charge 6s higher but with the size bank we use here we're certainly not losing performance. .

 

[mat3833 10+ year member]

Yes but really I've been meaning to get my alternator shipped out to be externally regulate so I can do 15 and a bit. Or pending testing with 5S bank of Toshiba cells I may just keep with that. I'd prefer to charge 6s higher but with the size bank we use here we're certainly not losing performance. .

Yea, I think 80ah is more than enough for my power level so I won't be stressing the cells much at all. I'm thinking 5s2p is the way to go for me since my factory charging voltage is supposed to be13.8-14v and my alt guy can regulate anywhere between 13.5-16v.

Matt

 

[HondaCRV03]

Yes but really I've been meaning to get my alternator shipped out to be externally regulate so I can do 15 and a bit. Or pending testing with 5S bank of Toshiba cells I may just keep with that. I'd prefer to charge 6s higher but with the size bank we use here we're certainly not losing performance. .

Coventry industries sells a voltage adjuster for internally regulated alternators. I got one for my CR-V. I have to get around to installing it. You can adjust up to 15.8 I think. I'll post a link

Voltage Control Knobs | Coventry Industries

Voltage Regulator, Wire into any aftermarket alternator, easy to install, Comes in a variety of colors, order now.

coventryind.com

 

[hispls 5,000+ posts]

Coventry industries sells a voltage adjuster for internally regulated alternators. I got one for my CR-V. I have to get around to installing it. You can adjust up to 15.8 I think. I'll post a link

Voltage Control Knobs | Coventry Industries

Voltage Regulator, Wire into any aftermarket alternator, easy to install, Comes in a variety of colors, order now.

coventryind.com

How does that connect? Know anybody who owns one? Honestly for 120ish I can own an external regulator and I'm sure Nate can add the external regulating terminal on mine for not much more cost than the ride there and back.

 

[winkychevelle 10+ year member]

The pcm bypass is rather simple.

Pwm+ to alt pwm+ disconnect factory pwm+

Then the other 2 is ignition and ground

 

[HondaCRV03]

How does that connect? Know anybody who owns one? Honestly for 120ish I can own an external regulator and I'm sure Nate can add the external regulating terminal on mine for not much more cost than the ride there and back.

It comes with directions. I'll see if I have the pic in my phone

 

[hispls 5,000+ posts]

The pcm bypass is rather simple.

Not when your alternator just has one wire. That unit isn't actually for internally regulated alternators but for alternators regulated by ECM.

 

[hispls 5,000+ posts]

Not when your alternator just has one wire. That unit isn't actually for internally regulated alternators but for alternators regulated by ECM.

If I sent my alt back to Nate to have the field lead added and internal regulation pulled I'd just buy the blue aluminum regulator I've used in the past.

 

[metalheadjoe 10+ year member]

Alright, small update. From what my VW friends say there is a Regulator for the ECU. Since my car gets grumpy below 15v but above 14.5ish they are suggesting they my ECU Regulator might be going out. A simple modification to make the car accept 15v charging is to add a load resistor with a heat sink to the ECU power line in the harness.

So, I'm going to look into that but the ECU should be happy at anything below 15v. That means I can charge at 14.8v with a harness mod and run 6s LTO and get 75-80% of their capacity. I will need to figure out some kind of balancer that works at that lower voltage threshold, but that's a project for another day.

The alternator shop is trying to figure out what parts they can actually get to build the alt so no more information on that yet.

Matt

Does the load resistor function as a voltage divider? Sounds like a lot of wasted energy.
Does "gets grumpy" mean check engine light?
What I'm getting at is a tuner could correct many of the ecu's gripes. More money, but I'm not a fan of tricking the ecu.