High output alternator charge rate

Darkspeed · September 20, 2015, 09:41:19 AM

I know some of these buses have a very high output alternator, has anyone fried their batteries because of the fast charge rate?

If you had a flat battery bank how are you regulating the high charge rate?

Thank you!

pvcces · September 20, 2015, 02:13:11 PM

This would mean that a 250 amp hour battery such as an 8D should be recharged from empty to full in about 5 hours.

I understand that AGMs might be able to handle up to twice that rate. Compare this to lithium batteries which can approach a full charge in an hour or less.

Alternators are a current limited design; they don't regulate the maximum current. Instead, they use voltage regulation to prevent an overcharge. Since changing battery performance from a temperature change is dramatic, a fixed voltage regulator is a poor method of controlling the charge rate.

Voltage regulators which have a profile that closely matches the battery bank should give the best longevity.

For what it's worth.

Tom Caffrey

bevans6 · September 20, 2015, 04:38:29 PM

As I understand it the internal resistance of the battery is what limits the charge current. A high current alternator is kind of like having a 200 amp service at your home - i fyou only have a 100 watt light lit up, that's all it draws. what happens, or could happen, with a battery failure is anyone's guess.

Brian

Tony LEE · September 20, 2015, 06:46:09 PM

I have a 512Ah 24V AGM battery in the MC8 and only ever saw a maximum charge current of about 180 amps out of the alternator into the house battery. This tapered off fairly quickly over the first hour as the voltage rose towards 28V so there was little or no chance of it reaching the gassing point and damaging the batteries.

luvrbus · September 20, 2015, 08:29:00 PM

I have a Humvee with a 200 amp 24V system (military) that has a ambient temperature sensor alternator made by Technology Ventures when it senses to much ambient heat (106.5) the regulator will reduce the charge by 50% a neat setup for desert use

Darkspeed · September 20, 2015, 09:53:07 PM

Quote from: luvrbus on September 20, 2015, 08:29:00 PM
I have a Humvee with a 200 amp 24V system (military) that has a ambient temperature sensor alternator made by Technology Ventures when it senses to much ambient heat (106.5) the regulator will reduce the charge by 50% a neat setup for desert use

Interesting.. I am wanting to build DC charger using 400A Niehoff but if (?) it is a PMA there is no way to modulate the field coil to control charge rate other than the internal resistance of the battery bank, I am planning on using LiFeYPO4 batteries and want to stat under C1 so this becomes a problem. If it is not PMA it gets a lot easier to do. Will have to see when I get my hands on it.

It had just occurred to me that the buses with the 250+ amp alternators would be rough on a smaller dead battery bank without some form of current limiting device.

luvrbus · September 21, 2015, 04:52:18 AM

Check out the Balmar marine line of regulators the marine world gets way out there with their batteries and charging ? general cost of the ION battery bank if you don't mind I am looking into 2-24 volt 180 amp Victron Lithium -Ion batteries if we can agree on a price

Darkspeed · September 21, 2015, 07:40:48 AM

Quote from: luvrbus on September 21, 2015, 04:52:18 AM
Check out the Balmar marine line of regulators the marine world gets way out there with their batteries and charging ? general cost of the ION battery bank if you don't mind I am looking into 2-24 volt 180 amp Victron Lithium -Ion batteries if we can agree on a price

Victron makes a really good solution for charging Lithium batteries. I think the Victron Lithium was their way of capturing more $$$ because they saw people buying the Chinese Lithium batteries and pairing them with a Victron charger. Im pretty sure its a Chinese in a custom Victron case.

I am eventually going to build a bank out of 700ah 3.2v Winston or Thundersky cells with a monitor board on each cell. The best prices i have seen in the US come from a direct importer http://www.alliancerenewableenergy.com/Thunder-Sky-LiFeYPO4-Batteries_c3.htm but I have friends in china that say they can buy them locally a lot cheaper and then ship them over to me when i am ready.

For example an 8 cell bank would be around 24v @700ah ( 17.8kwh ) 22" x 24" and weigh 455lb no charge memory and last into the 5-7k charge cycles.

The only issue is they need to live where you do, you cant stick them in a non climate controlled bay and expect them to live very long.

Darkspeed · September 21, 2015, 07:53:57 AM

It is interesting that they require a DC:DC isolator for all dc loads that use the frame as the negative wire, on a bus that could be a lot of load > http://www.victronenergy.com/upload/documents/Datasheet-BMS-12-200-EN.pdf

Tony LEE · September 22, 2015, 05:28:43 AM

Quoteyou cant stick them in a non climate controlled bay and expect them to live very long.

So then you need another bank of AGMs to run the aircon for the lithiums. Good one.

Oonrahnjay · September 22, 2015, 07:00:42 AM

Quote from: Darkspeed on September 21, 2015, 07:53:57 AM
It is interesting that they require a DC:DC isolator for all dc loads that use the frame as the negative wire, on a bus that could be a lot of load > http://www.victronenergy.com/upload/documents/Datasheet-BMS-12-200-EN.pdf

It's a little unclear to me, but all that seems to be needed if there is a single charge system that it connected equally and openly to both the start batteries (which the assume to be lead-acid) and the Li-Ion batteries. But I'm not sure.