Charging Batteries Driving

[Defjr333]

I have seen numerous posts from people in reference to charging their deep cycle batteries via the alternator while driving. The replies seemed mixed. Anything from a "just hook em together with crappy wire" to "cant be done, wont work". While both these are somewhat true, I wanted to share how I have done this in the past on my old ambulance and friends vehicles. This device allows for charging of the "house batteries" with the best charging I have seen from a 12v source. While not cheap, it does what it says:

https://sterling-power.com/collectio...20a-waterproof

It gives you a 4 stage battery charge curves based on battery type selected. Isolates the start battery so alternator does not sense a full battery and decrease output. Steps up and down voltage/ currents to give best output to batteries. And more safety related items. While the price is not cheap, if you drive a lot, I see it being very useful. They do have lower priced units like this one:

https://sterling-power.com/collectio...ers-up-to-130a

It is not as easy to install and can cause issues with some vehicles with regenerative breaking and such. They offer models from 20Amp to 400Amp! I have used the 60 and 120 units with no issue. The 1st link is literally the EASIEST INSTALL EVER!
Doug

[Dead pirate]

This is a great thing. I have struggled. My alternator can charge my " house" solar batteries, but if they are too low ohms law and all. Three wires burn or out blows all my fuses

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[cadillackid]

ive got huge welding wire running to my house batteries.. and there is an isolator which is voltage activated.. so it cycles in and out if the batteries are really dead ands just starting to charge.. as it pulls the main voltage down a bit in the beginning.. there are ionternal timers to its micro which have it so it doesnt cycle multiple times per second, it goes every few seconds until the voltage begins to rise enoug hthat the current pull isnt too high to droip the main voltage.. i also have 150 amp breakers that are auto reset against that welding cable..

im sure im not gettin g the bestest charge using the alternator but seems to suit me just fine..
-Christopher

[Dead pirate]

Got a link on that isolator?

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[david.dgeorge07]

Originally Posted by cadillackid

ive got huge welding wire running to my house batteries.. and there is an isolator which is voltage activated.. so it cycles in and out if the batteries are really dead ands just starting to charge.. as it pulls the main voltage down a bit in the beginning.. there are ionternal timers to its micro which have it so it doesnt cycle multiple times per second, it goes every few seconds until the voltage begins to rise enoug hthat the current pull isnt too high to droip the main voltage.. i also have 150 amp breakers that are auto reset against that welding cable..

im sure im not gettin g the bestest charge using the alternator but seems to suit me just fine..
-Christopher

Planning to do something like this. Do you have your build documented somewhere?


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[Defjr333]

Be sure it is a microprocessor controled isolator, diode ones have MUCH larger voltage drops. This is same concept as CadilacKids just all in one type. Plus true 4 stage charger. If you upgraded alternator it could do a nice job. Only if u move around a lot though.

[gbstewart]

I ran a heavy wire off a start battery to a starter solenoid , then to my house battery, I have a switch on the dash to turn it on/off. should I have a dead start battery and boost myself off the house battery, if the alternator stops working I can start my generator and charge all the batteries to keep going, all from the comfort of the drivers seat.
gbstewart

[cadillackid]

this ias the isolator I used.. it is a micro type with a solenoid.. I wanted this type as it has much less drop than a solid state type.. plus i can force the solenoid on if I want to attach the house batteries to the starter batteries manually for any reason.

https://www.powerstream.com/battery-isolator.htm

I have never measured the current going through as putting a shunt in the high amp line would cause voltage drop in and of itself..

my Bus alternator is a Bosch SB-200 which is a 200 amp that pushed out 80% of its power at 1200 RPM (alternator RPM not to be confused with engine RPM)..

I have very little voltage drop with the welding wire. I ran the welding wire back to the batteries and then ran welding wire from the batteries to my GoPower sine wave inverter.

Yes my batteries are Indoors.. however the only time they are charging is when the bus is running.. the bus is stock (a few seats and all windows except for my DEV work area) so I dont worry about off-gassing.. they are Batteries-plus AGM deep cycle group 31's. 2 of them.

the only time I really use the batteries is if I park at a rest area for a few hour nao and want A/C or light heat (I have a portable inverter 2 hose A/C.. when I want cool I put the hoses in a bus window and it runs on the batteries for 4-6 hours at full power.. or close to all night if it is not under full load.

that same device if i sit it outside on the ground and run the hoses into the bus window blowing in acts as a heat pump... puttint it on turbo cool means it ignores the thermostat.. it will shut off if it freezes up.. but if that cold outside Ill leave the bus turned on anyway..

only runs like 3 hours as a heat pump before killing the batteries.

-Christopher

[Tedd]

Although alternators are not sufficient to charge deep cycle batteries properly, you might consider upgrading your alternator to a 200+ amp unit and install a Battery Isolater/Relay which will prevent the house batteries from discharging the bus SLI (starter, light, ignition) batteries but allow charging current from the alternator to charge the house batteries while under way.

A lot of folks suggest using the Stinger. I've installed one in my system to augment my on-board charger and it seems to do the job very nicely. Cheap ... under $75.00

https://www.caraudiogiants.com/produ...yABEgL0TPD_BwE

I would also suggest installing an old style Ford starter solenoid into the system which would allow you to jump start your bus from the houses batteries if your bus SLI batteries should go dead. A dash mounted switch make this solenoid work. These are cheap also, under $15.00.

https://www.dbelectrical.com/product...CABEgInpvD_BwE

I see NEW GM AD244, 250 amp alternators at about $150.00

If you do this, make sure that you run all new #1 welder wire from the battery + terminal on the alternator to ALL connections, hot AND ground, to carry amperage to and from the battery. Make sure that ALL your connections are clean, tight and dry! If you are not going to use proper gauge wire and have corroded or loose connections, expect nothing but trouble.

Total on this modification could be about $250-$275.

For the record, I have two 875 amp SLI Batteries for the bus and three 900 amp deep cycle batteries for the house. The system operates and charges just fine.

[somewhereinusa]

Ford starter solenoids are not rated for continuous duty and also are not rated for all that high of amperage. Something like this would be better.

https://www.ebay.com/itm/NEW-HD-12-V...xVW3rF&vxp=mtr

I've burned out the coil on Ford solenoids by leaving them on all the time.

[Tedd]

Originally Posted by somewhereinusa

Ford starter solenoids are not rated for continuous duty and also are not rated for all that high of amperage. Something like this would be better.

https://www.ebay.com/itm/NEW-HD-12-V...xVW3rF&vxp=mtr

I've burned out the coil on Ford solenoids by leaving them on all the time.

I just put a momentary switch on the dash to trigger the solenoid.

[cadillackid]

I concur that ford solenoids are not continuous duty.. i used one once on a hotrod to run the 2 radiator fans that were 30 amps each and found that on a really hot day where the fans stayed on for an hour.. yeah I ended up alongside the road when the solenoid burnt out!..
-Christopher

[Jules083]

I know you end up converting from 12 to 120 to 12, but why not just run a power inverter off the bus battery when the motor is running, then use that to power your 'camper' side of the electrical system, including the charger that will charge the deep cell.

I used this one in my cargo trailer conversion I did a while ago, planning on doing something similar for the bus.



https://www.amazon.com/PowerMax-PM3-...attery+charger

[Ronnie]

Why would deep cycle batteries not be able to be fully charged by the bus alternator? Do they need a higher voltage for charging then the starting batteries? Assuming a high output alternator and battery isolater, diode type, and welding cable.

[Twigg]

Originally Posted by Ronnie

Why would deep cycle batteries not be able to be fully charged by the bus alternator? Do they need a higher voltage for charging then the starting batteries? Assuming a high output alternator and battery isolater, diode type, and welding cable.

Yes.

Flooded lead/acid batteries of the type used for "house" batteries, require a bulk charge rate of 14.8V (depending on temp) to fully charge, at a fairly high amperage.

Most vehicle alternators are regulated at 14.2-14.4V, and few have the output power to get the job done.

You'll charge them, but rarely fully charge them.

[Ronnie]

Thanks. I will try charging my house batteries from "shore" power and see if that helps. I have optima batteries and they always seem a bit lower then I would expect. Also have optima starting batteries. This is in my current camper.

The bus needs complete renovation, and thinking of solar on it for battery charging. It has 6 batteries for "house" currently.

[Twigg]

Originally Posted by Ronnie

Thanks. I will try charging my house batteries from "shore" power and see if that helps. I have optima batteries and they always seem a bit lower then I would expect. Also have optima starting batteries. This is in my current camper.

The bus needs complete renovation, and thinking of solar on it for battery charging. It has 6 batteries for "house" currently.

Read this:

https://handybobsolar.wordpress.com/

Bob is a little dogmatic, but his articles on battery charging, and chargers, is legendary (and most RV builders hate him because of it).

The point is, even charging from solar won't fully charge the batteries unless the charger can hit 14.8V (up to 15.3V depending on temperature). Even high-end RVs are guilty of only ever charging batteries to 75% because the chargers are wrongly specified, or set up too conservatively.

He's excellent on solar in RVs too, although some will quibble with his advice on charge controllers.

Anyway, you can never have too much info.

[Ronnie]

ok, read it just a bit and looks like that will answer a lot for me. Will look the site over better in the next few days. Thanks for the link.