Skip to main content ↑ ↓
Topic: Charging chassis battery (Read 2511 times) previous topic - next topic

Charging chassis battery

We recently bought our 2nd Foretravel and discovered we have a parasite draw on our chassis batteries. We tested for draw and it's not bad but enough to be a little hard start if setting for 2-3 weeks without starting.
I looked to see what is on market to charge the chassis batteries and discovered that the trick l start or amp l start b2b chargers are no longer being made.  I found from searching that a new one on market called House2Start is very similar to the b2b chargers not made anymore.
IMG_4091.png (448.2 KB)
The following is questions and answers from them...
Please help me to understand the voltages of h2s.
I have a 36' class A motorhome. It has 3 house batteries that are gel cell, the start or chassis batteries are 3 Optima's.
My inverter charges my house batteries and I usually am either plugged into shore power or moving location(alternater). Inverter is set to deliver 13.5 volts. Then goes into float mode.
I installed the h2s and removed jumper that makes in my case On at 13.1 volts. After being installed for 24 hours my house batteries are constantly 13.5 volts but the chassis batteries are reading 14.3 volts. For fear of voltage to high I removed both fuses and rechecked the chassis batteries now reading 13.3 volts.
 


Q.1) I don't understand how chassis batteries are reading more than what engine batteries are putting out?
 
A. I believe you meant "I don't understand how chassis batteries are reading more than what house batteries are putting out". If that is what you intended to write, here is my response:
 
The House2Start module has a power supply inside, the voltage from the house battery (say 13.5V) is increased to 17V. In turn, the 17V powers the battery charger, which produces the smart charging algorithm. This is what makes House2Start different than all other products on the market, and allows H2S to work with any battery chemistry for the house supply.
 
 

Q. 2) When chassis batteries reach 14.4 volts charging would they had gone into float mode? If so would they go back into charge mode when parasitic draw brings them down to 13.5 volts?
 
A. House2Start stays in absorption mode until the output current decreases to 300~400 mA. During absorption mode the output will be 14~14.5V depending on the current and the temperature. At 77F and 300 mA, immediately before the charger switches from absorption to float, the output voltage will be 14.5V.
 
If you just installed House2Start, it will could take several days for the current to taper below 300mA and the LED to switch from BLUE to GREEN. If there is large parasitic load on the chassis, the time can be longer. A Class C with single starter battery, say a Winnebago Navion, they usually take a day or two (24-36 hours) for the LED to go GREEN. So your rig with 3 starter batteries, probably 3 times longer, 3-6 days as an estimate.
 
If the parasitic load on the chassis electronics is greater than 300 mA, then House2Start module will never switch from absorption to float, and could overcharge the batteries. However, if you measured 14.4V output, then the current is likely close to 300 mA, it only gets up to 14.4V when the current is almost down to 300 mA. It is around 1Amp at 14V.
 
Do you have a current clamp meter? if so, then you could disable H2S & measure the parasitic current draw from your 3x starter battery bank. Be sure to measure when the doors shut, interior lights off, engine off for at least 30 mins, etc, to obtain accurate background reading. If the current is over 300 mA then let me know and we can work out a solution.
 
 
 
Q. I am going to move jumper tomorrow to the next setting of On at 13.4 volts to see what happens, but the default setting of greater than 13.6 never happens in my case because of inverter settings.
 
A. The jumper setting does not affect the absorption / float behavior. The jumper only changes the turn on and off voltages for the charger. Once the charger is on (LED is green or blue), then the output voltage and current is based on the battery voltage and willingness to accept current. Based on what you've told me so far, "B" is what you want.
 


I really appreciate you clearing up my questions...or if it's installer error! LOL.
Oh and the solenoid to the right if battery isolater is on a switch so to start chassis batteries in event they are to low to start on their own.

Upon checking my parasitic draw I have 72mA of draw, I have not had time to remove fuses to find the draw yet.
IMG_4089.jpg (364.64 KB)

We have a 2002 U295 with the 400hp ISL, since Foretravel had such a clean install of battery isolater and boost solenoid at foot of bed in the engine compartment I mounted the H2S on a steel plate and fused on both the house battery side and also the chassis battery side with 3A fuses. The H2S is internally fused with a 3.5A fuse.
 Since the main cables from house and chassis come into solenoid then run to isolater I chose that location to run wires from H2S charger.
The plate everything in this location is mounted to is grounded by large steel strips to chassis.
IMG_4082.jpg (409.43 KB)
IMG_4086.jpg (438.99 KB)

After a day of charging with the H2S my chassis batteries were at 12.7 volts
IMG_4090.jpg (400.88 KB)
Since the H2S module hadn't gone into float or green light I emailed Brad and he confirmed that I should continue charging the chassis batteries. After another day of charging module went into float mode.

One thing I am very impressed with is Brad is truly quick to respond to an email, which says a lot in this day and time of customer service!

Re: Charging chassis battery

Reply #1 –
If your rig has the diode isolator the house battery system does not charge the chassis batteries automatically. The boost switch should  be a maintained switch. Turn it on the battery banks will be tied and the chassis batteries will then be charged by the house battery system. Be aware that when disconnected from power, the loads will be taking power off both banks until this switch is turned off. Be sure to turn it off when not plugged in or running the generator.

Re: Charging chassis battery

Reply #2 –
Quote from: Dennis H –
If your rig has the diode isolator the house battery system does not charge the chassis batteries automatically. The boost switch should  be a maintained switch. Turn it on the battery banks will be tied and the chassis batteries will then be charged by the house battery system.

Looking at the House2Start website, they show you how to wire it across the isolator.  Doing so allows it to charge the chassis batteries when one has shore, generator, or solar connected that can charge the house batteries.  In this aspect, it's the same as the old Trik-L-Start and Amp-L-Start devices (H2S appears to be a little more sophisticated in its charging profile, though.)

The boost switch should not be used to keep the house batteries charged.  Original solenoids weren't constant-duty, and even with a swap-out, if one loses shore power one risks draining both battery banks. 

Re: Charging chassis battery

Reply #3 –
Hi Everyone,
This Brad, owner of House2Start. I joined the forum because Klb70 sent me an email mentioning the post. I am happy to answer any questions about install or use. Unfortunately I am not very familiar with the layout of your rigs, but can help as much as possible. If you have special setups, like isolators, dc-dc chargers, etc I can provide suggestions for a smooth install.

House2Start goal is similar to Trik-L-Start, to use excess house battery to keep the starter battery charged. However House2Start is a proper battery charger, with multi-stage charging, temperature compensation, etc. It works with either lithium or lead acid (wet cell, agm, etc) house inputs.

And in response to other comments, I agree that the 'boost' feature should not be used when the RV is parked/stored. Solar/shore charger maintains the house battery. And then House2Start maintains the starter (using the house power).

Re: Charging chassis battery

Reply #4 –
House2Start,

Thanks, and welcome to the ForeForum.

From the factory (i.e. unmodified by owner) a diode-based battery isolator is used.  So, if the goal is to find the easiest place to connect wire from house battery and from chassis battery to any "charge sharing device" is at the respective lugs on the isolator, since they are only a few inches apart.

Same electrically as running wires from the battery banks themselves.

Re: Charging chassis battery

Reply #5 –
Echoing Brett's welcome to Foreforums!

Re: Charging chassis battery

Reply #6 –
Putting a simple switch, or pulling a fuse is needed to keep start battery loads from being powered if you disconnect start battery cable from battery for any reason.

BTW glad to have this hot new product, house2start device.  See trademark was recently registered on 10-16-2024.

Re: Charging chassis battery

Reply #8 –
Appreciate all the welcome notes and comments. Here are my responses:

Yes installing at the isolator is a great spot, due to convenience as mentioned by wolfe10.

Barry & Cindy: Yes a switch or removable fuse is recommended to allow convenient disabling of House2Start for when the starter battery is disconnected (maintenance, winter storage, etc). If H2S is not disabled then it will try to power the chassis electronics even if the starter battery is removed.

If the rig has a DC-DC aka B2B (battery to battery charger), like a Victron Orion, then a DPDT relay or similar device should be added so that when the engine is off, House2Start is active and DCDC is disabled, and if the engine is on, House2Start is disabled and DCDC is enabled ('either or').

If the rig has shore or solar to keep the house charged, then House2Start will maintain the starter battery, hopefully eliminating the need to 'charge the batteries' per the owner's manual.

House2Start engineering was done last year and the product officially launched Nov 2024. The first sell was to a random gentleman who found found our website when looking for TRIK-L-START -- bless him for giving us a chance.

-brad

Re: Charging chassis battery

Reply #9 –
Michelle and Steve photo. TriklStart on 2003 Foretavel . 

Re: Charging chassis battery

Reply #10 –
Hey Brad, thanks for all the detailed info! I've got a couple questions about an install with an Orion.

If I wire the Orion to trigger on via an ignition wire instead of using the smart alternator detection feature, is it still necessary to use a relay?

Can you provide an example diagram of how to wire the DPDT relay you mentioned?

Just ordered your unit yesterday and wanting to make sure I get it installed correctly.

Re: Charging chassis battery

Reply #11 –
If someone orders one of these, an install video would be appreciated!
 

Re: Charging chassis battery

Reply #12 –
Hi Clay,
You asked about how to install House2Start with an Orion DCDC (starter -> house) charger.
The best way is to use a relay so that only the Orion or H2S is active at any given time. This ensures there isn't any funny interactions between the two chargers.

You can get a "DPDT" type relay, also called "2 Form C" and wire House2Start and Orion as shown in the first image.
One relay option is the Omron LY2N-DC12 or the many knock offs that can be found on amazon/ebay. This relay has 3/16" spades that mate to 3/16" quick connect terminals. 3/16 is not the common size, that is 1/4" wide. Search for "3/16 quick disconnect crimp".
Another relay option is J1512CT12VDC.9D or J1512CF12VDC.9D. These will be a hard to find on amazon/ebay, but Digikey carries them. These relays have 0.25" spades.

Another approach, use a relay for the House2Start yellow wire, but the Orion 'H' terminal is connected directly to IGN/D+ (see second image, "b) H-pin wiring" for Orion on/off). This approach requires a relay with just one switch inside ("1 Form C"), these can be easier to find. A standard 12V 5-pin automotive relay would work here. Must be a 5pin, the 4pin will not work. Wire H2S as shown in figure image. If H2S and Orion are not located near each other, then this approach might be easier to wire.