Horton Ambulance Battery Question

MESDA6

Member
Jun 2, 2010
920
Central IL and PHX
We have a 1992 Horton Ambulance (Ford E350) that is used as a Command Post, an equipment hauler, and a place to get EM personnel out of the weather on scene when necessary. The unit only sees extended use a few times a year, and otherwise sits, plugged-in using the on-board Kussmaul unit.


This unit was manufactured so that the Kussmaul charges only the engine starting battery. The 2nd battery seems to operate items such as tail lights, turn signals, some other lights and accessories, etc. The problem is that the 2nd battery rarely gets up to full charge since the alternator is the only way to charge it, and even when it does, starting the unit and running it on short trips once or twice a month is not enough to keep the battery at full duty. (Battery - Optima Yellow Top tests good and was installed within the last year. it simply seems to be a matter of not enough use.)


Given the age of the unit, we think it's easier to stick a battery tender on the 2nd battery and just add a 2nd extension cord to be plugged in, instead of trying to do some re-wiring or changing to a dual battery Kussmaul. I have yet to find the Kussmaul charger. It's buried within the vehicle behind a panel somewhere, not in a compartment.


Is there any reason not to add a battery tender for the 2nd battery? I figured someone here (maybe John?) has experience with Horton units of this vintage and can relate any experience with them. Thanks.
 

fordtruck661

Member
Jul 31, 2011
96
CT
The battery's are not in parallel? I have never really looked at the way they are hooked up in my dept. Horton ambulance.
 

MESDA6

Member
Jun 2, 2010
920
Central IL and PHX
fordtruck661 said:
The battery's are not in parallel? I have never really looked at the way they are hooked up in my dept. Horton ambulance.

Doesn't seem to be in parallel. The battery cutoff is a simple Off/On, not a multiple battery switch like I've had on other ambulances.


We received this unit after it was owned by a fire department and then a private individual. It's entirely possible that the original hookup was changed somewhere along the way which is one of the reasons for my post. I'm hoping that someone who has worked on Horton units of that era would know what the normal configuration was.


I will get back in there this week and make a diagram of the cables to figure out if maybe the original setup was changed.
 

MESDA6

Member
Jun 2, 2010
920
Central IL and PHX
firefighter_2000 said:
Does it have an isolator anywhere? Maybe it's wired backwards?

I fished around a little more today and did find a positive cable running between the two batteries (buried in a wire loom) that wasn't obvious without fishing for it and tracing it out, so it does look like there is a parallel connection. Having found that. I'm betting on a bad cable or corroded connection since that battery should be charging in conjunction with the other one.


I had a PM from another member also advising to look for an isolator, but I haven't found one.


I'm going to clean all of the battery connections and throw a meter on them with and without the Kussmaul plugged in and see what I come up with. I see enough surface rust on some of the hardware to think that corrosion could really be the issue. I just need to wait for a warmer day next week to dig into it.


Thanks for the reply.
 

fordtruck661

Member
Jul 31, 2011
96
CT
Start with cleaning the cables really well. and make sure the bolts are nice and tight when you put them back on.


Also take the battery's out and have them tested. You might just have a bad battery. If one does test bad change both of them.
 

MESDA6

Member
Jun 2, 2010
920
Central IL and PHX
fordtruck661 said:
Start with cleaning the cables really well. and make sure the bolts are nice and tight when you put them back on.

Also take the battery's out and have them tested. You might just have a bad battery. If one does test bad change both of them.

Batteries test good. I took the unit over to Interstate and had them both bench tested a couple months ago when I first noticed intermittent issues. Noticed the issue again recently when we used the unit for medical standby at Football Games. Might be time for some new hardware and cables if cleaning doesn't help or if they are just too corroded when I get into them.
 

HILO

Member
May 20, 2010
2,781
Grand Prairie Texas
There will be an isolator somewhere in the line. Follow the power wire from the alternator. It will probably be mounted in the engine bay, but can be mounted in the battery box. With any vehicle, the alternator will not start charging the battery (or batteries) until steady RPM is reached for a steady time. Typically 40mph for 10 miles will recharge the battery charge used to start the vehicle. A light duty diesel (F and E series Fords, 3500 GM and Dodge/Ram) with the idle/pto raised (parking brake engaged) for an hour will put the charge back into the main body battery. With a dual battery system, the alternator will charge the main battery, once the isolator detects the main battery is charged up, it diverts the voltage to the second battery. If there is not enough time and distance traveled, the second battery will not get charged up. It is possible, but uncommon for the STT/marker lights to be ran off the second battery, as the lighting is part of the factory set up and wire harness.


You should be able to get a trickle charger and plug it into the box in an outlet that is tied into the Kussmal plug. I've had good luck with a small solar panel tied to a trickle charger, but that requires the vehicle be outside in sunlight frequently.
 

RecElect

Member
Jan 26, 2011
331
Loveland, Colorado
check your isolation solenoid for sure, if you don't have one, ADD ONE. This will help maintain a good starting battery and a good aux battery. Then add one of these IN ADDITION to it:


BatteryLink™ Automatic Charging Relay - 12V/24V DC 120A - Blue Sea Systems


This will charge BOTH battery banks when plugged into the kussmaul automatically, no trickle charger needed. They are wicked easy to hook up and cost about the same as another GOOD charger. We have added this solution to many of the ambulances in our area and it fixes this exact issue.


NOW, this unit technically can act as an isolator solenoid as well, BUT what we have found that when the vehicle is at idle with all the lights on, the battery voltage will still drop below 12.7 volts which makes this auto combiner shut off. If this were to happen, you truck would be running but not be charging your aux battery bank. SO we just leave the standard combiner solenoid in as a fail safe.


I can't tell you how many ambulances we have had come through the shop with EITHER all battery banks tied together all the time (DUMB!!) Or they are isolated, BUT the shore power only charges a single bank. Our thought is we want a dedicated starting battery, so that the ambulance will always start, and a dedicated aux battery, so we can use a deep cycle battery to get better life.


Just last week we had a 2013 ambulance come through that had 2 aux batteries and 1 start battery. They were all tied together, and the aux batteries were STARTING batteries not deep cycle. When they would go to the er, shut off the truck, and open the back doors, they would drain ALL the batteries with all the interior lights being on. When they came back from delivering the patient, their truck would be dead and they would have to have a jump. This constant draining to dead is extremely harmful to starting batteries, and they were already shot even though the batteries were less than a year old. This was on an ambulance that runs all the time, and when it is in the station, it is plugged into shore. Now, it is all automatic, and if they do drain their aux batteries at the ER, they can still start the rig without a jump.


Hope this helps alittle...
 

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